SDR-stick and RTL_433 or how to monitor road traffic

I stumpled across this intersting post on RTL-SDR.COM talking about monitoring TirePressureMeasurementSystems with a cheap SDR stick and a clever piece of software. The rtl_433 software receives and decodes signals transmitted by tire pressure sensors inside the wheels of modern (I assume at least from the last 10 years) cars.

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My initial idea is, that I can monitor the traffic in front of my house - at least traffic of modern cars. As Germany is a car centric country, I expect to catch most of the traffic.

Hardware used

Software used

  • rtl_433 to control the SDR stick and decode a large bunch of wirelss protocolls (version rtl_433 version 21.12-93-g8228f0d4 branch master at 202204010924)
  • MQTT server running on a Raspbeery Pi
  • NodeRed server running inside a DOCKER container on a SYNOLOGY NAS
  • InfluxDB server running inside a DOCKER container on a Raspbeery Pi 4 pumping its data to an M2.SSD
  • Grafana server running inside a DOCKER container on a Raspberry Pi 4



rtl_433 is currently running on my regular Shack-PC using this command line:

rtl_433-rtlsdr.exe -v -M level -C si -R 89 -R 90 -R 93 -R 82 -R 59 -R 60 -R 88 -R 95 -R 110 -R 123 -R 156 -R 168 -R 180 -R 186 -R 203 -F "mqtt://,retain=0,[type]/[model]/[id]" -F kv

I configured rtl_433 to listen only to the various protocols for TPMS. rtl_433 posts the received data packets in JSON format to a local MQ broker.

 {"time":"2022-04-03 09:56:01","model":"Toyota","type":"TPMS","id":"f211a9d6","status":128,"pressure_kPa":193.05321,"temperature_C":1.0,"mic":"CRC","mod":"FSK","freq1":433.92701,"freq2":433.87645,"rssi":-7.68193,"snr":15.06707,"noise":-22.749}


A simple NodeRed-flow listens to these topics on the MQ Broker and 

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transforms the received JSON-data into JS objects. These are inserted into an InfluxDB time-series database.


Grafana is reading the InfluxDB data and visualizes this data:

2022 04 03 10 00 03 Window

The "empty" span during the night - rtl_433 was off ;-)

Next steps


Move the rtl_433 software and RTL-SDR stick to another unused Raspberry Pi and place it under the roof of my home.

I expect the RF coverage will be much better - lets see.


Currently the software detects and counts the number of TPMS sensors.

As a car usually has 4 sensors - you will get 1-4 readings depending on the transmit interval of the sensors in this specific car.

So there is no direct correlation between a single reading and a specific car. Lets see how I can handle this in the near future.