[aprssig] GPS to TNC APRS packet processor

scott at opentrac.org scott at opentrac.org
Fri Mar 17 18:04:12 CST 2006

> Just wondering if anyone has invented such a device, perhaps using a
> microcontroller of some sort, that would sit in between a GPS and a
> TNC so that TNC's which are not out-of-the-box stand alone tracker

I don't think so, mostly because it costs just as much to make one that does
the same thing without needing a TNC.

> and the TNC could take care of transmitting it.  Using a real TNC
> would have its advantages versus a TinyTrak, et al on HF since the
> method of carrier detection is by audio voltage.  On HF, I find it

You can just add an XR2211-based carrier detect circuit to an OpenTracker or
TinyTrak.  The newest OpenTracker board I'm working on (the Tracker2) is
already in beta testing and has a '2211 circuit built in.  It'll cost a bit
more than a regular OT kit, though.  And I haven't written the software DCD
code yet - white noise will trigger it right now.  That's a 5-minute fix,
though - there's already a flag that tells it if the DPLL is synced, just
need to feed that into the CD counter.

I guess maybe using a T2 doesn't count as 'without a TNC', though.  It's a
TNC in itself, and will do KISS and operate as a digipeater.


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