DVB S2 "Pilot" signal (1 Viewer)

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jvinccler

Member
Mar 5, 2009
8
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Miami
Coolsat 8000, 8100 and Pansat 9200 HD receivers have the "Pilot On / OFF" function, user selectable.

I did noted, some S2 brodacasts require set the Pilot "On" in order to get signal, others broadcasts does require set the Pilot "Off".

Please, could someone explain what the "Pilot" function is ? :confused:

Thanks in advance. :)
 
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dunnsept

SatelliteGuys Pro
Nov 10, 2008
358
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Central Meechigan
I am by no means an expert on this, and hopefully someone else will eventually chime in too. that being said:
Pilot symbols are added to help maintain frame synchronization.
Phase noise is more detrimental to 8psk than to qpsk so pilot symbols are added to help the demodulator minimize "slips"

if I'm wrong or off on this, hope someone else will chime in.. I'm just reading through the literature trying to learn what all this stuff is myself

hth
 

prasada2002

New Member
Jul 13, 2010
1
0
India
DVBs2 Pilots

Hi guys
hope this answers the question much more precisely

Frame synchronization is needed to indicate the start of each FEC block for the decoder. It also provides the necessary information for the receiver to apply the appropriate demodulator and decoder to demodulate and decode the transmitted information. Given that some overhead is necessary for frame synchronization, it is also designed such that it can be used to reduce initial frequency and phase uncertainty of the modulated signal. The frame synchronization is designed to provide reliable operation in the worst case Signal to Noise ratio with minimum overhead. It is also used to minimize the demodulator implementation loss in the presence of consumer quality low-noise-block (LNB) phase noise. In fact, phase noise is particularly detrimental to demodulator performance for higher-order modulation such as 8PSK, 16APSK, and 32APSK. To preserve the near Shannon limit performance of the DVB-S2 FEC, pilot symbols may be added to assist the demodulator to minimize probability of cycle-slips and to provide more accurate phase estimates. These pilot symbols are also designed to use a minimum overhead of the overall bandwidth, and can be turned on or off as desired.
 
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