The RTL-SDR is an inexpensive software defined radio dongle based on the RTL2832u chipset. The dongle was designed to be used as a digital video and radio receiver, but with some custom firmware can be re-purposed as a wideband software defined radio receiver.

Effectively this means that for under £10, you can get a radio scanner capable of receiving between around 22mhz and 1.8ghz. I started playing around with my SDR long before I became interested in amateur radio, and here are some of my favorite uses:

• Tracking aircraft with ADS-B data
• Listening to NFM radio transmissions (amateur bands, air traffic control, PMR446)
• Decoding APRS packets from the International Space Station
• Sniffing signals from wireless consumer electronics
• Using the SDR with my android phone as a portable scanner (great for airshows)

These are just a few of the capabilities of the dongle. A longer list can be found on the RTLSDR website.

Where to get a dongle

The SDR dongle is available all over the internet, and in a few different versions. The most common one I’ve seen (and the one I use) is listed as RTL2832u + R820T. I bought itfrom Ebay, and it cost me just under £10 at the time.

Here is a link to a search on Ebay, which should come up with the right thing. Ebay search link

The product image should look something like this:

Antenna

The SDR dongle usually comes with an included whip antenna for picking up FM radio signals. The dongle has a MCX (Micro Coaxial) connector on it, which can be easily adapted to a SO259 connector (link). Personally I use my dongle with a discone antenna in the loft for general wideband reception, and with a crossed dipole satellite antenna for receiving data from satellites. More information about my antenna setup can be found on my QRZ profile.

Software Setup

The most commonly used SDR software is called SDR# (SDR-Sharp). The installation process is relatively simple, and includes drivers for the dongle. Do not install any of the included software that comes with the dongle.

1. Download the software from airspy.com/download
2. Extract the zip file
3. Run the “install-rtlsdr.bat” which will download the latest drivers
4. Plug in the SDR dongle, and wait for Windows to attempt to install drivers.
5. In the sdrsharp folder, right click on the file called “Zadig.exe” and select “Run as Administrator”
6. When the Zadig application opens, click “Options” and select “List All Devices”
7. Select “Bulk-In, Interface (Interface 0)” from the drop down list. If RTL2832U or RTL2832UHIDIR show as options, these are also fine to use.
8. Check that WinUSB is shown in the box above “Replace Driver” and then click “Replace Driver.” Your computer may warn you about using unverified drivers, but it is safe to install the drivers regardless.
9. Run “SDRSharp.exe”
10. Press the settings button in the top-left corner, and set the gain (requires some experimentation to be set correctly)
11. Press the play button in the top-left corner

Now SDR# should be set up and functioning correctly. If you have any issues, have a look at the Quick Start Guide, or leave a comment below.

SDR Sharp Guide

This is the SDR# User Interface. In the middle is the Spectrum Analyser and Waterfall, and on the left are all the settings for the program.

Firstly you’ll need to correctly set the gain. To do this, hit the play button in the top left and tune the radio to a frequency with some signals (such as 99.5mhz). Then open the settings menu (cogwheel in the top-left corner) and have a play with the gain control. The correct settings varies from dongle to dongle, but the general advice is to set it as high as you can without noticing an increase in the noise floor.

Using SDR#

This is the Radio control panel. It contains the most commonly used settings. At the top, there is a list of modes that you can select. Below this are bandwidth, squelch, step size controls. More information on SDR# can be found on the SDR# quick start guide

Conclusion

I hope this provides you with some useful information about the RTL SDR dongle. It was money well spent for me, as I have used my SDR for loads of different applications, and it was probably the main thing that got me interested in amateur radio. Hopefully you find this guide useful, and if anyone has any questions, just post them in the comments below.

-Peter Barnes (M6KVA)