Re: [amsat-bb] Digipeating via AO-16

[Paul Williamson <kb5mu@xxxxxxxxx>]

At 10:59 PM 4/9/2001 +0100, you wrote:
>Perhaps it's something simple & I have the UNPROTO set wrong: it's set at CQ
>VIA PACSAT-1 at the moment.

That's right.

Your 2m rig is in FM mode, and set for simplex (no repeater offset) and no 
PL, I hope.

It should be tuned to 145.900, 145.920, 145.940, or 145.960 MHz. Sometimes 
one frequency will work when another one doesn't. I think this is due to 
terrestrial interference. Usually, you don't need to worry about Doppler 
shift on 2m, but you can get a little edge by tuning about 3 kHz lower at 
the beginning of the pass, on frequency in the middle, and 3 kHz higher at 
the end.

If you have another 2m rig, listen to what you're sending on the uplink. Check:

1. Are you really transmitting? If you don't have the TNC set to full 
duplex, you won't transmit while you're hearing the satellite.

2. Are the levels reasonable? The packet noise should be about the same 
volume as open squelch noise, or a little quieter. It shouldn't sound too 
harsh, indicating audio clipping.

3. Is your TXDELAY high enough? You can hear this as a distinctly audible 
preamble at the beginning of every packet. If you can hear a little 
preamble, you're good. Lots of preamble is harmless but unnecessary. If you 
don't hear anything different at the beginning of the transmission, you 
need to increase TXDELAY in the TNC.

I have not used the PSK-1, so if there are any special tricks for it, 
somebody else will have to provide them.

I'll try to remember to get on AO-16 this evening and make sure it's still 
digipeating OK.

73  -Paul
kb5mu@amsat.org

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