OP25 No audio.
- Thread starter veceme
- Start date
- Status
wgbecks
Active Member
A good start to in seeking help is to post your op25 configuration files. IE: your rx.py command line or milti_rx.py JSON file.
Be sure to detail the hardware and Linux repo that you're using to run op25.
Be sure to detail the hardware and Linux repo that you're using to run op25.
There is, good.
This: ./rx.py --args "rtl" --gains 'lna:36' -S 2500000 -X -q 0 -v 1 -2 -V -U -T OP25SSP.tsv 2> stderr.2 -l http:0.0.0.0:8080
Or
./rx.py --args 'rtl' -S 2500000 -n --gains 'LNA:38' -T OP25SSP.tsv -f 173.170 -U 2> stderr.2 -l http:0.0.0.0:8080
And without http
There is, my notebook uses a normal audio card and has a virtual cable and an HDMI adapter with audio output, so I guess I must be sending it to the wrong port.
But I don't know where to change it to work.
Thank you very much for your attention.
boatbod
Member
You could try using "-O pulse" and that should direct the audio to the system's PulseAudio daemon rather than ALSA. If regular sound works ok this should too.
I did as indicated, -O or -O 0 or -O 1 or -O 2 or -O 3 and all gave the same return...
Using Python /usr/bin/python2
And now what should I do?
Thank you for your attention and I look forward to it.
wgbecks
Active Member
On the surface it doesn't look like you have an audio issue. I am not seeing any signs of op25 decoding Trunk Signaling Blocks (tsbks)
that should normally be incrementing when op25 is not following a call. The FFT (spectrum) plot doesn’t indicate any signal sitting at the
tuned frequency of 173.170 MHz. Are you sure you have the correct control channel frequency? What system are you trying to monitor?
Below are examples of what your FFT and Constellation plots should basically resemble.
Last edited:
boatbod
Member
As Bill observed, it really doesn't look like you are tuned to anything useful. Your screenshot "Plot.jpg" shows the tuning line resting firmly over dead-air and "Principal.jpg" shows no data received.
What system are you trying to receive, and what are the contents of your OP25SSP.tsv file?
It may also be helpful to reduce the sample rate to "-S 1000000" as running an RTL at 2.5Mhz is right at or above the max range of it's abilities.
What system are you trying to receive, and what are the contents of your OP25SSP.tsv file?
It may also be helpful to reduce the sample rate to "-S 1000000" as running an RTL at 2.5Mhz is right at or above the max range of it's abilities.
Now with you explaining, I began to understand. Come on, I'm trying to receive the Police signal that was analogue and passed to P25 here in Brazil. And you see, here there is no information about these frequencies as in the USA. I tried with DSD+ and it didn't work because it's encrypted and it stays silent and doesn't open. Or I couldn't open it. I even sent this doubt here on the forum and they actually told me that it does not open.
For the short time of study, I think the OP25 should open this system. Because it is the basis of their own radios that they use.
So I don't know this data from " op25 signal decoding trunk signaling blocks (tsbks) " And I don't know how to find it. When taking the picture there was no signal, but when it does it gets too big, and as I am 3 km from the base the signal fills up and there are even two sides that are full as well. I can even take a picture or send it because I think I have it on file. The system is P25 I saw it on their radio because I was close to an HT when he started talking and P25 appeared.
I ask for help on how to find out this data?
I remembered this encrypted too.
But out of curiosity, even without a signal, it wouldn't have to CHIAR XXXXXXXXXXXX like any radio.
Last edited:
As I said it's the P25. " What system are you trying to receive, and what are the contents of your OP25SSP.tsv file?"
I'll send you the data I put, I believe it's wrong but it was the little I know.
Sysname: P25 SSP
Control Channel List: 173.170000
Offset: 0
NAC: 0x293
Modulation: cqpsk ( I don't know if this is really the type of modulation ) TGID Tags File:
Whitelist:
Blacklist:
Center Frequency:
" It may also be helpful to reduce the sample rate to "-S 1000000" as running an RTL at 2.5Mhz is right at or above the max range of it's abilities "
And I'm going to do that or even less because I saw in the readme that it can be smaller.
I appreciate the help to find out if I can or if this system can receive this type of audio.
I remembered this encrypted too.
wgbecks
Active Member
A couple of thoughts. It might be that your system isn't a Trunked Radio System (TRS) and would not therefore have a control channel
where you'd expect Trunk Signaling Blocks (tsbks) and might be P25 conventional. Moreover, if the system is fully encrypted, then there
is no point is trying to getting op25 running on it.
However, I would recommend that you run DSD+FL on whatever frequency that you've observed activity and allow it run long enought to gather data that can be used to better analyze what exactly the system is, and if indeed it's encrypted. Be sure to set the logging level to
-v4 that will provide greater detail about the communications protocols received.
where you'd expect Trunk Signaling Blocks (tsbks) and might be P25 conventional. Moreover, if the system is fully encrypted, then there
is no point is trying to getting op25 running on it.
However, I would recommend that you run DSD+FL on whatever frequency that you've observed activity and allow it run long enought to gather data that can be used to better analyze what exactly the system is, and if indeed it's encrypted. Be sure to set the logging level to
-v4 that will provide greater detail about the communications protocols received.
It's really partially encrypted, like: the base wants to talk to everyone or to a specific person, that's all. The rest like everything that could be active is not. From what I've been told.
About DSD + FL I have a file that I can send for evaluation. A TXT with part of this encryption. Thanks for the help on how I can hear again. I will make the change to log 4
wgbecks
Active Member
OK, the logfile appears to be either a P25 Conventional or perhaps is one of the Traffic Channels associated with a Trunked Radio System.
If you don't have any hard data on the system then I would suggest using FMPx from DSD_FL to manually tune across the entire VHF spectrum to search for the presence of a control channel that would be transmitting continuously.
If you find a P25 Control Channel the FMPx spectrum window will appear similarly to the image shown below. If you should find what
appears as a control channel then clear your DSD+FL logs and capture a minute or so of data from this signal for further analysis.
Those are the images.
Attachments
I have attached the requested images above. In the post.
wgbecks
Active Member
Making some good progress now. Still appears to be Conventional P25 but the incoming signal level is overloading your SDR.
Lower the LNA setting to maybe something like 20. The signal spike optimally should be approximately 30-35 dB above the
noise floor in the FFT plot.
Getting the LNA gain set will reduce decoding errors and this is always an important first step in getting op25 operating
properly. Once you've got the LNA adjusted per the above then please capture a Mixer plot and post that. It looks like
the PPM is probably very close but would like to verify as next steps.
boatbod
Member
Nice constellation, but unfortunately the DSD logs are indeed showing AES encrypted communications. OP25 isn't going to be able to decode it.
- Status
Similar threads
