Has anybody ever done the above? I can get at the discriminator tap, of a suitable radio, to obtain the audio. I am wondering if anyone has firmware to program either a PIC or AVR to decode into NMEA-HS (38,400 baud).
I'm not sure if this will help but all the NMEA data seems to be in this format NMEA. So I assume if you use any controller with a USART on board this would receive the data, which you could then decode as required. There is also a lot of code examples available on the web - what language are you hoping to use?
The raw audio is GMSK encoded. What I am looking for is a way to decode this into NMEA-HS.
I understand NMEA alright, not the decoding required to get to the NMEA strings.
I am not interested in decoding the NMEA !AI sentences directly. There is plenty of freeware that can do this already. eg NMEA monitor.
Sorry if I wasn't clear enough. There is also freeware that can use the sound-card of a PC to encode to NMEA, which NavMon can then use. Cannot remember the name at the moment though.
What I would like to do is to do the sound-card to NMEA decoding.