Sensor - SDR rtl_433

Kismet can leverage the cheap rtl-sdr software defined radio and the amazing rtl_433 tool to collect information about RF sensors, weather stations, tire pressure monitors, switches, humidity, power meters, gas meters, water meters, lightning detectors, and more.

The SDR RTL_433 source can autodetect rtl-sdr devices automatically, and can be manually specified with type=rtl433:


Required software

The Kismet SDR RTL_433 source is a basic Python glue between the rtl_433 tool and Kismet: All the decoding, heavy work, and handling of protocols is done by rtl_433; Kismet collects the JSON output of the tool and turns it into device records.

Kismet thus requires that rtl_433 be available. On some distributions this is available as the rtl-433 package (Ubuntu Jammy )

Supported hardware

While the rtl_433 tool has some support for other SDR hardware via the soapysdr API, currently the Kismet implementation requires a RTL-SDR USB device.

The RTL-SDR is a repurposed digital TV tuner which functions as an extremely cheap SDR, or software defined radio.

It is not possible to use Bluetooth or Wi-Fi devices to capture data with rtl_433; a SDR is required for tuning to the proper frequencies and capturing raw radio sample data.

SDR RTL_433 interfaces

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:


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


Not all rtl433 hardware populates the serial number field, and some hardware ships with a default serial number of 0.

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

Multiple RTL-SDR devices

Every datasource in Kismet must have a unique identifier, the source UUID. Kismet calculates this using the serial number of the RTL-SDR device.

Not all RTL-SDR hardware supplies a valid serial number; often devices will report a serial number of “00000000”. This will not cause any problems for Kismet if it is the only RTL-SDR device, however when using multiple RTL-SDR radios either locally or via remote capture, each one must have a unique ID.

A unique ID can be set using the rtl_eeprom tool to assign a proper serial number, or by using the uuid=... parameter on the Kismet source definition. A unique UUID can be generated with the genuuid tool on most systems.

Capturing different frequencies

While rtl_433 was created to capture on 433MHz initially, it can decode devices on other frequencies as well. A common alternate frequency for sensors, meters, etc is 915MHz.

A SDR RTL_433 source in Kismet can be configured to other frequencies with the channel parameter. To listen to 915MHz, for instance:


SDR RTL_433 source parameters

Naming and description options

All data sources accept the common naming and description options.

Channel control options

  • channel={xyz}

channel={ frequency }

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

Frequency can be in MHz:


or KHz:


or raw hz:


Radio control options

ppm_error={ error_value }

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

gain={ gain_value }

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