[aprssig] Tiny Telemetry

Rick Green rtg at aapsc.com
Tue Aug 31 09:14:46 EDT 2004

On Tue, 31 Aug 2004, Robert Bruninga wrote:

> Need a small APRS gizmo for remote telemetry?
> The pocket tracker which combines a TinyTrak
> and a small 144.39 transmitter and a 9v battery
> into a shirt pocket device (fits in an Altoids can)
> is ideal.
> Of course, it only processes GPS data, but wait!
> For other purposes, remember that GPS data is
> just numbers and there is nothing that says it
> has to mean LAT/LONG.  So if you want to have
> a quick way to get a unique telemetry system on
> the air, just have your little project output a GPS
> NMEA string but let the 13 or more digits mean
> whatever you want.  THen decode them on the
> other end...
> Anyway, just a quick way to get some unique
> telemetry on the air in a small off-the-shelf package...
> de WB4APR, Bob

  ...consider that you might totally confuse some APRS clients with the
nonsensical or potentially invalid lat/lons they would receive.
..but for an absolutely minimal binary status transmission, the sensor
could be wired to the 'alternate config' pin on the Pockettracker's PIC,
and the meaning inferred from the change in digi path or some other
parameter, while still maintaining valid APRS transmissions.

Rick Green

"They that can give up essential liberty to obtain a little
 temporary safety, deserve neither liberty nor safety."
                                  -Benjamin Franklin

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