Recently, I have heard a number of Dstar users discussing the configuration of GPS and the forwarding of GPS positions to the analogue APRS system, so I thought that I’d add some basic information here on how to set it up. I say basic as there is a lot of information out there on the internet with detailed descriptions on how it is linked. and how it works. If you want to know the details then have another look, but the basics of setting it up are here.
There are 2 types of GPS configurations within a DStar radio GPS and GPS-A.
You will need your radio setup for GPS which basically involves insuring that your radio is setup in ‘Gateway mode’ i.e. within your Callsign menu you are setup in RPT2 with the callsign of the repeater or node your operating through and that you have the G in the 8th position,(GB7xx G) also that you are transmitting Data only when you press the PTT and that the data is on, (G-D on the display of a 2820 for example)
Radio Configuration – GPS Mode
Because there is no error detection or correction on the data channel, D-PRS must have a specific message format for radios running in GPS mode. This message can be calculated on the D-PRS Calculator page.
Only the RMC and GGA GPS strings are used in GPS mode. Set your radio to only use those two GPS strings.
Radio Configuration – GPS-A Mode
Radios in GPS-A mode do not need to set their GPS message per the D-PRS Calculator page. Instead, they should set their UNPROTO to APInnn,DSTAR* Note that the first part which is commonly called the “unproto” or “destination” field is comprised of the APRS standard for Icom, API, followed by the first 3 digits of the radio model number. In the case of the handhelds (only 2 digits), you may optionally use the first character following the model number (92AD would be API92,DSTAR* or API92A,DSTAR*).
NB: It is important that the UNPROTO does not contain any extra spaces and that it only contains the “,DSTAR*” as the only “digipeater” in the path. The asterisk (*) at the end in important and must be included.
GPS-A UNPROTO Setting
Hopefully this makes sense and I look forward to seeing you and your GPS location popping up on my screen soon.