For the radio enthusiasts, this setup is capable of following trunked, digital voice radio transmissions with a single receiver.
Read the full howto here: https://sites.google.com/site/policescannerhowto/
Video of completed setup:
I have to give a lot of credit to the creator of the following guide: http://public-xrp.s3.amazonaws.com/docs/sdrsharptrunk.htm This how to is based largely from that, and other sites listed in the Resources section.
Please use the information in this guide responsibly.
Step 1: Hardware Requirements
In this guide I will be using a Newsky TV28T v2 with a RTL2832U & R820T tuner.
Step 2: Software Requirements
Software defined radio application. Allows for tuning and receiving of audio from receiver.
A modified version will be needed that is capable of connecting to UniTrunker.
Download (secondary): https://googledrive.com/host/0BwBTquKxCLOBc3hFLVoxM0o2LW8/Release-latest.zip
Updated file for SDRSharp
Download (secondary): https://googledrive.com/host/0BwBTquKxCLOBc3hFLVoxM0o2LW8/RelWithDebInfo.zip
Version used: 18.104.22.168
Allows for receiver driver installation.
Download (secondary): https://googledrive.com/host/0BwBTquKxCLOBc3hFLVoxM0o2LW8/zadig_v22.214.171.124.7z
Version used: 126.96.36.199 preview
Provides decoding support for trunking control channels and issuance of tuning commands.
Download (secondary): https://googledrive.com/host/0BwBTquKxCLOBc3hFLVoxM0o2LW8/UniTrunker-188.8.131.52.msi
Virtual Audio Cable
Version used: 4.10
Provides audio routing between components. Trial available, purchase for $25.
Trial Download (secondary): https://googledrive.com/host/0BwBTquKxCLOBc3hFLVoxM0o2LW8/vac412.zip
Digital Speech Decoder (DSD)
Version used: 1.6.0 Beta
Provides digital voice decoding support.
Download (secondary): https://googledrive.com/host/0BwBTquKxCLOBc3hFLVoxM0o2LW8/dsd160.exe
Linux support for Windows. Required by DSD.
Download: (secondary): https://googledrive.com/host/0BwBTquKxCLOBc3hFLVoxM0o2LW8/setup.exe
Microsoft Visual C++ 2010 Runtime
Required by remote.dll
Download (secondary): https://googledrive.com/host/0BwBTquKxCLOBc3hFLVoxM0o2LW8/vcredist_x86.exe
Step 3: Resources
SDRSharp Quick Start Guide:
Digital Speech Decoder (DSD) Install Tutorial:
Digital Speech Decoder (DSD) Guide:
Unitrunker Configuration Guide:
http://public-xrp.s3.amazonaws.com/docs/sdrsharptrunk.htm <-- See for two receiver configuration
Massive Radio Frequency Database:
Step 4: Installing Drivers for the SDR Receiver
Next to Driver it should now say WinUSB and the version number. I don’t believe it is required, but if you like you can do the same for Interface 1.
Step 5: Install SDRSharp / Test Receiver
If you like you can test to make sure your radio is working properly. Open SDRSharp, set the front end to “RTL-SDR / USB” select WFM and type in a known FM radio station to the center/frequency boxes and press play. For example, if you would like to tune to 97.9 type in 97900000. You can drag the red line to align with the stream in the waterfall.
Step 6: Install Virtual Audio Cable
Step 7: Windows Sound System Configuration
Step 8: Install Cygwin
Step 9: Download DSD
Step 10: Configuring UniTrunker
After downloading and installing, run UniTrunker. Choose “First Time Installation” and Continue.
Two receivers must be configured in UniTrunker, a ‘Signal’ receiver used to receive the control channel signal, and a ‘Control’ receiver used to receive the voice channel transmissions. This can be a little confusing as the signal that the ‘Signal’ receiver is receiving is typically called a ‘Control Channel’.
Step 11: Create Signal Receiver
For the Audio Port setting, select the Virtual Audio Cable created earlier. Set the Sample Rate to 48000, and check all of the decoding protocols.
Step 12: Create Control Receiver
Set the Model to “Debug”, and select all three control protocols: P25, ProVoice, and VSELP.
Step 13: Enable Listening in UniTrunker
Step 14: Start Receivers in UniTrunker
Step 15: Configure SDRSharp
<add key="minOutputSampleRate" value="48000" />
Open SDRSharp and configure with the following settings:
1. set the radio to NFM
2. Press the “Front end” button, disable RTL AGC, and enable Tuner AGC
3. set the Filter bandwidth to 12500
4. ensure Squelch, Snap to grid, Correct IQ, and Swap I & Q are all disabled
5. under the Audio dropdown ensure Filter Audio is unchecked, and the audio output is the Virtual Audio Cable.
Step 16: Find a Control Channel
On radioreference.com, browse to your area and find the section labeled “Trunked Radio Systems”. Browse through the systems and find one that has a good amount of information. See the example below.
We are interested in the control channels, shown in red and blue.
Step 17: Testing a Control Channel
Control channels will be a continuous stream in the waterfall window, unlike voice transmissions which are intermittent.
If you cannot find a signal, try other trunked systems listed in your area, listed in surrounding areas, or by manually browsing the spectrum.
If you find that a control stream is to the near right or near left of the red line after typing in a known frequency, manually move the line to be in the center of the stream. It may be helpful to zoom in. This problem will be dealt with under the calibration section.
After about 10-15 seconds of being tuned to a control channel, a new window should pop up in UniTrunker.
After a few more seconds to a few minutes several frequencies should populate and channel activity will start scrolling by. If you see a red “Frequency Needed” and 0.00000, wait a few more minutes to see if it goes away. If not, click on the small calculator icon at the top and then standard.
Step 18: Calibrating the Tuner
Enter the known control frequency (either from radioreference, or the red frequency listed in UniTrunker) in the center and frequency boxes.
You may see that red line not aligned with the channel. Open the “Front End” dialog box and adjust the Frequency correction value until the red line is centered onto the channel.
Step 19: Lock UniTrunker to the Control Channel
Double click the Signal line under the Receivers tab and change the “Lock Mode” to Dedicated.
Double click the Control line and change the Park frequency to the control channel. In my case it’s 856.21250.
Note: If you change systems or want to find a new control channel you will need to change the Lock Mode back to none.
Step 20: Setup UniTrunker to control SDRSharp
Close and then reopen UniTrunker. Ensure SDRSharp is tuned to the control channel and UniTrunker is receiving the control signal.
Under the Trunking tab in SDRSharp set the “UniTrunker Install Directory” to the directory containing the ‘sdrsharptrunking.log’ file. This is the file that UniTrunker makes to tell SDRSharp which channels to tune to.
NOTE: The code currently makes the poor assumption that you’re running UniTrunker directly from the install directory. If you run it from the shortcut, you will find the ‘sdrsharptrunking.log’ file in your %AppData% directory, typically C:\Users\<username>\AppData\Roaming\UniTrunker. This is the folder you need to select, and because it does not see UniForm.exe or Remote.dll in the same directory, it may complain. Ignore that.
Check the “Delay Re-Tune Until Call Completes” box. This setting controls the level at which SDRSharp will retune back to the control frequency after an audio transmission ends. This value will need some adjusting as you go along, but to roughly set it look at the peak signal strength of the control channel, in my previous screenshots you can see it’s around -15db. Subtract another 15db or 20db and set it to that number.
Set the “Tune to Control Channel” to the known control channel frequency.
Step 21: Start Listening!
You will more than likely need to adjust the AF Gain value under the Audio dropdown. As a general rule you want to try and get the inlvl value in DSD to around 30% for the best quality audio decoding. Note that your computer may work better at another value, so experiment a little.
In my case, setting AF Gain to around 60% worked well.
Also experiment with adjusting the AGC settings in the “Front end” dialog box. Try enabling/disabling the RTL AGC, Tuner AGC, and RF Gain values to get the best signal. Note if you change the AGC values you will likely need to change the “Delay Re-Tune Until Call Completes” value as well.
Step 22: Go Further
I read somewhere that connecting the USB receiver to your computer through a USB extension cable can help reduce interference. I had an old cable lying around from a wireless mouse and it seems to work well.
Also, read over the other resources, they can help you better calibrate your setup.