Tagged: P25

Help Support RadioCapture – A Project that Records Entire Trunked Radio Systems and Provides Online Access to Audio

RadioCapture.com is a website run by Matt Mills that is capable of automatically capturing trunked radio communications from various agencies such as the emergency services and creating publicly accessible historical and live logs of the audio. This is a concept different to radio scanner streams, as all audio is logged and historical audio can be accessed easily at any time.

The system is based on SDR hardware such as the RTL-SDR. Currently Matt runs a receiver in Denver and captures Denver PD which can be listened to on the site without needing to log in. Once logged in (registration is free), other talkgroups available include various agencies in Colorado, New Jersey and Pennsylvania.

RadioCapture.com currently available Talkgroups being logged
RadioCapture.com: Currently available talkgroups being logged

Recently Matt has put a call out for people to help support the site via Patreon. He notes that RadioCapture is currently run as a hobby, but with monetary support he hopes to be able to expand the site into a business and have receivers listening and uploading worldwide. He writes:

Hey! Thanks for supporting the continued operation and development of Radiocapture.com. This is a hobby project I've been working on this since late 2011. I'd like to turn it into a real business with your help.

Radiocapture.com is a software defined radio system I built that captures entire trunked radio systems. It demodulates and captures every call on every channel of one, or many systems.

A single RadioCapture server can capture hundreds of simultaneous voice transmissions and a bunch of sites, additionally it's designed in such a way that it can run across multiple computers. My biggest RF site uses 3 machines to capture 19 P25 systems, and easily hits more than 100 active voice channels recordings simultaneously every day.

Matt has also noted that if the site is able to become self-sustaining via Patreon, he hopes to also be able to bring out a RadioCapture kit consisting of 10-16 RTL-SDR dongles, hubs and cables which would allow anyone to easily capture and upload almost all trunked communications from their area. He also notes that at the time of writing:

RadioCapture has 701790271 unique recordings of 503779875 unique transmissions (some calls get captured on multiple transmitters) from the 21 systems that have been captured

If you're interested in talking to Matt about the site, you can also join his Rocket.Chat room at radiocapture.chat.

RadioCapture logged audio
RadioCapture playing logged audio

SignalsEverywhere: Setting Up Priority and Groups in DSDPlus Fastlane

In his last video, Corrosive from the SignalsEverywhere YouTube channel showed us a quick guide on setting up a Phase 1 P25 digital voice decoder with two RTL-SDR dongles and the DSDPlus Fastlane decoder.

Now in his latest video Corrosive continues with the DSDPlus tutorial and this time explains how to set up priority and groups. On a trunked radio system there may be many different agencies using the same system simultaneously. Without priorities and groups, you would be listening to all communications in the system, and following a conversation within a particular agency would be difficult. Setting up priorities and groups allows you to filter out the conversations that you are not interested in, allowing you to focus on listening in to a particular agency only.

RTL SDR Digital Radio Scanning Priority and Groups With DSDPlus Fastlane Setup Tutorial

SignalsEverywhere: Using DSDPlus Fastlane for Listening to Phase 1 P25 Trunking

DSDPlus is a popular piece of software often used with RTL-SDR dongles to listen to unencrypted digital voice signals such as P25 and DMR. Digital voice is now commonly used by many Police and emergency services as well as business radio. DSDPlus fastlane is DSD's paid upgrade which allows subscribers to access to the latest releases of DSDPlus early.

Over on the SignalsEverywhere YouTube channel, Corrosive has uploaded a quick video guide that shows how to use DSDPlus Fastlane and two RTL-SDR dongles to set up a Phase 1 P25 voice decoder that automatically follows a P25 trunking channel. The basic process involves running two FMP instances which is a program in the DSDPlus suite that connects to the RTL-SDR's and receives the signal. One DSDPlus instance monitors the trunking channel, and this tunes the second FMP+DSD instance to the frequency currently active in the trunking system.

Corrosive also explains how people who are subscribed to RadioReference can download pre-populated data files that will allow the DSDPlus event log to display talkgroup information so that you can see who is talking to who.

Digital Radio Scanning With DSDPlus Setup Fastlane | Tracking Phase 1 P25 Trunking System Tutorial

Listening To Multiple DMR Channels with DSD+ and a HackRF on Linux

Thanks to Tony C who wrote in and wanted to share a method that he's found to listen to  multiple DMR digital voice channels in Linux. DSD+ is a Windows program that can be used to decode DMR. Although for Windows it is possible to use in Linux via the emulator known as Wine, and pipe the digital audio to it from GQRX. In the quote below, DSD+ "FL" is short for "Fast Lane" which is DSD+'s paid beta service that you can join to get  newer code with more features. Tony writes:

I believe that can bridge the gap between using Linux with the ease of use programs of windows. As I am sure we both can attest that setting up trunk tracking / anything SDR is not as easy on Linux as it is on windows. For example, DSDplus FL makes it extremely easy to identify/decode DMR networks. There are similar things that can be done on Linux, but as I stated, it isn’t as easy to setup.

So the method that I setup and have been using successfully, using Ubuntu and a HackRF, setting up DSDplus 2.98 on wine, that gets audio piped from GQRX using a virtual sink as outlined in https://www.hagensieker.com/wordpress/2018/04/29/dsd-in-ubuntu-18-04/. It was a great blog, but I felt that it was incomplete when trying to get all the voice traffic passed on a network, as it only works on 1 channel at a time.

So I found the control channel for the network and created 5 bookmarks in GQRX and gave them the tag “DMR”. From there I downloaded gqrx scanner https://github.com/neural75/gqrx-scanner followed the install and setup instructions. From there I activated the scanner and GQRX will cycle through the frequencies and when voice traffic is passed, it will stop, and DSDPLUS via wine will decode and record the audio.

[The screenshot] example was for P25, but it has worked in connect+ as well, the only thing is that you cannot bookmark the control channel. I know other options exist out there such as SDRtrunk / op25 which I have used, but I believe this provides a good alternative to those who have used windows and are comfortable with the ease of use of dsdplus FL but want to be on the Linux OS. 

DSD+ Decoding Multiple DMR Channels on Linux
DSD+ Decoding Multiple DMR Channels on Linux

 

A Web and RTL-SDR Based Trunking Scanner

During the Cyberspectrum Wireless Village talks a few days ago Gavin Rozzi gave a talk about his online RTLSDR-based trunking scanner website at ocradio.live. Recently he wrote in and wanted to share a little more about his system. He writes:

[The talk focuses] on my experience implementing several open source software packages to create an online RTLSDR-based trunking scanner website, https://ocradio.live/ that serves the part of New Jersey that I live in. Using multiple RTLSDR receiving locations, the site is demodulating, recording, and timeshifting multiple talkgroups of local and state trunked radio systems to create a live streaming service and archive of past scanner calls. Data from the site is also accessible over a REST API and we allow the creation of custom scan lists. My presentation is going to center on the advantages the site has over traditional hardware scanners and some of the technical challenges that we had to overcome to get the project off the ground.

In the Cyberspectrum YouTube video, Gavin's talk starts at around 2:40:22 and his slides are available at https://cyberspectrum23.ocradio.live

OCRadio Streams Screenshot
OCRadio Streams Screenshot

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

SDRTrunk Setup and Use Tutorial

Over on his blog John Hagensieker has uploaded a tutorial that shows how to set up SDRTrunk with RTL-SDR dongles. SDRTrunk is an application that allows you to follow trunked radio conversations, and decode some digital voice protocols such as P25 Phase 1. It is similar to Unitrunker and DSDPlus combined into one program. It is also Java based so it is cross platform and so can be used on Linux and MacOS systems as well.

John’s tutorial contains many useful screenshots, so it should be great for a beginner. He starts from the beginning, with finding trunking frequencies over on radioreference.com, then goes on to the installation and use on Linux. He also later explains how the Airspy can be used instead of multiple RTL-SDR to cover 10 MHz of bandwidth so that multiple systems can be monitored.

SDRTrunk Running and decoding a P25 Phase 1 System
SDRTrunk Running and decoding a P25 Phase 1 System

Installing and Using SDRTrunk on Linux for Live Trunk Tracking with an RTL-SDR

SDRTrunk is a cross platform Java based piece of software that can be used for following trunked radio conversations. In addition to trunk tracking it also has a built in P25 Phase 1 decoder. Compared to Unitrunker SDRTrunk is an all-in-one package, and currently it supports most trunking system control channels, but unlike Unitrunker it still misses out on some systems EDACS and DMR.

Over on his YouTube channel AVT Marketing has uploaded an excellent 6-part video series that shows how to install SDRTrunk and the Java runtime environment on Ubuntu Linux. The sections covered include, installing Java, setting the Java environment variables, installing other SDRTrunk prerequisites such as Apache Ant and the JMBE audio codec for decoding P25, and finally actually using and setting up SDRTrunk. Like all of AVT’s other videos, this is an excellent tutorial that takes you through the entire process from the very beginning so is useful for beginners as well.

Java JDK Install for SDRTrunk on Ubuntu Linux

If you’re new to trunking: Trunking systems are typically used with handheld radio systems (e.g. those that police, security guards, workmen etc carry around). The basic idea is that each radio constantly listens to a digital control channel which tells it what frequency to switch to if a call is being made. This allows the frequency spectrum to be shared, instead of designating one fixed frequency per user which would be very inefficient. But this system makes it difficult for scanner radios to listen in to, because the voice frequency could change at any time. Therefore software like Unitrunker and SDRTrunk which can decode the control channel is required. In addition many new systems use digital audio like P25 or DMR which requires digital decoders like SDRTrunk or DSDPlus.