[amsat-bb] ISS Beacons (APRS-FAQ!)

Robert Bruninga bruninga at usna.edu
Tue Apr 19 14:55:00 UTC 2016

Re ISS beacons:  Here is the beacon gouge for APRS via ISS

APRS was designed for channel sharing using the ALOHA protocol.   That is,
peak success occurs at around 20% channel capacity.  For 1 second packets,
that's only 12 packets per minute per digipeater area.  This usually means
maybe 5 mobiles at a 1 minute rate and 30 other home stations and weather
stations, etc at a 10 minute rate using 1 hop and 60 other assets
beaconing every 30 minutes when using the maximum of 2 hops.

But on ISS, the digi neighborhood covers the entire USA at once!

So, it is a travesty that people transmit unattended beacons via the ISS
at such high rates causing nothing but interference with those trying to
actually operate the pass.

See the original APRS-ISS FAQ:  http://aprs.org/iss-faq.html

It recommends 1 beacon per minute for LIVE keyboarders,
1 beacon per 2 minutes for active special live mobiles engaged in travel
or special operations,
and one beacon per 5 minutes for unattended status/position reporting.

The goal is to optimize the channel for live operators during a pass but
for non-moving remote unattended position/status packets to be successful
only about once a day (NOT every pass!) on http://ariss.net

Bob Bruninga,wb4apr

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