Manual for the MTA 805MHz Automated Conditioning Program
Hardware
Dell Optiplex GX620 Intel Pentium 4 3.4GHz cpu, 1Gb 533MHz DDR2 memory
National Instruments PCI-5105 8 channel 60M samples/second digitiser with 128Mb
on-board memory
National Instruments GPIB PCI card
Input signals:
Reflected power signal from directional coupler.
Voltage signal from voltage pickup 2.
Forward power signal from directional coupler.
All signals are passed through envelope filters to smooth out the 805MHz oscillations.
Currently, only the reflected power and the voltage pickup signals are needed.
Software
Main program file is c:\work\mtaRFDAQCard\rfMain-v5_0.vi
Parameters
Initial parameters tab
Name
DAQ Card Name
DAQ Card Name Dup
Reflected Power
Channel
Reflected Power range
Description
Device name of DAQ card.
Copy of DAQ Card Name.
Channel number that the reflected
power signal is connected to.
Voltage range of the Reflected
power channel.
Reflected Power
Attenuation of the reflected power
attenuation
signal.
Reflected Power offset
Voltage offset of the reflected power
signal.
Reflected Power
Coupling of the reflected power
Coupling
signal.
Reflected Power
Input impedance of the reflected
impedance
power channel.
Voltage Probe Channel
Channel number that the voltage
probe signal is connected to.
Voltage Probe range
Voltage range of the Voltage probe
channel.
Voltage Probe
Attenuation of the voltage probe
attenuation
signal.
Voltage Probe offset
Voltage offset of the voltage probe
signal.
Voltage Probe Coupling Coupling of the voltage probe
signal.
Voltage Probe
Input impedance of the voltage
impedance
probe channel.
Forward Power Channel Channel number that the Forward
power signal is connected to.
Forward Power range
Voltage range of the Forward power
channel.
Forward Power
Attenuation of the Forward power
attenuation
signal.
Forward Power offset
Voltage offset of the Forward power
signal.
Forward Power Coupling Coupling of the Forward power
signal.
Forward Power
Input impedance of the Forward
impedance
power channel.
min sample rate
Minimum sampling frequency.
min record length
Trigger Level
Minimum number of points of each
captured waveform.
Voltage level to trigger waveform
capturing.
Default Value
Dev1
Dev1
0
2
1.0
0
DC
1 mega ohm
1
0.4
1.0
0
DC
1 mega ohm
2
0.04
1.0
0
DC
1 mega ohm
30M
samples/second
2000
2.5x10-1V
Trigger Slope
Trigger Source
Sig Gen VISA session
Dup VISA session
Initial Frequency
Initial Amplitude
Initial Amplitude Target
minStepSize
Write to Log file
Rep Rate (Hz)
high ref level
mid ref level
low ref level
ref units
method
histogram size
polarity
Default Pulse Width
Pulse Width Err
Calibrate Pulse Width?
Num Calib waveforms
Trigger on positive(rising) or
negative(falling) slope.
Channel to trigger on.
VISA label of the Signal Generator.
Copy of Sig Gen VISA session.
Starting frequency of the
conditioning procedure.
Staring amplitude of the signal
generator.
Initial value of the amplitude target.
Minimum frequency
increment/decrement for finding the
resonant frequency.
Write initial parameters, breakdown
events, amplitude increments and
decrements, frequency and probe
voltage values to a log file.
The repetition rate.
Peak finding high reference level.
Peak finding mid reference level.
Peak finding low reference level.
Units of the reference levels.
Method to use for peak finding if ref
units is set to percent.
Size of histogram to use for peak
finding if ref units is set to percent.
Find peaks with a leading rising or
falling edge.
Default separation of the two peaks
of the reflected power signal.
Tolerance of the pulse width
measurement.
Determine actual separation of the
two peaks of the reflected power
signal.
Number of waveforms to average to
determine the separation of the two
peaks of the reflected power signal.
Positive
0
GPIB0::19::INSTR
GPIB0::19::INSTR
810.57MHz
-14dBm
-10dBm
0.002MHz
No
10
61
60
59
Percent
Auto select
256
Rising
20x10-6s
1x10-6s
Yes
50
rf Monitor tab
Name
Long Interval
Long Breakdown Limit
(pulses)
Long Amp Dec
Long Amp Inc
Interval(s)
Short Interval
Short Breakdown Limit
(pulses)
Short Amp Dec
Short Amp Inc
Interval(s)
Sliding Window
Interval(s)
Sliding Window Amp
Dec
Sliding Window Amp
Inc Interval(s)
Consecutive Breakdown
limit
Consecutive Amp Dec
Consecutive Amp Inc
Interval(s)
Big Spark Width
Big Spark Amp Dec
Big Spark Amp Inc
Interval(s)
Description
Time over which the Long
Breakdown Limit is monitored.
Limit of the number of pulses with
breakdown over the period Long
Interval.
The amplitude decrement if Long
Breakdown Limit is exceeded.
The number of seconds to wait
before increasing the amplitude if
Long Breakdown Limit is exceeded.
Time over which the Short
Breakdown Limit is monitored.
Limit of the number of pulses with
breakdown over the period Short
Interval.
The amplitude decrement if Short
Breakdown Limit is exceeded.
The number of seconds to wait
before increasing the amplitude if
Short Breakdown Limit is exceeded.
Minimum time allowed between
previous two breakdowns.
The amplitude decrement if the time
between the previous two
breakdowns is less than the sliding
window interval.
The number of seconds to wait
before increasing the amplitude after
having made a Sliding Window
Amp Dec.
Limit of the number of consecutive
pulses with breakdown.
The amplitude decrement if the
number of consecutive breakdowns
is over the limit.
The number of seconds to wait
before increasing the amplitude if
Consecutive Breakdown Limit is
exceeded.
If the measured pulse width is below
this value the breakdown is a big
spark.
The amplitude decrement if the
breakdown is a big spark.
The number of seconds to wait
before increasing the amplitude if
Default Value
60s
4
0.2dBm
5s
10s
2
0.5dBm
5s
4s
1dBm
10s
2
1dBm
10s
12x10-6s
1dBm
10s
Amp Increment Check
Res Delay
Amp Decrement Check
Res Delay
Check Res. Freq.
Interval(s)
Graph Update
Interval(ms)
Amplitude
Frequency
Probe voltage at
Resonance (V)
Voltage Probe
Correction Factor(v1/v2)
Nominal Pulse Width (s)
Measured Pulse Width
Reflected Power
Correction Factor
Amplitude target
Amp Increment
Normal Amp Inc
Interval
Hold at target?
Turn off rf on ABORT?
the breakdown is a big spark.
The time to wait before checking the
resonant frequency after an
amplitude increment.
The time to wait before checking the
resonant frequency after an
amplitude decrement.
The maximum time to wait before
checking the resonant frequency
again.
How often the history graphs are
updated.
The current amplitude value.
The current frequency value.
The mean probe voltage (after
scaling) at the resonant frequency.
The scale factor by which to correct
the Probe Voltage signal. This is
determined by taking the ratio of the
peak value of the signal from probe
1 and probe 2 (read off the
oscilloscopes).
Time separation between the two
peaks of the reflected power signal.
If Measured Pulse Width is less than
this value minus Pulse Width Err
then a breakdown has occurred.
The measured time between the first
and last peak of the reflected power
signal.
Scale factor of the captured reflected
power waveform.
The target amplitude to reach
The amount to increase the
amplitude by
Time to wait before increasing the
amplitude if a breakdown has not
just occurred.
Continue monitoring breakdowns
after the amplitude target has been
reached
Sets whether the Rf will be turned
off at the signal generator if the
program aborts.
0
2s
200s
1000ms
1.085
1
-10dBm
1dBm
5s
YES
YES
Debug parameters
Name
Amp Inc Interval(s)
Min Pulse Width
Num of peaks
Pulse Time Count
Description
Time to wait before increasing the
amplitude.
“Nominal Pulse Width” – “Pulse
Width Err”
Number of peaks measured in the
current pulse.
Number of pulses to display at a
time in “Pulse Times”
Default Value
20
Algorithm
Signal Generator
Amplitude
t1
D
A
t2
A
t1
time
In the diagram above A= “Amp Increment” and t1= “Normal Amp Inc Interval”.
The program monitors “Measured Pulse Width” and if this is below “Min Pulse
Width” then a breakdown has occurred. The conditions are then tested in the
following order, “Big Spark Width”, “Consecutive Breakdown Limit”, “Short
Breakdown Limit”, “Sliding Window Interval” and “Long Breakdown Limit”. The
first condition that is met sets the value of D and t2 in the diagram above.
Operating Instructions
Login as user mta with password rfMonitor5.
Double click on the rfMain-v5_0.vi icon on the desktop.
Certain parameters have been locked as these should not be changed.
Go to the “Initial Parameters” tab.
The initial value for the amplitude and frequency will be read from the scope by
default. If you want to change the initial frequency and amplitude change “Initial
Frequency” and “Initial Amplitude” and then set “Set initial params?” to yes.
Enter the initial amplitude target. The default amplitude increment is 1dBm. If you
want to change this go to the “rfMonitor” tab.
If any of the monitoring intervals, breakdown limits or amplitude
increments/decrements need to be changed, click on the rfMonitor tab and change
them. However, the default parameters should be sufficient.
All other parameters should be left at their default value.
Click the run arrow at the top of the screen.
You will be prompted to enter the name of the log file. Go to c:\mtaRuns and create a
new file called YYYYMMDD-BT-runX.txt where YYYY=year, MM=month,
DD=day, B=magnetic field strength and X=run number.
E.g. 20080425-0.25T-run1.txt.
Everything sent to the log file is copied to the log window on the “rfMonitor” tab.
The program will first check the resonant frequency, calibrate the pulse width and
then switch to the rfMonitor tab and begin conditioning.
When the target has been reached the program will keep monitoring for breakdowns if
“Hold at Target?” is set to yes. The amplitude target and the increment can be
changed and the program will then work towards the new target.
If “Hold at Target?” is set to no then the program will turn the rf off and stop.
Pressing the abort button or if there are no input signals will turn off the rf and stop
the program.
Diagnostic Tools
SoftScope (desktop icon)
Software emulation of an oscilloscope for the DAQ card. Useful for checking
DAQ card parameters (e.g. voltage ranges and trigger parameters).
c:\work\mtaRFDAQCard\diagnostics\readScope2.vi
Check DAQ card parameters (e.g. voltage ranges and trigger parameters) and
peak finding parameters.
c:\work\mtaRFDAQCard\diagnostics\plotResPeak.vi
Scans the resonant peak, i.e. measures amplitude of the voltage probe signal as
a function of frequency.