In TV Transmission the use of FM is made for Audio
transmission and AM for Video transmission.
Vestigial Sideband modulation (VSB) is used for the
following reasons :
1. Video signal exhibits a large bandwidth and significant
low-frequency content which
suggests the use of VSB
2. The circuitry for demodulation in the receiver should be
simple and therefore cheap.
VSB demodulation uses a simple envelope detection.
But the practical TV signals are not exactly VSB modulated
due to the following
I) The power at the transmitter is very high and it would
be expensive to rigidly control the
filtering of sidebands. Instead, a VSB filter is inserted
in the receiver where the powers are
VSB i.e. Vestigal Sideband Modulation is usedfor TV
transmission. Vestige means "PART". The part of side band
is used to transmit the video signal and the remaining is
used for transmitting the voice signal.
TV signal consists of audio and video signals. for audio FM
is used and for video AM is used. this is in india.
different countries follow different modulation techniques
for audio and video signals. in india we use PAL system.
thats why we use above said modulation techniques.
in TV transmission for audio signal FM modulation is used
and for video AM modulation is used and also the VSB for AM
in this method we know about AM in this two side bands and
carried also in this only one side band fully and other half
part of other side band
IN TV signal Transmission a technique is employed called
as vestigal sideband technique.
Such technique limits the band to 7mhz per television
channel that could be 11.25mhz since video info. has 5mhz
band and requires 5 x 2= 10mhz + .5(freqency rolloff
response of filter per side band,here usb) + .5 (lsb) + .25
(guard band for sound carrier) = 11.25 mhz for its
transmission. Since usb and lsb are replica of each other
having same variation in their band with the change in
modulating video signal we could remove one of the band
partially. This partial removal technique is what we
called vestigal sideband technique (VSB)