Use Fitlet with RTL-SDR Software Defined Radio Dongle

Application notes using fitlet. Credit goes to user Hassellbear for publishing more than enough cool application notes to justify a dedicated sub-forum.

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Use Fitlet with RTL-SDR Software Defined Radio Dongle

Post by hassellbear »


In around 2010, it was discovered that widely available DVB-T, USB television tuner dongles could be used as inexpensive, yet very capable software defined radios. Since that time, quite a few software packages have been developed which make very good use of the RTL-SDR's capabilities. The available applications include aircraft trackers, fm radios, spectrum analyzers, rf-scanners, etc.

Fitlet works well with the RTL-SDR system.


Required Hardware
1. Fitlet
2. RTL-SDR (DVB-T), USB dongle
3. Antenna.
Nooelecnanosdr.jpg (245.37 KiB) Viewed 6149 times
Suitable DVB-T dongles use the Realtek RTL2832U, DVB-T COFDM demodulator ic in conjunction with a suitable wide range tuner ic such as the Elonics E4000 or Rafael Micro R820T.

For this project, I am using the Nooelec NSDR Nano dongle which is available for $18 US including shipping. The Nooelec Nano uses the Rafael Micro R280T tuner which provides a tuning range of 25 - 1700 MHz. The Nano reportedly includes component upgrades designed to provide improved performance as compared to other generic DVB-T dongles.



The rtl-sdr package includes the required librtlsd library and a variety of command line utilities including rtl_test, rtl_sdr, rtl_tcp, and rtl_fm. The command line utilities allow you to test your rtl-sdr setup and implement items such as an fm radio.

Software Installation

A. Using the Package Manager

Using your package manager install the package rtl-sdr

B. From Source

Required Packages
1. git
2. cmake
4. build-essential
5. rtl-sdr

The packages git, cmake, libusb-1.0-0-dev, and build-essential, if not already installed on your Fitlet, are available in the package manager.

To obtain and install sdr-rtl using cmake, execute the following commands in your terminal.

git clone git://
cd rtl-sdr/
mkdir build
cd build
sudo make install
sudo ldconfig

Installation Notes

1. When installing from source, I recommend executing the above commands in /usr/local/src in keeping with somewhat common source installation convention.

2. Running cmake with the with the -DINSTALL_UDEV_RULES=ON argument allows you to use the RTL-SDR dongle as a non-root user.

3. If ldconfig generates the warning /sbin/ldconfig.real: /usr/lib/ is not a symbolic link, execute the command unlink /usr/lib/; ln -s /usr/lib/ as a root user.

Installation Testing

To test your rtl-sdr installation execute the command rtl_test in the terminal. For a successful installation, the results should be:
rtl_test.png (45.49 KiB) Viewed 6149 times

If however, rtl_test returns something like "Kernel driver is active, or device is claimed by second instance of librtlsdr", your installation is using an existing kernel DVB driver instead of the correct driver installed with rtlsdr.

For a temporary fix, unload the incorrect driver using the command:
sudo modprobe -r dvb_usb_rtl28xxu.

For a permanent fix add the line
blacklist dvb_usb_rtl28xxu
to the file /etc/modprobe.d


1. The Noolec Nano works well with Fitlet.
2. Fitlet demonstrates its versatility.

Further Reading ... erver.html

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