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horiz0n, 02/19/2016 10:51 PM

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DVB-T dongles based on the Realtek RTL2832U can be used as a cheap SDR, since the chip allows transferring the raw I/Q samples to the host, which is officially used for DAB/DAB+/FM demodulation. The possibility of this has been discovered by the V4L/DVB kernel developer [ Antti Palosaari].


The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, '''dongles that use the Elonics E4000 offer the widest possible range (64 - 1700 MHz)'''.

Supported Hardware

So far, the following devices are supported:

People over at reddit [ are collecting a list (v2)] of other devices that are compatible.

Other dongles based on the RTL2832U might be added in the future as well.

This is the PCB of the ezcap-stick:brbr
More pictures can be found [ here].


rtl-sdr is a commandline tool that can initialize the RTL2832, tune to a given frequency, and record the I/Q-samples to a file.

The code can be checked out with: {{{
git clone git://

It can also be browsed on

=== Progress ===

=== Building the software ===

==== rtlsdr library & capture tool ====

'''You have to install development packages for libusb1.0''' and can either use cmake or autotools to build the software.

Please note: prior pulling a new version from git and compiling it, please do a "make uninstall" first to properly remove the previous version.

Building with cmake: {{{
cd rtl-sdr/
mkdir build
cd build
cmake ../
sudo make install

Building with autotools: {{{
cd rtl-sdr/
autoreconf -i
sudo make install

The build executable (rtl_sdr) can be found in rtl-sdr/src/.

==== Gnuradio Source ====

'''The gnuradio source requires the rtl-sdr package and a recent gnuradio (>= v3.5.3) to be installed.'''

Please note: prior pulling a new version from git and compiling it, please do a "make uninstall" first to properly remove the previous version.

Building with cmake: {{{
git clone git://
cd gr-osmosdr/
mkdir build
cd build/
cmake ../
sudo make install
sudo ldconfig

==== Automated installation ====

Marcus D. Leech has kindly integrated the forementioned build steps into his gnuradio installation script at []. This is the most user-friendly option so far.

=== Usage ===

Example: To tune to 392.0 MHz, and set the sample-rate to 1.8 MS/s, use:

./rtl-sdr /tmp/out.bin -s 1.8e6 -f 392e6

If the device can't be opened, make sure you have the appropriate rights to access the device (udev-rules, or running it as root).

=== Known problems ===

  • If the samples are written to a harddrive, and not a ramdisk, samples may get dropped. An improved version with proper buffering and asynchronous usage of libusb is in the works.
Using the data

To convert the data to a standard cfile, following GNU Radio Block can be used:br
The GNU Radio Companion flowgraph (rtl2832-cfile.grc) is attached to this page. It is based on the FM demodulation flowgraph posted by Alistair Buxton [ on this thread].

Please note: for realtime operation you may use fifos (mkfifo) to forward the iq data from the capture utility to the GRC flowgraph.

What has been successfully tested so far is the reception of FM/AM radio, [ TETRA], [ GMR], [ GSM], [ ADS-B] and [ POCSAG].

Tell us your success story with other wireless protocols in ##rtlsdr channel on freenode IRC network.

Multiple GMR-carriers can be seen in a spectrum view with the full 3.2 MHz bandwidth (at 3.2 MS/s).

Updated by horiz0n almost 6 years ago · 35 revisions

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