Trunk Recorder - decoding Phase 2 TDMA

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Premium Subscriber
Dec 23, 2004
Honoka'a, HI

I haven't seen a lot of discussion on Trunk Recorder, but I stumbled across it recently and thought it looked pretty cool so I thought I would give it a try. I've been able to successfully install and configure OP25 in the past, so I hoped this wouldn't be too difficult.

I started with a fresh install of Ubuntu 16.04 and followed the instructions in the Readme on the Github page. Installation went fine, and I have it configured so that it appears to be tracking my local VHF P25 phase 2 system. I see it recognizing the control channel, and I see the talkgroups being recognized when there is voice traffic.

The issue I'm having is that I see an error "can't set XOR Mask for TDMA" before it starts to record to the .wav file. When I listen to the .wav file, the audio is garbled and sounds very similar to an encrypted transmission even though it isn't. I have the modulation set to "qpsk". I've tried "fsk4", but that results in no audio writing to the wave file at all.

So, I'm curious if anyone has had success decoding a phase 2 TDMA system using Trunk-Recorder, or if they have any suggestions to try.

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