Wireless Network Engineering Software
Aster Model Calibration
Technical Note
TN_056 (November 2021)
Aster Model Calibration
Release: TN_056 (November 2021)
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Aster Model Calibration
Table of Contents
TN_056
Table of Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1
Collecting CW Measurement Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.1
1.1.1
1.1.2
Before You Start. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Geographic Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Measurement Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
1.2
1.2.1
1.2.2
1.2.3
1.2.4
Guidelines for CW Measurement Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Selecting Base Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Planning the Survey Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Radio Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Additional Deliverable Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
1.3
1.3.1
1.3.2
1.3.3
1.3.4
1.3.5
Advanced CW Measurement Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Creating a CW Measurement Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Drawing a CW Measurement Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Merging Measurement Paths for a Same Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Smoothing Measurements to Reduce the Fading Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Calculating Best Servers Along a CW Measurement Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
1.3.5.1
1.3.5.2
1.3.5.3
1.3.5.4
1.3.5.5
1.3.5.6
2
Adding Transmitters to a CW Measurement Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Selecting the Propagation Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Setting the Display to Best Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Calculating Signal Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Displaying Statistics Over a Measurement Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Displaying Statistics Over Several Measurement Paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Calibration Preparation in Atoll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1
2.1.1
2.1.2
Creating an Atoll Calibration Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Setting Coordinates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Importing Geo Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
2.2
2.2.1
2.2.2
2.2.3
Importing CW Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Importing a CW Measurement Path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Importing Several CW Measurement Paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Creating a CW Measurement Import Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
2.3
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
Defining the Display of CW Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Defining the Display Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Using the Actions Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Defining the Visibility Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Defining the Tip Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Adding CW Measurement Points to the Legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
2.4
Verifying Geographic Consistency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.5
2.5.1
2.5.2
Filtering Measurement Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Filtering on Clutter Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Signal and Distance Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
2.5.2.1
2.5.2.2
2.5.2.3
2.5.2.4
2.5.3
2.5.3.1
2.5.3.2
2.5.3.3
© 2021 Forsk. All Rights Reserved.
Typical Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Using Manual Filtering on CW Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Creating an Advanced Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Using the Filtering Assistant on CW Measurement Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Filtering by Geo Data Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Displaying CW Measurement Points by Signal Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Using the CW Measurement Analysis Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Deleting a Selection of Measurement Points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3
Aster Model Calibration
Table of Contents
2.5.3.4
2.5.3.5
2.6
Selecting Base Stations for Calibration and for Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3
Calibrating the Aster Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.1
Calibration Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.2
3.2.1
Initial Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Initial Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.2.1.1
3.2.1.2
3.2.1.3
3.2.1.4
3.2.1.5
Initial Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Analysing Aster’s Performance from Atoll. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Analysing Aster Performance by Using the Analysis Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.4
3.4.1
3.4.2
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Creating a Calibration Copy of Aster. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Calibrating an Aster Instance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.4.3
3.4.3.1
3.4.4
3.4.5
3.5
4
Configuration Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Indoor Calculation Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Clutter and Geo Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Ray Tracing Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Advanced Calibration Parameters (Inputs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.3
3.3.1
3.3.2
3.4.2.1
3.4.2.2
3.4.2.3
4
Using Filtering Zones on CW Measurement Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Filtering by Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Advanced Calibration Parameters (Inputs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Calibration Algorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Calibration Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Verifying Calibration Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Calibration Results Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Manual Calibration Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Committing Calibrated Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Survey Site Form. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
© 2021 Forsk. All Rights Reserved.
Aster Model Calibration
Introduction
TN_056
Introduction
Aster is a high-performance propagation model for Atoll that supports macro, micro, and small cell urban
propagation scenarios. Aster also includes a dedicated mmWave propagation model for 5G frequencies above
6GHz. Aster is based on advanced ray-tracing propagation techniques and combines high accuracy with superior
calculation speed.
This Aster Model Calibration technical note is intended for project managers or anyone else responsible for
calibrating the Aster standard or mmWave propagation models using continuous wave (CW) measurements. The
purpose of this technical note is to provide guide you through the calibration process for both types of models.

For information about working with Atoll, see the Atoll User Manual and the Atoll Technical Reference Guide.

For information about installing and configuring Atoll, see the Atoll Administrator Manual.

For a basic overview of the Aster propagation model and using it with Atoll projects, see the Aster User Manual.

For technical information about Aster calculations and formulas, see the Aster Technical Reference Guide.
The Aster Model Calibration follows the calibration process from planning the CW survey, to incorporating the CW
measurements into Atoll, to using the CW measurements to calibrate the model.
If this is the first time you are calibrating the Aster, it is recommended that you read through the entire Aster Model
Calibration technical note before starting your calibration project.
About Atoll
Atoll is a multi-technology wireless network design and optimisation platform that supports wireless operators
throughout the network lifecycle, from initial design to densification and optimisation. Atoll offers unique
capabilities of using both predictions and live network data throughout the network planning and optimisation
process.
Atoll includes integrated single RAN–multiple RAT network design capabilities for both 3GPP and 3GPP2 radio
access technologies including 5G NR, LTE, NB-IoT, UMTS, GSM, and CDMA. It provides operators and vendors with
a powerful framework for designing and optimising current and future integrated multi-technology networks.
Atoll supports the latest technology advances such as massive MIMO, 3D beamforming, and mmWave propagation
for the design and roll-out of 5G networks.
Atoll Microwave is a state-of-the-art point-to-point and point-to-multipoint backhaul planning and optimisation
software. It allows designing large microwave link networks, according to ITU recommendations, industry
standards, and operator guidelines.
Atoll’s integration and customisation features help operators smoothly streamline planning and optimisation
processes. Atoll supports a wide range of implementation scenarios, from standalone to enterprise-wide serverbased configurations. Atoll has become the industry standard for radio network planning and optimisation.
If you are interested in learning more about Atoll, please contact your Forsk representative to inquire about our
training solutions.
About Forsk
Forsk is an independent software company providing operators and vendors with wireless network design and
optimisation products. Atoll, Forsk’s flagship product, is the market-leading wireless network planning and
optimisation software on the market; it allows operators to streamline planning and optimisation activities by
combining predictions and live network data.
© 2021 Forsk. All Rights Reserved.
5
Aster Model Calibration
Introduction
With more than 9000 active licenses installed with 500+ customers in 140 countries, Atoll has become the industry
standard for wireless network design and optimisation.
Forsk distributes and supports Atoll directly from offices and technical support centres in France, USA, and China
as well as through a worldwide network of distributors and partners.
Getting Help
The online help system that is installed with Atoll is designed to give you quick access to the information you need
to use the product effectively. It contains the same material as the Atoll 3.4.0 User Manual.
You can browse the online help from the Contents view, the Index view, or you can use the built-in Search feature.
You can also download manuals from the Forsk web site at:
http://downloads.forsk.com
Printing Help Topics
You can print individual topics or chapters from the online help.
To print help topics or chapters:
1. In Atoll, click Help > Help Topics.
2. In the Contents tab, expand the table of contents.
3. Right-click the section or topic that you want to print and click Print. The Print Topics dialog box appears.
4. In the Print Topics dialog box, select what you want to print:

If you want to print a single topic, select Print the selected topic.

If you want to print an entire section, including all topics and sections in that section, select Print the
selected heading and all subtopics.
5. Click OK.
About Atoll Documentation
The following PDF manuals are available to customers with a valid maintenance contract for Atoll and Atoll
Microwave and can be downloaded from the Forsk web site at:
http://downloads.forsk.com/
To read PDF manuals, download Adobe Reader from the Adobe web site at:
http://get.adobe.com/reader/
Hardcopy manuals are also available. For more information, contact to your Forsk representative.
Contacting Technical Support
Forsk provides global technical support for its products and services. To contact the Forsk support team, visit the
Forsk web site at:
http://downloads.forsk.com
Alternatively, depending on your geographic location, contact one of the following support teams:
6
© 2021 Forsk. All Rights Reserved.
Aster Model Calibration
Introduction
TN_056
Forsk US
For North and Central America, contact the Forsk US support team:

Tel.: 1-888-GO-ATOLL (1-888-462-8655)

Fax: 1-312-674-4822

Email: support_us@forsk.com
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Forsk China
For Asia (except Japan), contact the Forsk China support team:

Tel: +86 20 8557 0016

Fax: +86 20 8553 8285

Email: atollsupport@forsk.com.cn
Opening Hours: Monday to Friday 9.00am to 5.30pm (GMT+08:00) Beijing, Chongqing, Hong Kong, Urumqi.
Forsk Head Office
For all other regions, contact the Forsk Head Office support team:

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
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7
Aster Model Calibration
Introduction
8
© 2021 Forsk. All Rights Reserved.
Aster Model Calibration
Chapter 1: Collecting CW Measurement Data
TN_056
1 Collecting CW Measurement Data
Continuous Wave (CW) measurements are measurements that are made in the field for a single transmitter at a
given frequency and are used to calibrate propagation models. CW measurements can be created in Atoll either by
importing measurements or general data samples (including Planet data) or by pasting measurement results
directly into the document.
When you import measurements, you can save the settings that were used during the import procedure in a
configuration that can be reused the next time you import similar measurements.
Atoll enables extensive management of CW measurements and provides features that allow you to update
geographical data, define additional fields, or define how the path will be displayed.
This section presents guidelines for planning a CW survey in order to get the most accurate and useful
measurements. Once you have made a CW survey and have collected the CW measurements, importing them into
Atoll and using them to calibrate an Aster propagation model is explained in "Calibration Preparation in Atoll" on
page 19.
Atoll offers other possibilities for working with CW measurements. For more information, see "Working with CW
Measurements" on page 55.
1.1 Before You Start
Before you make a CW survey, it is essential to properly prepare for it. This section describes the data you must have
before you start your CW survey:
1.1.1

"Geographic Data" on page 9

"Measurement Data" on page 10.
Geographic Data
Accurate geographic data is needed for realistic coverage predictions by Aster, but also for proper CW
measurement analysis and preparation in Atoll. Consider the following guidelines to ensure that your geographic
data is up to date:

Under a year for vector building data or fast changing cities.

Under two to three years for clutter height data.

Compare your geographic data with reality (current photos and satellite imagery).
If you perform a CW survey on an area for which you do not have up-to-date geographic data of sufficient quality,
you will not be able to use the CW measurements you have collected to calibrate the propagation model. In any case,
up-to-date geographic data will be later required to produce realistic results in coverage predictions.
The recommended types of geographic data for Aster are the following:

Raster geographic data: a DTM (Digital Terrain Model) layer and either (or both) the Clutter Classes and
Clutter Heights layer. These files must have a sufficiently high resolution to obtain high-quality and accurate
results for the prediction and calibration process.

Vector data (optional): two types of vector data are useful:

Building vectors, for refining the precision of the Aster height model

Road vectors, representing at least major roads, useful for verifying measurement survey routes.
© 2021 Forsk. All Rights Reserved.
9
Aster Model Calibration
Chapter 1: Collecting CW Measurement Data

Scanned maps: scanned maps are useful for verifying measurement survey routes in urban areas.
The recommended geo data resolutions for Aster are summarized in the following table:
2G/3G/4G
Urban
5G
Rural
< 6 GHz
> 24 GHz
DTM
(mandatory)
≤ 10 m
≤ 25 m
1-5m
1-5m
DLU
(mandatory)
≤ 10 m
with 15 classes minimum
≤ 25 m
with 15 classes minimum
1-5m
with 15 classes minimum
1-5m
with 15 classes minimum
Clutter
Heights
≤5m
if no 3D vectors
≤2m
if no 3D vectors
≤2m
if no 3D vectors
Building, bridges, and
vegetation
Building, bridges, and
Building, bridges, and
vegetationb
vegetationc
(optional)
3D Vectorsa
a. Building height data is can be in raster format, vector (TAB) format is recommended.
b. Vegetation data is not mandatory.
c. Vegetation data is recommended
1.1.2
Measurement Data
It is recommended to use CW measurements for Aster calibration: CW measurements are collected in the field for
a single transmitter using a single frequency, and provides the highest accuracy in the calibration process.
Drive test data can in theory be used (and is supported by Aster), but the resulting calibration process is impaired
due to the various limitations inherent to this kind of data:

Since drive test data are made on a real network, part of the measured signal is actually due to interference.

Using directional antennas implies that the propagation calculation strongly depends on the accuracy of
antenna patterns, and only the measurement points in the direction of the main beam are relevant.

Several frequencies are measured for drive test data, although propagation models are calibrated only for a
given base frequency.

The sampling rate of each measured station is low because a lot of stations are scanned at the same time.
Therefore, the Lee criterion cannot be fulfilled (see "Guidelines for CW Measurement Surveys" on page 11).

Only the signal from the best server is scanned and, therefore, the signal level is measured over only a short
distance from each transmitter. Therefore, the model will only be calibrated for coverage predictions and not
for the evaluation of interference.
Before planning and performing CW a measurement survey, you should consider the following points:
10

Determine the number of required propagation models depending on representative area types (micro-urban,
macro-urban, macro-suburban, rural, etc.), and on the number of frequency bands. You should calibrate one
propagation model for each "area type/frequency band" combination.

Select a representative area for each area type where the measurement survey campaigns will be performed.

For each area type, select at least 8 sites (6 for calibration and 2 for verification), which respect the conditions
described in "Guidelines for CW Measurement Surveys" on page 11.

For each selected site, define a survey route, which respects the conditions described in "Guidelines for CW
Measurement Surveys" on page 11.

Ensure that it will be possible to respect all other criteria described in "Guidelines for CW Measurement
Surveys" on page 11 when performing the measurement survey.
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1.2 Guidelines for CW Measurement Surveys
The quality of the calibrated propagation model is strongly dependent on the quality of the CW measurements. The
CW measurements, on which the calibration will be based, must be of good quality and the radio data must be
correct.
This section provides basic guidelines for planning a CW measurement survey. Keeping this information in mind
when you are planning the survey route will help guarantee high-quality measurements that can serve as input for
the Aster calibration project.
This section covers the following topics:
1.2.1

"Selecting Base Stations" on page 11

"Planning the Survey Routes" on page 11

"Radio Guidelines" on page 12

"Additional Deliverable Data" on page 13.
Selecting Base Stations
When selecting base stations that are to be used in the CW measurement survey, the following guidelines should
be respected:

A minimum of six to ten stations should be measured for each propagation model. The exact number of
stations depends on the environment (rural, urban, and so on), the expected accuracy, and the robustness of
the calibrated model.
+
1.2.2
To ensure redundancy in case the measurements of one or more stations must be
rejected, a minimum of 10 stations for each propagation model to be calibrated is
recommended.

The selected stations should have good RF clearance and should not be obstructed in any direction.

An omnidirectional antenna should be used.

The antennas on the measured stations should be representative of the full variation of antenna heights
(typically from 20 m to 50 m for macro cells) in the area covered by the survey. A histogram displaying the
antenna heights can be a useful tool in determining what antenna heights should be represented.

The terrain within a relevant radius around each selected station should be representative of the area covered
by the survey. For example, in a relatively flat region, all rural stations selected should be surrounded by
relatively flat terrain within a radius of 10 km; a single station surrounded by hilly terrain in an otherwise flat
area will not provide representative results.

If there is a variety of different types of clutter in the survey area (open, urban, suburban, dense urban, etc.),
there should be as equal a distribution as possible of the major clutter categories within a relevant radius of
each station.

There should be sufficient roads available to enable easy access with transmission equipment on all sides of
each station.
Planning the Survey Routes
When selecting survey routes to be used in the CW measurement survey, the following guidelines should be
respected:

Measurement surveys should be performed over a long enough distance to allow the noise floor of the
receiver to be reached. Typical distances for sub-6 GHz frequencies are:

Rural areas: approximately 10 km

Suburban areas: approximately 2 km
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
1.2.3
Urban areas: approximately 1 km

The measurement routes must be laid out so that they have equal numbers of samples near as well as far
from the station in all directions.

When planning the survey routes, any proposed routes should be presented for approval to the project
manager in the form of vector maps in a format that can be imported in Atoll.

The maps used to plan the survey routes should use the same projection system as the scanned maps in the
Atoll calibration project. This will allow you to validate the survey routes beforehand.

The GPS of the CW measurement equipment should be configured to match that of the mapping data.

If possible, before actually making the survey, you should try to ensure consistency between the coordinates
given by the GPS on the survey route with those used in Atoll by making a test drive without taking
measurements.
Radio Guidelines
When planning a CW measurement survey, the following radio guidelines should be considered:

The area to be covered by the CW measurement survey must be scanned before performing the drive test to
ensure that there is no interference.

It is possible to measure several frequencies simultaneously, under the condition that the measurement
equipment verifies the Lee criterion for the acquisition of the number of samples per frequency.

The frequency measured must be clean:


For GSM, there must be 3 contiguous unused channels (i.e., a clearance of 200 kHz on either side of the
measured signal).

For UMTS and CDMA2000, there must be one unused carrier. This can be verified by checking whether the
reception level is at zero when the transmitter is off.

For LTE, measurements must be on RS signal levels on a bearer and not the RSRP (the RSRP being a
measurement on a sub-carrier of 15kHz).

For 5G NR, measurements must be on SS-RSRP signal levels on a bearer and processed separately for sub
6GHz and mmWave bands.
The Lee criterion must be satisfied in terms of sampling rate to overcome the effects of fast fading.
At least 36 samples must be collected over a distance of 40 λ. But, because the required rate depends on the
highest speed the vehicle would travel during the survey, the vehicle speed must be adapted accordingly. The
following table provides a list of required rates corresponding to different vehicle speeds in order to respect
the Lee criterion for a frequency 900 MHz.
Highest Speed (Km/h)

12
Sampling Rate (samples per sec)
60
45
90
68
120
90
150
113
The measured signals over the distance of 40λ should be averaged, with the mean signal level (50th
percentile) being the one stored.

The maximum distance between 2 stored measurement points should be equal to one half the resolution of
the clutter file used. This is necessary to obtain a good representative sample of each clutter class.

At least 5,000 points per station must remain after averaging. A typical number of points per measured station
is between 10,000 and 20,000 points.
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1.2.4
Additional Deliverable Data
During the survey, certain types of information should be collected in addition to measurements. This additional
information will aid in interpreting the collected CW measurement data and will increase the overall quality of not
only the CW survey but of the subsequent calibration.
The following data should be collected during the survey:

Measurement data: The radio data collected should meet the following criteria:

The measurements to be imported should correspond to the average of the measured signals over the
distance of 40λ.


The maximum distance between 2 stored measurement points should be equal to one half the resolution
of the clutter class file used. This is necessary to obtain a good representative sample of each clutter class.

The survey should have at least 5,000 points per station. A typical number of points per measured station
is between 10,000 and 20,000 points.
A rooftop sketch: A rooftop sketch must be provided indicating the locations of:

The transmitting antenna

Any rooftop obstacles (including their relative location, distance from transmitter, and height)

Any nearby obstacles (for example, other buildings) within 400 m. of the transmitter (including their relative
location, distance from transmitter, height, and width)

Panoramic photographs: Panoramic photographs should be taken from each rooftop of each station starting
from north and turning clockwise. These photographs should show the surroundings in all directions. The
azimuth and station number should be recorded for each photograph.

Transmission data: The following data should be recorded for all stations:



Precise coordinates of each station measured during the CW survey

Antenna patterns, downtilt, azimuth (if the antenna is not perfectly omnidirectional), and antenna height

Transmission power, and transmission gain and losses
Reception data: The following data should be recorded for all stations:

Receiver height, receiver sensitivity, and reception gain and losses

The voltage standing wave ratio (VSWR) (should be < 1.5).
Vector maps: Vector maps of each survey route should be collected to be imported into the Atoll calibration
project prior to the measurement survey.
Each CW measurement file should be accompanied by a "Survey Site Form" indicating:

Details describing the station

The locations of any spurious measurements where the physical clutter data does not coincide with the
mapping data

Any useful information about incidents that may have occurred.
You can find an example of a survey site form in "Survey Site Form" on page 59.
1.3 Advanced CW Measurement Management
In addition to the CW measurement features described in previous sections, Atoll provides more advanced tools for
working with CW measurements. These are described in this chapter:

"Creating a CW Measurement Path" on page 14

"Drawing a CW Measurement Path" on page 15

"Merging Measurement Paths for a Same Transmitter" on page 15

"Smoothing Measurements to Reduce the Fading Effect" on page 15

"Calculating Best Servers Along a CW Measurement Path" on page 16.
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Chapter 1: Collecting CW Measurement Data
1.3.1
Creating a CW Measurement Path
In Atoll, you can import CW measurements as described "Importing a CW Measurement Path" on page 21 if they are
in plain text or comma-separated value (CSV) format. However, if the data are stored in tabular format in, for
example, a spreadsheet or word-processing document, you can import them by copying and pasting them directly
into Atoll.
To create a CW measurement path:
1. In the Network explorer, right-click the CW Measurements folder and select New from the context menu. The
New CW Measurement Path window opens.
Figure 1.1: The New CW Measurement Path dialogue
2. Enter a Name for the CW measurement path.
3. Under Reference Transmitter, select the Transmitter with which the CW measurements were made and select
the Frequency.
4. Under Receiver, enter the Height of the receiver, the Gain, and the Losses.
5. Under Measurements, define the Unit used for the CW measurements.
6. If the Coordinates used for the CW measurement data are different than the one displayed, click the Browse
button ( ) and select the coordinate system used.
†
CW measurements are usually made using WGS84. By default the coordinate
system displayed in the coordinates field is the display system used in the
document. If the CW measurements were made using WGS84, be sure to select
WGS84, a geographic system as indicated by the globe symbol (
).
7. From the document with the CW measurements, select the X and Y coordinates and CW measurements to be
imported and copy them.
8. In the New CW Measurement Path dialogue, click the Paste button.
9. Click OK.
Once you have created the CW measurement path, you can modify the values of the path in the table. You can open
the CW measurement table by right-clicking it in the CW Measurements folder on the Network tab of the explorer
window and selecting Open Table from the context menu.
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1.3.2
Drawing a CW Measurement Path
When you have created or imported a CW measurement path, you can use the mouse to add points to it. You can
either add the CW measurement points one by one, or you can draw a path segment with the points separated by a
defined distance.
To add points to a CW measurement path:
1. In the Network explorer, expand the CW Measurements folder and the folder of the reference transmitter.
2. Right-click the CW measurement path to which you want to add points and select Add > Points from the
context menu. The pointer changes ( ).
3. Click the map at each location where you want to add a CW measurement point.
4. When you have finished, press ESC or double-click.
To add a path segment to a CW measurement path:
1. In the Network explorer, expand the CW Measurements folder and the folder of the reference transmitter.
2. Right-click the CW measurement path to which you want to add points and select Add > Path from the context
menu. The Path Creation dialogue appears.
3. Enter the Step between each point and click OK. The pointer changes (
).
4. Draw the path of the path segment by clicking on the map to draw the starting point and each time the path
segment changes direction.
5. When you have finished, press ESC or double-click.
1.3.3
Merging Measurement Paths for a Same Transmitter
In the case several measurement paths refer to the same transmitter, it might be useful to merge all the data in a
unique table so that the filtering wizard may be used on it.
To merge several measurement paths of a same transmitter:
1. In the Network explorer, expand the CW Measurements folder.
2. Right-click the folder of the reference transmitter for which you want to merge the referring paths and select
Merge Measurement paths from the context menu.
3. Choose if you want to merge all the considered paths or only a part of them.
4. Click OK. The selected CW measurement paths will be merged in a unique table.
1.3.4
Smoothing Measurements to Reduce the Fading Effect
When the fading effect is not limited by the measurement equipment itself, you can smooth the measured signal
strength by averaging them during the calibration pre-process over a sliding window with a view to minimise the
errors and standard deviations. In other words, you can define the width of a sliding window within which, for each
measured point, the measured data is arithmetically averaged.
This part of the calibration pre-process has to be done before the data filtering described in "Filtering Measurement
Data" on page 29.
To smooth the values of an existing CW measurement path:
1. In the Network explorer, expand the CW Measurements folder and the reference transmitter folder.
2. Right-click the CW measurement path and select Smoothing > Smooth Measurements from the context
menu. The Measurement Smoothing window opens (see Figure 1.2).
© 2021 Forsk. All Rights Reserved.
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Chapter 1: Collecting CW Measurement Data
Figure 1.2: Measurement Smoothing Window
3. Enter the width of the smoothing window (in meters) and click OK. This parameter defines the number of
samples to be considered when averaging the path data.
In the path table, the smoothed values overwrite the initial ones in the M column. The initial measurement data
are reported in new column called (M (Initial)).
+
1.3.5
You can restore the initial values in any CW measurement path by selecting
Smoothing > Restore Initial Values.
Calculating Best Servers Along a CW Measurement Path
Under certain circumstances, you might need to calculate which is the best server along the CW measurement path.
This is particularly the case along, for example, rail lines using radio technology for communication. Atoll enables
you to approximate a best server coverage prediction by adding one transmitter to the CW measurement path of
another one and calculating signal levels.
The process consists of the following steps:
1. Adding transmitters to a CW measurement path: The first step is to add additional transmitters to the CW
measurement path along which you want to calculate best servers. For information, see "Adding Transmitters
to a CW Measurement Path" on page 16.
2. Selecting the propagation model for the CW measurement path: You must select the propagation model to
be used to calculate signal levels. For information, see "Selecting the Propagation Model" on page 16.
3. Defining the CW measurement path display: You must set the display of the CW measurement path in order
to display the measurement points by best server. For information, see "Setting the Display to Best Server" on
page 17.
4. Calculating signal levels: Once you prepared the CW measurement path, you can calculate the signal levels.
For information, see "Calculating Signal Levels" on page 17.
5. Displaying comparative statistics between measurement and predicted values: After having calculated the
signal levels over measurement paths you can display global statistics or statistics per clutter class, per
transmitter or per measurement path. For information, see "Displaying Statistics Over a Measurement Path"
on page 17 and "Displaying Statistics Over Several Measurement Paths" on page 17.
1.3.5.1
Adding Transmitters to a CW Measurement Path
To add a transmitter to a CW measurement path:
1. In the Network explorer, expand the CW Measurements folder and the folder of the reference transmitter along
whose CW measurement path you will calculate signal levels.
2. Right-click the CW measurement path and select Calculations > Add a Transmitter from the context menu.
The New Prediction dialogue appears.
3. Select the transmitter to add from the Transmitter list and click OK. The transmitter will be added to the CW
measurement path data table.
1.3.5.2
Selecting the Propagation Model
To add a transmitter to a CW measurement path:
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1. In the Network explorer, expand the CW Measurements folder and the folder of the reference transmitter along
whose CW measurement path you will calculate signal levels.
2. Right-click the CW measurement path and select Properties from the context menu. The Properties window
opens.
3. On the Propagation tab of the Properties window, select the Propagation Model.
4. Click OK.
1.3.5.3
Setting the Display to Best Server
You must set the display properties of the CW measurement path to discrete values by best server. For information
on changing object display properties, see the Atoll User Manual.
1.3.5.4
Calculating Signal Levels
Atoll calculates signal levels, updating the values in the data table for that CW measurement path and updating the
map according to the settings selected in "Setting the Display to Best Server" on page 17.
To calculate the signal levels:
1. In the Network explorer, expand the CW Measurements folder and the reference transmitter.
2. Right-click the CW measurement path to which you want to calculate the signal levels and select
Calculations > Calculate Signal Levels from the context menu.
1.3.5.5
Displaying Statistics Over a Measurement Path
Assuming signal levels have been calculated along a measurement path, you can display the statistics between the
measurements and the predicted signal levels on a specific measurement path.
To display the statistics for a specific measurement path:
1. In the Network explorer, expand the CW Measurements folder and the reference transmitter.
2. Right-click the CW measurement path to which you want to display comparative statistics and select Display
statistics from the context menu. A window appears containing the measurement and predicted value
statistics over all the filtered points.
1.3.5.6
Displaying Statistics Over Several Measurement Paths
Once signal levels have been calculated along a measurement path, you can display the statistics between the
measurements and the predicted signal levels over several measurement paths.
To display the statistics for the entire set of the measurement paths:
1. In the Network explorer, right-click the CW Measurements folder and select Display statistics from the context
menu.
2. Select whether you want to display the statistics for all the considered paths or only a part of them. A window
appears containing the measurement and predicted value statistics over all the filtered points.
To display the statistics for a part or all the measurement paths referring to a unique transmitter:
1. In the Network explorer, expand the CW Measurements folder.
2. Right-click the folder of the reference transmitter to which you want to display comparative statistics and
select Display statistics from the context menu.
3. Select whether you want to display the statistics for all the considered paths or only a part of them. A window
appears containing the measurement and predicted value statistics over all the filtered points.
© 2021 Forsk. All Rights Reserved.
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Chapter 2: Calibration Preparation in Atoll
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2 Calibration Preparation in Atoll
Before you can begin the calibration process, you must ensure that you have properly prepared for the process. This
chapter explains the process of creating or selecting the project you will use to calibrate the model as well as
importing the CW measurements into Atoll.
The first step consists of creating an Atoll document with all of the network and geographical data necessary to
recreate the CW measurement survey area. When the Atoll document has been created with all the necessary data,
you can import the CW measurement data and filter them in order to ensure that only meaningful data is used for
calibration.
When you have imported the CW measurements, your next step is to verify that the CW measurement data you have
just imported correspond to the geographical data of the Atoll document you will be using for calibration. This step
is very important because Atoll will use the geographical data of the document to evaluate the CW measurement
points. If the points are not properly situated on the map, Atoll will not be able to apply the correct geographical data,
especially clutter to each point. This is explained in "Verifying Geographic Consistency" on page 29.
In theory, the imported measurement values are supposed to be smoothed by the measurement equipment so that
they are not subject to any fading effect. In the case the fading effects occur on the measured samples, and in order
to improve the input data for calibration, you can average them by defining a smoothing sliding window as explained
in "Smoothing Measurements to Reduce the Fading Effect" on page 57.
Once you are satisfied that the positions of the CW measurement points correspond properly to the geographical
data in the Atoll document, you can filter out the CW measurement data that, for various reasons, can not be used
in the calibration process. This is explained in "Filtering Measurement Data" on page 29.
2.1 Creating an Atoll Calibration Document
When you set up the calibration project, you must first create or select an Atoll document with the network and
geographical data necessary to recreate the CW measurement data survey area. Creating the Atoll document is
explained in "Creating an Atoll Calibration Document" on page 19. If you already have an Atoll document that you
will use to calibrate the propagation model, you can continue directly with "Importing CW Measurements" on
page 20.
You can create the Atoll calibration document in one of two ways:

From a template: You can create a new Atoll document from a template. Atoll is delivered with a template for
each technology you will be planning for. For information on creating a document from a template, see the
User Manual.

From an existing document: If you already have an existing document covering the CW measurement survey
area, you can make a copy of it to use in the calibration process so that you can calibrate the propagation
model without making changes to the original document. For information on making a copy of an existing
document, see the User Manual.
Once you have created the calibration document, you must set a few necessary parameters and import or create
the preliminary data. These steps are explained in the following sections:

"Setting Coordinates" on page 20

"Importing Geo Data" on page 20.
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Chapter 2: Calibration Preparation in Atoll
2.1.1
Setting Coordinates
In Atoll, you define the two coordinate systems for each Atoll document: the projection coordinate system and the
display coordinate system. By default, the same coordinate system is used for both.
The maps displayed in the workspace are referenced with the same projection system as the imported geographic
data files; thus, the projection system depends on the imported geographic file.
q
All imported raster geographic files must be use the same cartographic system. If
not, you must convert them to a single cartographic system.
For more information on the projection and display coordinate systems in Atoll, see the User Manual.
2.1.2
Importing Geo Data
The geographic data is an important part of an Atoll document when the document is going to be used for a
calibration project. Several different geographic data types are used in a calibration project:

Digital Terrain Model: The DTM describes the elevation of the ground over sea level and is indispensable in a
calibration project.

Clutter Classes: The clutter class geo data file describes land cover or land use. Either clutter classes or
clutter heights must be present in a calibration project.

Clutter Heights: Clutter height maps describe the altitude of clutter over the DTM with one altitude defined per
pixel. Clutter height maps can offer more precise information than defining an altitude per clutter class
because, in a clutter height file, it is possible to have different heights within a single clutter class.
q
Aster prioritises the height specified in vector data over DTM data.

Vector Maps: Maps with possible survey routes defined as vectors can be imported to verify the planned
survey routes against other maps.

Scanned Images: Scanned images are geographic data files which represent the actual physical
surroundings, for example, road maps or satellite images. They are used to provide a precise background for
other objects. Although they are not used in calculations, they can be used to verify the accuracy of proposed
survey routes.

WMS Raster-format Geo Data Files: Raster images from a Web Map Service (WMS) server. The image must
be in TIF format and be referenced in the document; it can not be embedded. You can use a WMS image to
add a precise background for other objects, or to add place names, or a map of roadways. WMS images are
not used in calculations.
For more information on any of the geographic data formats that can be used in Atoll, see the Atoll User Manual, and
the Atoll Technical Reference Guide.
For information on importing geographic data and understanding how Aster prioritises geographic data imported
into Atoll and into the model, see Chapter 2 of the Aster User Manual.
2.2 Importing CW Measurements
In Atoll, you can import CW measurement files in the form of ASCII text files (with tabs, commas, semi-colons, or
spaces as the separator), with DAT, TXT, and CSV extensions. For Atoll to be able to use the data in imported files,
the imported files must contain the following information:

20
The position of the CW measurement points. When you import the data, you must indicate which columns give
the abscissa and ordinate (X/Y coordinates) of each point.
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
The measured signal level at each point.
The imported files can also contain other information, such as point names and field characteristics, that can be
used to define the display of measurement points, for example, to filter points.
You can import a single CW measurement file or several CW measurement files at the same time. If you regularly
import CW measurement files of the same format, you can create an import configuration. The import configuration
contains information that defines the structure of the data in the CW measurement file. By using the import
configuration, you will not need to define the data structure each time you import a new CW measurement file.
In this section, the following are described:
2.2.1

"Importing a CW Measurement Path" on page 21

"Importing Several CW Measurement Paths" on page 23

"Creating a CW Measurement Import Configuration" on page 24

"Defining the Display of CW Measurements" on page 25.
Importing a CW Measurement Path
To import a CW measurement file:
1. In the Network explorer, right-click the CW Measurements and select Import from the context menu. The Open
dialogue appears.
2. Select the file or files you want to import and click Open. The Import of Measurement Files dialogue appears.
3. On the General tab:
a. Enter a Name for the CW measurement. By default, the CW measurement is given the name of the file being
imported.
b. Under Reference Transmitter, select the Transmitter with which the CW measurements were made, its
technology, and its transmitting Frequency during the measurement survey.
c. Under Receiver, enter the Height of the receiver, the Gain, and the Losses.
d. Under Measurement Conditions, define the Units used for the CW measurements.
e. If the Coordinates used for the CW measurement data are different than the one displayed, click Browse
(
) and select the coordinate system used.
†
CW measurements are usually made using WGS84. By default the coordinate
system displayed in the coordinates field is the display system used in the
document. If the CW measurements were made using WGS84, make sure that
WGS84 is selected. The WGS84 geographic system is indicated by the globe
symbol (
).
4. Click the Setup tab and, if any is available, select an Import configuration for the data structure of the imported
file.

If you select an import configuration, go to step 9.

If no import configuration is available, continue with step 5.
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Figure 2.1: The Setup tab of the Import of Measurement Files dialog box
q

When importing a CW measurement path file, existing configurations are
available in the Files of type list of the Open dialogue, sorted according to
their date of creation. After you have selected a file and clicked Open, Atoll
automatically proposes a configuration, if it recognises the extension. In case
several configurations are associated with an extension, Atoll chooses the
first configuration in the list.

The defined configurations are stored, by default, in the file "MeasImport.ini",
located in the directory where Atoll is installed. For more information on the
MeasImport.ini file, see the Administrator Manual.
5. Under File, on the Setup tab:
a. Enter the number of the 1st Measurement Row, select the data Separator, and select the Decimal Symbol
used in the file.
b. Click Setup to link file columns and internal Atoll fields. The CW Measurement Setup dialogue appears.
c. Select the columns in the imported file that give the X-Coordinates and the Y-Coordinates of each point in
the CW measurement path file.
q
You can also identify the columns containing the XY coordinates of each point in
the CW measurement path by selecting them from the Field row of the table on the
Setup tab.
d. In the Measurements box, select the field that contains the value of the measured signal for each defined
point.
e. Click OK to close the CW Measurement Setup dialogue.
f. If there is other data available in the file, in the table under File, define the Type for each additional column
of data.
6. Click Import. The CW measurement data is imported into the current Atoll document.
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2.2.2
Importing Several CW Measurement Paths
To import several CW measurement files:
1. In the Network explorer, right-click the CW Measurements folder and select Import from the context menu.
The Open dialogue appears.
2. Select the file or files you want to open.
+
You can select contiguous files by clicking the first file you want to import, pressing
SHIFT and clicking the last file you want to import. You can select non-contiguous
files by pressing CTRL and clicking each file you want to import.
3. Click Open. The Import of Measurement Files dialogue appears.
4. On the General tab:
a. Enter a Name for the CW measurement. By default, the CW measurement is given the name of the file being
imported.
b. Under Reference Transmitter, select the Transmitter with which the CW measurements were made, its
technology, and its transmitting Frequency during the measurement survey.
c. Under Receiver, enter the Height of the receiver, the Gain, and the Losses.
d. Under Measurements, define the Unit used for the CW measurements.
e. If the Coordinates used for the CW measurement data are different than the one displayed, click Browse
(
) and select the coordinate system used.
†
CW measurements are usually made using WGS84. By default the coordinate
system displayed in the coordinates field is the display system used in the
document. If the CW measurements were made using WGS84, be sure to select
WGS84, a geographic system as indicated by the globe symbol (
).
5. Click the Setup tab (see Figure 2.1). If you already have an import configuration defining the data structure of
the imported file or files, you can select it from the Configuration list on the Setup tab of the Import of
Measurement Files dialogue. If you do not have an import configuration, continue with step 5.
a. Under Configuration, select an import configuration from the Configuration list.
b. Continue with step 9.
q

When importing a CW measurement path file, existing configurations are
available in the Files of type list of the Open dialogue, sorted according to
their date of creation. After you have selected a file and clicked Open, Atoll
automatically proposes a configuration, if it recognises the extension. In case
several configurations are associated with an extension, Atoll chooses the
first configuration in the list.

The defined configurations are stored, by default, in the file "MeasImport.ini",
located in the directory where Atoll is installed. For more information on the
MeasImport.ini file, see the Administrator Manual.
6. Under File, on the Setup tab:
a. Enter the number of the 1st Measurement Row, select the data Separator, and select the Decimal Symbol
used in the file.
b. Click Setup to link file columns and internal Atoll fields. The CW Measurement Setup dialogue appears.
c. Select the columns in the imported file that give the X-Coordinates and the Y-Coordinates of each point in
the CW measurement path file.
+
© 2021 Forsk. All Rights Reserved.
You can also identify the columns containing the XY coordinates of each point in
the CW measurement path by selecting them from the Field row of the table on the
Setup tab.
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d. In the Measurements box, select the field that contains the value of the measured signal for each defined
point.
e. Click OK to close the CW Measurement Setup dialogue.
f. If there is other data available in the file, in the table under File, define the Type for each additional column
of data.
7. If you wish to save the definition of the data structure so that you can use it again, you can save it as an import
configuration:
a. On the Setup tab, under Configuration, click Save. The Configuration dialogue appears.
b. By default, Atoll saves the configuration in a special file called "MeasImport.ini" found in Atoll’s installation
folder. In case you cannot write into that folder, you can click Browse to choose a different location.
c. Enter a Configuration Name and an Extension of the files that this import configuration will describe (for
example, "*.csv").
d. Click OK.
Atoll will now select this import configuration automatically every time you import a drive test data path file
with the selected extension. If you import a file with the same structure but a different extension, you will
be able to select this import configuration from the Configuration list.
q

You do not have to complete the import procedure to save the import
configuration and have it available for future use.

When importing a CW measurement file, you can expand the MeasImport.ini
file by clicking the button ( ) in front of the file in the Setup part to display all
the available import configurations. When selecting the appropriate
configuration, the associations are automatically made in the table at the
bottom of the dialogue.

You can delete an existing import configuration by selecting the import
configuration under Setup and clicking the Delete button.
8. Once you have defined the import parameters, you can import the selected files:

When importing several files for the same transmitter: Click Import All. The CW measurement data are
imported into the current Atoll document.
q

When you click the Import All button, Atoll does not import files that do match the
currently selected import configuration. It displays an error message and continues
with the next file.
When importing several files for different transmitters:
i. Click Import. The CW measurement data are imported into the current Atoll document.
ii. Click the General tab to ensure that the information on the General tab, especially the Reference
Transmitter selected, reflect the current file being imported.
iii. If necessary, click the Setup tab and redefine the import configuration for the current file being imported.
iv. Click Import to import the current file.
v. Repeat these steps for each file being imported.
2.2.3
Creating a CW Measurement Import Configuration
If you regularly import CW measurement files of the same format, you can create an import configuration the first
time you import the CW measurement files. The import configuration contains information that defines the
structure of the data in the CW measurement file. By using the import configuration, you will not need to define the
data structure each time you import a new CW measurement file.
To create a CW measurement import configuration:
1. Click the Network tab in the explorer window.
2. Right-click the CW Measurements folder. The context menu appears.
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3. Select Import from the context menu. The Open dialogue appears.
4. Select the file or files you want to open.
5. Click Open. The Import of Measurement Files dialogue appears.
6. Click the Setup tab (see Figure 2.1).
7. Under File, on the Setup tab, define the data structure of the file or files you have selected:
a. Enter the number of the 1st Measurement Row, select the data Separator, and select the Decimal Symbol
used in the file.
b. Click Setup to link file columns and internal Atoll fields. The CW Measurement Setup dialogue appears.
c. Select the columns in the imported file that give the X-Coordinates and the Y-Coordinates of each point in
the CW measurement path file.
+
You can also identify the columns containing the XY coordinates of each point in
the CW measurement path by selecting them from the Field row of the table on the
Setup tab.
d. In the Measurements box, select the field that contains the value of the measured signal for each defined
point.
e. Click OK to close the CW Measurement Setup dialogue.
f. If there is other data available in the file, in the table under File, define the Type for each additional column
of data.
8. On the Setup tab, under Configuration, click Save. The Configuration dialogue appears.
a. By default, Atoll saves the configuration in a special file called "MeasImport.ini" found in Atoll’s installation
folder. In case you cannot write into that folder, you can click Browse to choose a different location.
b. Enter a Configuration Name and an Extension of the files that this import configuration will describe (for
example, "*.csv").
c. Click OK.
Atoll will now select this import configuration automatically every time you import a drive test data path file
with the selected extension. If you import a file with the same structure but a different extension, you will
be able to select this import configuration from the Configuration list.
q

You do not have to complete the import procedure to save the import
configuration and have it available for future use.

When importing a CW measurement file, you can expand the MeasImport.ini
file by clicking the Expand button ( ) in front of the file in the Setup part to
display all the available import configurations. When selecting the
appropriate configuration, the associations are automatically made in the
table at the bottom of the dialogue.

You can delete an existing import configuration by selecting the import
configuration under Setup and clicking the Delete button.

The defined configurations are stored, by default, in the file "MeasImport.ini",
located in the directory where Atoll is installed. For more information on the
MeasImport.ini file, see the Administrator Manual.
2.3 Defining the Display of CW Measurements
You can define how CW measurements are displayed in Atoll’s map window. CW measurements are organised in
folders according to their reference transmitter on the Network tab of the explorer window.
You can define the display of individual CW measurements but also set the same display parameters for all CW
measurements or for all CW measurements for the same reference transmitter.
To define the display of a CW measurement path:
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1. In the Network explorer, expand the CW Measurements folder and the folder of the reference transmitter.
2. Right-click the CW measurement whose display you want to define. The context menu appears.
3. Select Properties from the context menu. The Properties dialogue appears.
4. Select the Display tab. The following options are available:

"Defining the Display Type" on page 26

"Using the Actions Button" on page 27

"Defining the Visibility Scale" on page 27

"Defining the Tip Text" on page 28

"Adding CW Measurement Points to the Legend" on page 28.
5. Set the display parameters.
6. Click OK.
2.3.1
Defining the Display Type
Depending on the object selected, you can choose from the following display types: unique, discrete values, value
intervals, or advanced.
To change the display type:
1. Open the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"
on page 25.
To modify the appearance of the symbol:
a. Click the symbol in the table below. The Symbol Style dialogue appears.
b. Modify the symbol as desired.
c. Click OK to close the Symbol Style dialogue.
2. Select the display type from the Display Type list:

Unique: defines the same symbol for all CW measurement points.

Discrete values: defines the display of each CW measurement point according to the value of a selected
field. This display type can be used to distinguish CW measurement points by one characteristic. For
example, you could use this display type to distinguish CW measurement points by the clutter type they are
on, or by their reference transmitter.
i. Select the name of the Field by which you want to display the objects.
ii. You can click the Actions button to access the Actions menu. For information on the commands
available, see "Using the Actions Button" on page 27.

Value intervals: defines the display of each object according to set ranges of the value of a selected field.
This display type can be used, for example, to distinguish population density, signal strength, or the altitude
of sites.
i. Select the name of the Field by which you want to display the objects.
ii. Define the ranges directly in the table.
iii. You can click the Actions button to access the Actions menu. For information on the commands
available, see "Using the Actions Button" on page 27.

Advanced: allows you to display measurement points by more than one criterion at a time.

only available for transmitters; Atoll automatically assigns a colour to each transmitter, ensuring that each
transmitter has a different colour than the transmitters surrounding it.
i. Click the symbol in the table below. The Symbol Style dialogue appears.
ii. Modify the symbol as desired.
iii. Click OK to close the Symbol Style dialogue.
iv. You can click the Actions button to access the Actions menu. For information on the commands
available, see "Using the Actions Button" on page 27.
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2.3.2
Using the Actions Button
The Actions button on the Display tab of the Properties dialogue allows you to modify the display type as defined
in "Defining the Display Type" on page 26.
To access the Actions menu:
1. Open the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"
on page 25.
2. Click the Actions button. The Actions menu gives you access to the following commands:

Select all: Atoll selects all the values in the table.

Delete: Atoll removes selected value from the table.

Insert before: When the selected display type is value intervals, Atoll inserts a new threshold in the table
before the threshold selected in the table.

Insert after: When the selected display type is value intervals, Atoll inserts a new threshold in the table after
the threshold selected in the table.

Shading: Atoll opens the Shading dialogue. When "Value Intervals" is the selected display type, you select
Shading to define the number of value intervals and configure their colour. Enter the upper and lower limits
of the value in the First Break and Last Break boxes respectively, and enter a value in the Interval box.
Define the colour shading by choosing a Start Colour and an End Colour. The value intervals will be
determined by the set values and coloured by a shade going from the set start colour to the set end colour.
+
Predictions and CW measurements are shaded differently. Nevertheless, you can
obtain a similar colouring by excluding the last break of the CW path display. To do
this, select the ’Filter up to Last Break’ check box.
When "Discrete Values" is the selected display type, you select Shading to choose a Start Colour and an
End Colour.
2.3.3
Defining the Visibility Scale
You can define a visibility range for CW measurement points. A measurement point is visible only if the scale, as
displayed on the zoom toolbar, is within this range. This can be used to, for example, prevent the map from being
cluttered with symbols when you are at a certain scale.
Visibility ranges are taken into account for screen display, and for printing and previewing printing. They do not
affect which measurement points are considered during calculations.
To define the visibility range:
1. Access the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"
on page 25.
2. Enter a Visibility Scale minimum in the between 1: text box.
3. Enter a Visibility Scale maximum in the and 1: text box.
q
© 2021 Forsk. All Rights Reserved.
For most object types, you can also display object information in the form of a tool
tip that is only visible when you move the pointer over the object. This option has
the advantage of not filling the map window with text. For more information on tool
tips, see "Defining the Tip Text" on page 28.
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2.3.4
Defining the Tip Text
For most object types, such as sites and transmitters, you can display information about each object in the form of
a tool tip that is only visible when you move the pointer over the object. You can display information from every field
in that object type’s data table, including from fields that you add.
To define tip text for an object type:
1. Access the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"
on page 25.
2. Click Browse (
) beside the Tip Text box. The Field Selection dialogue appears.
3. Select the fields which you want to display in the label:
a. To select a field to be displayed in the label for the object type, select the field in the Available Fields list
and click
to move it to the Selected Fields list.
b. To remove a field from the list of Group these fields in this order, select the field in the Selected Fields list
and click
q
to remove it.
You can also display information about data objects in the form of a label that is
displayed with the object. Given the large number of CW measurement points in a
CW survey, defining labels that are always visible is not recommended.
Once you have defined the tool tips, you must activate the tool tip function before they appear.
To activate the tool tip function:

2.3.5
Click Display Tips (
) on the toolbar. Tool tips will now appear when the pointer is over the object.
Adding CW Measurement Points to the Legend
You can display the information defined by the display type (see "Defining the Display Type" on page 26) in your Atoll
document’s legend. Only visible objects appear in the Legend window. For information on displaying or hiding
objects, see the User Manual.
In Figure 2.2, on the Display tab of a signal level prediction, the intervals defined are:

Signal level >= -70red

-70 > Signal level >= -105shading from red to blue (9 intervals)

Signal level < -105not shown in the coverage.
The entries in the Legend column will appear in the Legend window.
Figure 2.2: Defined thresholds as they will appear in the Legend
With value intervals, you can enter information in the Legend column to be displayed on the legend. If there is no
information entered in this column, the maximum and minimum values are displayed instead.
1. Open the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"
on page 25.
2. Select the Add to legend check box. The defined display will appear on the legend.
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2.4 Verifying Geographic Consistency
You can quickly verify the correspondence between the CW measurements and the Atoll geo data by importing the
CW measurements and a set of vector files representing roads or a scanned map of the area and checking that the
CW measurement survey routes correspond with the geo data. You can also check whether the measurement path
starts or ends at approximately the location of the base station used for the CW measurements.
It is also important to check that the CW measurement survey routes used correspond to the planned survey routes
to ensure that the CW measurement points are evenly distributed around the station. In case measurement paths
do not exactly match the vector roads (due most of the time to inconsistencies between several coordinate
systems), you can move a set of points to the appropriate location.
To move measurement points to another location:
1. On the map, click any point to select it. To select more than one point, press CTRL as you click the other points.
To select a entire segment of points, press SHIFT as you click the other extremity of the segment.
2. Click and drag the set of points to the desired position. If you want to exactly put points on a vector line, drag
them to it until it is highlighted.
3. Release the points where you would like to place them. In the case of a vector which has to be matched, the
shape of the paths might be modified accordingly after the points have been released.
If the IDs of the CW measurement points do not reflect the order in which the measurements were collected, you
can check whether the station location is consistent with its relative measurement path by displaying measurement
points according to measurement levels, as shown in Figure 2.3.
Figure 2.3: Distribution of the Measured Signal Strength around a station
If panoramic photographs of the area surrounding the base station are available, you should verify that there are no
nearby obstacles disturbing propagation. If there is an obstacle close to the base station, you can filter out the
obstructed CW measurement data using an angle filter or remove the station from the set of CW measurement data
if the obstruction is too wide. For information on defining an angle filter, see "Filtering by Angle" on page 40.
2.5 Filtering Measurement Data
One of the most important steps in preparing CW measurement data for use in a calibration project is filtering the
measurement points. When you are filtering CW measurement data, the goal is to eliminate the points that are the
least representative of the survey area while retaining a number of points that is both representative and large
enough to provide statistically valid results.
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The filtering process is often, therefore, a series of trade-offs. Although you would normally consider filtering out
certain data if, for example, their values appear high or low, if filtering them all out leaves you with too small a
sample, you might consider leaving some of them in. By the same token, if filtering out the points on a clutter class
means that that clutter class will no longer be represented at all, you might consider leaving those points on the CW
survey path where they are best represented.
There are several reasons why you would not want to take certain measurement points into consideration:

The measurement points might appear potentially invalid, they might be in clutter classes that are of no
significance in terms of the propagation model to be calibrated, they may show extreme signal levels, they
might be too close to the transmitter, or they might suffer from too much diffraction.

The zones where the measurement points are located might be in an area where the results can not be
considered accurate (for example, any points coming from behind a directional antenna should not be used in
a calibration project).
If you wish, you can permanently delete the points you filter out. You can always re-import the original measurement
data if you want to add those points again. Or you can filter them out for the current calibration, but leave them in
the measurement data.
Filtering CW measurement data is made in several steps. Depending on the CW measurement data available and
the individual calibration project, it is possible that not all steps will be necessary, however, the basic steps are:
1. Filtering by clutter class: The first step in filtering CW measurement data is to filter out points by clutter class.
Typically you will want to remove all points on clutter classes that are represented by less than 5% of the total
measurement points in the CW survey. For information on filtering by clutter class, see "Filtering on Clutter
Classes" on page 30.
2. Filtering by signal strength and distance: The next step is to filter out points that lay outside of a defined range
of signals and that are either too close to or too far from the reference transmitter. For information on filtering
by distance and signal strength, see "Signal and Distance Filtering" on page 32.
3. Removing sections that are not representative: The final step in filtering CW measurement data consists of
examining the CW measurement data to remove points that are affected by obstruction or that are potentially
invalid, i.e., measurement points affected by diffraction or measurement points that are too high or too low.
For information on filtering by distance and signal strength, see "Filtering by Geo Data Conditions" on page 36.
†
2.5.1
If you set filters on the CW Measurements folder, any filters set on individual CW
measurement paths will be erased.
Filtering on Clutter Classes
The first step in filtering measurement points is to filter out the points by clutter class. If only a few measurement
paths have points on a given clutter class or only a few points are located on this class, then the clutter class should
be filtered out. There are not enough points to give a statistically good sampling of the conditions for that clutter
class. In other words, keeping these points will likely cause the clutter class to be incorrectly calibrated, leading to
incorrect coverage prediction results when the calibrated propagation model is used. Therefore, it is highly
recommended not to take irrelevant clutter classes into account during the calibration process, and to deduce the
clutter losses afterwards using similar clutter classes and typical values.
The rule of thumb is 5%: if only 5% of the points on a measurement plan are on a given clutter class, the points for
that clutter class should be removed. However, this should just be used as a guideline. Under certain circumstances,
for example, if that clutter class is not well represented in any survey path, you might want to keep them. You can
always try calibrating the propagation model once with the clutter class and once without and comparing the
results.
You should also remove the measurement points located on clutter classes that are not at all representative of the
survey area. For example, there may be a park along the survey route that is classified as "Forest" in terms of clutter
class. If the area itself is mostly dense urban, keeping the points in the forest clutter class will lead to inaccurate
results.
You can view the point distribution statistics for all CW measurements, or all CW measurements for a single
reference transmitter, or for a single CW measurement path. Figure 2.4 shows the distribution of statistics for all
CW measurements.
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†
Before the point distribution statistics can be displayed, you must calculate signal
levels on the CW measurement points. You can calculate signal levels by rightclicking the CW Measurements folder and selecting Calculations > Calculate
Signal Levels from the context menu.
To display the point distribution statistics for CW measurements:
1. In the Network explorer, right-click the CW measurements whose statistics you wish to display:

All CW measurements: Right-click the CW Measurements folder.

All CW measurements for a single reference transmitter: Expand the CW Measurements folder and rightclick the folder of the reference transmitter.

A single CW measurement path: Expand the CW Measurements folder and the folder of the reference
transmitter. Then, right-click the CW measurement path.
The context menu appears.
2. Select Display Statistics from the context menu.
If more than one CW measurement path is selected, a dialogue appears where you can choose the statistics
of which CW measurement paths you want to display. Select or clear the check boxes to choose the CW
measurement paths and click OK.
The statistics dialogue appears, with the distribution of the selected CW measurements (see Figure 2.4).
3. Take note of the clutter classes that have few measurement points (with only 5% or lower of the total number
of points).
4. Click Close to close the dialogue.
Figure 2.4: Point distribution in the different clutter classes
To filter out the measurement points from the under-represented clutter classes:
1. In the Network explorer, right-click the CW measurements whose statistics you have just examined:

All CW measurements: Right-click the CW Measurements folder.

All CW measurements for a single reference transmitter: Expand the CW Measurements folder and rightclick the folder of the reference transmitter.
The context menu appears.
2. Select Filtering Assistant from the context menu. The Filtering Assistant on CW Measurement Points
dialogue appears.
3. In the Clutter classes window, clear the check boxes of the clutter classes you want to filter out. Only the
clutter classes whose check box is selected will be taken into account.
4. If you want to keep the measurement points inside the focus zone, select the Use focus zone to filter check
box.
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5. If you want to permanently remove the measurement points outside the filter, select the Delete Points Outside
Filter check box.
†
By selecting the Delete Points Outside Filter check box, you are defining a property
of the CW measurement path. Once you have defined this property, points that you
filter out using other methods, for example, using the Filtering Assistant (see
"Using the Filtering Assistant on CW Measurement Points" on page 34) will also be
permanently deleted.
If you permanently delete measurement points and later want to use them, you will have to re-import the
original measurement data.
6. Click OK. The selected CW measurement data will be filtered according to the defined parameters.
The filter settings can also be saved to a filter configuration which can be retrieved afterward.
You can also filter out the measurement points from the under-represented clutter classes on a single CW
measurement path by using the Filtering assistant (see "Using the Filtering Assistant on CW Measurement Points"
on page 34).
See "Displaying Statistics Over a Measurement Path" on page 58 and "Displaying Statistics Over Several
Measurement Paths" on page 59 for more information on measurement path statistics.
+
2.5.2
The Clear All button resets the existing filters.
Signal and Distance Filtering
The goal of the calibration process is to produce an accurate propagation model which can be used to reliably
calculate the propagation of each base station within the area. To respect this goal, the propagation model’s own
constraints with respect to signal levels have to be taken into account. There are limitations in the measurement
equipment, which also have to be considered.
In this section, filtering out CW measurement points based on the signal strength or their distance from the
reference transmitter is explained:
2.5.2.1

"Typical Values" on page 32

"Using Manual Filtering on CW Points" on page 33

"Creating an Advanced Filter" on page 33

"Using the Filtering Assistant on CW Measurement Points" on page 34.
Typical Values
The values to be used to filter CW measurements depend on a lot of factors. In this section, some typical values are
given. These values are by definition general. Atoll provides a filtering assistant that can be used for each CW
measurement path; it is highly recommended to use the filtering assistant to define a specific signal and distance
filters for each CW measurement file. For information on the filtering assistant, see "Using the Filtering Assistant on
CW Measurement Points" on page 34.
When filtering out CW measurement points by signal strength, generally, signal levels above -40 dBm are filtered out,
because they would be inaccurate because of receiver overload. When you filter on the minimum signal level, the
sensitivity of the receiver and tolerance have to be considered. Therefore, signals below “Receiver Sensitivity +
Target Standard Deviation” have to be filtered out to avoid the effect of noise saturation in the results. A typical value
for the minimum signal level filter can be then considered to be:
-120 + 8 = -112 dBm
When filtering out by distance from the reference transmitter, measurement data at a distance of less than 200 m
from the station should be discarded because these points are too close to the station to properly represent the
propagation over the whole area. A typical maximum value is 10 km for rural areas.
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2.5.2.2
Using Manual Filtering on CW Points
When you filter CW measurements on signal strength or distance, you can filter the values in either all CW
measurement paths, in all the CW measurement paths for one reference transmitter, or in a single CW measurement
path.
To filter out CW measurement points on signal strength or distance:
1. In the Network explorer, right-click the CW measurements whose points you want to filter:

All CW measurements: Right-click the CW Measurements folder.

All CW measurements for a single reference transmitter: Expand the CW Measurements folder and rightclick the folder of the reference transmitter.
The context menu appears.
2. Select Filtering Assistant from the context menu. The Filtering Assistant on CW Measurement Points window
opens.
3. Define the settings for signal strength and distance:

Distance between CW measurement point and reference transmitter: Enter the Min. Distance and Max.
Distance. Atoll will keep only CW measurement points which are within this range.

Measured signal: Enter the Min. Measurement and Max. Measurement. Atoll will keep only CW
measurement points whose value is within this range.
You can also use this dialogue to filter on the following criteria:

Clutter class: For information on filtering by clutter class, see "Filtering on Clutter Classes" on page 30.

Angle with the antenna azimuth: For information on filtering by the angle with the antenna azimuth, see
"Filtering by Angle" on page 40.

Additional fields: For information on filtering with additional fields, see "Creating an Advanced Filter" on
page 33.
4. If you want to keep the measurement points inside the focus zone, select the Use focus zone to filter check
box.
5. If you want to permanently remove the measurement points outside the filter, select the Delete Points Outside
Filter check box.
†
If you permanently delete measurement points and later want to use them, you will
have to re-import the original measurement data.
6. Click OK. The selected CW measurement data will be filtered according to the defined parameters.
The filter settings can also be saved to a filter configuration which can be retrieved afterward.
You can also filter out CW measurement points on signal strength or distance on a single CW measurement path by
using the Filtering assistant on a single CW measurement path (see "Using the Filtering Assistant on CW
Measurement Points" on page 34).
+
2.5.2.3
The Clear All button resets the existing filters.
Creating an Advanced Filter
Atoll enables you to create an advanced filter using several fields and expressions with which you can filter CW
measurement points. You can create an advanced filter to filter the values in either all CW measurement paths, in
all the CW measurement paths for one reference transmitter, or in a single CW measurement path.
To filter out CW measurement points using an advanced filter:
1. On the Network tab of the explorer window, right-click the CW measurements whose points you want to filter:

All CW measurements: Right-click the CW Measurements folder.

All CW measurements for a single reference transmitter: Expand the CW Measurements folder and rightclick the folder of the reference transmitter.
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The context menu appears.
2. Select Filtering Assistant from the context menu. The Filtering Assistant on CW Measurement Points
dialogue appears.
3. Click the More button. The Filter dialogue appears.
4. In the Column row, select the name of the column to be filtered on from the list. Select as many columns as
you want.
5. Underneath each column name, enter the criteria on which the column will be filtered as explained in the
following table:
Formula
Data are kept in the table only if
=X
value equal to X (X may be a number or characters)
<> X
value not equal to X (X may be a number or characters)
<X
numerical value is less than X
>X
numerical value is greater than X
<=X
numerical value is less than or equal to X
>=X
numerical value is greater than or equal to X
*X*
text objects that contain X
*X
text objects that end with X
X*
text objects that start with X
6. Click OK to filter the data according to the criteria you have defined.
Filters are combined first horizontally, then vertically.
The filter settings can also be saved to a filter configuration which can be retrieved afterward.
You can also filter out CW measurement points using an advanced filter on a single CW measurement path by using
the Filtering assistant on a single CW measurement path (see "Using the Filtering Assistant on CW Measurement
Points" on page 34).
+
2.5.2.4
The Clear All button resets the existing filters.
Using the Filtering Assistant on CW Measurement Points
In Atoll, you can use a Filtering Assistant to filter the CW measurements points.
The Filtering Assistant can be used whether on individual CW measurement paths, or on groups of CW
measurement paths.
If a filter is applied on a folder or on a sub-folder, it is applied to all the CW measurement paths belonging to the
folder. An individual filter can be directly applied to a folder or a sub-folder element.
To use the Filtering Assistant:
1. In the Network explorer, expand the CW Measurements folder and the folder of the reference transmitter.
2. Right-click the CW measurement path and select Filtering Assistant from the context menu. The Filtering
Assistant window opens (see Figure 2.5).
The Filtering Assistant dialogue displays measurements by 10log(d), where "d" represents the distance. This
enables you to check whether measurement points are homogeneously distributed for the relevant signal level
and distance according to a linear function.
The Filtering Assistant enables you to filter by entering the values for Min. distance, Max. distance, Min.
measurement, and Max. measurement. Or, you can filter by drawing a rectangle in the graph. You can select
the points to keep or you can select areas with few points to exclude the points. After including or excluding
points, you can verify the number of points remaining and their percentage of the whole.
3. Under Clutter, clear the check box of any clutter class that is either under-represented or unrepresentative of
the survey zone. For more information, see "Filtering on Clutter Classes" on page 30.
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4. Filter the measurement points by selection. Typically, you will first select the points to include, respecting
minimum distance and minimum and maximum values, and then you will exclude the anomalous points from
that selection.
To select points to include:
a. Click on the graph where you want to start the rectangle that will contain the points to keep.
b. Drag to the opposite corner. The selection rectangle appears outlined in red.
When you release the mouse, the values reflected by the current selection are displayed in the fields on the
left.
c. Right-click the rectangle. The context menu appears.
d. Select Filter Selected Points from the context menu (see Figure 2.5). All points outside the rectangle are
filtered out.
The Number of Points field displays the number of points kept as well as their percentage of the whole.
Figure 2.5: Filtering selected points in the Filtering Assistant
To select points to exclude:
a. Click on the graph where you want to start the rectangle that will contain the points to exclude.
b. Drag to the opposite corner. The selection rectangle appears outlined in red.
When you release the mouse, the values reflected by the current selection are displayed in the fields on the
left.
c. Right-click the rectangle. The context menu appears.
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Figure 2.6: Point Exclusion Tool in the Filtering Assistant
d. Select Excluded Selected Points from the context menu (see Figure 2.6). All points inside the rectangle are
filtered out.
The Number of points field displays the number of points kept as well as their percentage of the whole.
5. If necessary, click the Save button under Filter configuration to save the filter settings as a filter configuration.
You can then select the same configuration the next time by selecting it from the list under Filter
configuration.
6. Click OK to apply the filters and close the dialogue.
+
2.5.3

When moving the mouse over the graph, the related distance, measurement,
and point index are displayed in the left of the dialogue.

The Clear All button resets the existing filters.
Filtering by Geo Data Conditions
After you have made an initial selection of CW measurement points based on clutter classes and signal strength
and distance, you can filter points based on geographic data conditions.
There are several reasons why you should remove certain CW measurement points from a CW measurement path.
Under certain conditions, certain sections of CW survey routes must be removed before calibration. The values of
the CW measurements in these sections could have been influenced by conditions in the profile between the
measurement point and the reference transmitter. For example:

A section of measurement points on a bridge, unless the bridge is properly identified in the map data with its
actual receiver height.

A section of measurement points in a tunnel.

A section where the profile between the transmitter and the receiver is obstructed near the transmitter, unless
the map data contains high resolution 3D data. In this case, Aster can model close obstruction of the antenna.

A section of CW measurement points behind an antenna that is not omni-directional.
These points can be selected and deleted or filtered out by:
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2.5.3.1

Selecting them in the data table: For information, see "Deleting a Selection of Measurement Points" on page 39

Creating an exclusion zone: For information, see "Using Filtering Zones on CW Measurement Points" on
page 40

Filtering them out by their angle to the antenna: For information, see "Filtering by Angle" on page 40.
Displaying CW Measurement Points by Signal Level
You can check whether propagation is homogeneous for all measurement paths by displaying each CW
measurement point on a single path by signal level and displaying a grid around the reference transmitter (see
Figure 2.7). This way you can check on the map whether the propagation loss is spatially homogeneous. Any sudden
drop in signal level or any areas where the received signal does not match your expectations will be immediately
visible.
Figure 2.7: Distribution of the point positions around a station
To display the signal level of CW measurement points on the map:
1. In the Network explorer, expand the CW Measurements folder, and clear the display check box beside all CW
measurement paths except the one you want to display.
This will limit the number of points displayed to those that you want to examine.
2. Define the display settings of the CW measurement path:
a. In the CW Measurements folder, right-click the CW measurement path you want to display and select
Properties from the context menu. The Properties window opens.
b. Click the Display tab.
c. Set the Display type to "Value intervals" and select signal strength from the Field list. For more information,
see "Defining the Display Type" on page 26.
3. Add the CW measurement points to the legend, as explained in "Adding CW Measurement Points to the
Legend" on page 28.
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4. Select View > Legend Window. The Legend window appears.
5. Define the grid around the reference transmitter:
a. Right-click the reference transmitter in the map window. The context menu appears.
b. Select Grid from the context menu. The Radial Grid dialogue appears.
c. Define a radial grid around the reference transmitter that covers the survey area.
d. Click OK.
By examining the displayed CW measurement points on the map, you can see on the map whether the
propagation loss is spatially homogeneous.
2.5.3.2
Using the CW Measurement Analysis Tool
You can use the CW Measurement Analysis Tool to analyse variations in the signal level on all points on the CW
measurement path. The CW Measurement Analysis Tool indicates any sudden drop in signal level or any areas
where the received signal does not match your expectations.
Once you have verified the signal level, potentially invalid measurements can be selected and deleted or filtered out
by:

Selecting them in the data table: For information, see "Deleting a Selection of Measurement Points" on
page 39

Creating an exclusion zone: For information, see "Using Filtering Zones on CW Measurement Points" on
page 40

Filtering them out by their angle to the antenna: For information, see "Filtering by Angle" on page 40.
To analyse data variations using the CW Measurement Analysis window.
1. In the Network explorer, expand the CW Measurements folder and the folder with the CW measurement path
you want to analyse.
2. Right-click the CW measurement path and select Open the Analysis Tool from the context menu. The CW
Measurement Analysis window appears (see Figure 2.8).
Figure 2.8: The CW Measurement Analysis window
3. You can display the data in the CW measurement path in two ways:

Click the values in the CW Measurement Analysis window.

Click the points on the CW measurement path in the map window.
The CW measurement path appears in the map window as a line connecting the reference transmitter and the
CW measurement point, which is indicated by the pointer (
).
4. You can display a second Y-axis on the right side of the window in order to display the values of a second
variable. You can select the secondary Y-axis from the list on the right-hand side on the top of the CW
Measurement Analysis Tool window.
5. You can change the zoom level of the CW Measurement Analysis window in the following ways:

Zoom in or out:
i. Right-click the CW Measurement Analysis window.
ii. Select Zoom In or Zoom Out from the context menu.

38
Select the data to zoom in on:
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i. Right-click the CW Measurement Analysis window on one end of the range of data you want to zoom in
on.
ii. Select First Zoom Point from the context menu.
iii. Right-click the CW Measurement Analysis window on the other end of the range of data you want to
zoom in on.
iv. Select Last Zoom Point from the context menu. The CW Measurement Analysis window zooms in on
the data between the first zoom point and the last zoom point.
6. Click the data in the CW Measurement Analysis window to display the selected point in the map window. Atoll
will recentre the map window on the selected point if it is not presently visible.
+
2.5.3.3
If you open the table for the CW measurement path you are displaying in the CW
Measurement Analysis Tool window, Atoll will automatically display in the table the
data for the point that is displayed in the map and in the CW Measurement Analysis
Tool window.
Deleting a Selection of Measurement Points
When you have identified unreliable or irrelevant sections, you can remove them by deleting them from the data
table.
To delete measurement points from the data table:
1. In the Network explorer, right-click the CW measurement path with the points you want to delete and select
Open Table from the context menu. The data table appears.
2. Right-click the column name for the Id column. The context menu appears.
3. Select Sort Ascending or Sort Descending from the context menu. The contents of the data table are sorted
by the Id of the CW measurement point.
Because the CW measurement points on the map are ordered sequentially by their Id, ordering the contents
of the data table by Id makes it easier to select and delete contiguous selections of CW measurement points.
4. In the data table, click the first point of the sequence to be deleted, press SHIFT and click the last point of the
sequence.
+
When you select a CW measurement point on the map, Atoll automatically selects
the same point in the data table. So, by arranging the map window and the data
table so that both are visible, you can locate the first and last points of the selection
in the data table by clicking them on the map.
5. Press the Delete key to delete the CW measurement points permanently from the data table.
†
© 2021 Forsk. All Rights Reserved.
If you permanently delete measurement points and later want to use them, you will
have to re-import the original measurement data.
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Figure 2.9: Displaying the measurement path and the data table (in a second tab group)
2.5.3.4
Using Filtering Zones on CW Measurement Points
When you have identified unreliable or irrelevant sections on a CW measurement path, you can filter them out by
creating a filtering zone over the points you want to exclude. A filtering zone applies only to the CW measurement
path on which it is made. This filter is added to any other filters applied to the CW measurement path.
To define a filtering zone on measurement points:
1. In the Network explorer, expand the CW Measurements folder and the folder of the reference transmitter.
2. Right-click the CW measurement from which you want to exclude some points with a filtering zone and select
Filtering Zones > Draw from the context menu. The Vector Editing toolbar appears.
3. Draw the filtering zone:
The filtering zone is delimited by a red line. The points of the path inside the filtering zone are filtered out of the
display and the data table. They are not taken into consideration in any calculations.
You can create several filtering polygons for each path.
q
2.5.3.5
When you have created several filtering polygons for a path, you can delete all of
them at the same time by selecting the Delete Filtering Polygons check box in the
CW Measurement filter dialogues.
Filtering by Angle
When you have sections of the CW measurement path that are obstructed by obstacles in the profile close to the
transmitter between the CW measurement point and the reference transmitter or when the antenna is not
completely omni-directional, you can filter out CW measurement points that are outside of a set angle from the
reference transmitter antenna beam.
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To define a filter by angle:
1. In the Network explorer, right-click the CW measurements whose points you want to filter by angle:

All CW measurements: Right-click the CW Measurements folder and select Filter.

All CW measurements for a single reference transmitter: Expand the CW Measurements folder, right-click
the folder of the reference transmitter and select Filter from the context menu.
The CW Measurement Filter window opens.
2. Under Azimuth/Point Angle, select one of the following:

Relative: Select Relative if the antenna is directional. The entered angles will then be offset from the
antenna’s azimuth.

Absolute: Select Absolute if the antenna is omnidirectional. Because an omnidirectional antenna has no
azimuth, the entered angles will then be offset from the north.
3. Define the negative and positive angles of the aperture:
a. Min. Angle: Enter a minimum angle from 0 to -180 degrees.
b. Max. Angle: Enter a minimum angle from 0 to 180 degrees.
In the example in Figure 2.10, a filter from -140 to 140 degrees relative to the antenna azimuth has been
created to filter out CW measurement points in the 80 degrees directly behind the antenna.
Figure 2.10: Angular filter around a station
4. If you want to keep the measurement points inside the focus zone, select the Use focus zone to filter check
box.
5. If you want to permanently remove the measurement points outside the filter, select the Delete points outside
filter check box.
†
If you permanently delete measurement points and later want to use them, you will
have to re-import the original measurement data.
6. Click OK.
The filter settings can also be saved to a filter configuration which can be retrieved afterward.
You can also filter out CW measurement points using a filter by angle on a single CW measurement path by using
the Filtering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 34).
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2.6 Selecting Base Stations for Calibration and for Verification
Once you have imported and filtered the CW measurement data, you can select the base stations that you will use
for calibration and those you will use for verification. Selecting the correct base stations for calibration and
verification is an important step in the process of calibrating the propagation model.
In "Selecting Base Stations" on page 11, it is recommended to have at least six base stations. With a total of six base
stations, two base stations will be required for verification.
If not enough base stations are available (in other words, if there are fewer than six base stations per propagation
model being calibrated), you should use all the base stations for calibration. You can verify the calibration later by
using the same measurement paths as in the calibration process.
When selecting base stations for calibration and for verification, you should keep the following guidelines in mind:
42

For calibration: Select paths that cover the entire area so that all the area characteristics can be taken into
account during the calibration process.

For verification: Select several paths (the number depends on the total number of available paths) that are
within the covered area and not at the outer boundaries. Ensure that the areas covered by the verification
paths are also covered by the calibration paths.
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3 Calibrating the Aster Model
The Aster Propagation Model is optimised for urban areas, where the radio propagation is calculated with two major
components:
◼
Vertical diffraction over the rooftops (Deygout and Ikegami-Walfisch)
◼
Horizontal reflection/diffraction (ray launching)
Aster is fully integrated with Atoll. Therefore, its main inputs are directly retrieved from the Atoll project:
◼
Model parameters are stored in the Aster model properties
◼
Transmitter and Antenna parameters are retrieved from the Atoll tables
◼
Geo inputs are retrieved from Atoll geo layers
◼
Continuous wave measurements are retrieved from the CW Measurements folder in the Network explorer of
Atoll.
This section details the Aster propagation model calibration process when the necessary CW measurements are
available.
The calibration process consists of the following steps:
◼
"Calibration Strategy" on page 43
◼
"Initial Setup" on page 44
◼
"Initial Analysis" on page 46
◼
"Calibration" on page 49
◼
"Validation" on page 57
3.1 Calibration Strategy
Once measurement data is acquired and prepared as described in "Calibration Preparation in Atoll" on page 19, the
Aster calibration process can start.
A preliminary task is to determine the number of different Aster calibrated instances you want to calibrate. It is
possible to:
◼
◼
Calibrate a single model instance with all the measurements data, based on the semi-deterministic principle
of Aster. A single calibrated Aster instance can accurately model the following:
◼
Different frequencies.
◼
Different environments: micro-urban, macro-urban, macro-suburban, and so on.
Create an instance of Aster for a subset of measurements representing different environment types, and/or
different frequency bands: the prediction performance of each calibrated model may be better for transmitters
in this specific type of environment (or frequency).
Choosing between these two strategies can be done by trying both, then analysing the quality performance provided
by the calibrated models. If the two strategies provide almost similar prediction quality on measurement surveys, it
is recommended to use the first one as it is simpler to manage (i.e. assigning to each transmitter its own calibrated
model).
This chapter describes the calibration of a single Aster instance from a set of related measurements.
© 2021 Forsk. All Rights Reserved.
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3.2 Initial Setup
You can configure an Aster model instance with two types of settings:
3.2.1
◼
Configuration parameters: parameter set used by Aster for inner calculation methods and formulas.
◼
Model configuration: specific geo data and targeted coverage prediction type.
Initial Configuration
Some configuration parameters cannot be calibrated and must be defined before calibration in the Aster
Propagation Model Properties dialog box. The Parameters tab and items on other tabs will only appear if the
"hideAdvancedParamUI" option is set to 0 in the [Core] section of the Aster.ini or AsterMmWave.ini file (advanced
mode).
3.2.1.1
◼
General: Aster model instance name, view the register signature, and enter comments.
◼
Configuration: indoor calculation and indoor antennas parameters.
◼
Clutter: clutter parameters. The Calibration Correction (dB) and Building Calibration Correction (dB) columns
appear only in advanced mode.
◼
Geo: geo data configuration.
◼
Ray Tracing: ray launching algorithm parameters. The Reflection/Diffraction Parameters frame appears only
in advanced mode.
◼
Parameters: configuration parameters. This tab appears only in advanced mode.
Configuration Parameters
It is recommended to start using Aster with one of the predefined configurations:
◼
For the standard Aster propagation model: Macro_900MHz_2GHz, Macro_3.5GHz, Macro_900MHz_2GHz,
Macro_3.5GHz, Rural.
◼
For the mmWave Aster propagation model: Default_Model, LOS_Model, Micro_28Ghz, or Macro_28Ghz.
Select the corresponding configuration as explained in the Aster User Manual.
When a configuration is selected, its settings are applied to the Aster model. These are the settings that the
calibration module will improve on.
Other basic parameter configurations are performed at this stage, such as enabling ray tracing or not, setting
appropriate internal parameters, and embedding parameters that cannot be calibrated.
A configuration set can also be specified:
◼
By loading a previously saved configuration file as explained in the Aster User Manual.
◼
From a calibration result file.
The currently selected configuration is displayed in the under Configuration on the Settings tab of Aster properties.
q
3.2.1.2
The Calibration menu can be disabled in the Aster.ini or AsterMmWave.ini file. For
more information, see the Aster Technical Reference Guide.
Indoor Calculation Settings
You can then define the Indoor calculation modes, which specify how the model performs calculation for indoor
location.
Usually field measurements are done only outdoor, so no indoor measurement points should be expected. However
due to errors in measurement geolocation or in the geo database, Aster may consider a number of measurement
points as indoor.
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By default, Aster ignores these points as will be seen in the Calibration wizard. In that case, the actual configuration
selected on the Settings tab of Aster properties has no effect.
However, in some cases Aster can be instructed to use these points, for example when actual indoor measurements
have been performed. In that case, it is recommended to select the indoor calculation mode which will be used for
the model in production:
◼
Enable indoor calculation: should be activated.
◼
Apply Indoor losses: should be set if the "Case 3: User-defined indoor loss from Aster" workflow described in
the Aster User Manual is used. The other workflows ("Case 1: Service level maps" and "Case 2: Clutter-based
indoor loss in Atoll") are not supported with the calibration of indoor points. In those workflows, indoor points
should be ignored.
◼
Indoor calculation within antenna building: should be selected as will be used for the model in production.
†
If you force the calibration module to use indoor points while these measurements
points are actually outdoor, then the Apply Indoor losses option should always be
deactivated. Since Aster performs interpolation of surrounding outdoor points,
these points will provide useful information as long as no additional indoor losses
are applied.
Regarding the indoor antennas relocation mode, it is recommended to keep it
activated (Relocate outdoor set to "Always" in Indoor Antenna Relocation Settings
dialog box) when dealing with scanned data from real transmitters, and deactivate
it when dealing with CW measurements.
In any case, it is unwise to rely on such automatic transmitter reposition features in
a calibration project. It is preferable to review all Aster warning messages and
manually relocate all the transmitters which were wrongly detected by Aster as
indoor.
As a rule of thumb, make sure that most measurement points are correctly geolocated as outdoor by:
3.2.1.3
◼
Verifying that the geo data is accurate enough to model the buildings with high precision
◼
Correcting the measurement points geolocation manually or via some pre-processing tools
◼
Filtering indoor points either from Aster or from Atoll's CW measurements filtering feature
Clutter and Geo Data
For a good and accurate use of the Aster model, the terrain features must be mapped to their appropriate
propagation classes. As explained in the Aster User Manual, this is usually performed from the Clutter tab by
specifying a correspondence between clutter classes and propagation classes. The Geo tab also contains some
mapping to be used when high resolution clutter heights or vectors are present.
For each propagation class, the auto-calibration module will not calibrate some parameters that are related to:
◼
Penetration loss and linear loss when the signal runs into an obstacle.
◼
Clearance area for statistical classes.
It is recommended to leave these parameters to their default values.
Calibration Correction (dB) and Building Calibration Correction (dB) columns appear only in the advanced Aster
interface. For more information, see the Technical Reference Guide.
3.2.1.4
Ray Tracing Settings
The configuration parameters related to horizontal reflection/diffraction cannot be calibrated and should be defined
prior to calibration:
◼
Enable ray tracing: select this check box to enable ray launching. Aster can perform ray launching regardless
of the fact that vectors are provided or not (direct use of geo raster data).
◼
Radius: defines the area where horizontal reflections/diffractions are considered during the ray launching
process. Outside this area, signal level calculations are still made but the rays are considered without
diffractions/reflections.
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Max number of diffractions and reflections: defines the maximum number of diffractions and reflections during ray
launching. Beyond, the signal level calculations are made until a ray encounters a new obstacle and processing
stops.
+
It is recommended to keep the following default values in the selected
configuration type:
◼
◼
Micro and macro cells: Ray tracing enabled with the following settings:
◼
Radius: 800m
◼
Max number of diffractions/reflections: 4
Rural: Ray tracing disabled.
Only the following parameters in the advanced Aster interface can be calibrated:
◼
3.2.1.5
Reflection/Diffraction parameters: for each propagation class, two reflection and diffraction losses are
defined; one for the first obstacle encountered during the ray-launching process, and one for the other
obstacles:
◼
Reflection Loss (dB) / First: reflection loss due to the first obstacle encountered during ray launching.
◼
Reflection Loss (dB) / Others: reflection loss due to other obstacles encountered during ray launching.
◼
Diffraction Loss (dB) / First: diffraction loss due to the first obstacle encountered during ray launching.
◼
Reflection Loss (dB) / Others: diffraction loss due to other obstacles encountered during ray launching.
Advanced Calibration Parameters (Inputs)
The Parameters tab appears only in the advanced Aster interface. For more information, see the Technical
Reference Guide. Most of the parameters on this tab can be calibrated, except the following parameters which must
be defined prior to calibration:
◼
Calculation method: This is the method used when antennas are directional. Recommended: "Standard 3D
interpolation method".
◼
Angle of incidence: defines how the angle of incidence is calculated. Even if it cannot be calibrated, you can
create different calibration scenarios, each with a different option for this parameter. Recommended:
"Receiver".
q
The default configurations use these recommended settings. Therefore, you
should not need to modify these parameters.
3.3 Initial Analysis
This step is optional but is useful to get a feel for the model accuracy using the default parameters. It is also useful
for early detection of any misconfiguration.
◼
Pathloss Computation (optional): For each transmitter to be calculated, select the "Aster Propagation Model"
in the Propagation tab of the Transmitter Properties then calculates the path loss matrices, for example by
calculating a new "Coverage by Signal Level" prediction in Atoll. Analysis of the coverage can provide some
insights on the behavior of the propagation model.
You can measure Aster performance by using either of the following methods:
◼
"Analysing Aster’s Performance from Atoll" on page 47
◼
"Analysing Aster Performance by Using the Analysis Mode" on page 47
Both methods should provide identical or very similar results, in particular for the Resolution and Indoor points
values. When performing the analysis in Atoll, the resolution is determined by the Gridstep option that is covered in
the Aster Technical Reference Guide.
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3.3.1
Analysing Aster’s Performance from Atoll
To analyse the performance of Aster on a set of CW measurements from Atoll, the predicted signal levels should
first be added to the CW measurements in Atoll.
To analyse Aster’s performance from Atoll, you need to:
◼
Add predicted signal levels to CW measurements in Atoll.
◼
Calculate the signal levels predicted by Aster.
◼
Verify that the signal levels predicted by Aster were added in the corresponding measurement path table.
◼
Display the statistics of CW measurement paths in Atoll.
To add predicted signal levels to CW measurements in Atoll:
1. In the Network explorer, right-click the CW Measurements folder and select Properties from the context menu.
The CW Measurements Properties dialog box appears.
2. In the CW Measurements Properties dialog box, select the Propagation tab.
3. On the Propagation tab, set Propagation Model to "Aster Propagation Model".
4. Click OK to close the CW Measurements Properties dialog box.
To calculate the signal levels predicted by Aster for all the CW measurement points:
1. In the Network explorer, right-click the CW Measurements folder and select Calculation > Calculate signal
levels from the context menu. Atoll calculates the signal levels for all CW measurement paths and adds the
signal levels it predicted to all CW measurement points.
To verify that the signal levels predicted by Aster were added in the corresponding measurement path table:
1. In the Network explorer, expand the CW Measurements folder, right-click a CW measurement path, and select
Open Table and verify that some values were added in the corresponding P (dBm) column.
To display the statistics of CW measurement paths in Atoll:
1. In the Network tab in the explorer window, right-click the CW Measurements folder, and select Display
Statistics from the context menu. The Measurement Path Selection dialog box appears.
2. In the Measurement Path Selection dialog box, select All measurement paths.
3. Click OK.
The CW Measurements dialog box appears with the initial global Aster performance under Global Statistics
and the average and standard deviations per clutter class, per transmitter, and per measurement path. For
more information, see the Atoll User Manual.
3.3.2
Analysing Aster Performance by Using the Analysis Mode
The performance of Aster on a set of CW measurements can be analysed from Aster by using its built-in analysis
mode.
To analyse Aster performance:
1. In the Parameters explorer, right-click Aster Propagation Model and select Analysis from the context menu.
The Analysis wizard appears.
2. Select the Parameters tab.
3. Under CW measurement path(s) to be used, select the check boxes of the measurement paths you want to
consider:
◼
Click Select All to select all measurement paths or Unselect All to unselect them all.
◼
Select contiguous rows by clicking the first row, pressing SHIFT and clicking the last row.
◼
Select non-contiguous rows by pressing CTRL and clicking each row separately.
Under Analysis method, the settings of Resolution (m) and Indoor points are read-only. The values are
inherited from the Calibration wizard and can be modified there if necessary.
4. Click Start analysis. A progress bar appears and, when analysis is finished, the results appear on the Result
tab:
© 2021 Forsk. All Rights Reserved.
47
Aster Model Calibration
Chapter 3: Calibrating the Aster Model
Figure 3.1: Aster Analysis Results
◼
◼
◼
48
Global Performance: provides overall statistics on the model fit to measurements for the initial default
model. The values are similar to the ones calculated by Atoll.
◼
No points/Total: Number of measurement points used in analysis / total number of points in all
measurement paths used in analysis.
◼
Mean (dB): Mean error value between predictions and measurements.
◼
Std Dev (dB): Standard deviation of the differences between predictions and measurements.
◼
RMS (dB): Root mean square of the differences between predictions and measurements.
◼
Corr: Correlation coefficient between measurements and predictions.
◼
95% Error Range (dB): 95% percentile values of the distribution function of the difference between
predictions and measurements. This means that 95% of the points are in the [Min,Max] range.
◼
Spread of Means (dB): Standard deviation of the mean errors of the different measurement paths.
Detailed Performance: gives similar statistics individually on each measurement path.
◼
Measurement path: measurement path name.
◼
No points/Total: Number of points used in analysis per measurement path / total number of points in
the same measurement path.
◼
No points: Number of points per measurement path.
◼
Mean (dB): mean error between predictions and measurements.
◼
Std Dev (dB): Standard deviation between predictions and measurements.
◼
RMS (dB): Root mean square of the differences between predictions and measurements.
◼
Corr: Correlation coefficient between measurements and predictions..
◼
95% Error Range (dB): 95% percentile values of the distribution function of the difference between
predictions and measurements. This means that 95% of the points are in the [Min,Max] range.
◼
Used Points Distribution: The distribution ratio between No points and No points/Total.
Input Parameters: lists the following additional information:
◼
Used CW measurement path: names of the measurement paths used in this analysis.
◼
Resolution (m): resolution used in this analysis, as displayed in the Analysis wizard.
© 2021 Forsk. All Rights Reserved.
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Chapter 3: Calibrating the Aster Model
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◼
Indoor points: "Use", "Ignore", or "Reposition outdoor" indoor points, as displayed in the Analysis wizard.
q
◼
Both parameters Resolution and Indoor points can only be modified in the
Calibration wizard.
Context:
◼
Duration: elapsed time from beginning to end of analysis.
For more information on Aster analysis indicators, see "Calibration Results Indicators" on page 54.
3.4 Calibration
The goal of the calibration process is to reduce the mean error and standard deviation of measured values versus
calculated values. For each parameter, the calibration process tries to find the best value that gives the best
standard deviation and the best mean error. The acceptable data ranges and step for each parameter have to be
defined.
The following sections describe the steps to follow to calibrate an Aster instance:
3.4.1
◼
"Creating a Calibration Copy of Aster" on page 49.
◼
"Calibrating an Aster Instance" on page 49.
◼
"Verifying Calibration Results" on page 53.
◼
"Committing Calibrated Parameters" on page 56.
Creating a Calibration Copy of Aster
Before starting a calibration, it is recommended to work on a new instance of the Aster model. You can later
calibrate the original model if needed.
To create a new instance of the Aster model:
1. In the Parameters explorer, expand the Propagation Models folder, right-click Aster Propagation Model, and
select Duplicate from the context menu. A new Aster instance, Copy of Aster Propagation Model, is added in
the Propagation Models folder.
2. You can rename the new Aster instance on the General tab of its properties dialog box, for example: Aster
Copy.
3.4.2
Calibrating an Aster Instance
To start the calibration process of an Aster instance:
1. In the Parameters explorer, right-click the Aster instance that you want to calibrate and select Calibration from
the context menu. The Aster Copy Calibration wizard appears.
2. Select the Parameters tab.
3. Under CW measurement path(s) to be used, select the check boxes of the measurement paths that you want
to consider:
◼
Click Select All to select all measurement paths or Unselect All to unselect them all.
◼
Select contiguous rows by clicking the first row, pressing SHIFT and clicking the last row.
◼
Select non-contiguous rows by pressing CTRL and clicking each row separately.
4. Under Calibration method:
© 2021 Forsk. All Rights Reserved.
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Aster Model Calibration
Chapter 3: Calibrating the Aster Model
◼
Optimize spread of means: select this option to optimise the dispersion of mean errors across all
measurement paths. For more information, see "Basic Spread of Means Optimisation" on page 52.
◼
Spread of means weight: see "Advanced Spread of Means Optimisation" on page 52.
◼
Resolution (m): Enter a resolution or select Auto and let Aster decide according to the geo data resolution.
◼
Indoor points: Select one of the following options:
◼
Select Use to consider indoor points in the calibration process.
◼
Select Reposition outdoor to reposition indoor points to outdoor.
◼
Select Ignore to ignore indoor points.
q
The settings defined in this dialog box for Resolution (m) and Indoor points are
inherited as read-only settings in the Analysis wizard. You can only modify them
from the Calibration wizard.
◼
Click Reset to reset the parameters in this dialog box to their default values.
◼
Click Advanced Parameters (available only in advanced mode) to open the Advanced Calibration
Parameters dialog box. For more information, see "Advanced Calibration Parameters (Inputs)" on page 51.
◼
Click Save Parameters to save the current settings if they are different from the default settings.
5. Optionally, if you are using the mmWave Aster propagation model, you can tune the linear loss through
vegetation by precalibrating the deterministic propagation classes associated with vegetation:
a. Click Precalibration. The Precalibration Results window opens.
The Vegetation Propagation Classes list displays the linear loss (in dB/m) for each vegetation type.
Figure 3.2: Precalibration Window for mmWave Vegetation
b. Click Start Precalibration to run the precalibration calculation.
c. When the precalibration is finished, information about the number of points is displayed. You can choose
to Commit the result.
d. Click Close.
6. Click Start Calibration. A progress bar appears.
When calibration is finished, the results appear on the Result tab. For more information, see "Verifying
Calibration Results" on page 53.
50
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Aster Model Calibration
Chapter 3: Calibrating the Aster Model
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3.4.2.1
Advanced Calibration Parameters (Inputs)
The Advanced Calibration Parameters dialog box contains all the Aster parameters that can be calibrated. The
calibration module chooses for each parameter the value that minimises the standard deviation or the mean error
and you can select the parameters that you want to calibrate.
◼
Parameters: contains the list of all the parameters to be calibrated. There are two types of parameters, the
parameters used to minimise the standard deviation (e.g. "K3 - los") and others used to minimise the mean
error (for example: "K1 - los").
◼
Current Value: contains the current parameter value prior to calibration.
◼
Use: indicates if the parameter is to be calibrated or not. Some recommendations and rules are needed in
order to have coherent results.
◼
Min Value, Max Value, and Step:
◼
For the parameters used to minimise the standard deviation (e.g. "K3 - los"), a minimum value, a maximum
value, and a step must be defined. For each parameter, the calibration module scans all the possible values
between the defined minimum and maximum, with the defined step. It then finds the value that best
minimises the standard deviation.
◼
For the parameters used to minimise the mean error (e.g. "K1 - los"), these columns are not needed. The
calibration module finds automatically the value that makes the mean error equal to zero.
In general, no changes need to be made in the Advanced Calibration Parameters dialog box and the default values
can be kept. If necessary, the parameter range can be Reset on the Parameters tab of the Calibration wizard.
3.4.2.2
Calibration Algorithm
The calibration algorithm main goal is to reduce the mean error and standard deviation of the measured signal level
versus the calculated signal level. The calibration process is the following:
1. A first prediction calculation is carried out with default parameters on the transmitters whose CW
measurements are selected. For each measurement point, the calculation module finds the corresponding
calculated value. The module stores all data it needs for quick generation of new values when the parameters
are modified.
2. A search algorithm is then run to find a set of suitable calibrated parameters. It mainly consists in a double
loop executed several times, with the following basic steps:
a. The initial standard deviation and the mean error are calculated.
b. For each parameter to be calibrated, a first sub-loop is executed in a greedy fashion:
i. The module finds the best parameters for the minimisation of a given cost function.
ii. The module finds the best parameters for the mean error to become zero.
iii. The new standard deviation and mean error are calculated.
For each parameter to be calibrated a similar second fine-tuning sub-loop is executed in a gradient fashion. The cost
function used in this search algorithm is usually a measurement of the standard deviation between measured and
predicted signal levels, but can also include a Spread of Means component, as shown in "Basic Spread of Means
Optimisation" on page 52 and "Advanced Spread of Means Optimisation" on page 52.
Sub-loops correspond to each parameter class to be calibrated:
◼
Antenna calibration
◼
Frequency correction calibration
◼
Roof to mobile calibration
◼
Antenna to roof calibration
◼
Gradient calibration
◼
Horizontal reflection/diffraction calibration
◼
LOS calibration
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Aster Model Calibration
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3.4.2.3
Calibration Method
Some calibration parameters can be changed from the Aster interface while others can only be modified from the
Aster.ini or AsterMmWave.ini file.
3.4.2.3.1
Calculation Resolution and Indoor Points
The calculation of the initial prediction is carried out at a given resolution. This resolution can be user-defined or
determined by Aster according to the geo data resolution.
In general, it is best to use the calculation resolution intended for final use of Aster. This will insure the best
matching results between calibrated models and path loss predictions.
q
3.4.2.3.2
For indoor points, the calculation module can be instructed to either "Ignore" or
"Use" the points detected as indoor.
Basic Spread of Means Optimisation
The spread of means is the measurement of the dispersion of mean errors across all measurement paths. Hence
by optimising the spread of means, you make each measurement path closer to 0dB in terms of average error
between prediction and measurement.
To enable the optimisation of the spread of means, select the Optimize spread of means check box in the
Calibration wizard. Let’s assume that:
◼
σ is standard deviation of the differences between predictions and measurements.
◼
σm is the standard deviation of the mean errors of the different measurement paths.
During a standard calibration, the calibration engine looks for the best parameters to minimise the standard
deviation σ , while keeping the overall average close to zero. Hence, the minimised cost function will be equal to the
standard deviation:
cos tFunction = σ
When the spread of means optimisation is enabled, the cost function becomes:
cos tFunction = σ + α σm × σm
where the weighting α σm can be configured from the Aster interface (default value = 1).
In this case, the calibration engine will look for the best set of parameters to minimise both the standard deviation
and the spread of means.
3.4.2.3.3
Advanced Spread of Means Optimisation
It is possible to define a more complex cost function via the Aster.ini or AsterMmWave.ini configuration file, by
specifying the following parameters:
α σm Spread of means weighting
t σm Spread of means target
α σ Standard deviation weighting
t σ Standard deviation target
cos tFunction = α σ × Cost σ + α σm × Cost σm
Where:
σ
Cost σ = 
 t σ + 10 ( ( σ + t σ ) )
52
σ ≤ tσ
σ > tσ
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Aster Model Calibration
Chapter 3: Calibrating the Aster Model
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 σm
Cost σm = 
 t σm + 10 ( ( σm – t σm ) )
σ ≤ tσ
σ > tσ
This means that when one of the two items (standard deviation or spread of means) is above the target, the penalty
for that part above this target is 10 times the standard value. This cost function will tend to make both the spread
of means and standard deviation converge to the target values. For example:
[Calibration]
spreadOfMeansWeight = 1.0
spreadOfMeansTarget = 2
standardDeviationWeight = 1.0
standardDeviationTarget = 6.75
In this case, the module will try to have the spread of means below 2 dB and the standard deviation below 6.75 dB,
with equal weight between the two targets. When the targets are set to zero, this is equivalent to the standard default
cost function
3.4.3
Verifying Calibration Results
When calibration is finished, the results are displayed on the Results tab of the Calibration wizard:
Figure 3.3: Aster Calibration Results
◼
Global Performance: this section provides overall statistics on the model fit to measurements for the initial
default model and the final calibrated model. The initial values are similar to the values calculated by Atoll.
For more information, see "Calibration Results Indicators" on page 54.
◼
Detailed Performance: this section gives similar statistics individually on each measurement path.
For more information, see "Calibration Results Indicators" on page 54.
◼
Input Parameters: lists the following additional information:
◼
Used CW measurement path: names of the measurement paths used in this calibration.
◼
Resolution (m): resolution used in this calibration, defined in the Calibration wizard.
© 2021 Forsk. All Rights Reserved.
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Aster Model Calibration
Chapter 3: Calibrating the Aster Model
◼
◼
Indoor points: "Use" or "Ignore" indoor points, as defined in the Calibration wizard.
Context:
◼
Duration: elapsed time from the beginning to the end of this calibration.
◼
Date: end date (<YYYY-MM-DD HH:MM:SS>) of this calibration.
The following buttons are also available on the Result tab:
◼
Advanced Parameters: Click this button (available only in advanced mode) to display the Advanced
Calibration Parameters dialog where initial and final values are indicated for each calibrated parameter.
◼
Export: Click this button to perform one of the following tasks to either export the calibration results to a .TXT,
.HTML, .XML or .XLS file; or to export the .INI configuration file of the model after calibration.
◼
Commit: to apply the calibrated values directly in this Aster model instance.
◼
Close: to close the dialog box without committing the results.
The Graph tab displays the value of the error ( E = P – M ) as a function of either distance ( log ( d ) ) or the
measurement level. This is useful for monitoring the stability of the E = P – M error over distance, which
determines the quality of the calibration.
Figure 3.4: Aster Calibration Graph
The graph can be displayed with the following options:
3.4.3.1
◼
Before and after calibration (for calibration results only).
◼
For each component type (LOS, NLOS, and Ray Tracing) or CW measurement path.
Calibration Results Indicators
The calibration results indicators on the Result tab of the Calibration wizard are the following:
◼
◼
No points: number of measurement points ( N ) used in this calibration. In the "Global Performance" section,
it is the total number of points. In the "Detailed Performance" section, it is the number of points per
measurement path.
Mean (dB): mean error ( m ) between predictions and measurements.
N
1
m = ---N
 pred ( i ) – mes ( i )
i=0
◼
54
Std Dev (dB): standard deviation ( σ ) of the differences between predictions and measurements.
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Chapter 3: Calibrating the Aster Model
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N
σ =
1
---N
 ( pred ( i ) – mes ( i ) )
2
–m
2
i=0
◼
RMS (dB): Root mean square ( rms ) of the differences between predictions and measurements.
N
1
---N
rms =
 ( pred ( i ) – mes ( i ) )
2
i=0
◼
Corr: Correlation coefficient between measurement (x) and prediction (y) variables.
N
1
---- x i y i – x ⋅ y
N
1
p (x,y) = -----------------------------------σx ⋅ σy

Where:
N
1
x = ---N
 xi
i=0
N
1
y = ---N
 yi
i=0
σ x is the standard deviation of measurements
σ y is the standard deviation of predictions
◼
95% Error Range (dB): The 95% percentile values of the distribution function of the difference between
predictions and measurements. This means that 95% of the points are in the range [Min,Max]. This percentile
ratio can be modified from the Aster.ini or AsterMmWave.ini file:
[Calibration]
percentileMinMax = 95
◼
Spread of Means (dB): Standard Deviation of the mean errors ( σm ) of the different measurement paths.
M

2
1
m j2 –  ----m j
M

 j=0 
j=0
M
σm =
1
----M


Where:
M is the number of measurement paths
m j is the mean error between predictions and measurements for path " j ".
◼
Used Points Distribution: The distribution ratio between No points and No points/Total.
You can display additional performance results at the end of the calibration results. The Advanced Results section
displays the initial and calibrated values for the following indicators:
◼
No points
◼
Mean (dB)
◼
Std Dev (dB)
◼
RMS (dB)
Results are provided for All, LOS, NLOS, and RT radio components.
You can enable the Advanced Results section from the Aster.ini or AsterMmWave.ini file:
© 2021 Forsk. All Rights Reserved.
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Aster Model Calibration
Chapter 3: Calibrating the Aster Model
[Calibration]
CalibAdvancedResults = 0
The following option enables the display of each individual measurement in the calibration Results tab, as shown in
Figure 3.5.
[Calibration]
MeasurementPointsDisplay = 1
Figure 3.5: Optional measurement points display
3.4.4
Manual Calibration Adjustments
†
This section is for advanced users only.
Do not make manual adjustments if you are not an advanced user.
When the calibration is complete, and before committing the new calibrated model parameters, advanced users can
make manual adjustments to compensate for values that could not be calibrated due to missing or incomplete data.
For example, missing values can be extrapolated from existing data or from standard values.
To make manual calibration adjustments:
1. Click Start calibration in the Calibration wizard. When calibration is finished, the results appear on the Result
tab.
2. On the Result tab, click the Advanced Parameters button. The Advanced Calibration Parameters dialog box
appears.
3.4.5
◼
Parameters: for each parameter in this column, there is an Initial Value and a Final Value.
◼
Initial Value: initial value before calibration. This value is read-only.
◼
Final Value: final value after calibration. This value can be modified by advanced users.
Committing Calibrated Parameters
In order for the calibrated parameters to be taken into account by the model, they need to be committed by clicking
OK in the Advanced Calibration Parameters dialog box, then Commit and Close on the Result tab of the previous
window. The new parameter values will then appear in the Aster properties.
+
56
When a calibration has been committed:
◼
The Commit button is disabled (greyed).
◼
The calibration date and Aster build version are indicated on the Settings tab
of Aster properties.
© 2021 Forsk. All Rights Reserved.
Aster Model Calibration
Chapter 3: Calibrating the Aster Model
TN_056
3.5 Validation
After calibration has been performed and committed, you can verify the calibration accuracy directly in Atoll by
performing the same steps as in the initial analysis of the Aster model.
The Global Statistics section provides the global performance of the model. These values are usually the same as
the ones displayed on the Result tab of the Calibration wizard.
© 2021 Forsk. All Rights Reserved.
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Aster Model Calibration
Chapter 3: Calibrating the Aster Model
58
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Chapter 4: Survey Site Form
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4 Survey Site Form
This section shows an example of a survey site form that you can use to elaborate your own survey site form. The
purpose of this form is to record the following information:

Details describing the station

The locations of any spurious measurements where the physical clutter data does not coincide with the
mapping data

Any useful information about incidents that may have occurred.
© 2021 Forsk. All Rights Reserved.
59
Aster Model Calibration
Chapter 4: Survey Site Form
Survey Site Form
Station Details
Site ID:
ZHF993
Address
Survey Site No: 1
18 Smith street
Site Access Details
Ask for James Brown at reception desk in regards to getting access to the site on the roof.
Co-ordinates:
E: 26,38773
N: 50,59358
Map GPS x
Transmitters:
43
Nominal power
Cable length / type
Cable losses max /UMTS
Type
K800 1111
Gain
2
Type of site
Roof top
dBi
40
EIRP min.
20,4 + 3
dB
On mast / tripod ?
installation
Ant. Height
3
Outdoor, on the roof
location
Omni Antenna
dBm
5m 1/4"
dBm
23,4
m
General Site Comments
(Enter construction details, etc.)

Site under construction (mast without antennas)

Lift

Power supply 220V available from shelter

No obstruction for propagation
Notes:

Separation: Horizontal antenna separation can be problematic and should be avoided. As long as antennas
are aligned, then vertical separation is not a problem.

Site photos: Take photos of the sites both from the ground and from the site itself. You also need a set of
panoramic photos, starting from 0° (North) and moving clockwise by 45° increments. You can use a laser
telemeter to measure the height of the site.

Site drawing: Provide an accurate (as far as possible) drawing of the site. Indicate where the North lies in
relation to the site.
Photos:
60
Number:
Comments:
1
Building view
1
Rooftop
4
Panoramic
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Aster Model Calibration
Chapter 4: Survey Site Form
Site Photos
Global view:
Rooftop:
© 2021 Forsk. All Rights Reserved.
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Aster Model Calibration
Chapter 4: Survey Site Form
Panoramic Photos
↑ North
↑ East
↑ South
↑ West
62
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Chapter 4: Survey Site Form
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Survey Details
Measurement Files:
Number:
Comments:
1
2
3
4
5
6
7
8
9
10
Frequency Band
GSM
1
Frequency
935.200
1815.200
2170
Channel Bandwidth
200 khz
200 khz
200 khz
X
X
X
Output before survey
40 dBm
40 dBm
40 dBm
Output power after
39.8 dBm
39.8 dBm
39.8 dBm
1.3
1.3
1.3
Interference free control?
-Before antenna-
UMTS
563
Channel Used
TX transmitter
DCS
56
VSWR
Survey Comments:
(Information about issues that will necessitate data filtering, etc.)
Notes:

Take note of any areas on the survey path which are not suitable data collection areas (avoid them if
possible), for example, tunnels, bridges, raised motorways, etc. Keep in mind that the planning tool assumes
that you are at ground level; any raised or lowered areas produce errors.

Before making the survey drive, measure the RF output at the antenna, after the cable.

Measure the RF output at the antenna again after the survey drive, to ensure that the transmitter is still
© 2021 Forsk. All Rights Reserved.
63
Head Office
US Office
China Office
7 rue des Briquetiers
31700 Blagnac, France
Tel: +33 562 747 210
Fax: +33 562 747 211
200 South Wacker Drive – Suite 3100
Chicago, IL 60606, USA
Tel: +1 312 674 4800
Fax: +1 312 674 4847
Suite 302, 3/F, West Tower, Jiadu Commercial Building,
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