Note: This post is now old (written in 2014). As of mid 2015 the latest version of DSD+ can be downloaded from www.dsdplus.com. Also note that in 2015 DSD+ changed their version numbers for some reason, so 1.5 is actually older than 1.1.

Version 1.5 of Digital Speech Decoder Plus (DSD+) has been released. DSD+ is a popular Windows software tool used for decoding digital speech such as P25 with the RTL-SDR. The latest version comes with a simple GUI interface that has an event log that shows call target and source ID history and an audio waveform plot which can help determine if DSD+ is receiving audio correctly. This version of DSD+ has the ability to decode the following protocols.

• D-STAR
• NXDN4800
• NXDN9600
• DMR/MotoTRBO
• P25 Phase 1
• X2-TDMA
• ProVoice

In addition to the above, the new version comes with an LRRP decoder and display program which should allow you to see on a map the GPS location of broadcasting radios.

DSD+ V1.51 can be downloaded from this link (UPDATE: dead link, use www.dsdplus.com now). The forum thread on RadioReference where the developer releases and discusses the DSD+ software can be found here.

This version of DSD+ comes with all the files needed to make it run already. To use DSD+ V1.5 simply extract the zip file into a folder and double click on DSDPlus.EXE. DSD+ will listen to your default audio device that is set in the Windows sound recording properties. Simply tune to a digital voice signal in SDR# or any other SDR receiver and set the output audio settings accordingly. To start the LRRP display program simply open LRRP.exe.

The post DSD+ Version 1.5 Released appeared first on rtl-sdr.com.

Over on YouTube user jdlucas78 has uploaded a video showing a P25 LSM modulated digital voice signal being decoded by the Osmocom OP25 software for Linux. Although DSD and DSD+ can decode P25 voice, it seems that the Osmocom OP25 software is better at decoding P25 signals as it implements better error correction algorithms.

Over on the RadioReference forums there is a thread discussing the use of the OP25 decoding software which can be found here. There is a post in the thread that shows an easy Linux install procedure for the OP25 software.

The post Monitoring a Trunked P25 LSM Simulcast System with OP25 and an RTL SDR appeared first on rtl-sdr.com.

The latest version of Digital Speech Decoder+ (DSD+) has just been released, bringing it up to version 1.071. There appears to be no changelog, so we are unsure as to what is new, but one obvious change is that they now include a new program called FMP which is a simple NFM demodulator, similar to rtl_fm, although it does have a GUI with point and click tuning. FMP can be used as a replacement for SDR# or similar software, and is especially useful to use on low end devices such as netbooks.

An active discussion on the latest release of this software can be found in this thread on the RadioReference.com forums.

DSD+ is a Windows program which can be used to decode and listen to digital voice protocols such as D-STAR, NXDN4800, NXDN9600, DMR/MotoTRBO, P25 Phase 1, X2-TDMA and ProVoice with an RTL-SDR or other radio. On some DMR systems you may also be able to use the included LRRP software, which allows you to view the GPS locations of broadcasting radios. The last major release was version 1.05.

The DSD+ team are now also offering a “fast lane” early access program, which for a small donation will allow you to have early access to new and upcoming DSD+ features. They aim to release a new update to donators every 7 to 30 days, while stable public releases will continue to be released every 4 to 6 months. The donation costs $10 for one year of early access, and $25 for lifetime updates. Some features they are currently working on include:

• Better tablet support
• IDAS/NEXEDGE/Cap+/Con+/TIII trunk voice following
• Per-call audio recordings
• Other needed DSD+ upgrades
• FMP upgrades
  • Squelch
  • Drift tracking
  • Selectable sampling rates
  • Adjustable windows sizes
  • TCP client/server mode (eliminates VAC / VB-C)
  • Multiple VFOs
  • Airspy support

The post New Version of Digital Speech Decoder DSD+ 1.071 Released appeared first on rtl-sdr.com.

APCO P25 is a digital voice signal and is commonly used like public safety departments such as police and fire. With an RTL-SDR and the open source Linux based OP25 decoder these signals can be decoded, assuming they are unencrypted. Software like DSD+ can also be used, but OP25 can supposedly decode more systems. Before the RTL-SDR, hardware scanners like the $~360 USD Uniden BCD996T digital scanner radio were typically used. 

Over on YouTube user Rob Fissel has uploaded a video showing a comparison between an RTL-SDR using the OP25 decoder and a Uniden BCD996T. Both radios are used to decode a weak P25 Phase 1 LSM signal. He uses a Scantenna antenna with an antenna splitter to run both radios at the same time. His results show that even though the constellation is poor, OP25 does a good job at decoding the signal and producing voice, whereas the BCD996T doesn’t even manage to hear the control channel.

The post P25 Decoding: OP25 + RTL-SDR vs a Uniden BCD996T appeared first on rtl-sdr.com.

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.

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.

The post Installing and Using SDRTrunk on Linux for Live Trunk Tracking with an RTL-SDR appeared first on rtl-sdr.com.

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.

The post SDRTrunk Setup and Use Tutorial appeared first on rtl-sdr.com.

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.

The post Tutorial on Setting up OP25 for P25 Phase 2 Digital Voice Decoding appeared first on rtl-sdr.com.

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

The post A Web and RTL-SDR Based Trunking Scanner appeared first on rtl-sdr.com.

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. 

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.

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.

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.

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.

Over on YouTube Corrosive from the SignalsEverywhere channel has uploaded a new video showing us how to set up P25 trunking and decoding with DSDPlus Fastlane and only a single RTL-SDR.

Normally two dongles are required to follow a P25 trunking system. One dongle continuously receives the trunking channel, and a second tunes to the voice channel chosen by the trunking channel. However, the latest DSDPlus Fastlane has a feature that allows one only dongle to be used. It works by tuning back and forth between the control and voice channel. The disadvantage is that trunking information could be missed while tuned to a voice channel, so some calls could be missed.

Trunk Recorder is an RTL-SDR compatible open source Linux app that records calls from Trunked P25 and SmartNet digital voice radio systems which are commonly used by Police and other emergency services in the USA. It can be used to set up a system that allows you to listen to previous calls at your leisure, however it does not have any UI for easy browsing.

Recently Chrystian Huot wrote in and wanted to share his new program called "Rdio Scanner", which is a nice looking UI for Trunk Recorder. Rdio Scanner uses the files generated by Trunk Recorder to create a web based interface that looks like a real hardware scanner radio. Some of the features include:

• Built to act as a real police radio scanner
• Listen to live calls queued to listen
• Hold a single system or a single talkgroup
• Select talkgroups to listen to when live feed is enabled
• Search past calls stored in the database
• Just upload Trunk Recorder files with Curl

On this weeks episode of SignalsEverywhere, host Corrosive tests out our KerberosSDR coherent RTL-SDR unit for radio direction finding. If you didn't already know KerberosSDR is our experimental 4x Coherent RTL-SDR product. With it, coherent applications like radio direction finding (RDF) and passive radar are possible. Together with the KerberosSDR direction finding Android app it is possible to visualize the direction finding data produced by a KerberosSDR running on a Pi3/Tinkerboard.

In the video Corrosive uses the KerberosSDR together with the recently updated companion Android app to determine the location of a P25 control channel. By driving around with the app constantly collecting data he's able to pinpoint the location within about 15 minutes.

If this interests you, we also have some more driving demo videos available here.

In addition to his video, Corrosive has also created a very useful calculator that can be used to calculate the required antenna spacing for a circular or linear direction finding array that can be used with the KerberosSDR.

Thank you to Matthew Cowley for submitting news about his new program called "Radio Analyser". Radio Analyser is a program that imports DSDPlus radio and group files into a postgresql database. The data can then graphed on the web interface allowing you to view talk group and radio statistics. DSDPlus is a program that can be used to listen in to digital P25, DMR and other digital voice protocols with an RTL-SDR or similar SDR.

Matthew writes the following, and some screenshots of the interface and graphs are shown in the slider and the end of the post:

I've been learning Ruby on Rails and as a first project I wrote a project that you host at home which imports the DSDPlus.radios and DSDPlus.groups files and displays their activity in graph form. It will show you total site activity, talk group activity and radio activity.

Back in April 2019 we posted about Matt Mills' Radiocapture.com website which is a web service that you can feed that automatically captures analogue and digital trunked radio conversations with an RTL-SDR, and allows public users to play back conversations via the web interface. The Radiocapture page which shows what the software is capable of is also active at radiocapture.com/radio. 

Back in April Matt was fundraising via Patreon and hoping to make development of Radiocapture his day job, but unfortunately he's had to call it quits for now. Since he no longer has time to work on it, Matt has open sourced the RF side of the software. The software description reads:

[Radiocapture-rf] is capable of using multiple networked computers and multiple SDR radios to demodulate the control channel of P25, EDACS, and Motorola trunking systems, as well as some limited support (alpha quality) for scanning for systems, LTR trunking, and "police scanner" style audio capture.

It is designed to effectively scale to an infinite capacity of trunked systems, captured transmission volume, and dongle bandwidth (more dongles = more available bandwidth, more cpus = more channels and more systems). (There is one remaining feature to be implemented to really make this work well, dongle redis autodiscovery (frontend_connect should autodiscover and use available dongles) and splitting the rc_frontend/receiver.py into one process per dongle.

The frontend initializes the SDRs in whatever configured frequency range, and presents a server interface where clients can connect and request a specific channel be created and forward to them. The frontend will then attach a channel, and output to a UDP sink (might be something better now, I forget). On the backend side, a control_demodulator is listening to that sink and doing the actual RF demodulation, which is passed into redis for distribution to other services. The backend is effectively a bunch of microservices that work together to track & record all ongoing transmissions and do some amount of deduplication. This entire setup is designed such that it can be scaled across as many servers/computers as necessary (although there are a few caveats/things I never got around to implementing in how it actually works). Recorded transmissions are decorated with a metadata scheme in their mp3 tags that is designed to be able to be loaded into the Radiocapture.com database. Finally completed mp3s are dropped into an activemq queue for publishing.

Matt notes that the software in it's current state isn't considered as "ready to distribute" as you may need some decent experience with Linux and Python to get it up and running.

Over on Twitter Annunaki (@StupotSinders) has been teasing some screenshots of a GUI for DSD+ that he's been developing over the past few weeks. And now he has released the software which is called "DSDPlusUI". DSD+ is mostly command line based, so a GUI could be useful for newbies. The software can be downloaded from the DSDPlusUI groups.io page.

DSD+ (aka Digital Speech Decoder) is a free closed source program that is compatible with RTL-SDR and various other SDRs which is used to decoder digital speech protocols such as P25 P1, DMR, NXDN and more. DSD+ Fastlane is a paid upgrade which allows subscribers to receive the latest updates to the software early. 

Thank you to Carl Makin (VK1KCM) for submitting a video that he produced for his local ham radio club in Australia. In the video Carl first gives an overview on radio trunking systems and explains why they are used to improve spectrum efficiency.

He goes on to focus solely on P25 digital voice trunking networks. Carl is based in NSW, Australia so he talks a bit about what P25 services are available in his area and which ones are unencrypted. Finally he demonstrates the SDR Trunk software decoding one of his local P25 networks with two RTL-SDR dongles, and explains what information we can see in the software.

Over on YouTube Sarah from SignalsEverywhere has uploaded a new tutorial video showing how to use two RTL-SDR dongles with the free SDRTrunk software to create a P25 Police scanner.

In the video she first shows how to install SDRTrunk in Windows and Linux, then how to install the JMBE codec required for decoding audio. She goes on to show how to import trunked system network data from a (paid) RadioReference subscription, how to blacklist unwanted talkgroups, and how to optimize operation with two RTL-SDR tuners. Finally she also shows how to set up the system manually if you don't have a RadioReference subscription.