Update on P25 scanner — new version, and new installation instructions

Since I posted my original articles on configuring the Gnuradio-based op25 P25 trunking scanner, there’s been a lot of progress in the code. In particular, there is a new fork that changes the program to a command-line version, which saves a lot of CPU resources and also offers added features. The new version will run nicely on a Raspberry Pi 3, and probably on an RPi 2 as well. Following are instructions to install it from scratch on the PI.

Download the “raspian-stretch” image from raspberrypi.org and copy the image to an 8GB SD card. There’s a very nice free tool to do that called Etcher. Install the card in your Raspberry Pi, and connect the Pi to the internet.

Open a terminal window to run all the following steps.

First, update the system and add the “sources” repository:

  • sudo nano /etc/apt/sources.list and remove the “#” from the beginning of the line that includes “deb-src”.

  • sudo apt-get update

  • sudo apt-get dist-upgrade

    • Reboot the system before the next step.

      Now, download and build the op25 code:

      • cd /home/pi

      • git clone https://github.com/boatbod/op25.git

      • cd op25

      • ./install.sh

      It will take a while to download and install all the packages, and then compile the op25 code. But when the installation finishes, you should be all set to go. But there are a couple of additional things that I do on my system to make life a little easier:

      • The program and config files are buried several layers down in the op25 directory. I make a symbolic link called “scanner” to that directory:

        ln -s /home/pi/op25/op25/gr-op25_repeater/apps /home/pi/scanner

      • The program command line requires a whole bunch of parameters that are hard to type (and to remember!). I create a shell script to start the program:

        /home/pi/scanner/rx.py --args 'rtl' --gains 'lna:35' -S 250000 -f 853.6e6 \
        -g 100 -q -1 -o 50000 -T /home/pi/scanner/trunk.tsv --udp-player -v 5 2>stderr.2