I am trying to use a STM32 MMDVM board with a Pi 3 to make a higher power hotspot. My DMR radios are a TYT MD380, TYT MD 390, and TYT MD-9600 which all work just fine on my OpenSpot and the local repeater. I have tried using an Icom IC-F221, using the flat input, and an Alinco DR-605T, using the 9600 input. In both cases, I have set the deviation using the Bessel cal function in MMDVM and made sure the transmit frequencies are accurate using a frequency counter. In all cases, except one, the radios decode my uplink just fine, the BER looks excellent, and send it to the server, I see the server reply, I see my radio transmit the downlink, spectrum looks good, but I am unable to decode the downlink on any of my DMR radios. The one exception is that using the Alinco as the hotspot radio, my MD-390 does decode, but it has a lot of artifacts.
I have messed with TXINVERT and DMRDelay and anything else I can think of that might have an affect. The only thing I can think of now is that this might be some sort of bandwidth issue in the radio, but I would expect at least the F221 to work.
Anyone have any suggestions?
Thanks,
Gerhard