"O.K. I just assumed you were using a Nuvi since you mentioned Garmin protocol. If you are using a Garmin GPS puck, then you have a choice of NMEA (default) or Garmin protocol (via Garmin config software) and both are rs-232 compliant TTL level outputs which would be easy to split to two outputs, one bi-directional to the T2 and one single ended."
Actually I am using an oldie but goodie, a GPS V. I connect using the Garmin protocol which allows different waypoint symbols with APRS. I see a car for me for one example. In the NEMA mode, waypoints sent to the GPS are simply dots. That is not that cool. There is one advantage with NMEA though. If I make all my waypoints something other than the dot, then I can clear APRS waypoints easy by just deleting based on the dot symbol. "Scott can correct me, but I believe the Gtrans circuit has a USB input like the Garmin cable rather than a level shifter. In which case you need to parallel both on the USB side, again with only one of the cables being connected to the ID pin on the mini-USB going to the GPS." Well, it does and I don't. In reality the GTRANS is the entire cable assembly. But... The processors in the T2 and GTRANS are the same. The only difference is the code running in each of them. The T2 processor runs APRS stuff and quite well at that. The GTRANS processor converts Garmin protocol to NEMA protocol. On the GPS side, the T2 can talk NMEA or Garmin. The GTRANS only talks Garmin on the GPS side. I bet the T2 and GTRANS actually share the same code for doing the Garmin protocol. Which means, any signal conditioning (level conversion, USB to RS232, etc) is done external to the processor. In the case of the T2, some is done in the T2 (U1, MAX232) and some in the cable (there is a bump which must have something in it or why have it?). Therefore, if the conditioned signal that goes to the T2 at pin 10 is also connected to pin 10 on the processor of the GTRANS, then I have effectively split the signal. Of course whatever is normally connected to pin 10 must be disconnected in the GTRANS first. That is why I only want the GTRANS PCB. I suspect the signal going into each processor is identical. The beauty is I get my regular operations on my T2 (Garmin mode) and I get a NMEA output for other things without having a second GPS hanging about. I can feed it to a laptop, D-Star radio or something else. What would you use a NMEA output for? Best regards, Fred
