Tagged: dual coherent channel

RTL-SDR Based Passive Aircraft Radar

Over on YouTube we’ve discovered a video from earlier in the year showing the RTL-SDR being used as a passive aircraft radar. This is different to ADS-B which is a type of active radar. A passive radar works by using a very strong radio signal from a readily available source such as a TV or FM radio transmitter and detecting the reflections from aircraft.

A RTL-SDR based passive radar system can be built by connecting two RTL-SDR dongles to a single clock source and by using two directional antennas.

We’ve also posted about RTL-SDR based passive radar being used to track aircraft here and here in the past. Another post about coherent multichannel RTL-SDR receivers can be found here.

Passive RADAR With a Dual Coherent Channel RTL-SDR

Juha Vierinen from the Kilpisjarvi Atmospheric Imaging Receiver Array has been working on a Dual Coherent Channel RTL-SDR modification. This modification essentially involves using the same clock source for two RTL-SDR dongles, which can be done by desoldering and removing the clock on one dongle, and then using a cable to connect the clock from another dongle to the clock input of the desoldered dongle.

RTL-SDR Dual Coherent
Dual Channel Coherent RTL-SDR Receiver

Juha then was able to use his new dual coherent channel RTL-SDR to create a passive RADAR system. To do this, he connected the two RTL-SDRs to two log periodic Yagi antennas. From this setup he was able to detect airplanes and meteor echoes. An image cap and video showing RADAR detections over time is shown below.

Passive RTL-SDR RADAR
Passive RTL-SDR RADAR
Longer rtlsdr fm radio passive radar video