I noticed huge amounts of electrical noise in my sensors at work, of which were powered from a decent power supplies. So I hooked up an oscope to the power supply output and noticed this really odd signal.
Thinking it was the power supplies which was broken, I tried 3 others, each of a different model/brand. They all outputted this strange signal.
Thinking it was the oscope, or EMI, I measured a lead acid battery. No signal/noise measured from the battery, so clearly it was something in the mains.
I also used the ADC from my Axon, without the oscope, and still see the noise.
The signal, after passing through a power supply, looks like this:
- exactly 92 sine waves, about 0.9Hz, of amplitude ~70mV
- a 10 second pause with no noise and no signal
Between each sine wave is another very short pulse of what appears to be a very high frequency signal. It is perfectly synchronized with the sine wave.
I've managed to filter out the low-frequency sine wave by adding > 300uF capacitor, but haven't yet figured out which cap to use for the high frequency stuff.
But my real question is . . . What the heck does this?!