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[aprssig] Meteor Scatter tests

Robert Bruninga bruninga at usna.edu
Thu Oct 11 20:48:26 UTC 2012


Meteor Scatter APRS tests?

For what it is worth, I have a long term goal to put up a 6 meter and 2
meter meteor scatter experiment here at the Naval Academy.  To make MS
work, one has to transmit at high channel rates.  To save power and QRM, I
hope to come up with a remote controllable MS station.  If you want to
conduct an experiment you send it an APRS message (normal APRS on 144.39).
It will come up in high data rate transmit for maybe 10 minutes and then
automatically shut down.

Ideal experimenters would live between about 600 to 1200 miles from
Maryland and just point a horizontal beam towards us and see what they
get.  If any other station wants to consider putting up such an
"interrogatible" MS transmitting station, then here is what I am
considering...

I'm thinking about putting it on the Propnet Freq?  147.585?   When it is
interrogated, it will come up and transmit 1/2 second packets at a 2
second duty cycle for the full 10 minutes of each experiment.  The 10
minute time out is just to make sure it does not remain always on when not
in use.

I'm thinking the interrogation message might simply be: message to
W3ADO-4: ?2mSW and it will respond with its SW pointing beam on 2 meters.
Another interrogation might be ?6mSW for the same thing on 6 meters.

It will respond with a message to your callsign saying "MS 6mW up".
Notice it did not have a SW beam, so it responded with what it had... in
this case a west beam.

The format of the APRS MS packets is IAW:
http://aprs.org/APRS-docs/METEOR.TXT

W3XYZ>APRS:>GG##gg$USNA^HP

     Where ">" makes it an APRS STATUS packet
     The first word is a 6 character Grid Square
     - is the APRS Symbol or ICON (a house in this case)
     COMMENT will be USNA
     ^HP encodes my beam heading & power according to the following:
              P = SqrRoot(P/10): 2=40, 3=90, 5=250, 9=810
              H = heading /10:   2=20, 9=90, A=100, Z=350

In my case the beam heading is SW (240 degrees) from Maryland to hit the
most states and maybe 40 watts.  So my ^HP will be ^M3.

We are building the beams now.  But who knows how long till we finishe the
whole project.

Just sampling interest.  The design will simply use a low power 144.39
APRS radio for the APRS communication and a small PIC processor doing the
messaging, and then pulling in the appropriate relays to bring up the
transmitters and beams.  NO PC involved.

Bob, WB4APR



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