The peril of making videos late at night. I completely screwed up the frequency by a significant factor. The 5ns waveform is around 200MHz (0.2GHz), so it could be the oscillator frequency.
A fairly standard style of module used in solar powered lighting systems. The circuit board has a very intriguing mix of RF, analogue and digital circuitry.
Having reverse engineered the design without testing it first, it was a bit annoying to find out that it was faulty. But it was a good excuse to scope out the filtered doppler waveform.
Not sure what was causing the specific frequency of the rogue waveform. It might have been a hybrid of the 300kHz switching 5V supply combined with an unstable RF oscillator to create a harmonic effect.
Seeing the bursts of low frequency doppler frequency shift was quite cool (if that's what it actually was). The fact it changed frequency with speed of objects approaching the oscillator does hint at doppler detection, where a signal reflection from a moving object will be at a slightly different frequency from the RF transmitter. In this case I think it disturbs the oscillators natural frequency and causes it to modulate its current draw.
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