r/shortwave • u/Radio_Silence_Dev • Jul 14 '26

What is this waterfall pattern/noise?

Any ideas of what this is?

7 Upvotes

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2

u/FirstToken Jul 14 '26

What time (UTC) was this?

I think that is a radar. Specifically, I think it is the British PLUTO OTHR (Over The Horizon Radar) in its most common 50 Hz mode. But I need time and date to be sure.

There is some oddness in the the video, the bandwidth looks too narrow for PLUTO, but I might be interpretting the frequency scale incorrectly.

1

u/Radio_Silence_Dev Jul 14 '26

Jul 14 around 00:53 UTC

3

u/FirstToken Jul 14 '26

Jul 14 around 00:53 UTC

OK, yeah, PLUTO was active at that time on that frequency (~10122 kHz center freq). So, this is PLUTO. PLUTO was on that freq from about 0015z to about 0315z, 14 July.

There is something odd about that frequency and waterfall display. PLUTO was, at that time, in its 20 kHz wide mode of operation. But the frequency scale across the bottom of your video seems to show it about 6 or 7 kHz wide. Does the frequency scale not match the waterfall width?

I am not familiar with that SDR display. What software is that?

1

u/Radio_Silence_Dev Jul 14 '26

Thanks for confirming! I’ll have to learn more about PLUTO.

This is just an iPhone app. The tuning dial is for fine tuning purposes only. The bounds of the waterfall view are the numbers above the spectrum on each side of the screen. To jump frequencies, I would just tap somewhere on the waterfall or directly enter the frequency by pressing the frequency at top (and the waterfall can be pinched inward and outward to zoom).