[aprssig] Re: Protocols (OTA)
tkomljan at yahoo.co.uk
Sun Apr 6 14:02:53 CDT 2008
Sure there are more efficient protocols that could be put into service for APRS. But from my experience in the Toronto to Niagara Falls area tying to use an OT2 with a 5W mobile (car mounted antenna) package, the issue is not with the number of bytes, but with packet collisions and Aloha!
I can get semi-reliable mobile operation only within about 3 kms from an urban digi. Any more distance than that and the number of successful packets getting into the database goes down exponentially.
The same scenario into an isolated (rural) digi yields reliable coverage to the limit of the 5W range.
I'd sure like to see over-the-air traffic control to reduce/eliminate packet collisions! How about AIS (although it is patented and GMSK)? http://oh7lzb.blogspot.com/2007/08/ais-ship-tracking.html Or any other existing and successful standard tweaked for amateur use?
Is there a generally accepted complimentary VHF APRS frequency that can be used in a DUPLEX configuration?
I've enjoyed APRS and appreciate all the work, software, hardware and servers that many people have put into it. Just need to make it more reliable in the cities.
>I have been doing some work with RADAR >protocols, that by nature have to be small in payload >and contain as much info as possible.
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