Building a Passive Radar System with RTL-SDR Dongles

Back in 2013 we posted about Juha Vierinen’s project in which he created a passive radar system from two RTL-SDR dongles, two Yagi antennas, and some custom processing code. Passive radar can be used to detect flying aircraft by listening for signals bouncing off their fuselage and can also be used to detect meteors entering the atmosphere. The radar is passive because it does not use a transmitter, but instead relies on other already strong transmitters such as FM broadcast radio stations. Juha writes:

A passive radar is a special type of radar [that] doesn’t require you to have a transmitter. You rely on a radio transmitter of opportunity provided by somebody else to illuminate radar targets. This can be your local radio or television station broadcasting with up to several megawatts of power. 

How passive radar works
How passive radar works

His previous write up was brief, but now over on Hackaday Juha has made a detailed post about his RTL-SDR passive radar project. In the post he explains what passive radar is, shows some examples of his and others results, shows how it can be done with an RTL-SDR dongle, and finally briefly explains the signal processing required. In his next post Juha aims to go into further detail on how passive radar works in practice.

Below we show a video that shows an example of one of his passive radar tests that was performed with a USRP software defined radio and two Yagi antennas. 

This video shows a lot of airplanes around the New England area detected using a simple passive radar setup, consisting of: one USRP and two yagi antennas, a quad core linux PC. Every now and then an occasional specular meteor echo is observed too.

In his other tests shown on YouTube Juha also used two RTL-SDR dongle’s with a shared clock and was able to get similar results.

4 comments

  1. Juha

    A detail about the drawing related to my passive radar observations with RTL and other gear:

    At least on low VHF most short natural scatters appear to be caused by high altitude electric discharges, like high lightnings.

    Their spectrum reveals. The fast linear movement related to meteors is missing. Instead, there is a spread spectrum distinctive to electric discharges in low pressure atmosphere.

    – Juha OH7HJ

    • Bill

      I am trying to use my new SDRPlay receiver for passive radar. Keep getting an “Error loading ft. This file was compiled using the wrong version of the XNA framework.

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