Tagged: unitrunker

Comprehensive Video Guide to Trunking and Digital Voice with the RTL-SDR

Over on YouTube user AVT Marketing has uploaded a five part video series that very clearly and slowly shows how to use an RTL-SDR to set up trunking and digital voice monitoring. In the videos he uses SDR#, Unitrunker, DSD+ and VBCable for the monitoring.

The first video in the series shows a brief overview of the digital trunking voice set up, and explains a bit about digital voice communications. The second video shows how to install an RTL-SDR, and walks you through downloading Unitrunker and DSD+. The third video is a tutorial about SDR# and also explains how trunking radio systems works. The fourth video shows how to install Unitrunker, DSD+, VBCable, and how to configure each program. Finally the fifth and last video in the series shows the final steps in using Unitrunker and DSD+.

This looks like a very good video series, especially for those that like to see every step in the process played out in full.

Uni-SDR Link: Control SDR Console V2 with Unitrunker

A new program called Uni-SDR Link has just been released. This software allows Unitrunker to control SDR-Console V2.

Unitrunker is software that allows you to follow trunked voice conversations, and SDR-Console V2 is a general purpose receiver, similar to other software such as SDR#. The authors write:

This applications sole purpose is to allow Universal Trunker (aka Unitrunker) to control the tuning frequency of individual VFO’s in SDR Console v2. This is achieved by translating Unitrunker Receiver Control commands into a format accepted by SDR Console. Communication occurs over virtual com / serial ports.

Uni-SDR Link has been tested on Windows 7 & Windows 8 and requires .NET Framework version 4.0 or greater.

Just download & launch. No installation required.

The Uni-SDR-Link.chm file contains help for the application should be placed in the same directory as the Uni-SDR-Link.exe.


Listening to Trunked Radios with One RTL-SDR

Usually to listen to trunked radio systems, two RTL-SDR dongles are required. One for decoding the trunking control channel and another for listening to the audio channel. However if the audio channels are within the same chunk of received bandwidth as the control channel it is possible to use just one dongle to follow trunked conservations.

Recently Pawel of pewusoft wrote in to RTL-SDR.com to let us know about a tutorial he uploaded showing how to get trunking to work with just one RTL-SDR dongle. His method uses Unitrunker and SDR# together with the AuxVFO plugin and a new plugin that he wrote for interfacing with Unitrunker.

Although there is already a Unitrunker interface plugin for SDR#, Pawel wrote a new plugin based on serial port commands as he found that the original interface plugin did not work properly for him.

Unitrunker Serial Port Interface SDR# Plugin
Unitrunker Serial Port Interface SDR# Plugin

ScanEyes: Software for Visualizing, Listening to and Archiving Trunked Radio Traffic

Back in March we showed a beta version of Tyler Watts ScanEyes trunked call log recorder software. Now Tyler has released a more complete version of his ScanEyes software. A live version of the software can be found at sdrscan.com. ScanEyes works by using a software defined radio such as the RTL-SDR combined with trunking following software Unitrunker and optional P25 decoder DSD/DSD+ to archive all calls made on a trunked radio system. A user can then later go into the web interface and view and listen to archived calls.

ScanEyes Flow Diagram
ScanEyes Flow Diagram

RTL-SDR Tutorial: Following Trunked Radio with Unitrunker

The popular trunking decoding software Unitrunker now supports the RTL2832U R820T RTL-SDR directly in its new version. This means that extra SDR receiver software like SDR# is no longer required to use Unitrunker.

You can download the latest version of Unitrunker here.

In a normal radio system, one company (or talkgroup) might use a single frequency for radio communications. However, this is very inefficient as the frequency may not be in use for the majority of the time. In a trunked radio system, a small set number of frequencies are shared between a large number of talkgroups. Each radio receives a special computer controlled control channel. The control channel determines a vacant frequency that a particular talkgroup should use. This helps to make radio frequency allocations more efficient.

Because a talkgroup might switch between various frequencies often, it can make listening to a conversation difficult for radio scanners. Unitrunker can be used to decode the control channel and follow a voice conversation as it hops across various frequencies. With two RTL-SDR dongles you can set up a trunking receiver station with just Unitrunker. What follows below is a tutorial on how to set this up.

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List of SDRSharp Plugins

There are a number of SDRSharp plugins that extend its functionality. Here is a collection of all the plugins and download links that I could find. The installation of most of these plugins will require editing the Plugins.xml file with a text editor such as notepad. Most files will contain a readme.txt or magicline.txt file that shows what line to add to the Plugins.xml file. Just copy and paste the plugin .dll into the SDR# folder and add the magicline line to the plugins.xml file to install the driver.

Note: Now that SDR# has updated to the .NET4.6 platform (October 2015), many old plugins that are not maintained may no longer work. However the actively maintained plugins have all been updated and are listed below.

Note 2: Many of these plugins may only work on the x86 version of SDR#.

Frequency Manager + Scanner and Scanner Metrics and Frequency Entry Package Plugin

This is a plugin package which comes with three plugins. It comes with a more advanced frequency manager than the one shipped with SDRSharp.

It also has a scanner option which can quickly scan through a group of your saved frequencies, looking for an active signal.

It also has a scanner metrics plugin, which records frequency activity to a database. Later this database can be analyzed to find out which frequencies are the most active, saving you time searching manually for active frequencies.

Finally, this package also has a frequency entry plugin, which works like the old SDRSharp frequency entry used to work. Basically, it just allows you to choose a center frequency and IF frequency easily by typing it in instead of adjusting it with the mouse.

Download the installation packager here

Frequency Manager + Scanner Plugin

Fast Scanner Plugin

Similar to the Frequency Manager and scanner plugin in that it automatically tunes to active signals above a certain power.

Download Link

Fast Scanner SDR# PluginFast Scanner SDR# Plugin

DDE Plugin

Allows programs like WXTrack to work with SDRSharp through a DDE interface.

Instructions and Download Link Here.

QPSK Demodulator Plugin

Used to demodulate QPSK signals from the Meteor M2 weather satellites. Used in conjunction with LRPT decoder. See tutorial here.

Download Here

DDE Tracking and Scheduler Plugin

Another plugin that allows software like WxTrack and Orbitron to interface with SDR#. This one is meant to be used with the QPSK decoder plugin for automatic scheduling of satellite passes. See tutorial here.

Download Here

DDE Orbitron Interface SDR# Plugin.

SDRSharp Net Remote

Allows you to remotely control SDR# through a network connection.

Download Here

CTCSS Detector and Squelch Plugin

Adds a Continuous Tone-Coded Squelch System (CTCSS) decoder.

Download Here


DCS Detector and Squelch Plugin

Adds a Digital Coded Squelch (DCS) decoder. Similar to the CTCSS detector.

Download Here


TimeShift SDR

Allows signal reception to be timeshifted to allow for time to click on a signal.

Download Here


Digital Audio Processor

Adds digital audio processing features such as an improved squelcher, an audio inverter and a bandpass and deemphasis filter.

Download Here


Audio Processor

Similar to the digital audio processor shown above, but adds the ability to graphically adjust the bandpass filter in the audio spectrum of SDR#.

Download Here



RDS Logger Plugin

Logs Radio Data System (RDS) data to a CSV file.

Download Here

RDS Data Logger SDR# Plugin

DSD+ GUI Interface Plugin

Adds a GUI interface for the popular DSD+ digital speech decoder program.

Download Here

DSD+ SDR# Plugin GUI

AUX VFO Plugin

Enables multiple VFO’s in SDR#. (In other words, you can tune to several stations simultaneously within the same swatch of live bandwidth)

Download Here


IQ Plugin Autocorrection

Replacement for the standard IQ autocorrection. Helps improve performance on slow computers.

Download Here


Audio Waterfall Plugin

Adds an audio spectrum waterfall to SDR#.

Download Here (Original plugin seems to be dead but the link is left up just in case it comes back)

Download Alternative Plugin Here



Allows you to watch analogue PAL TV channels in black and white through SDR#.

Download Here


IF Processor & Tracking Notch Filter Plugin

Adds the ability to set tracking notch filters in the IF stage and to asymmetrically filter the IF stage.

Download Here


Modified Baseband Recording Plugin

An enhanced version of the recording plugin that comes standard with all SDR# installations. Adds a scheduler, a feature to record only when there is a signal, select samplerate, and choose file output location.

Download Here


Modified Audio Recording Plugin

A modified version of the default audio recording plugin. Adds a scheduler.

Download Here


IF Recorder Plugin

Allows you to record an IQ file of just the current IF bandwidth. An IQ recording of just the IF bandwidth will be much smaller than one of the entire bandwidth.

Download Here

IF (Intermediate Frequency) Recorder SDR# Plugin

CSVUserlistBrowser SDR# Plugin

Allows users to interface with the CSVUserlistBrowser plugin intended for use with Winradio products. The CSVUserlistBrowser is a program that provides a database of radio stations.

Download Here


MPX Output Plugin

Allows programs like RDS Spy to work with the audio output from SDR#.

Download Here


Radio Sky Spectrograph Plugin

This allows SDR# to interface with Radio-Spy Spectrograph which is radio astronomy software that allows fine control over a waterfall display.

Download Here

The Radio-Sky Spectrograph SDR# Plugin

Aviation band 8.33 Calculator Plugin

Automatically converts the current frequency input to an aviation one according to the standard 8.33 kHz channel spacing.

Download Here


Frequency Lock Plugin

Simply locks the frequency settings in SDR# to prevent accidental changes.

Download Here


Unitrunker Serial Based Trunking Plugin

Allows Unitrunker to interface with SDR#. For example it can be used to allow unitrunker to control the frequency setting in SDR# to following trunked conversations over various frequencies.

Download Here


Passive Radar Plugin

Allows you to use the RTL-SDR as a passive radar detector.

Download Here

The Passive Radar plugin by Dr. Kaminski in SDR#.

IF Average

Averages the current bandwidth. Is useful for applications such as radio astronomy.

Download Here

The IF Average plugin by Dr. Kaminski.

Front End Plugins

Modified R820T FrontEnd with Manual Control and Decimation

Not really a plugin, but a modified front end interface and driver for the RTL-SDR that allows manual control over the LNA, Mixer and VGA gain stages. Also enables decimation which allows for better narrowband warefall views, and a easy control for activating a SpyVerter upconverter.

Download Here


File Player

This plugin give a playback interface when playing back recorded IQ files. Allows you to view the entire waterfall of the recorded file and quickly skip to any time.

Download Here


E4000 Gain Mod Enabler

A plugin which allows the E4000 Linrad gain profiles to be used in SDRSharp, via use of a modified rtl_tcp server.

Download Here

Plugins that no longer work

These plugins no longer work, but may still work with older versions of SDR#. Usually they stop working because of an SDR# upgrade that requires some minor modification to the plugin, but the plugin is no longer maintained. Some provide code so there may be hope in getting these running again if someone is willing to make the changes and recompile the code.

Orbitron Plugin (Not working with 1400+)

Superseeded by the DDE Tracking and Scheduler Plugin (shown in the above list)

Allows the Orbitron satellite tracking software to control the frequency in SDRSharp. This is useful as Orbitron can automatically correct for the Doppler shift when listening to satellites.

Download Here

Mirror At the bottom of this page

Satellite Tracker Plugin

Easy Scanner Plugin (Not working with 1400+)

Another scanner plugin similar to the scanners already shown above. Add frequencies to the database, then use the scanner to automatically find an active signal.

Download link and users guide here.

Easy Scanner SDR# Plugin

Audio FFT Plugin (Not Working with 1400+)

Adds a audio FFT display in the plugin window.

Download Here

Audio FFT SDR# Plugin

ScopeView Plugin (Not working with 1400+)

Adds a simple audio scope to the plugin window.

Download Here

Scope Viewer SDR# Plugin

Simple Audio EQ Balance Plugin (Not working with 1400+)

Adds a simple audio EQ balance setting option box in the plugin window.

Download Here

Audio EQ Balance SDR# Plugin

Level Meter Plugin (Not working with 1400+)

Adds a power meter for the currently tuned frequency and bandwidth.

Download Here

Level Meter SDR# Plugin

Signal Strength Logger (Not working with 1400+)

Logs signal strengths over time of specified stations.

Download Here


SDR# short-wave.info Plugin (Not working with 1400+)

Enables SW station names to be displayed within SDR#.

Download Here

short-wave.info SDR# Plugin

GlobalTuners SDR# Plugin (Not working with 1400+)

Allows SDR# to associate with a GlobalTuners.com account.

Download Here

Unitrunker Trunking Plugin (Not working with 1400+)

Allows the trunking control software Unitrunker to control the frequencies in SDRSharp. This allows digital and analogue trunking systems to be followed. Note that Unitrunker can now directly interface with the RTL-SDR, so using SDR# together with Unitrunker is no longer recommended.

Download Here

SDRSharp Trunker Plugin

AutoTuner Plugin (Out of date)

Automatically tunes to signals that appear in the spectrum which are above a certain adjustable signal strength. Can also create null areas to prevent automatically tuning to unwanted signals. There seems to be only an outdated version, which is built in to an old version of SDRSharp available.

Download Here

Auto Tuner SDR# Plugin

ADSB# Plugin (Missing)

Runs the ADSB# ADS-B decoding program as a plugin in SDRSharp. The main advantage to using this plugin is that you get to visually see the waterfall whilst decoding. It also adds a 1-bit CRC error check.

Download from the files section of this Yahoo group. (You will need to register first) (Note: File is gone now, still looking for updates to this plugin)

ADSB# SDR# Plugin

Modified ScopeView Plugin (Missing)

A modified version of the scope view plugin with Decimation, HoldOff and Hold options resides in the SDRSharp Yahoo group files section under the name TXmonitorScopeView.zip (you will need to join the group first to download).

Download Here


Other Plugin Lists






Using Unitrunker with SDRSharp

Trunking radio is a radio system where a finite number of frequency channels are shared between multiple radio users. This allows support of a much larger number of radio users. A special control frequency is used to determine which frequency a radio should be tuned to.

This all means that following a radio conversation with a software defined radio such as the rtl-sdr can be difficult, as the conversation can hop around multiple frequencies. Fortunately there is software called unitrunker which can listen to the control channel, and determine what voice frequencies need to be tuned to. More information about unitrunker and the signals it can decode is shown on this RadioReference wiki page.

A tutorial on how to set up unitrunker with SDRSharp has been posted here. Essentially, to follow trunked radio conversations you will need two rtl-sdr dongles (or any two software radios), unitrunker and virtual audio cable. One radio will be used for the control channel and unitrunker, and the other will be used for the listening to the voice channel. This can also be done with one software radio, and one hardware radio with discriminator tap if one have one of those. If you are trying to track digital voice communications, it can be done with one dongle and this is discussed in the tutorial too.

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