Passive radar

Passive radars are known already from WW2. Here I present my solution to use RTL-SDR dongle and fast Radeon video card (NVIDIA is also possible but the library are different). This software uses OpenCL libraries from Radeon (similar are also for NVIDIA). Program supports up to 2 coherent receivers but for passive radar one dongle is enough. I would like to thanks Frank from Finland for excellent idea and hard work!

Old x64 version of radar software (AMD OpenCL) may be downloaded from here.

The GitHub code and binaries of Passive Radar for Windows 11 64bit is here.

The code for super fast ambiguity function FAF (NVIDIA CUDA) is here. The library supports one or two dongles (correlated) 🙂

The Passive radar in action

The resolution is 40×40 with around 70 frames/s of continous data flow! The RTL-SDR dongle does not have the best parameters, but analyzing 2097152 bits per frame gives interesitng results. The movie was recorded in a not the best location because the DVB-T transmitter (490MHz) was located on the right at 0.5 km and some buildings close to the road shadowed the signal. Cars give a negative doppler shift as they drive away. Arriving vehicles produce a positive doppler shift. The distance is around 50–300 m. The car’s speed is around 30–50 km/h. Each displayed frame is an average of 30 frames. The background is substracted and the left-right symetric filter is applied (substract the lower value from both pixels on left and right from the main 0 doppler shift line).
The link to the movie is here.

 PassiveRadar in action. The DVB-t tower is around 20km from my antenna. The DVB-t power is 56kW. The signal comes from a small sport plane around 6-8 km from my place in the direction of DVB-t. The signal sometimes is below the line of trees because the plane has a low altitude of 1km.

PassiveRadar settings:

Nr. columns 200

Nr rows ~300

Signal average 40 frames

Static background correction after recording

Doppler zoom ~20

Amplification 2.8

With function remove symmetrices

Movie1 Movie 2 Movie 3