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AO-40 K-Band and FEC telemetry

Hi Group

During the last two available orbits, I have been able to compare FEC 
telemetry to the standard tlm on K-Band.  I am using the StaRCV soundcard 
software to receive the tlm.  This seems to work as well as AO40rcv 
for  standard telemetry.

With no passband activity,  some standard blocks and all FEC blocks are CRC 
OK.   With passband activity on, the level of the beacon is modulated by 
the user signals and this generally causes most standard blocks to be 
corrupted.   The FEC telemetry seems able to cope with this "amplitude 
modulation" and most blocks are recovered as good.

I am using CP to minimise spin fading.  I would guess that FEC would be 
able to cope with the deep  spin fading  present when linear polarisation 
is used.

Signal levels are currently quite good on K_Band.  This morning I measured 
16dB S/N ratio (at 5 deg squint).


Charlie G3WDG


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