OP25

Pi 3 Setup

Install current version (9) of debian flavor linux

Pre-built image with SDR tools, does not have OP25 installed: https://pisdr.luigifreitas.me

P25 (EBRCS)

Get the code and run the install script to build and install: https://github.com/AaronSwartzDay-SSP/op25

Configure trunk.tsv to set proper talk group (0x1f1) and mode

rx.py --args 'rtl' -N 'LNA:47' -S 2500000 -x 2 -f 772.8437e6 -o 17e3 -T trunk.tsv -V -2 -U 2> stderr.2

Specify 3.5mm audio jack as output on Raspberry Pi:

./rx.py --args 'rtl' -N 'LNA:47' -S 2500000 -x 2 -f 772.8437e6 -o 17e3 -T trunk.tsv -V -2 -U -O hw:CARD=Headphones,DEV=0  2> stderr.2

Talk groups broadcasting on this network: https://www.radioreference.com/apps/db/?sid=5317

Note: this tends to come in garbled, you also have to be in range of the actual signal, there are several sources around the bay area, this is specifically for the Southwest Region, which covers a large radius from around Union City. Nudging the frequency '<' or '>' from the terminal seems to help lock in a clear demodulation.

P25 (San Francisco)

pi@pisdr:~/op25/op25/gr-op25_repeater/apps
$ ./rx.py --args 'rtl' -N 'LNA:47' -S 2500000 -x 2 -f 769.84375e6 -o 17e3

NAC 0x2b0 WACN 0xbee00 SYSID 0x2bb 769.843750/799.843750 tsbks 3386
voice frequency 769.531250 tgid(s) 6002 None 11.0s ago count 194

Resources

• https://www.hagensieker.com/wordpress/2018/07/17/op25-for-dummies/
• https://www.sigidwiki.com/wiki/Project_25_(P25)
• https://drive.google.com/file/d/1siOQ2AIjDnvdMPWu7WqDhQKSByg7HIRJ/view
• https://hackaday.com/2019/12/20/all-your-sdr-software-in-a-handy-raspberry-pi-image/
• https://github.com/AaronSwartzDay-SSP/op25/blob/master/README-rpi3-liquidsoap