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How to measure Ultra Short Radar Bursts

Since the SPECTRAN V6 offers an ultra low POI, within the ns range, you can capture and even decode a radar signal with the cheap SPECTRAN V6 RSA250X unit.


The first screenshot shows our radar under test operating at 3350MHz with a regular 2048 point FFT and a POI of 33µs:

Radar Spectrum with 2048 FFT and 33µs POI


Although this shows a lot of burst packages it does not give you the real picture of the radar signal. This will change if we use a smaller FFT resulting in a lower POI. The next screenshot shows a 16 point FFT with a whopping POI of 195ns. The frequency domain gets sort of blurry, since we only have a 16 point FFT, but the time domain now gets realy interesting. We can see short and long bursts within the µs range:

Radar Signal with low POI within the ns range


The 2D and 3D waterfall views still have a time compression of factor 10. If we reduce that to 1 (real-time) we get a much better picture about what is going on. We can now see that the longer bursts have a length around 6µs and seem to have a own package structure:

Real-Time Capture of a Radar Signal Spectrum


If we now zoom into one of those bursts we get the full picture. They have some sort of coding with a pulse length of around 400ns. The 3D waterfall shows a great picture of the pulse. It shows this to be a phase modulated pulse using Barker code of length 13. Nice!

Radar Spectrum showing a Barker code with a length of 13

3D Doppler Radar Spectrum with a Barker Code of 13


An finally a Multi Spectral view of the RF emitted by the radar. A great finger print!

Doppler Radar Multi Spectral Finger Print

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