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Re: Squint



Not to mention that "squint" (Ofp) does not appear to function in WiSP. If there
is a trick, please clue me in! Which tracking programs can be relied on for
squint angle calculations? I haven't been able to locate much info on that
topic. Besides the squint (off pointing) issue, newcomers should remember that
the high gain S band antennas on the bird are very directive. My limited S-
beacon RX experience has been that most of the low altitude pass time I am in
the "side lobe" part of the antenna pattern. For now, without really good tools
to predict the offpointing and the footprint I have found that apogee passes are
the best bet.

The key thing for me was to get the LNA noise figure under 0.7db. Then I could
copy good CRC all the way out to 64,000km.

It also appears that the AGC circuit in my TS790A is playing a role in the
inability to copy through deep fades in the signal. The radio does allow for
"fast" AGC action but the delay still seems perceptible to me. Anyone tried to
disable the AGC completely in this rig? I am concerned that if I disable it, I
will have to reduce my downconverter signal which runs S9+20.

The other issue at these high squint angles is the polarization penalty. I'd be
willing to bet that the side lobes are not circularly polarized at all times
when they reach my antenna. If they differ 90 degrees(even for a moment) there
is a BIG loss. It would be interesting to mount an identical setup with the
opposite polarity on the same boom. Could I trust the results obtained with
truncated dishes mounted 90 degrees apart? Comments on that would be
appreciated.

Vince Risalvato KD7AI

> Wayne replies:
>
> If somebody is struggling to receive AO40 for the first time, they cannot get
the ALON/ALAT information from the beacon.
>
> So the obvious question is:  WHERE is up-to-date alon/alat information
published?
> I can't find it on the AMSAT-NA, AMSAT-DL, or AMSAT-UK web pages, and it is
not announced to AMSAT-BB on a regular basis.
>
> Wayne Estes W9AE
> Mundelein, IL, USA


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