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Re: ao-40



Hi Drew,

Drew Glasbrenner wrote:
> 
> This is not a criticism, but why is the beacon in the middle of the
> transponder? Wouldn't it make more sense for the beacon to be at the edge,
> outside of the passband like the RS and FO sats?

The GB, MB and EB are generated in the IF path and feed into
the MATRIX.  While GB and EB are outside the pathband, there
is a problem with V-TX and other modes with a too small pathband.
The 2m satellite segment for example is only 200 kHz and there is 
a filter in the TX to avoid out of band transmission.. thus, no GB and
EB on 2m. The only solution was to create the MB, in the middle
of the pathband..
Than you may indeed still ask, why is there only MB on S2-TX and
no EB or GB.  This is simple: the MATRIX only had a limited number
of possible crosspoints and at one time we needed to decided which
goes where.. If you look at the MATRIX design and description, you
will see what I mean..
And indeed, the MB is about 10dB stronger than the GB, to give
good telemetry downlink..  Once we are on S1, we will use the GB
to free some of it's RF output for the transponder..
It might also be possible to feed GB through the LEILA loop into
S2 instead of MB, but this needs some testing and might be done
later..

73s Peter DB2OS


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