[aprssig] Radio/GPS power control

Scott Miller scott at opentrac.org
Fri Jul 23 12:23:52 EDT 2004

The radio power control output function has been implemented in the latest
OpenTracker firmware.  It'll now send a signal (5 volts, 25 ma max) from 0
to 255 seconds prior to transmitting to allow an external relay or other
switching device to turn on the radio.

I seem to remember reading that the TinyTrak3 would do this for the GPS
receiver, too.  Does anyone actually use this feature?  Seems to me you'd
need a really low beacon rate to make it worth powering up the receiver and
waiting for a lock.

I'm thinking about producing a power control module that'd plug into the
OpenTracker and handle the switching, with a couple of 25-amp APPs for power
input and output.  Has anyone used the PCB-mount APP pins?  Any comments on
their durability?  I'm worried about the pins flexing and pulling up traces.

And on an unrelated subject, can someone point me to the 'official'
description of how wind gust speed should be calculated?  The APRS spec
doesn't really say.  Now that I've got the power control stuff working, as
soon as I get the 1-wire weather station support finished up I can finally
deploy some cheap, low-power weather stations.  Might even try one over


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