RadioWitness

RadioWitness is a P25 public safety radio archive with a web application and support for cryptographically authenticated mirrors through Dat Protocol. Running this software requires two or more RTLSDR radios and one or more local P25 "Phase 1" public safety radio networks.

Download & Build

$ git clone https://github.com/rhodey/radiowitness && cd radiowitness/
$ git submodule update --init --recursive
$ docker build -t radiowitness .
$ docker build -t usbreset lib/c/usbreset

Search for Radio Networks

Using the Radio Reference Database find your local county and search the county page for "Project 25 Phase I", for example Austin, Texas has the Greater Austin/Travis Regional Radio System. If your county has a P25 Phase 1 network there will be a table labeled "System Frequencies" and running behind one or more of these frequencies should be a P25 Control Channel. The following example uses -g for radio gain and it is shown that frequency 851137500Hz has the best reception of three control channel candidates:

$ chmod +x ./bin/rtl_devices.sh
$ docker run $(./bin/rtl_devices.sh) --rm \
    radiowitness search p25 -g 26 -f "851162500,851287500,851137500" 2> /dev/null
> 851162500 counted 0 frames.
> 851287500 counted 36 frames.
> 851137500 counted 43 frames.

Decode and Play

The following example shows options for 3 RTLSDR radios multiplexed by 2 to support five concurrent radio calls, this is six minus one for the -f 851137500 control channel. Sample rate -s 1200000 is chosen because it divides evenly by the P25 channel rate 48000 making for efficient resampling. Gain -g 0 is automatic gain control but it is recommended that a static value be found using the search command:

$ docker run $(./bin/rtl_devices.sh) --rm -i \
    radiowitness decode p25 --radios 3 --mux 2 -s 1200000 -g 0 -f 851137500 \
      | docker run --rm -i radiowitness play p25 \
        | play -t raw -b 16 -e signed -r 8k -c 1 -

Create Archive

After having successfully tested decoding create a new P25 archive, this example uses directory /tmp/archive-p25. Values of "System ID", "WACN", "RFSS", and "Site" can all be found on Radio Reference:

$ docker run --rm -v /tmp/archive-p25:/archive \
    radiowitness create p25 --name "GATRRS Austin/Travis County" \
      --lat "30.245016" --lon="-97.788914" --sys 318 --wacn 781833 --rfss 1 --site 1

Decode and Archive

The following example will decode, archive and replicate from directory tree /tmp/archive-p25 and serve the web app and mirrors using WebSockets on TCP port 8081:

$ docker run $(./bin/rtl_devices.sh) --rm -i \
    radiowitness decode p25 --radios 3 --mux 2 -s 1200000 -g 26 -f 851137500 \
      | docker run -i -v /tmp/archive-p25:/archive -p 8081:8081 \
          radiowitness archive p25

Multi-Host

Archive P25 decode stream from TCP port 1234 and replicate archive over WebSockets TCP port 8081. --limit 1000000 will limit the archive to the most recent one million calls and use storage approximate to 16KB/sec for recorded audio. One million ten second radio calls is 160GB of audio:

$ ncat -l -k -p 1234 -c \
    "docker run --rm -i --name vpn.archive-p25 -v /tmp/archive-p25:/archive -p 8081:8081 \
      radiowitness archive p25 --limit 1000000"

Decode with connectivity to vpn.archive-p25 TCP port 1234:

$ ncat vpn.archive-p25 1234 -c \
    "docker run $(./bin/rtl_devices.sh) --rm -i \
      radiowitness decode p25 --radios 3 --mux 2 -s 1200000 -g 26 -f 851137500"

Mirrors

Run a mirror if you want to add storage to your archive or mirror someone else. Mirror vpn.archive-p25 using TCP port 8081:

$ docker run -d --name vpn.mirror-p25 \
    -v /tmp/mirror-p25:/archive -p 8081:8081 \
      radiowitness mirror ws://vpn.archive-p25:8081 --limit 2000000

Web App

The web app must be configured to reference an archive or mirror, then serve the web/dist directory using whatever HTTP server you like. The following example would serve from localhost:8080:

$ curl http://vpn.mirror-p25:8081/dat.json \
    | docker run --rm -i radiowitness config \
        --title "Radio Venceremos" \
        --description "Austin Texas police and fire radio." \
        --host ws://vpn.mirror-p25:8081 > web/config.json
$ cd web/ && npm install && npm run build
$ cd dist/ && python -m SimpleHTTPServer 8080

License

Copyright Rhodey [email protected] Creative Commons Attribution-NonCommercial https://creativecommons.org/licenses/by-nc/4.0