SDR rtl433 sources

SDR

SDR, or software-defined radio, uses special generic hardware to capture radio signals, and performs signal processing in software.

SDR is extremely powerful, but also often extremely brittle - configuring SDR hardware and software to work reliably can be quite difficult. Kismet is able to use external SDR tools to interface with hardware and utilize some of the power of SDR.

Datasource - SDR RTL433

The rtl-sdr radio is an extremely cheap USB SDR (software defined radio). While very limited, it is still capable of performing some useful monitoring.

Kismet is able to process data from the rtl_433 tool, which can read the broadcasts of a multitude of wireless thermometer, weather, electrical, tire pressure, and other sensors.

To use the rtl433 capture, you must have a rtl-sdr USB device; this cannot be done with normal Wi-Fi hardware because a Wi-Fi card is not able to tune to the needed frequencies, and cannot report raw radio samples that are not Wi-Fi packets.

More information about the rtl-sdr is available at: https://www.rtl-sdr.com

The rtl_433 tool can be downloaded from: https://github.com/merbanan/rtl_433 or as a package in your distribution.

The Kismet rtl_433 interface uses librtlsdr, rtl_433, and Python; rtl433 sources will show up as normal Kismet sources using the rtl433-X naming.

rtl433 devices

Kismet identifies rtl433 hardware by either the serial number (if any) or by the radio position; for example:

The first rtl433 radio in the system:

source=rtl433-0

A specific rtl433 radio (if serial numbers are available):

source=rtl433-324452324332

Not all rtl433 hardware populates the serial number field.

Serial numbers can be found using the standard rtlsdr tools, like rtl_test:

$ rtl_test 
Found 4 device(s):
  0:  NooElec, NESDR Nano 3, SN: 2686186936
  1:  NooElec, NESDR Nano 3, SN: 1177459274
  2:  NooElec, NESDR Nano 3, SN: 2664167682
  3:  NooElec, NESDR Nano 3, SN: 0572734167

rtl433 parameters

RTL433 sources accept several options in the source definition, in addition to the common name, informational, and UUID elements:

  • channel=xyz

    Manually set the frequency; by default rtl433 tunes to 433.920MHz.

    Frequency can be in MHz:

    source=rtl433-0:channel=400MHz

    or KHz:

    source=rtl433-0:channel=500000KHz

    or raw hz:

    source=rtl433-0:channel=512000000

  • ppm_error=xyz

    Set the error correction level for your radio, passed as the -p option to rtl433

  • gain=xyz

    Set the gain, if supported, passed as the g option to rtl433

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