In my vehicle, I have a Byonics TinyTrac4 paired with an AvMap G6. I also have a Kenwood TM-D710 that I'm currently using for voice. I live in a region of the US where both 2m APRS and 70cm High Speed APRS are in common use, and am interested in using BOTH radios, one on each band, to feed the G6. I MIGHT be able to get away with an off-the-shelf NMEA0183 multiplexer, assuming they don't drop sentences they don't recognize, and they are a bit out of my budget.
Instead, I would like to use a Raspberry Pi, paired with some good NMEA multiplexing software.
Additionally, I do a lot of off-roading, and I like the idea of being able to digipeat across the bands as well, ensuring that 1) I'm heard in an emergency, regardless of what they are running, and 2) everyone else can see each other as well.
This is where things get a bit fuzzy:
To implement this functionality, I need to act as a digipeater, and I THINK that in turn requires the TNCs to be in KISS mode.
Fine, I can put the TNC in kiss mode, use APRSDigi (Or something similar) to run as a digipeater... But how to generate an NMEA Kenwood Sentence stream from there?
If I understand my problem correctly, I am looking for an APRS digipeater that generates an NMEA output...
Or I'm looking for an AX.25 to NMEA converter of some kind.
Or... Maybe I'm missing an obviously easy solution...