Echo caused by SP/LP?

On the Bands
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Today on my activation of Cracoe Fell G/NP-032 I worked 3 US stations on 15m CW @WF4I, KB4LCI and @KF9D. All three signals had a strong echo which made copying them a bit tricky. Was this caused by their signals getting to me by both short path and long path? Or is there another explanation?

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Could it be ‘auroral flutter’ where the RF path goes via the North Pole?

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Snap! It was worst with WF4I. KB4LCI was weak, in and out of the noise with me. But perseverance on both ends and he was in the log. It was more like “smeary” audio than an echo with KB4LCI. So 3 nice US QSOs, my second chase from Iceland in the same week and 30m was manic with super short skip… Don GW0PLP and Roger MW0IDX who is only about 300km distant. Great fun.

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I wondered that but the great circle route from Yorkshire to Illinois doesn’t even go over Greenland so is that far enough north?

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Interesting observation, Richard. I did not notice the echo on your signal. Of course I am using a directional antenna and so a long path return would be reduced considerably.

Roger, KF9D

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Auroral flutter can cause an echo-like effect on 15m contacts between the US and UK, even if the primary great circle route remains south of the Arctic Circle, While the short path between the US and UK typically stays at mid-latitudes, you can receive two versions of the same signal: one via the standard direct route and another reflected off the auroral zone. The slight time delay between these two paths creates a reverb or echo effect.

So your original assumption: SP and LP was correct.

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Folks, there were only minor magnetic field disturbances starting from about 1pm today, not much auroral though. All quiet before that anyway…

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VOACAP predicts around a 50% chance of a long path contact at that time.

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Even without the aurora, if there’s a significant contribution from the LP, you will get the echo effect. I remember in my youth listening to international broadcasters like the BBC WS and occasionally hearing on the more HF shortwave bands, an echo or double-echo sometimes called “around-the-world echo”.

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With SFI today at 196 these echoes are likely.

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I think you are saying the LP is from bouncing off an auroral region, but I meant LP as in all the way around the earth, the long way. So about 34000km with the SP of about 6000km. The difference between SP and LP would be less than 0.1s which seems reasonable for the echo I heard. I know it isn’t quite that simple as the signals will be hopping between the ionosphere and the earth rather than going direct.

Kp of about 2 so doesn’t appear very auroral to me either.

So it sounds like a reasonable possibility.

And yet I had nothing on 10m with only one RBN spot.

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I didn’t say [definitively] it is auroral; I framed it as a question, i.e. as a possibility. In my follow-up post, I said you can get SP and LP by mechanisms other than via the aurora.

Propagation over the polar and sub-auroral regions can be complex, and signals often arrive with bearings significantly displaced from the great circle direction.

You didn’t mention originally whether the echo was very short (essentially a reverb) or with a distinct gap before the echo (like the ‘round the world’ multi-bounce example I mentioned).

The one thing that seems clear is having a multipath signal involving direct and longer paths.

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