switch mode power supply? (Tone sweeps)

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switch mode power supply? (Tone sweeps)

Post by JEL » Sun Jul 19, 2020 4:25 am

It seems whenever people post spectrum-grabs like the one I have attached below, the source is called out to be a switched-mode-power-supply (Often known as 'SMPS' on google apparently)

Does the spectrum I attached look like such a thing?

There are multiple sweeps.

They do not all sweep the same way. Some sweep down while others make funny little bends up and down.

But they all repeat their individual sweep-pattern over and over again, at their individual frequency (They do not appear to drift off, but remain on their frequency. They may wiggle a few hertz from repeat to repeat, but overall they appear frequency-stable) and with the same repetitive pattern and timing. (Some of them repeat every 12 seconds, while others repeat every 24 seconds)

They range from about 2 MHz to about 4 MHz.
EDIT: I just noticed they also appear on 7 MHz, so apparently they span wide.

If this looks like such an SMPS, is there anything we can deduce from how these sweeps look, as to what it might be for a type of device that cause this?

Are there anything generally identifiable with SMPS signals at all? (As in; if it does this it may be this kind of device and if it does that it may be that kind of device)

Or can we only say they may be some sort of SMPS, but nothing beyond that?
Annotation 2020-07-19 053843.png
Annotation 2020-07-19 053843.png (805.47 KiB) Viewed 3887 times

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