Sarah from the SignalsEverywhere YouTube channel is back and this time showing off a new program she has created called "Pi25" or "OP25 Mobile Control Head". The program is a Python GUI for OP25 which runs on almost any platform including Android and Windows. OP25 is an advanced open source digital voice P25 Phase 2 capable decoder which can be used with an RTL-SDR and run on a Raspberry Pi.
Sarah's GUI software allows information from the OP25 software to be displayed on a nice large Android tablet screen, as well as having scanner forward/back buttons, and talkgroup skip and hold controls. This is very useful for in-car control on a mobile setup.
Sarah notes that she is also considering running a Kickstarter for a physical hardware OP25 head unit controller so please let her know in the YouTube video comments if you are interested.
Most police departments is the USA have now upgraded or are in the process of upgrading their radio systems to P25 Phase 2 digital radio. The frequencies can easily be received with an RTL-SDR, but a decoder is required to be able to actually listen to the voice. Software like SDRTrunk and DSDPlus can decode P25 Phase 1, but at the moment the only software that is capable of decoding P25 Phase 1 AND 2 is a program called OP25. However, OP25 has a reputation of being fairly difficult to set up as it does not have a simple to use GUI, and requires Linux.
Over on John's Tech Blog, John has uploaded a very helpful step by step tutorial that should help with those trying to get OP25 to work. The tutorial assumes that you have Ubuntu 18.04 already installed, and then starts from downloading and installing OP25. The next steps involve setting up OP25 for the particular system in your area, which mostly involves just editing a spreadsheet to input frequency data from radioreference.com. John also mentions that he's been able to get OP25 running perfectly on a Raspberry Pi 3 B+ as well, with less than 40% CPU usage.
In the video below John reviews some of the steps, and shows OP25 running and decoding voice.