DMRDelay vs DSP based repeater synchro issues

Help with DMR issues
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DMRDelay vs DSP based repeater synchro issues

Post by PY2LY »

I'm assembling a repeater using two DGM6100 programmed in flat analog mode, includding MMDVM and pi-star card.
I opted for these radios due to they have TX and RX based on DSP resulting in better quality.

I have adjusted the TX and RX by MMDVMCAL achieving a perfect reception by radio and the BER test practically at 0 errors in tests, but when I put them to work together, my radio did not get the TDMA synchronization and not passed the transmission to the Net.

I used to assembly and calibrate DMR repeaters, including Repeaters with DSP-based radios performing the DSP delay compensation by pi-star DMRDelay to get the TDMA synchronization, but I’v tested the DMRDelay from 0 to 255 for that setup using two Motorola DGM line without success. My transmission passed to the Net just three eventually times.

Does anyone have any experiences or tips to share? As I had the same difficulty trying to assembly with two Hytera 786s programmed in Flat analog as well, adjusting TX and RX separately, but not synchronizing the TDMA, I lead to believe that something else is missing.

Fabio PY2LY.
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Re: DMRDelay vs DSP based repeater synchro issues

Post by MW0MWZ »

I have seen TDMA issues on a handheld before, using a hotspot, in this case the TX of the hotspot needed some fine tuning, remember that the BER seen by the hot-spot/repeater is only one side, you also need to make sure the TX is on frequency too :)

I also found that extending the DMR hang time [Modem][DMRDelay] a little, and having [DMR][Beacons] enabled helped.

EDIT: Looking over MMDVMHost config, it might have been [DMR][TXHang] I was thinking of (rather than [Modem][DMRDelay])

Finally if you didn't already, disable OVCM.

See if that helps you.

73 de MW0MWZ
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