EE470 Analog Communication Theory
S 4.9: NTSC Television Broadcasting Systems
Monochrome TV transmitter
Video waveform for one full horizontal line.
Interlaced
scanning raster
with two fields.
Two interlaced
fields make up a
_____________.
Lines are blanked during the horizontal retrace.
Repeated Image with Unbroken Path
Video Spectrum for a Still Image
For NTSC f h =15.75 kHz and f v ≈
Hz
The required baseband bandwidth is
N − N vr
B=0.35( H /V )
T line −T hr
( H /V ) is the aspect ratio
N is the total number of raster lines
N vr is the number of lines lost during vertical retrace
T line is the duration of one line
T nr is the horizontal
time
For an NTSC signal the required bandwidth is 4.2 MHz
TV Standards Comparison
(a) Transmitted TV Spectrum
(b) VSB Shaping at ___________________
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Monochrome TV transmitter
Monochrome TV receiver
Color Television
The color TV signal was designed to be compatible
with monochrome television receivers.
The luminance signal is:
x Y ( t )=0.30 x R (t )+0.59 xG (t)+0.11 x B( t)
The
(a) Chrominance spectral lines
(b) Line to line phase reversal
Chrominance
lines (dashed) are
interleaved
between
luminance lines.
signals are:
x I (t )=0.60 x R (t )−0.28 xG (t)−0.32 x B (t )
x Q (t )=0.21 x R (t)−0.52 xG (t)+0.31 x B (t )
Line-to-line phase
The chrominance signals are broadcast using
____________ of
chrominance
variations on
luminance. (There
is also field-tofield reversal.)
-carrier multiplexing with a carrier
frequency that is halfway between the 227th
and 228th harmonic of f h :
f cc=
455
f =3.58 MHz
2 h
Color subcarrier modulation system
Color demodulation system
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