My previous post describes the $16 dual channel rtl_sdr dongle hack. In the last few days I’ve done some more testing and it turns out I can use the system for passive radar! I didn’t expect this, because the receiver only has 8 bits and passive radar requires a lot of dynamic range.
|Airplanes and occasional specular meteor echoes.|
I hooked up the two channels into yagi antennas that we have used with Echotek and USRP receivers for passive radar. One of the antennas was measuring the transmit waveform, and the other was measuring the echoes. I ran a measurement, and to my great surprise, it worked just fine.
I did tweak the signal levels a bit in order to ensure that I optimally use the dynamic range. I also had the bandwidth set to 2.4 MHz, giving me about 4.5 bits extra dynamic range after filtering the signal to 100 kHz in single precision floating point.
|Two log periodic antennas used to passive radar with the dual coherent RTLSDR R820T dongle.|
This really does give us a glimpse of the future where high end digital receivers will cost $10 per channel. The low end ones are already in that price range. Think of all the potential science that can be done!