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Help for AO40 signal verification needed



>Hello all, 

Hi Günter,

and congratulations on your well working
system !

>i am very interested to know if someone 
>else can receive a signal from the beacon 
>at this frequency: qrg= S2 MB - 978 kHZ 
>It is in the S1 band.But you need a big 

I will not confirm the signal level "live" 
(I have a 3 m dish, but will not be 
able to use it for a few days), but
I CAN confirm that you are quite correct !
The sidebands are symmetrically on both sides
of the passband center frequency (MB),
so you should hear it also above the S2 MB.

The sidebands you are hearing are leakage
of the HELAPS modulator switching frequency.
These spikes are about 40 dB down from the 
Middle Beacon when passband signals are 
9 dB below middle beacon, i.e. the absolute
level of the spikes will vary with 
transmitter (and receiver) AGC values. 

It is entirely normal operation of a 
HELAPS transmitter to have these spurious
signals and the -40 dB(MB) levels are
also normal.

As a challenge you can try copying the
carriers at twice this distance from the
MB but they are even 25 dB lower :-)

>dish-i think minimum 3m.Here i have at 
>the moment at MA11 Orbit 524 about 5db 
>S+N/N.(6m dish) With various tests i 
>can carefully say its not a local effect
>(intermod...mixing ...) The best times 
>to listen are between MA235 to MA25. 
>At apogee i also have problems to 
>detect the signal-its very weak then. 

You jolly well should be experiencing 
problems copying these signals - they
have been suppressed intentionally :-)

>So please have a look! 

>vy 73 Günter DF4PV 

Kind regards,
Michael, OH2AUE


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