What can I learn about my Pi from this graph?

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What can I learn about my Pi from this graph?
Image icon pi_sdr.png630.42 KB


I"m curious what the attached graphic tells someone more knowledgable than myself about my Raspberry Pi wspr transmissions.

I have a pi connected to a 20m dipole transmitting on 40m from my shed. The attachment is taken from a sdr receiver about 20 meters away in my roofspace or attic for American friends.

I see a similar 4 pronged signal when I connected the same pi to a battery rather than mains/usb charger which surprised me.

I have a qrblabs lpf between the pi and the antenna. Disconnecting the ground between the pi and lpf increased the amplitude of the signal and more spots in the roofspace. The shape of the signal remained the same,
4 pronged, it was just stronger.

Another quirk is that when using Wsprrypi if I want to tx on 7MHz I need to give Wsprrypi a tx frequency of 1MHz. I'm being approximate with the numbers there but it is a whopping difference.

Not 100% what version my pi is but it's definitely less than a version 2.

Thanks as always,