[aprssig] APRS Device in Mongolia?

Robert Bruninga bruninga at usna.edu
Mon Apr 14 12:03:32 EDT 2008


APRS remote instrument in Mongolia?

We might possibly have a ride to a mountain top in Mongolia for
an automated stand-alone APRS environmental sensor.  If anyone
wants to build one of these, maybe we might possibly get it
added to the expedition.  Here is what I am thinking:

1) 5W TX on 145.825 APRS satellite uplink
2) Solar powered
3) very small, simple and lightweight
4) Possibly camouflaged

Im thinking not a full WX station.  Too many parts and too
bulky.  Just something that demonstrates our ability to report.
Using the 5 channels of APRS telemetry from a KPC-3 or other
APRS telemetry device, maybe these parameters:

1) Battery voltage      (2 resistors)
2) Solar luminosity     (photodiode
3) Air temperature      (Thermistor
4) Ground temperature   (thermistor
5) Ground Conductivity  (two stainless steel screws)

This could tell us about the amount of sunshine, the moisture in
the ground, the temperatures and the balance between all of the

The device would need to beacon once every 2 minutes 24/7/365.
to be heard a few times a day by any of the APRS satellites.
Hoppefully a ground station in Japan would feed it into the APRS

At that rate, the average power is about say 10 mA at 8 volts
and would need about a 1 watt solar panel (about 6" square)...
I'd build it into a piece of PVC pipe that can be half buried,
with the top section clear to allow the solar cells to work.  A
whip antenna should hit the ISS or PCSAT..

Anyone with time on their hands?
Bob, Wb4APR

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