Tagged: zadig

Quick Start Guide

This page is a guide aimed at helping anyone set up a cheap radio scanner based on the RTL-SDR software defined radio as fast as possible on a Windows system.

Equipment Guide

Currently, the most common RTL-SDR dongle is the R820T which can be purchased here. See the Buy RTL-SDR dongles page for more information.

To get the most enjoyment out of RTL-SDR you will need a decent antenna. The stock antenna that is shipped with the dongle is okay for testing and will pick up a number of signals, but is generally considered as poor for any serious radio scanning. For beginners, a bunny ears antenna like those you get for TVs should already work much better than the stock antenna. The most recommended antenna for general scanning is a scantenna or discone due to their wide band receiving properties.

Set Up Guide (Tested on Windows Vista/7 + XP)

  1. Purchase an RTL-SDR dongle. The cheapest and best for most applications is the R820T dongle, which can be purchased here from Nooelec.
  1. SDRSharp is the easiest and most commonly used software defined radio software receiver for the RTL-SDR. Go to sdrsharp.com and head to the downloads page. Note that you must have the Microsoft .NET redistributable installed to use SDRSharp. Most modern Windows PCs should already have this installed by default, but older PCs running XP may need this to be installed.
  1. Ignore the downloads on the top of the page. Scroll down to where it says “Important note for RTL-SDR users”. Download sdr_install.zip from that link.

SDRSharp Download Page Screenshot

  1. Extract sdr_install.zip to a folder.
  1. Double click on install.bat from within the extracted folder. This will start a command prompt that will download SDRSharp and all the files required to make SDRSharp work with RTL-SDR. Everything will be placed into a new folder within the sdr-install folder called “sdrsharp”. The command prompt will automatically close when it is done.


  1. Plug in your dongle and do not install any of the software that it came with, but ensure you let plug and play finish trying to install it. If you’ve already installed the software drivers it came with previously, uninstall them first.
  1. Open the newly created sdrsharp folder. Find the file zadig.exe. Right click this file and select “Run as administrator” if using Windows Vista/7/8. If you are using Windows XP, download the XP version from this page. If you are on Windows 8 you may get signed driver issues. To get around this we recommend downloading and using the newer Zadig version 2.1 from here.
  1. In Zadig, go to Options->List All Devices and make sure this option is checked.
  1. Select “Bulk-In, Interface (Interface 0)” from the drop down list. Ensure that WinUSB is selected in the box next to where it says Driver. (Note on some PCs you may see something like RTL2832UHIDIR instead of the bulk in interface. This is also a valid selection).

Zadig Screen

  1. Click Install Driver. You might get a warning that the publisher cannot be verified, but just accept it by clicking on Install this driver software anyway. This will install the drivers necessary to run the dongle as a software defined radio. Note that you may need to run zadig.exe again if you move the dongle to another USB port, or want to use two or more dongles together.


  1. Open SDRSharp.exe. Set the drop down box at the top next to the Play button to ‘RTLSDR / USB’. Press Play. Your rtl-sdr software radio should now be set up and ready to use! If everything has worked you should be able to start tuning to frequencies. Be sure to also adjust the gain settings by pressing the Configure button up the top near the Play button.

Device Selection


  • Zadig takes a long time to install the driver, then fails
    You have probably not run zadig in administrator mode. Make sure to right click zadig, and select “Run as Administrator”
  • I don’t see Bulk-In, Interface (Interface 0)
    Ensure Options->List All Devices is checked. Some people report seeing something else other than the bulk in interface. It may also show up as the brand of your dongle or something prefixed with “rtl”. This option should work too.
  • I don’t see RTL-SDR/USB in SDRSharp
    You may have downloaded a version without rtl-sdr support. Check that you followed the instructions in step 3 and downloaded the version under the heading “Important note for RTL-SDR users”.
  • Zadig gives “System policy has been modified to reject unsigned drivers” error in Windows 8
    Windows 8 can cause signed driver issues with zadig. Some users report getting the error “System policy has been modified to reject unsigned drivers”. To solve this download and use the newer Zadig version 2.1 from here.
  • Reception in SDR# seems very poor/receiver is insensitive
    Make sure you have increased the gain slider which can be accessed by clicking on the configure button. Also, in poor reception areas using the stock antenna indoors may not be sufficient.
  • SDR# gives error “Application failed to initialize properly (0xc0000135).  Click OK to terminate.”
    This might mean that you do not have the .NET 3.5 Framework installed.

How to set the Gain

The gain can be adjusted in SDR# by clicking on the Configure button. When tuning the RF gain you are trying to get the signal as strong as possible, whilst keeping the noise floor as low as possible. Start with a low gain setting, and slowly increase the gain slider. Watch in the frequency spectrum as the signal strength increases, but stop just before the point at which the noise floor starts to rise.

The noise floor is the part of the frequency spectrum where there are no signals.

SDRSharp Plugins

A list of SDRSharp plugins can be found here.

SDRSharp Guide

A good guide to learning how to use SDRSharp and what all the options do can be found here. Another great illustrated guide can be found here.

Other SDR Windows Software Compatible with RTL-SDR

HDSDR – An advanced version of the WinRad SDR software. A free software defined radio package.

SDR-Radio v2 – A free Windows program for software defined radio.

SDR-J – Free Windows program capable of also decoding DAB signals in software.

See the Software Guide for a big list of other compatible RTL-SDR software.

Getting Started on Linux

A good guide to getting started on Linux and GNU Radio can be found at this blog post here.

Note that if you want to run Linux in a virtual machine it has been reported that performance with VirtualBox is rather poor due to it’s slow USB connection. VMWare Player on the other hand has good performance.

Installing SDR# with Mono in Linux

Install Mono and the Monodevelop environment.

sudo apt-get install mono-complete
sudo apt-get install monodevelop

Install libportaudio for sound

sudo apt-get install libportaudio-dev
sudo apt-get install libportaudio2

Use svn to checkout SDRSharp. If you don’t have svn installed use sudo apt-get install subversion to install subversion.

svn co https://subversion.assembla.com/svn/sdrsharp/trunk sdrsharp
cd sdrsharp

We first need to replace the version string in the SDR# solution file as Monodevelop currently does not recognize solution files created by Visual Studio 2012.

sed -i 's/Format Version 12\.00/Format Version 11\.00/' SDRSharp.sln

Open the solution file with monodevelop

monodevelop SDRSharp.sln

In Monodevelop set the build to Release|x86, then go to Build->Build All

Now we need to first symbolically link libportaudio to the Release folder where SDR# was just built.

cd Release

First we need to find out if you are running a 32-bit (x86/i686) OS or a 64-bit (x64/x86_64) OS. To do this type

uname –m

If you see the result as i686, you are running a 32-bit Linux so type in

ln -s /usr/lib/i386-linux-gnu/libportaudio.so.2 libportaudio.so

If you see the result as x86_64 you are running a 64-bit kernel so type

ln -s /usr/lib/x86_64-linux-gnu/libportaudio.so.2

Add RTL-SDR support to the SDRSharp.exe.config file by opening it with a text editor and finding the line that contains the text SDRSharp.RTLSDR.RtlSdrIO,SDRSharp.RTLSDR. Uncomment that line by removing the surrounding <!– –> characters.

Now you can run SDRSharp by typing

mono SDRSharp.exe