What is this thing?

This repo is an Ansible playbook that will build boatbod's OP25 implementation on a Raspberry Pi 3 B (or better) in a headless/remote configuration. If you're an advanced Ansible user there are other options for use, hoever this guide will not cover those.

This guide will help you set up your control machine and build the pi resulting in an audio feed you can listen to with a web browser on your local network. The control machine can be MacOS, Linux, or Windows.

NOTE: This playbook does NOT have security in mind. Please do not expose your scanner to the internet directly without considering the implications and taking steps to protect yourself and your network.

Installation Instructions

System Prep (MacOS)

The preferred method of installing prereqs on the control machine is with homebrew. If you haven't installed it already, go into a terminal window and copy/paste this in there:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

This guide has been tested on the following configuration:

• Raspberry Pi 3 B+
• 16GB SanDisk SSD
• RTL2832U USB dongle from RTL-SDR.COM and compatible antenna
• Raspberry Pi OS Lite (64-bit) Debian Bullseye (released Sept 22, 2022)
• MacOS control machine

Before getting started

You'll need the following things:

• Raspberry PI 3 B+ (or better)
• RTL-SDR.COM USB dongle (RTL2832U is highly recommended) and compatible antenna
• SD card (16gb or more, the faster the better)
• SD card reader on the control machine.
• SSH key (whatever is already in ~/.ssh is fine)

Environment Setup

Install packages shell brew update brew install git brew install raspberry-pi-imager brew install ansible

Clone repo - Find a directory you'd like to work from and run git clone https://github.com/mikerwilson/op25-ansible.git

Image SD card

1. Insert the SD card into your control machine and open the Raspberry Pi Imager.
2. Click Operating System and select Raspberry Pi OS Lite (64-bit) (0.3gb) making sure whatever you select has no desktop environment.
3. Click Storage and choose your sd card from the list.
4. Click Settings button (little gear icon) and make the following settings:
   • Hostname: radio.local (recommend using this name at least the first time around so the instructions match).
   • Check Enable SSH, and Allow public-key authenitcation only, and add your ssh public key.
   • Check Set username and password, Username: pi (don't change this), and Password: <your secure password>
   • Check Configure wireless LAN, SSID, Password, and your Wireless LAN country
   • (optional but recommended) Check Set locale settings, Time Zone, and keyboard layout.
5. Click SAVE, then WRITE

Once the card is done writing, pop it into your powered-off Raspberry Pi. Connect your USB RTL-SDR dongle to the Pi, then power it on.

Build the Pi!

Find the pi

Give your Pi a few minutes to power on and connect to your wireless network. Once it's up and ready for you, if you ping radio.local you should get an IP response like this meaning it's ready to go:

➜  ~ ping radio.local
PING radio.local (192.168.1.95): 56 data bytes
64 bytes from 192.168.1.95: icmp_seq=0 ttl=64 time=3.604 ms
64 bytes from 192.168.1.95: icmp_seq=1 ttl=64 time=3.395 ms
64 bytes from 192.168.1.95: icmp_seq=2 ttl=64 time=3.678 ms
64 bytes from 192.168.1.95: icmp_seq=3 ttl=64 time=4.860 ms
^C
--- radio.local ping statistics ---
4 packets transmitted, 4 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 3.395/3.884/4.860/0.573 ms
➜  ~

Create your Ansible inventory

cp hosts.local.yml-example hosts.local.yml
nano hosts.local.yml

Edit the contents of hosts.local.yml with what you'd like to name your scanner (sysname), control channel list, center frequency and NAC (super important!). You can find the frequencies and NAC on radioreference.com, but the defaults will at least let the scanner build and compile. You can change them in this file and rerun the playbook and it will automatically reconfigure the scanner for you.

Example:

---
scanner:
  hosts:
    radio.local:
  vars:
    sysname: EBRCS OP25 Scanner
    control_channel_list: 774.45625,773.90625,774.18125,774.73125
    center_frequency: 774.45625
    NAC: 0x1f5

If you changed the name of your pi to something other than radio.local in the Raspberry Pi Imager, replace radio.local in the example config with that name. If name resolution isn't working on your home network you can put an IP address in the same place instead. Just don't forget the trailing :!

You can find the full list of variables in the playbook (including usernames and passwords) in the following file: roles/scanner/defaults/main.yml. The vast majority of variables can be set/changed at any time and re-running Ansible will make the appropriate changes on your Pi like magic!

Run ansible!

This can take 30+ minutes to complete the first time. Run this command from the repo root directory.

ansible-playbook -i hosts.local.yml site.yml

The Pi will reboot at the end of the initial run. The output should look something like this:

[...truncated...]
RUNNING HANDLER [scanner : enable and restart op25-rx] *****************************************************************
changed: [radio.local]

RUNNING HANDLER [scanner : enable and restart liquidsoap] **************************************************************
changed: [radio.local]

RUNNING HANDLER [scanner : reboot machine] *****************************************************************************
changed: [radio.local]

PLAY RECAP *************************************************************************************************************
radio.local                : ok=39   changed=33   unreachable=0    failed=0    skipped=0    rescued=0    ignored=1

The Ansible playbook is idempotent so it can be run at any time to confirm the configuration, update packages, etc. It will only make the changes required to correct the configuration, including recompiling as needed if something updates. This means that subsequent runs are usually quick and are a good way to confirm your overall configuration is correct.

Use your scanner!

Assuming you haven't overridden any of the default variables, the following links should work for you:

• OP25 control interface: http://radio.local:8080
• Web-based radio audio feed: http://radio.local:8000/op25
• Web-based radio feed stats/control: http://radio.local (admin user: admin, pass: hackme)

Customize it!

Option A: Ansible

If you change the control channel list or center frequency you can rerun the ansible command to apply those changes. This runs in about 30 seconds and is pretty easy. Check out the README.md under the overrides directory for some handy options.

Option B: SSH

Radio configs can be found under /etc/op25 and can be edited with any text editor. You'll need to run sudo service op25-rx restart to apply any changes. Check out op25 and boatbod/op25's docs for details about how these work. You'll likely want to do this to set your whitelist.csv and blacklist.csv contents.