BTW, the cross-band repeater is a voice repeater, not APRS. You talk in on 145.990 (with PL 67Hz) and listen on 437.800. There's other voice amateur satellites. I've dabbled in making contacts but it's not something I can claim a lot of personal experience. What I've done of it has been with an dual band/dual VFO HT and handheld Yagi.
https://www.amsat.org/
The APRS segment of the ISS is a different system.
Sounds like you can setup a ADHOC network using ISS. I wonder how much bandwidth that ISS can receive and transmit. If it can do enough maybe you can establish the network somewhere on earth instead of the ISS. Either way I find this interesting.
We don't really have an APRS 101 thread, although Marco and TJ started threads that kind of serve as that.
Hi All, This will be super geeky but I figure if it's in this forum nobody can fault me for it. I have stolen the limelight in others threads for too long and have decided it is time to start my own thread to document my attempt to utilize APRS to my advantage while wheeling and exploring...
risingsun4x4club.org
I am slowly learning a little more about HAM radio capabilities. I still think APRS sounds really cool and I just figured out the FT-1 didn't need an external GPS b/c it had GPS internal. Now of course the FT-1 is discontinued. Does anyone know why they discontinued that radio? It looks like it...
risingsun4x4club.org
APRS is something a few in the club have but only a few of us do any more than beaconing positions. It's much more than just that, two-way messaging, weather reporting objects, broadcast messages, station telemetry or status, there's also an SMS gateway and an email gateway, etc.
We have Bob Bruninga, WB4APR, to thank for APRS itself.
http://www.aprs.org
Basically APRS is ad-hoc, stations may join and leave at will, that greatly favors short data burst (the largest frame is around 328 bytes, AX.25 formatted carried over the via simple Bell 202 modem) for wide area information exchange over sustained simplex or BBS type communication that's traditional packet radio.
The APRS on the ISS is a subset APRS network. It doesn't interact with the regular APRS network because the nature of an ISS repeater would end up being swamped. It would might have thousands of stations trying to fight for slots, each filling its 1200 baud link with 250 ms packets. As it is some of main top tier dipeaters in Denver are at 100% duty cycle most of the day and they're only covering a few square miles with a handful of lower dipeaters. The ISS APRS dipeater has a footprint so much larger, it would a real charlie-foxtrot.
The bandwidth limit is in the FCC rules. For 2m we're hard limited to 19.2 kbaud (symbol rate). On 70cm we can do 56 kbaud. The APRS VHF link on the ISS can do 1200 baud (this is typical for the AFSK modems we use for APRS) and for the most part 9600 baud is the practical limit on 70cm. In theory if someone wanted to build an v.34 or OFDM repeater for an AMSAT we could do pretty decent bitrates, although doing so over the air with Doppler shift isn't easy. The FCC rules allow up to 100KHz bandwidth on 70cm, for example, so that would be our limit. Even 9600 baud AFSK on terrestrial 70cm can be difficult. It's of course 100% doable.