[amsat-bb] QIKcom Satellite Modes?

Douglas Quagliana dquagliana at aol.com
Sun Feb 22 02:03:49 UTC 2015

Bob asks:

>I just cannot think of any neat must-do ideas for how to use
>the other bank settings.
>The settings in bank 0 are now:
>BTEXT:              USNA-W3ADO APRS Satellite every 2 minutes
>I just cannot think of any use for a separate bank settings?
>If you have ideas of how to use the A/B settings let me know.

If you don't have any other ideas:

Set BTEXT to a short beacon message that includes a
few sync bytes, your preferred text message and a few
bytes of forward error correction.  You would have to
pre-compute these and manually enter the FEC bytes
at the end of the BTEXT.  All of this would be sent
INSIDE the AX.25 packet as the BTEXT.  That way
standard TNCs would still see the BTEXT message
and a few binary bytes (if they get a valid CRC)
but we could write DSP software to ignore the HDLC
flags, look for the sync bytes, and process the FEC
too.  Depending on your message you might want to
8b10b encode it to avoid HDLC zero bit stuffing which
could complicate the ground software.

At four watts RF output, you don't need the FEC, but
it would be an interesting experiment, and easy to
do as you only need to pre-calculate the FEC once
and hardcode the BTEXT message.

Douglas KA2UPW/5

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