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[aprssig] 6 meter APRS or meteorscater formats?

Robert Bruninga bruninga at usna.edu
Mon Dec 31 22:05:59 UTC 2007


> What about ACKs from the gateway?  
> They'll have to go to the fake 
> message-to address, in this case 'wb4apr te'.

The Meteor Scatter Email messages are one way, out of the
affected area.   The ACK dies.

> 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?

The acks are sent only one-for one, hummh...
I wonder if they are continued to be sent when multiple incoming
copies are seen...

> Is it going to fill up clients' message lists 
> with weird messages?  

Good question.  But tthis way, at least the client will capture
a copy...

> Are IGates going to have a problem when they 
> start trying to gate a courtesy 
> position along with the message?

We do not expect any 6m Igates to be transmitting back.

> 
> 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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> > aprssig at lists.tapr.org
> > https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> > 
> > 
> 
> 





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