[aprssig] Airborne Digis

[Keith VE7GDH]

Bob WB4APR wrote...

> Maybe the best solution is the specialized trackers that can alternate
> paths.  Send every other packet on 144.99 for the potential when there
> is an aircraft in view.  But send on 144.39 most of the time...
>
> OOPS, most trackers cannot auto QSY like that.

The RTrak from RPC Electronics can do that. www.rpc-electronics.com

It is essentially an OpenTracker (OT1+) built into a 500 mW transmitter.
The current model has a built-in GPS receiver and a provided external
antenna.  It is frequency agile and can be programmed for any frequency
between 144 and 148 MHz. It has the ability to transmit on the alternate
frequency every X transmissions. It can also do SmartBeaconing and
profile switching based on altitude, speed, temperature, voltage, ADC
input, a jumper (external switch) or valid / invalid GPS fix.

While the T2-301 is frequency agile as well, it would require changing
the frequency with the SETFREQ command.  While this can be done at any
time from a terminal program or e.g. Nuvi 350, or even a built-in
script, you wouldn't want to constant toggle the frequency as it would
write to the flash ram every time you did it. With normal use and
occasional re-programming, it should last many years. Toggled every
minute, it would probably wear out in weeks or months. I don't recall
the exact details on how many times it can be written to, but it is a
limited number of times.

Perhaps someone could comment on the frequency agile Micro-Traks from 
www.byonics.com.

73 es cul - Keith VE7GDH
--
"I may be lost, but I know exactly where I am!"