ncook - 3/28/2025 09:51

The first thing that comes to mind is the base isn't sending some of the position information messages continuously, but only once on startup? This information doesn't change like the observation messages do, but if a rover doesn't receive them once, it doesn't fix. So once every 10 seconds on these redundant messages is enough. Here are the MSM messages I send from a NovAtel (Leica) base that work with other receivers, though I haven't tested with Topcon.
rtcm1074 ontime 1
rtcm1084 ontime 1
rtcm1094 ontime 1
rtcm1124 ontime 1
rtcm1006 ontime 10
rtcm1033 ontime 10
rtcm1230 ontime 10
It might be also helpful to send RTCM1008 ontime 10, some receivers might require this.

Edit to add a second thought: Do you know what baud rate the radios are transmitting over the air, and over the serial port if using external radios? A lot of older 450 MHz radios only did 9600, and these MSM messages with information about 4 constellations end up too large to do that in 1 second, so the buffer would get full and cause problems.