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Something to try to improve AO-40 telemetry reception



Hi,

I have been using AO40RVC, and my DSP-2232  using N4HY's enhanced modem
combined with P3T, running in parallel to capture AO-40 telemetry.  Averaged
over several passes, including very poor squint angles, the DSP-2232
outpoints AO40RCV by a small but consistent amount.  Perhaps 1 to 2 percent
better capture.  Of course that number might, and probably wood, change for
your particular receiving system.

However, the results were reversed until I tried a small tweak.  There is an
undocumented AGC command, AGC N/M, which applies to a whatever mode you are
using.  When you change modes, it resets to the default, AGC 2/2.  For the
400 baud TLM switching to AGC 3/3 seems to improve, slightly, the capture
efficiency.  By contrast, using 0 or 1 kills it completely.

I would be interested in anybody else's results.  You might try this with
other modes as well.  So far, no information from Timewave on what this
command is actually doing.


Alan
WA4SCA


-----------------------------------

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be it an elephant or a country, it
helps to know what part of it feels
pain. Be very, very sure, though, that
you want its full attention!

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