The great WSPR experiment ends.

Well, it doesn't matter how interested one is in WSPR, it's a big ask to get any station to surrender normal operations and keep transmitting signals over several days.

But, with a fine example of cooperation between Argentina and Wales, we have obtained very valuable data on solar minimum, mid-winter night propagation between hemispheres.  Valuable, because with every passing day, the solar cycle is slowly changing, and we will have to wait for many years before the next solar minimum.

Valuable also, because whilst there are a large number of amateur radio operators in Latin America, only a very small number - typically just one or two - operate WSPR on a fairly regular basis.

So, for the last time this winter, some very interesting results that at least confirm that a changing geomagnetic field modifies 14MHz propagation at this time quite dramatically.

First, the field, which showed moderate, high-latitude disturbance (Kp ~2) of the kind that we can expect on a more-or-less daily basis, but a little more energetic than fully quiet conditions:

Image: Tromso Geophysical Laboratory.

Next, my spots of LU8DPV:

This is an unusual pattern on two counts: (1) the usual smooth curve in signal strength before midnight is modified into a suppression of signals as the high latitude Z component becomes disturbed and (2) the peak in signal that does occur is later than usual, compressed into a sharp spike, and reaches a very strong +5dB SNR/2500Hz just before UT midnight.

Clearly, the disturbance is limited to very high latitudes, coincident with the auroral oval.  But some effect is being felt much further afield than this to allow LU8DPV to be heard here.

Also unusual overnight was the persistent detection of HZ1SK, who seems to enjoy some kind of 'favoured link' with Wales, as there are no other stations in that region - or anywhere near it - that come through at these dark hours:

Here, HZ1SK shows a decline in signal as the terminator recedes, with no signal from around 21:00UT to 00:30UT, when the high latitude disturbance is underway, and then a strong return as the field restores to quieter conditions.

The other few signals that kept coming overnight were G0CCL, IT9CJC, and, to a lesser degree and with much higher power (20W), PA3BTI.

First, G0CCL:

Again, something of a suppression in signals as the high-latitude disturbance was underway, followed by a definite peak in signal strength just after midnight, again as the field restored.

Next, IT9CJC, which follows much the same pattern, with a slight timing difference:

And finally, PA3BTI, which merely confirms the finding that a moderate disturbance at very high latitudes can have quite a strong effect on propagation, bringing signals that, under quieter conditions, would not be detected at all up to not only detectable but quite strong levels:

We keep on running...

Well, I kept listening for LU8DPV last night.  I was feeling a little guilty asking for Raul's extended cooperation, but I suppose this is how we learn.  Nobody who looks the other way makes any discoveries!

Yesterday was geomagnetically fairly quiet overall, but there were some minor disturbances, taking the field to a peak Kp ~3.  Out of all the possible magnetometer stations, the Norwegian line cluster (Z component) displays the clearest summary of the day:

Image: Tromso Geophysical Laboratory

The spots of LU8DPV looked like this, which is quite different from what we have seen over the past few, geomagnetically quiet days:

The spots around midnight (UT) are still there, but the spots between the ones at 18:20UT to 20:46UT are absent.  There is also a very incoherent  spike in signal strength between about 14:50UT and 15:50UT; it varies dramatically between -1dB and -20dB within the space of just 10 minutes.

The very small northerly pulse in the field at around 16-17UT seems to have some association with the signal from LU8DPV.  Certainly, the Looking at the timing of these pulses as recorded from east to west, I can see (the single plot for the E-W line is not currently working), that the Norwegian line variations are in much better, and very good agreement with the variations in LU8DPV's signal than lines further to the west, such as Greenland.  Iceland fails to show the disturbances in any detail, as it is directly under the oval at all times on this particular day.

The recovery of LU8DPV at around 20:30UT seems to be coincident with the field moving south through the mean quiet conditions level.  A further, and much larger southerly deviation keeps spot strengths low, until the field moves rapidly north, relaxing to quiet conditions just before UT midnight.  By then, the area of influence has moved towards Greenland, where the field restoration is in good agreement with the changes in LU8DPV's spots:

2019 January 14-15, Greenland East line.  Image: TGO.

One last time (for now!)

Thanks to the continued dedication of Raul, LU8DPV, we were able to gather more data on propagation during solar minimum midwinter night again overnight.

Beaming direction was 030 degrees, the great circle path between us.

Conditions were again extremely quiet, but with a sharp, short-lived spike in geomagnetic activity that extended to mid latitudes:

Spots of LU8DPV by me (now operating a special event call sign, and also using an FT-450 to receive, rather than the usual RSP1a SDR), looked like this:

The curve of signal strength from Raul now appears to have shifted from a peak at around 20:30UT, to a peak around UT midnight.  Further, spots continue at reasonable strength into the early morning hours.

It seems the field disturbance permitted LU8DPV to be heard in the post-midnight period, but the path and precise mechanism remain unclear. 

Back to 030 degrees...

LU8DPV returned to a beam heading of 030 degrees last evening, again under fairly quiet conditions.

There was a minor disturbance around 02:00UT, which may explain a single spot of LU8DPV at 02:32UT, albeit at a very weak, -30dB SNR/2500Hz.  Nobody else in night-time Europe heard him at this time, or near it:

The overall pattern before midnight suggests the path is a direct, great circle one.  But it is difficult to understand the distances involved for it to happen.  The post-midnight (UT) spot seems related to the geomagnetic disturbance.

Beaming 135 - LU8DPV WSPR special report, 2019 January 11-12

With the kind cooperation of Raul, LU8DPV overnight, WSPR was sent from Argentina along a heading of 135 degrees - taking Raul's signal into the austral twilight zone.

Terminator at peak spot strength from LU8DPV (00:38UT), beaming 135 degrees.

Raul did not transmit until mid-evening in the UK, which was by arrangement.

Here is how the spots looked:

As last evening, there was only a small field disturbance at very high latitudes, the Kp being ~ 1, so the general situation was very quiet.  The peak spot strength (a fairly strong -17dB SNR) was reached at 00:38UT.  This coincides with the field restoring to quiet conditions - a phenomenon we see regularly in these studies.  Plot shows Z (vertical) component:

Image: Tromso Geophysical Laboratory.

The peak spot strength when beaming this superficially 'useless' direction is interesting, because at -17dB SNR, it precisely matches the -17dB SNR heard at the time (09:22UT) of morning grey line on 11/01/19, and these two spots are significantly stronger than other times of day, and also significantly stronger than at much the same time yesterday, when the beam heading was 335 degrees:

So we are left with the suspicion that propagation along the grey line to the northern hemisphere might be responsible for this path.  The distance from my station to the grey line to the north of me at 00:38UT is 4500km, which is the typical maximum single hop distance from F2 height.

A quick look at the database (to be confirmed) this morning showed that I was the only one to hear Raul from within the 'dark side' at this time, and within a considerable period either side of 00:38UT.

The problem with this is that Raul continues to be able to get his signal into the local greyline well after 00:38UT, but I stop hearing him.  This, despite the fact the distance from my antenna to my local greyline is decreasing.

So there must be some geomagnetic element to this path.

All I need now is a directive antenna for 14MHz.  Plans are underway for something cheap and wind resistant: maybe a Moxon?

A bit busy this morning, so I will think and maybe write a bit more about this later today...

LU8DPV special WSPR report, 2019 January 10-11

The old way to connect Wales and Argentina: The Mimosa, that carried a small Welsh colony to Patagonia in 1865.

With the continued, kind cooperation of Raul, LU8DPV, 14MHz WSPR continued to be sent overnight, this time with Raul's fine 3 element Yagi beaming 335 degrees.

The idea behind 335 degrees was that the evening terminator runs closely along this heading, as the extract from DX Atlas below shows:

I was interested to see if Raul's signal would continue to be heard here, and also maybe by TF1VHF, who heard him at an unusual time last evening.  Was the signal travelling to the north along a region behind the receding terminator?

Well, this is how I heard Raul:

 

The spots within the shaded area, though weak, are certainly anomalous, especially with Raul's antenna in a beaming position where the elements are presented side-on to Europe.  With practically no change in the field conditions since the preceding evening (beaming 030 degrees), the spot pattern is very different.

We now have to consider whether, in the shaded box time period, there was any geomagnetic enhancement.  Kp was low, at ~2.  The stack plot on the Norwegian line looked like this (Z component):

Its clear that the near-midnight onset of a modest high latitude disturbance in the field coincides with Raul's post-midnight signal being heard for a while.

It's difficult to know whether Raul's spots travelled directly, along a great circle path, or along another, non-great circle path.  Even with the elements fairly side-on to Europe, the gain from a 3-element Yagi is still about 5.7dBi, without taking ground gain into account.  So a 5W signal has an ERP of at least 11W.  But I don't think this is, of itself, enough of a power gain to 'force' the signal to Wales.  After all, either there is propagation, or there isn't. 

Hardly anybody else heard Raul in the post-midnight period here.  LX1DQ lost the signal as the grey line period passed into true night at 16:08UT, but then recovered him at 23:56UT for just over 20 minutes.  A similar, but not identical situation was shown by EA8BFK:

It may be that the fact I continued to hear Raul into the post-midnight (UT) period, where EA8BFK (a regular number 1 receiver in the daily listening challenge) did not, might indicate the effect is related to the high latitude magnetic field.  It's too early to tell.

Tonight, I am hoping Raul can beam 135 degrees, which will send his signal into the austral twilight for several hours.  We'll see if we can make any sense, or no sense at all, from what emerges!

My continued and sincere thanks are extended to Raul for his dedication, reliability and friendliness - the characteristics of a true amateur radio operator.  With the weekend and the increased interference from contests and general operating that it brings now upon us, any more WSPR testing will have to wait for another day.

A modern day joining of nations!

Overnight WSPR report, 2019 January 09-10

Extremely quiet geomagnetic conditions overnight, with only the slightest field deviations, even at very high latitudes.

No unusual spots came in overnight, propagation ending for very short skip signals (e.g. ON) just after 01:00UT.  Models, using the correct antenna types at both TX and RX, predict the MUF between LU8 (TX) and Wales (RX) at 23:00UT was about 9MHz:

Image: www.predtest.uk

Raul, LU8ADV, had kindly offered to send WSPR at 37dBm with his 3-element Yagi pointing at northern Europe for an extended period.

The results are interesting in light of the quiet field, in that it all looks much less anomalous and easier to comprehend.

Peak reception strength comes (between ~20:30 and 21:30UT) when the grey line is passing half way between our respective stations, though the distance to that area is still about 6000km.  It therefore seems simply a case of very low angle radiation making it to the grey line zone in mid-Atlantic, and a rapidly vanishing D layer allowing Raul's signals to the F2 region, where they continue to Wales.

Of course, that is not the whole story, because Raul's signal keeps on coming to MW until the last spot of 23:58UT, when everyone else in Europe has lost him, too.

Then, a surprise! TF1VHF received LU8ADV at 01:06UT (-26dB), where the path is rather difficult to explain.

Looking at the azimuthal projection of the terminator with DX Atlas, one can see the path is about 11,800km if it is along a great circle path.

But also, the grey line area is within F2 line-of-sight of Iceland from his north west to the south east.  I initially thought the signal could be undergoing 'semi-antipodal' focusing (signals reaching TF from many directions), until I remembered Raul's Yagi, with something like 25dB front-to-back, is ensuring practically no signal is being sent to the south.  So focusing is not the answer!

Azimuthal projection of the grey line at 01:06UT, when LU8ADV was heard (once) in

 TF.

So I am wondering if the path is to Raul's west of north, perhaps along ionisation patches drifting from the far eastern Pacific region day side in the F2 layer, allowing continued, if weak propagation into the late (UK) evening.

Raul is not recovered in Europe until 08:46UT, when DK8FT/GPS hears him at -24dB along the immediate-post sunrise line, currently running directly between LU8 and Europe.


When Raul is able, it would be interesting to point his antenna about 335 degrees, to see if we still get any spots from northern Europe, and what their strength might be.

Interesting to note the signal from DL8ULF (TX: 27dBm), as this vanished in the early evening, reappearing much later in a strong peak centred on 00:00UT.  Again, I am not sure as to the mechanism involved, but it may be electrons precipitating from the dayside into the night side, across the north pole.

DL8ULF, WSPR (0.5W), received at MW1CFN 09-10/01/2019