op25-dev January 2025

op25-dev@lists.osmocom.org

2 participants
4 discussions

error message help [1 Attachment]
by n3zra＠yahoo.com [op25-dev] 25 Aug '26

25 Aug '26

I am very new to using Ubuntu OS and O op25. I cannot get the system running, my rtl sdr does work on the virtual box but op 25 is not starting. attached is the error message I am getting. I appreciate the the help. Thank you in advance. Andy N3ZRA

10 13

Seeking help/clarification on DMR Reverse Channel signalling
by Adrian Musceac 22 Aug '26

22 Aug '26

Hello OP25 devs, I'm an amateur radio operator working on implementing an open source DMR tier 3 trunked radio base station based on a multi-carrier SDR structure. I have reached a point where I no longer know how to interpret the ETSI standard and I thought to ask for help here due to your expertise with trunked radio systems. The outbound Reverse Channel PDU is used in DMR tier 3 for MS power control and MS de-key (transmit interrupt). Based on my interpretation of the standard, a couple of things are clear: 1. Reverse channel is only available if aligned timing is used 2. It is supposed to be embedded in voice burst F of a voice transmission on the alternate timeslot 3. The MS is supposed to monitor the alternate timeslot during transmit and derive RC information from it There are a few scenarios where it seems to me these tier 3 services (power control, priority interrupt) cannot be available at all... 1. Alternate timeslot is a control channel 2. Alternate timeslot is idle 3. Alternate timeslot carries something other than voice payloads The standard doesn't clarify these cases and I have doubt that these 2 services can even be reliably implemented. Are you able to help me understand how the Reverse Channel is used in the real world by existing industry implementations of DMR tier 3? Thanks, Adrian YO8RZZ

3 3

Fw: TX Support
by ikjtel 07 Jan '25

07 Jan '25

----- Forwarded Message ----- Sent: Tuesday, January 7, 2025, 1:50:23 PM ESTSubject: Re: [op25-dev] TX Support Should be straightforward to sectionalize this problem but will need your help - we'll assume for the moment there's been no regression (bug introduced). If your HackRF has not been stabilized (using GPSDO or other), I'd guess there could be a frequency-offset error between TX and RX - probably sufficent to cause RX failure. Can you run one of the RX apps (rx.py or multi_rx.py) and enable the "datascope" (eye pattern diagram), and attach a copy of that plot... Max On Tuesday, January 7, 2025, 12:26:32 PM EST, absi.joey(a)gmail.com <absi.joey(a)gmail.com> wrote: Hey there, I was testing the P25 Tx support of OP25 with a hackrf but I am encountering strange behavior. I am able to transmit "something" with the hackrf using the cmd: ./dv_tx.py -p p25 --args 'hackrf' -f ./test.wav -Q 145000000 -q 0 --gains 'RF:0,IF:20' On SDR# (img: https://ibb.co/C58Q592) I am getting signal so something is being transmitted but the squelch won't open. Even when disabling squelch I am getting a signal (that seems distorted/noisy), check at DSD+ Source Audio window (img: https://ibb.co/mJJy3J0). I tried lowering the gain but the signal is still "noisy" so I figured I would ask the experts over here. Thanks

2 1

TX Support
by absi.joey＠gmail.com 07 Jan '25

07 Jan '25

Hey there, I was testing the P25 Tx support of OP25 with a hackrf but I am encountering strange behavior. I am able to transmit "something" with the hackrf using the cmd: ./dv_tx.py -p p25 --args 'hackrf' -f ./test.wav -Q 145000000 -q 0 --gains 'RF:0,IF:20' On SDR# (img: https://ibb.co/C58Q592) I am getting signal so something is being transmitted but the squelch won't open. Even when disabling squelch I am getting a signal (that seems distorted/noisy), check at DSD+ Source Audio window (img: https://ibb.co/mJJy3J0). I tried lowering the gain but the signal is still "noisy" so I figured I would ask the experts over here. Thanks

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