[amsat-bb] Thoughts on ISS packet switch back to 145.825 MHz (long)

Mike Diehl diehl.mike.a at gmail.com
Mon Apr 17 21:51:55 UTC 2017


You make a good point about the complications of dropped packets. I have some good recordings of voice stations getting a call back when as little as a single letter of their call was heard. It's amazing how well we can learn the voices of other ops when you're on regularly. This simply doesn't happen on packet.

Another complication is that it is on simplex. That means on a 10 minute pass the maximum amount of time possible to digipeat is 5 minutes if the channel is fully saturated. Subtract out the ISS beacons we end up with less than 50% of the pass available for ISS to hear you.

I'm not sure what the best solution is. You do bring up an interesting point about APRS-IS. Maybe it's possible to have them black list fixed beacon stations and remove the vanity aspect like you mentioned. 


Mike Diehl

> On Apr 17, 2017, at 1:26 PM, Greg D <ko6th.greg at gmail.com> wrote:
> Gabriel Zeifman wrote:
>> It's not complicated. However much it may be insisted ISS packet is not
>> SO-50, it is practically the same thing (single channel operating on FM).
> Actually, the ISS digi is worse.
> With voice communication, one can sometimes pick up the start or tail of
> a call sign, as the astronaut demonstrated, and use that to filter a
> second try.  With digital, any bits that get corrupted result in no
> reception at all.
> I hate to suggest this, and admit I am assuming a cause without
> supporting evidence, but it might be necessary to remove the "vanity"
> aspect of ISS digipeating, and take down or hide from general view the
> reporting sites that support it.  While a useful tool for
> troubleshooting, I suspect the vanity aspect of seeing your call in a
> public list day after day from an unattended station may be too strong a
> draw for some, resulting in the clogged channel.  The SatGates that
> monitor for ISS and other APRS satellite traffic are still important
> part of the infrastructure, so that the information can be datamined
> from APRS-IS if you need it for troubleshooting.  But the consolidated
> lists of who has been seen digipeating through the ISS, I think, may be
> contributing more trouble than they are worth.
> Greg  KO6TH
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