SDRTrunk Linux device permissions?

[LethalDosage]

I am using SDRTrunk on Linux. It can't see the USB device if I run it as myself. However, it does if I run it as root. I added myself to the "video group". I thought that would do it, but no. Does anyone know what permissions are needed?

These device files are created or touched when I insert the USB device:
drwxr-xr-x 3 root root 60 Mar 21 22:46 dvb/
drwxr-xr-x 4 root root 560 Mar 21 22:46 input/
drwxr-xr-x 21 root root 4820 Mar 21 22:46 ./
crw------- 1 root root 89, 4 Mar 21 22:46 i2c-4
crw-rw---- 1 root video 234, 0 Mar 21 22:46 media0
crw------- 1 root root 89, 5 Mar 21 22:46 i2c-5
crw-rw----+ 1 root video 81, 0 Mar 21 22:46 swradio0
crw-rw---- 1 root video 511, 0 Mar 21 22:46 lirc0
drwxr-xr-x 2 root root 4960 Mar 21 22:46 char/
crw-rw-rw- 1 root tty 5, 2 Mar 21 22:46 ptmx

Also, if I run it as user root, I don't have sound. Go figure...

Thanks,
Guy

 

[lwvmobile]

Just out of curiosity, which Linux Distro are you using and which type of SDR device?

 

[LethalDosage]

Linux Mint 20 Ulyana
This device:
Amazon.com: JahyShow DVB-T DAB FM RTL2832U & R820T Tuner Mini USB Stick RTL-SDR SDR for SDR# HDSDR FM+DAB & ADS-B Receiver Set: Electronics
It had the keywords I was looking for "RTL2832U & R820T" and a really good price.

As I understand it, I will need a second tuner for frequencies outside the 2.4MHZ range of the control channel. So I plan to buy another, but worried the one above is not a good one. The waterfall has crisp vertical lines, so it seems to be working.

A few minutes ago I solved the permissions issue with this command:
sudo chgrp video /dev/bus/usb/005/002
But I expect it needs to be run every time I reboot or reinsert the USB device.

I can now run sdrtrunk as my own user, but I have not yet heard a sound, except in Preferences/Output/Tones.
I tried to tune in a local FM radio station, but no sound came out.
I used channels/new/NBFM and put in 101.9, but no sound. I don't know if NBFM is correct, was just guessing.
I do have the JMBE Audio Library setup. Version 1.0.7b.

If I get this working, I want to redo it on a Raspberry PI and stream Parkville police. I wish there was a command line only option for sdrtrunk. I hate having a display, keyboard and mouse connected to the Raspberry PI.

 

[lwvmobile]

Yeah, that's pretty strange, never encountered the need to change permissions in order to be able to use a dongle I had plugged into the USB port, or run SDRTrunk as root, especially on an Ubuntu based distro. I'm not quite sure why that was necessary. Did you install the rtl-sdr package from the repo/store along with all the stuff it comes with.

I have several of those black dongles, and they work well enough without having to do anything other than start up whatever application I'm using it on at the moment.

You might try NOAA weather radio, those FM stations require a wider FM band than NBFM, so look around 164 Mhz and see if you can tune one of those weather radio channels in. Might also take the time to recommend trying out GQRX for analog signals, its also pretty convenient for being able to explore the frequencies around you and dropping the needle on them, so to speak, just to see what strong signals you have nearby, be it analog or digital, it'll give you an idea of what's out there that may not be on the RR database.

 

[lwvmobile]

Also, should mention, don't know how much luck you'll have with SDRTrunk on a Raspberry Pi, but considering it takes quite a bit of resource to run on a PC, I have a feeling it probably won't work so well. Even Denny has it listed as experimental/not tested, so I don't have any idea of how well it would work.

Alternatively, on the RPi, or LM, I would suggest looking into Boatbod's OP25 found here:

GitHub - boatbod/op25: Fork of osmocom OP25 by boatbod

Fork of osmocom OP25 by boatbod. Contribute to boatbod/op25 development by creating an account on GitHub.

github.com

Boatbod will even pop up in person if you're nice enough and have questions on how to use OP25.

 

[LethalDosage]

I see "sudo apt-get install rtl-sdr" has something. Will see what it does!
I don't recall reading anywhere to install that. Might have missed it because I watched a youtube howto.

I think it made a new group (plugdev) and put me in the group. The device file is now group owned by that group. it was group root before. sdrtrunk now works without the chgrp command I had used before. Still CRC errors and SYNC LOSS, sometimes talk groups show up. Still no sound.

 

[lwvmobile]

Still CRC errors and SYNC LOSS, sometimes talk groups show up. Still no sound.

Those could be chalked up to bad signal, where its just strong enough to see there is a signal there, but not truly strong enough of a signal to properly decode.

Yeah, I would definitely run the sudo apt install rtl-sdr gqrx-sdr I want to say those will actually install the correct driver you should be using on those dongles as well as set up the appropriate kernel modules and permissions for you to use. How that will clash with the changes you already made, I honestly have no idea. I've never had to do any user/group things on LM or Ubuntu to set this stuff up, mostly just install the rtl-sdr package and its dependencies and plug it in and it works.

 

[boatbod]

Also, should mention, don't know how much luck you'll have with SDRTrunk on a Raspberry Pi, but considering it takes quite a bit of resource to run on a PC, I have a feeling it probably won't work so well. Even Denny has it listed as experimental/not tested, so I don't have any idea of how well it would work.

Alternatively, on the RPi, or LM, I would suggest looking into Boatbod's OP25 found here:

GitHub - boatbod/op25: Fork of osmocom OP25 by boatbod

Fork of osmocom OP25 by boatbod. Contribute to boatbod/op25 development by creating an account on GitHub.

github.com

Boatbod will even pop up in person if you're nice enough and have questions on how to use OP25.

SDRTRunk has a much nicer UI than op25 so I totally understand people wanting to go that route, but it is fairly resource heavy since it is written in java rather than c/c++. For a trunked system monitor op25 - especially headless in a streaming environment - it does a good job but it takes a while to learn the intricacies of setting it up. Happy to help anyone that needs it.

 

[LethalDosage]

I think I have weak signal here in Parkville. There are really strong signals in the waterfall, but those aren't the signals I am looking for.

I might get this dongle (it has 3 different antennas) and 2 of them fit a Rasberry PI, like they were made for each other!
https://www.amazon.com/gp/product/B01GDN1T4S
Does anyone have a better recommendation?

If I get a config that works for me I will buy a second.
I will also look at op25. Only heard about it today. sdrtrunk was the only sdr software I could find that worked on Linux.
About performance, sdrtrunk uses 20-50% of 1 core if I turn off the pretty waterfall and minimize it. CPU is i7-2600. So, was hoping a Pi could handle it.

I did hear the weather radio (162.4). So I know sound can work.

Thanks lwvmobile and boatbod for the info.

Guy