Tutorial on Setting up OP25 for P25 Phase 2 Digital Voice Decoding

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.

OP25 Running
OP25 Running

In the video below John reviews some of the steps, and shows OP25 running and decoding voice.

OP25 Tracking 2 Control Channels


    • Rob Dale

      With 15,000 local police agencies in the US it is going to need to be a longer list before we get to “most” 😉

  1. Rob Dale

    Small error correction off the top… Most police departments are analog and are not changing anytime soon. A good number are P25 Phase I. Some are Phase 2. More will be shifting up with time, but clearly P25 Phase II is in the minority now.

    • Ron

      Wrong! Lately most large police departments either just changed to digital or planning on it. Maybe the small communities which don’t have the money to upgrade are using analog, but I have seen many medium to large cities move to digital, and mostly P25 Phase II. That is why I don’t have a trunker monitor anymore, the last 4 places I have moved to are all P25 Phase II now. At least that’s how it is in the US.

      • Rob Dale

        Here in the US, MOST POLICE DEPARTMENTS (using the phrase from the opening line of this post) are NOT on Phase 2. Most are not even on P25. Some larger departments are, but MOST are not.

        Let’s try the largest. NYPD: Analog. Chicago PD: Analog. LAPD: Analog. Detroit PD: P25 Phase I – might go Phase II in the next decade.

        • AD5NL

          Digital is definitely rolling out though. I’m in rural-ish Maury County TN and I believe both Spring Hill and Columbia (the two largrst cities in the county with about pop 40,000) are on digital now for the police. The County Sheriff and Fire/EMS are migrating but still have an analog simulcast.

          Austin TX was on Phase I P25 when I left about six months ago. Ironically it might be harder to move larger systems than smaller ones.

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