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[aprssig] 6 meter APRS or meteorscater formats?

Scott Miller scott at opentrac.org
Mon Dec 31 21:36:31 UTC 2007


What about ACKs from the gateway?  They'll have to go to the fake 
message-to address, in this case 'wb4apr te'.  What are the side effects 
going to be of messages to and from these bogus addresses, which might 
contain spaces or other characters not normally expected there?  Is it 
going to fill up clients' message lists with weird messages?  Are IGates 
going to have a problem when they start trying to gate a courtesy 
position along with the message?

I'm all for shorter messages, but I think it's pushing the spec a little 
too far, and in an area where there's a lot of ill-defined behavior on 
the part of clients.

Scott
N1VG

Robert Bruninga wrote:
> An idea to make the outoing APRS Email message 10 bytes shorter
> is to modify the format slightly.  The existing format is:
> 
> WB4APR>APRSXX::EMAIL    :wb4apr at amsat.org test message
> 
> To:
> 
> WB4APR>APMAIL::wb4apr at am:sat test message
> 
> The EMAIL engine would look for the unique AX.25 TOCALL of
> "APMAIL" to indicate an email message.  The MESSAGE format
> remains, but the full 9 byte field is simply used as the
> beginning of the message.  This way, all existing APRS clients
> software will capture and display this message as an APRS
> message, it is just that it saves 9 bytes which is important for
> Meteor Scatter.  In fact, I can invision a few other shortcuts
> such as:
> 
> WB4APR>APJUNO::wb4apr te:st message
> WB4APR>APARRL::wb4apr te:st message
> WB4APR>APAMST::wb4apr te:st message
> 
> These would be emails to wb4apr at juno.com, or arrl.net or
> amsat.org, etc.
> 
> Total duration at 1200 baud of the above message is 290 ms.
> 
> 
> 
>> -----Original Message-----
>> From: Robert Bruninga [mailto:bruninga at usna.edu] 
>> Sent: Wednesday, December 19, 2007 5:56 PM
>> To: bruninga at usna.edu; 'TAPR APRS Mailing List'; 'Stephen H.
> Smith'
>> Subject: RE: [aprssig] RE: 6 meter APRS or meteorscater?
>> 
>> Here is more of the idea for an APRS meteor Scatter first
>> response communications system:
>> 
>> 1) I already mentioned adding 51.63 MHz receive monitors
> running
>> 1200 baud APRS to many strategic Igates.  This listens 24/7
> for
>> outgoing emergency emails from the affected area.
>> 
>> 2) How about we use 2 meters, 147.585 at 9600 baud to throw
> any
>> emergency response traffic back into the area...
>> 
>> Using 100 Watts, a good beam pointed at the affected area from
>> about 500 miles away, and then continuously beaconing any
> needed
>> APRS one line messages back into the area at 9600 baud, would
>> let anyone driving around in the area possibly receive this
>> traffic on their D7 or D700 radios without having to keep a PC
>> runnning.
>> 
>> We have demonstrated that 6m works great, and 2m can work
> during
>> meteor scatter, so this is an area ripe for experimentation.
> I
>> think the 6m will work fine.  But we need people to test the
>> success rate of forcing a message into an area using 2m.  And
> to
>> determine if 9600 baud is that much better than 1200 in this
>> case...  
>> 
>> It is the one-hand-clapping advantage of APRS that can help
> make
>> this testing more successful.  Receivers just inject into and
>> Igate,  Then Transmitters test at will.  When the other end
>> receives their packet, they can see it themselves on the
>> APRS-IS.  For this test, then I would receommend transmitting
>> every single packet with a unique serial number embedded in it
>> so that the APRS-IS dupe filters will not filter out all the
>> successes.
>> 
>> Any teams want to start testing?
>> 
>> Bob, WB4APR
>> 
>> > -----Original Message-----
>> > From: aprssig-bounces at lists.tapr.org 
>> > [mailto:aprssig-bounces at lists.tapr.org] On Behalf Of Robert
>> Bruninga
>> > Sent: Wednesday, December 19, 2007 5:40 PM
>> > To: 'Stephen H. Smith'; 'TAPR APRS Mailing List'
>> > Subject: RE: [aprssig] RE: 6 meter APRS or meteorscater?
>> > 
>> > >> Since Meteor scatter is a continuous statistical
>> > >> process, then as long as the outgoing message has 
>> > >> been in the TX queue for X minutes, then there is 
>> > >> a 99% probability that it was received and injected 
>> > >> into the internet.  Done.
>> > >>
>> > >> We can experiment to find out what X is.
>> > >> One X for using a 2 dBi gain vertical and 
>> > >> another X for using a small beam.  
>> > >
>> > > Huh??   How would you aim a beam at randomly 
>> > > occurring events? 
>> > 
>> > Say if you were in New Orleans, you would point your beam
>> > towards the highest density of potential listeners that are
>> > about 500 to 1000 miles away.  That is the optimum range for
>> MS.
>> > So I'd point towards the Eastern Seaboard.  Then hammer
> away.
>> > See my meteor.txt with the original APRSdos:
>> > http://www.ew.usna.edu/~bruninga/meteors.html
>> > 
>> > > I'd be ready to give this a try...here in the 
>> > > greater L.A. area,  weak-signal 6M receive is 
>> > > totally buried under 50-100 uV of lower-sideband 
>> > > "grunge" from channel 2 ...
>> > 
>> > You could still make a great TX site for the TX end of the
>> > test...
>> > Bob, WB4APR
>> > 
>> > 
>> > 
>> > _______________________________________________
>> > aprssig mailing list
>> > aprssig at lists.tapr.org
>> > https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
>> > 
>> 
>> 
> 
> 
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