random interruptions in DMR reception

General support for the Pi-Star System
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hb9hrd
Posts: 10
Joined: Wed Jan 18, 2023 11:32 am

random interruptions in DMR reception

Post by hb9hrd »

Hello
I experience random interruptions in DMR reception. The interruption may occur after 10 or 20 seconds of PTT, sometimes more. I notice that it seems to happen more often at 18.4 seconds, for some reason. What is strange is that the BER is always less than 1.

Code: Select all

M: 2023-01-21 20:11:51.176 DMR Slot 2, received RF voice header from HB9HRD to TG 6
M: 2023-01-21 20:11:52.618 DMR Talker Alias (Data Format 1, Received 6/6 char): 'HB9HRD'
M: 2023-01-21 20:11:52.618 DMR Slot 2, Embedded Talker Alias Header
M: 2023-01-21 20:11:52.618 0000: 04 00 4C 48 42 39 48 52 44 *..LHB9HRD*
M: 2023-01-21 20:12:09.713 DMR Slot 2, RF voice transmission lost from HB9HRD to TG 6, 18.4 seconds, BER: 0.7%, RSSI: -91/-91/-91 dBm
M: 2023-01-21 20:12:10.258 DMR Slot 2, received RF late entry from HB9HRD to TG 6
I'm using Pi-Star:4.1.6 / Dashboard: 20221114 on a raspberry pi 4, with BI7JTA MMDV Hat
FW: 20201214
TX is anytone UV878-II plus

My first question would be to understand if the problem comes from the pi-star or from the radio...
Does anyone already expriences such "RF voice transmission lost" ? I tried openspot and cannot reproduce the issue, so the TX seems OK.

73 Julien HB9HRD
hb9hrd
Posts: 10
Joined: Wed Jan 18, 2023 11:32 am

Re: random interruptions in DMR reception

Post by hb9hrd »

OK, I found the cause of the problem. It has nothing to do with pi-star, but I think it can be useful for other OMs.

The problem was with a Motorola GM-340 connected to pi-star. In DMR, the TDMA signal ends up crashing the radio, which then reboots and loses signal.
Workarround: change the "Configuration Byte 2" to 04
See here: https://www.hamdigitaal.nl/2019/01/gm34 ... mr-signal/

Best 73, Julien
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