RTLSDR usage

Setup rtlsdr

By rtlsdr usually call RTL2832U chip based tv-tunners which can be used for not just receiving DVB-T frequencies but much more and yes price is ~$10 it mean that anyone can just buy and try without "loosing" money. None of examples below requires any modifications or extra hardware to run.

As of 2022 the version r820t2 that is commonly available.

Get sources

Main development repository is on http://sdr.osmocom.org/trac/wiki/rtl-sdr on github you can find more repos with experimental features (https://github.com/keenerd/rtl-sdr).

Getting sources from git:

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git clone git://git.osmocom.org/rtl-sdr.git

I prefer using plain binaries without any kind of installation. Just compile and use binary without any troubles. Build:

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cmake .
make

All binaries is in src dir.

Util Desc
rtl_adsb recieve plain ADSB plain packets
rtl_eeprom read
rtl_power log power over frequency range
rtl_fm demodulate signals
rtl_sdr output raw rtlsdr data
rtl_tcp remote rtlsdr server
rtl_test test rtlsdr

Drivers

Linux kernel have some drivers for rtlsdr stick and DVB-T. When you will plug rtlsdr then kernel probably will load DVB-T drivers and you will not able to use you rtlsdr for sdr. Way yo fix is it add some drivers to black list and next time when you will plug rtlsdr this drivers will not be loaded.

Check if rtlsdr related drivers is loaded:

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lsmod | grep rtl28

If there is some drivers then blacklist driver by creating file in /etc/modprobe.d/ with content:

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blacklist dvb_usb_rtl28xxu

Next thing that could appear is permissions on rtlsdr usage when its plugged in. To allow everyone to use create file in /etc/udev/rules.d/ with content:

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SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", \
  GROUP="adm", MODE="0666", SYMLINK+="rtl_sdr"

Check if works

How to test if rtlsdr works? Run one of commands:

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rtl_test

I like to run rtl_adsb as you can see there that something is received and you see that everything "works":

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rtl_adsb

There should be line by line showing up some "hex" lines. If some data is shown then adsb data from plains is received.

Collection of tools

rtl_fm, FM modulation

Get some sound transmitted from FM radio stations. Find local radio station and set frequency choose wide band FM modulation -M wbfm set SDR sample rate to any supported, but more then 150kHz, for example -s 200000. Resample SDR output to audio frequency -r 48000. Pipe output to any audio tool here is example for aplay where sampling rate set to same resampled rate of SDR. IQ format from rtlsdr is signed 16 bit little-endian -f S16_LE.

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rtl_fm -f 96.3e6 -M wbfm -s 200000 -r 48000 - | aplay -r 48k -f S16_LE

rtl_power, Spectrum diagram

Scan spectrum to find some activities on different frequencies. Good link with all description is http://kmkeen.com/rtl-power/ . Main usage of rtl_power is :

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rtl_power -f 76M:108M:125k -i 1 fm_stations.csv

and then draw image :

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heatmap.py fm_stations.csv fm_stations.png

rtl_adsb, ADS-B

ADS-B ( Automatic dependent surveillance broadcast ) in simple words airplane geo location, speed, height and flight number broadcasting. You can receive this data and see how many plains is around and sometimes flight number.

rtlsdr have default one rtl_adsb program but it shows only received data, without any decoding. Here is dump1090 specifically for rtlsdr and nothing more:

https://github.com/antirez/dump1090

description howto install could be found also here

http://www.satsignal.eu/raspberry-pi/dump1090.html

Using in interactive mode with height in meters:

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dump1090 --interactive --metric

Output:

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Hex    Flight   Altitude  Speed   Lat       Lon       Track  Messages Seen .  
  ------------------------------------------------------------------------------
  71be01          10052     1009    36.434    33.544    45    9         1 sec
  424913 SDM6329  10966     711     36.440    33.405    221   65        0 sec

GQRX, FSK1200

Gqrx is graphical SDR software where you can scan across frequencies and demodulate and listen FM broadcasts and HAM bands frequencies. Easy way how to explore the available frequency range

http://gqrx.dk/

It have built-in AFSK1200 demodulator or in simple words ham radio packets. And you could try to see what people sending in text around the world.

Multimon-ng

Support many digital transmission modes.

https://github.com/EliasOenal/multimon-ng

Waterfall

Here is few waterfalls for rtlsdr

https://github.com/roger-/pyrtlsdr

It have demo waterfall and also thats is python bindings to libsdr that could used for fast prototyping

rtl-entropy

https://github.com/EliasOenal/multimon-ng

Project that make rtlsdr as entropy source, uses FIPS 140-2 standard to verify that data is random enough to pass test.

rtl_433

Generic ISM data receiver. Can use to track remote sensors, weather stations and many other devices.

https://github.com/merbanan/rtl_433

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rtl_433

Projects where rtlsdr used

WebSDR

WebSDR probably best site where you can go and click on some radio receiver and listen what happens in some particular country. WebSDR site contains about 80 radio receivers around the world that can be accessed trough web interface.

http://websdr.org/

If you want setup your own radio reliever read FAQ, prepare mail and send mail after that you could receive p recompiled websdr software with is easy to setup with rtlsdr stick.

Problems

Sync errors

Once there was sync error when was trying to use rtl_test or rtl_adsb. To fix that changes for better quality usb cable.

More then 1 dongle

When you run you run usually more then 5 dongles you could get error saying something about libusb error (-5) you need to decrease buffer as default one is (16 * 16384) and it should work

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rtl_test -b [NEW_SIZE]

thx goes to libera.chat/##rtlsdr chan

Links

  1. http://kmkeen.com/rtl-demod-guide/
  2. http://kmkeen.com/rtl-power/
  3. http://sdr.osmocom.org/trac/wiki/rtl-sdr
  4. http://www.rtl-sdr.com/
  5. https://github.com/antirez/dump1090
  6. http://gqrx.dk
  7. https://github.com/roger-/pyrtlsdr
  8. https://github.com/EliasOenal/multimon-ng
  9. https://github.com/merbanan/rtl_433