[aprssig] Re: GPS to TNC APRS packet processor

Warren Brown vk3byd at amsat.org
Sun Mar 19 00:15:22 EST 2006


Hi Mark,

I have built an interface like this for my mobile station.

It use an Atmel Micro-controller to interface the GPS into a Kantronics Kam Plus
TNC.
This allows me to run HF (10Mhz)  and VHF at the same time whilst mobile.

73
Warren VK3BYD

>
> 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
> compatible still able to be used for APRS tracking without a computer.
>  Even for TNC's that have this capability like the KPC3+, they send
> raw NMEA packets, which are long and cannot contain altitude, speed
> and heading all at the same time.  The microcontroller could buffer
> and parse the NMEA data and put it all into a Mic-E formatted packet,
> 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
> very difficult to set the squelch at a level in which it will only
> open up for a packet signal and for every packet signal, not just the
> ones that are 20 over 9 on the meter.
>
> So is there such a creature out there?  If not, does anyone else see a
> real market for something like this?
>
> 73,
> Mark VO1ONE
>
>
>





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