rx only satgate with terrestrial fill-in digi/igate quirks

[Darren Long]

Hi all,

I run an Rx only Satgate, G0HWW-4 and a terrestrial digi/igate, G0HWW-12
now and then, and occasionally a third UHF digi/igate when I'm also
experimenting on 70cm, G0HWW-9, although the latter can be ignored in
respect of the quirks I shall describe.

G0HWW-4 is Rx only but I do run a perl script that doppler tunes my
FT-847 for whichever satellite is up and that beacons on behalf of
G0HWW-4. For now it just follows the ISS and NO-44 and beacons when
they are overhead. All this is done using 3 Linux kernel AX.25
interfaces.

It seems that aprx is so efficient at feeding G0HWW-4's beacons into the
APRSIS, which it receives directly on the local AX.25 interface, that
there is no no indication anywhere that the beacon actually got out onto
RF, unless G0HWW-4 itself hears a digipeated packet and I look in the
aprx-rf.log, or I ask EI7IG to look in his logs for me, for example.

It would be nice if there was a way to filter packets sent from the
interface's callsign-SSID from the feed into the APRS-IS. I can of
course do this if the beacons originate from within aprx, but beaconing
for G0HWW-4 from the perl script is much easier as I can ensure that the
rig doesn't QSY for doppler compensation whilst there's a beacon packet
in-flight and inhibit beaconing when there's no birds in sight.

Another quirk is that traffic received via ARISS by G0HWW-4 meant that
related traffic received from APRS-IS by aprx was transmitted on the
terrestrial APRS network by the G0HWW-12 digi/igate. I resorted to
severe filtering to block this traffic but I don't really understand why
aprx chose to forward those packets through G0HWW-12 when the related
packets were heard by G0HWW-4 which may not transmit (within the aprx
configuration). Ideally it would have considered gating them through
G0HWW-4 but then drop them as transmission is not allowed through that
interface, or so I would have thought.

Other than these corner cases I've observed, aprx works very nicely for
me and my little island of connectivity here in Bury St Edmunds :)

Suggestions are welcomed.

Cheers,

Darren, G0HWW