28MHz WSPR

It's a long time since I did any WSPR activity at 28MHz, but recent conditions are now making this worthwhile, as operators return in much larger numbers to the band (although many could well do with forgetting what they did 5 years ago, and turn their power down from 5W!)

The clear thing with 10m WSPR is that, because signals are coming in via Es, which is inherently irregular in nature, the SNR pattern is extremely noisy when compared with lower bands; rapid deviations of ~20dB occur regularly in the following plot of my signal heard by DK6UG yesterday evening and into the morning today:

DK6UG hearing my 1W at 28MHz (TX: vertical delta loop, at 1st harmonic).

Meanwhile, a monster PMSE cloud is emerging through this morning.  It may well be another busy day on the higher bands!

PMSE echoes, Arctic Norway today.

QRSS, 28MHz

Following on from John, EI7GL's interesting recent post, partly about following propagation changes at 28MHz with QRSS, I had a go at the same myself this afternoon.

I found a small number of stations happily coming and going over a single transmission period.  Quite difficult to follow the code at times, due to the QSB. 

Anyhow, the whole thing actually managed to grab the attention of my kids, now near-adult teenagers, which is quite an achievement.  It's a little like reading  a book when you read QRSS - you just have to settle down and slow down; it can't be hurried!

Certainly, the strong and brief spikes in signal strength at centre image from G6NHU are fascinating, probably being specular reflections off a Es wavefront.  It could have been aircraft scatter, but it did repeat from time to time.

Most signals were old-timer G callsigns, but I did also get a strong and very stable signal from TF3HZ earlier in the afternoon.

Thanks for pointing me in the direction of something new, John.  I guess I will have to buy a TX kit for the mode now!

RFI-free keyboard

Whenever I find RFI-free products, I like to tell others about them here.  Remarkably, despite the ubiquity of computing devices and RFI in amateur radio, I've never found an online resource that keeps a list of things that are 'good', and things that are 'bad'.

Good 'SR-mini' keyboard for the past few years, no RFI.

I've used a very cheap compact keyboard called 'SR-mini' with my Raspberry Pi, which has no RFI at all, unlike a previous (metal-backed) keyboard I had, a 'HiPoint', sold specifically for the Raspberry Pi, which was absolutely terrible in RF hash generation.  All Microsoft full-sized keyboards I've bought are RFI-free.

Incidentally, an 'Artek' backlit keyboard I once bought, whilst RFI-free, was good quality, but simply couldn't maintain a good Bluetooth connection.  Useless!

No RFI!

Anyway, the 'SR' keyboard is sometimes not available, so I had to try and pick a similar alternative field-use keyboard, hoping it would also be RFI-free.

Well, I'm happy to report the Compoint CP-K7070 keyboard is, indeed, both a good quality and RFI-free keyboard, currently about £11 in the UK. 

Cabo Verde (reprise)

Well, I did it again!

A marine duct has formed between the UK and the equatorial Atlantic, with D4VHF appearing early this morning.  Despite two way reports, I didn't manage a QSO at that point.

Wahoo!  Made it.  Noise lines are due to the 8-ele pointing directly at my laptop.

A little later, the signal became strong enough to make it.  D4VHF was all but invisible on the waterfall, despite the beams and fairly high power at both ends (12 ele, 400W there; 8-ele, ~130W here).  It's instructive to consider that, with HFTA predicting just over 21dB antenna-and-terrain total gain (and this at very low angles, below 1 degree), that ~130W input equates to ~17.1kW ERP. 

Marine duct - narrow but just enough to allow the QSO.  Image: F5LEN.

Conditions at lunchtime were pretty stable, but I could only see one EI station also making the connection at the time.

Beaming 210 to Cabo Verde.

Not quite as exciting as January 1st, when I achieved the 2-way D4 QSO with just 3 elements and 50W.

UPDATE:

Amazingly, I managed +10dB, rising to +16dB into EA8CXN.  A few moment later, we managed a clear 2-way SSB QSO!  FT8 then went up to +20dB at EA8.  Wow!

Noise of the Waves

Following on from recent beach work, John, EI7GL, asked a very valid question about the potential difference in HF noise floor between home and beach.

I'd always judged this on experience, and considered there was little or no difference in the noise floor.  But that's no way to go about science, so I set off for a very brief session of noise assessment this evening.

A quick noise floor assessment at the beach, looking landward (East).

I used a Windows 10 laptop to run SDRUno software, coupled to a RSP1a receiver and a 14MHz, 1/4 wave elevated vertical with two elevated radials for both sites.

I wouldn't claim that the result is accurate in absolute terms, not least because there is always a fair bit of fluctuation in the output.  But I think it is, as a comparison between sites, perfectly valid.  I kept the settings exactly the same for both sites, over a bandwidth of 1800Hz.  The weather was electrically quiet, nearest lightning slight, over eastern Europe and central Spain, a fine sunny day with a gentle breeze.

The result?

Home noise floor, with LED TV on in the living room, various other domestic things, but none of a known noise-generating nature:  -110dBm (a 'rural' noise level, according to the ITU).

At the beach: -111dBm.

It seems my ears are pretty good at comparing the noise floors!  From the more considered online discussions, it seems the RSP1a itself, when using a terminated input, yields a noise floor of about -120dBm.

ITU Noise floor classifications.

12m Yesterday,.

Well, forget the old addage that solar minimum means you need not bother with the higher bands.

This is the plot of all stations heard hear at 24MHz yesterday, most of which, other than the Indonesian spot, I also worked on FT8.

24 hour reception (and, for the most part, 2-way QSOs) at 12m here yesterday.

The strength of signals from the Caribbean and Latin America was nothing short of astounding, easily of a level able to support low power SSB, though I didn't think to check!

J68HZ, blasting out of the waterfall at 12m!

For example, look at J68HZ, at 6638km, which was hitting an astounding +17dB here at around 21:30UT, but was up at that level for perhaps an hour either side.  Not until 01:38UT did the last signals from the Dominican Republic stop coming in here.  QSOs with the US were also made, but the path there was much weaker and intermittent.

Even out at 10642km, signals both ways with CE1OEB were up at +5dB at 21:43UT.

By this morning, 11954km away, YB0DJ, who I have not heard from in a while, came in here at 09:04UT at -10dB.

All rather exciting!

Pi Upgrade: the work never stops

After more than two years of operating my Pi 3B+ in the car, in the fields, and on the beaches (to completely corrupt Winston Churchill!), I've decided to upgrade the backpack Pi to a model 4B.

One issue with the Pi 3B+ using the SDRPlay image and suite of software with the RSP1a receiver was that GQRX, which is a very clear and simple package, especially for a small display, was fixed at 48kHz audio sampling, which was more than the 3B+ could cope with, resulting in badly corrupted audio being fed to WSJT-X.

The 'rucksack' SDR system under test, now under Pi 4B control.

Luckily, Cubic SDR resolved that problem, as it has modifiable audio sampling rates.  Even though Cubic SDR worked perfectly well with the 3B+,  the menu items are far too small for comfortable field use.  Tuning Cubic SDR was also rather irritating, though it wasn't so much of a problem per se.

So, with nothing much to do this afternoon, I unplugged the 3B+ and attached everything to the 4B.  I was a little concerned my battery pack might be too weak for the 4B, as the AC adapter provides up to 3.1A.  In the event, it seems perfectly happy operating the Pi and screen.  But I have also ordered an upgrade USB battery pack (22.4Ah) that can provide up to 3.4A if needed, which I doubt it ever will.

With the 50% additional processing power and 4GB RAM of the Pi 4B, GQRX now works perfectly fine, with no audio glitches, although you should check with headphones connected that this is so.  Checking against others' reception also confirmed excellent performance in WSPR spots.  GQRX is a lot easier to use in terms of visibility of controls, the simplicity of the interface, and the fact it always goes back to the frequency I last used; very handy as I only really use this unit for 14MHz WSPR!

GQRX, for some reason fixed at 48kHz audio sampling; too much for the 3B+, but fine on the 4B.

As I write, the 4B has been running smoothly for two hours, with the aluminium heatsink reaching only 45 degrees Celsius - hugely below the CPU throttling temperature of ~80 degrees C.  From earlier tests, I know it will keep going on the battery for at least another three hours, and probably more; more than enough for most field operations.  There is also no sign of RFI from the Pi 4B, which was not the case with the 3B+.

A Summer Wind Storm

A big area of low pressure is moving off the coast of Ireland today, bringing remarkably strong winds for the end of May - up to 95km/h here in Wales.

Well, at least the sun is shining, and it's warm!

EURAO - Free Liability Insurance.

I joined EURAO a couple of years ago, because I liked the way it challenged, especially, the very old-fashioned way of doing things amongst the likes of the RSGB and IARU.

After a while, though, I allowed the membership to lapse.

But, this week came an invitation to rejoin EURAO, with a free benefit that is of utterly fundamental importance to anyone who takes a radio out into a public space like a beach, park, and so on: free public liability insurance!

EURAO's insurance covers the costs of being sued if your portable radio goes horribly wrong.

Is this worth the membership fee?  It absolutely is!  All it takes to be sued, if you come across the wrong type of person, is for that person to trip over your invisible radials at the beach and sprain their ankle.  Or that your antenna flops over in the wind, smashing someone's eye glasses in the process.  Even without going out onto the beach, you might poke someone's eye as you take a whip antenna off your car at the roadside.

The possibilities for public liability are truly endless, and something nobody, in my view, should risk exposing themselves to without adequate insurance, simply because the whole business of being sued is ruinously expensive.

EURAO provides 9 million Euro's worth of free liability insurance in exchange for the tiny 10 Euro membership fee.  The RSGB, in contrast, sometimes offers such insurance - but you have to pay for it, despite their membership fee being some £60 per year (well, you can't pay your Managing Director ~£60,000 per year and give members something worth having, can you?)

Well done EURAO for coming up with such an useful and attractive offer.  I've rejoined already! (NOTE: I have not seen the terms of the insurance, and an English text is not yet ready.  Check that the insurance is suitable for you before you join - though it seems you will have to email EURAO directly to find out!  Also, if you pay, as most people will, via Paypal, then you are now setting up an automatic, repeating annual membership.  You can cancel at will, of course.)

Latest announcement on the insurance here.

Coastal WSPR: ground or sea (or both)?

I've been wondering over the past weeks how much of the very significant benefit (typically about +10dB) seen at the coast is due to ground loss reduction, and how much due to the sea itself.

Yesterday, I looked at data gathered from the inland direction (i.e. signals coming from mainland Europe and somewhat beyond), and those coming in over the sea from North and South America.

Sea and coastal ground - all good for RF!  Image (C) MW1CFN

The median difference for signals coming in from the rear (land) direction was +3dB.  For the sea path signals, it was a median of +9.5dB.  So the sea itself yields +6.5dB additional 'gain'.

The run of data capture could ideally have been longer, and at some point, I will make that effort. 

But the emerging picture is that the seawater-saturated sand underneath my antenna at the coast is acting as we would expect from theory.  Being a near-perfect RF reflector, the sand-water mix almost eliminates ground losses and creates a similarly near-perfect second virtual element in the ground that yields this doubling of RF power received.

14MHz Open all night now

For a couple of weeks, the 20m band has been showing signs of remaining open all night, as the ionosphere locally remains sunlit for the full 24 hours.

Last night, the 5W WSPR signals from VK3MO and VK3QN (both operated by VK3MO), also came through all night long.  Again, the low angle-optimised 12-element array of VK3QN pointing long path was outperforming the 20-element VK3MO.

My 14MHz WSPR reception of VK3MO/QN 2020 May 19-20

With so much higher band and even VHF Es now underway, WSPR on the lower bands often seems like a wasted opportunity.  Even so, on the 18th of May I managed number 8 globally in the 14MHz RX challenge, slipping to number 12 yesterday - both times using the SDRPlay RSP1a receiver.

Weatherwise, we are nice and warm today, but with a 90km/h wind forecast for Friday.  It never really stops being windy on Anglesey...

Space Cloud season is upon us!

Yes folks, thanks to the MAARSY mesospheric radar up in Andøya, Arctic Norway, we can see that the season for PMSE/noctilucent clouds/summer Es is firmly upon us - although we already know that from last week's increased radio activity at upper HF!

Very strong returns from the mesopause past days.

It won't be long (actually, it may be as early as next week), before we start seeing NLC again.  Typically, the nearly three months of continual good weather has just started to break down into wind and rain!

To be weak, or not to be weak?

A couple of days ago, I was motivated to contact a fellow operator holding a UK Foundation licence, about his WSPR output.

Now, there are no rules, beyond the licence conditions, as to how much power you can put out through WSPR.  The rules, such as there are, are of the nature of a 'community norm' - what others are doing, and whether your idea about anything causes trouble for others.

So this person, who was sending 50W at 14MHz, was not breaking any legal rules. If he had sent 50W for a brief experimental period (I have seen up to 1kW reported for short experiments lasting an hour or so), then that would also be perfectly fine.

But this guy had decided to send 50W every couple of minutes, for days at a time.  I suspect that my concern wasn't so much that I received about 8 harmonic spots for him every time his rig keyed up.  Rather, it may have been concern that, as a Foundation licence holder, he may not appreciate the shortened life he could expect from his rig.

Typically for people these days, the response from the operator was terse and defensive: "Weak signal doesn't equate to low power.  But I have dialled it down a bit".

Well, he's in some sense right about the first part of his reply.  But it doesn't make any reasonable sense when just about everybody else is getting 200mW around the world quite comfortably, whilst he decides to use 50W and saturate the waterfall for countless others, hundreds of km and more away from him. 

Historically, 5W was the maximum output people using WSPR would tend to use.  Some still do use this, what is now a very high output.  But very few.  For those that do feel they need to use 5, or even 50W, then it is definitely the case that you should first look very seriously at your antenna arrangements that lead you to this conclusion.  It can only mean the situation is close to useless.

In any case, the Foundation man's continued response was, inevitably, to be defiant and carry on sending 50W every few minutes for a further day or so.  Either that, or he didn't change the output reporting setting in his software.  By yesterday, he had disappeared.  I hope he returns, but with a little more humility, learning, and community spirit.

Despite all this, I still managed to get to number 10 yesterday in the PE1ITR daily RX challenge, despite not being on WSPR for most of the daylight hours and, when I was on WSPR, TXing for 16% of the time!

Time travel

Apparently, PSKReporter is now able to tell us not only where our signals did get to in the recent past, but where they will get to in the future!

This morning, the site showed that I would be received, 54 minutes in the future, by DL0PF, at -14dB!

PSKREporter's new 'Where you will be heard' feature.

Well, as it happens, this opens up thoughts of Wheeler-Feynman Absorber Theory (more recently developed into the 'Transactional Interpretation' of quantum mechanics), which posits that, at the quantum level, the equations of physics are time-symmetric.

This is actually very thought-provoking in terms of our use of radio.  Under the Transactional Interpretaion (TI), we place ourselves in an external 'pseudo' time to understand what is happening between an emitter and an absorber (or, a transmitting antenna and a receiving one).

In very simple terms, TI says that an emitter sends a wave symmetrically, into the future and the past.  The future wave meets an absorber somewhere in the Universe. 

The absorber, in turn, sends an 'acknowledgement' wave back down the path of the original 'future' wave, into the 'past', and also into its future.

Everywhere in the Universe, except for the direct path between emitter and absorber, the waves cancel out.  Between the emitter and absorber, a reinforcment of waves - a 'handshake' - develops that forms what we understand as reality.

The basics of Absorber Theory/TI, as conceived in 'pseudo time'.

If you think this is nuts,it really isn't.  Spend some time reading about it online, or in books, especially John Gribbin's Schrodinger's Kittens and (much more mathematically) John Cramer's The Quantum Handshake.  That way, you will see how TI resolves all those endless 'problems' of non-locality and how particles an arbitrarily large distance away from one another can, nevertheless, instantly communicate their state between them.  No need for the ludicrous ideas of the 'Copenhagen Interpretation', which anyone with half a brain can see is a load of rubbish.

One way to think about this is from the photon's point of view.  Travelling at the speed of light, Lorentz contraction means it experiences no distance and no time: it can be everywhere, at all times. You can even devlop an argument (as John Wheeler did), that there is only one (in this case, electron) in the Unvierse!

Actually, Wheeler's idea is not true, because if there were only one electron in the Universe, it couldn't be absorbed and could, therefore, not emit.  Experiments with radio telescopes to try and detect a lack of absorbers in certain directions have actually been conducted, and confirm there is no such lack of absorbers.  If there was, the radio telescope would 'refuse' to transmit in those directions.

Anyhow, in our frame of reference, where we move through space hardly at all, but move through time at essentially the speed of light, time seems real enough.   But in another frame of reference, the antenna receiving your signal 'knows' you will send it (in your frame of reference) before you transmit it!

You can also branch out from here into the fascinating world started a long time ago with Kaluza-Klein theory, where the forces of nature combine in one, large matrix known as the Riemann metric tensor (much easier to understand than it sounds - try Michio Kaku's Hyperspace).

With this set of ideas more recently developed into string theory, we can understand electromagnetism in our four spacetime dimensions as the rippling of gravity in the fifth dimension.  That's quite a thought to have, as you look at your antenna through the window!

As Plato said in his Allegory of the Cave, "Earthly knowledge is but shadow".  Your head may hurt, but in a nice way...

Gender and Minority Troubles?

I've commented many times on the deeply troubling gender and ethnic minority imbalance in amateur radio.

Whilst this is not unique to the UK, or the RSGB, the UK's representative society is a good place to keep an eye on the image presented to the wider public.

This month's RadCom, the RSGB magazine (not available in any shop), carries a rather flag-waving cover that tries to claim amateur radio has made some kind of difference to the Covid-19 crisis.  A lot of happy faces are presented as some numerical 'evidence' of this positive influence.

Let's look at those faces.  I can see 38 in total.

Of those, 33 (86.8%) are male, 4 (10.5%) are female, and 1 (2.6%) is of two dogs at the rig(?)

None are of anybody who has anything other than white skin (but the dogs are brown).

23 (60.5%) are comfortably identifiable as of an older, post-retirement age group.

9 (23.7%) of men are wearing a full phones-and-mic headset.  None of the women are.

Although this is not a scientific analysis by any means, it is still not wildly away from what we know amateur radio is like.  It is hardly suprising, faced with those statistics, that we struggle to attract more people to the hobby.  Like Sir Trevor McDonald, the famous newsreader says on an advert currently running, "we are changed by what we see, just as we are changed when we are seen".

West Coast Evening

Time for some radio and physical exercise again!

Emphasis for this run was to assess whether the Raspberry Pi 3B+/RSP1a SDR/Cubic SDR/WSJT-X system, which does away with the need for a conventional 12V-powered rig as receiver, works properly.

Three WSPR RX systems running at 14MHz last evening:

(1) Home: FT450, HP laptop, WSJT-X, vertical delta loop

(2) Home: TS480-SAT, Raspberry Pi 4B, WSJT-X, elevated 1/4 wave vertical, 2 elevated radials

(3) Beach (west-facing coast) RSP1A SDR, Raspberry Pi 3B+, WSJT-X (via Cubic SDR), identical 1/4 wave vertical to home.

WSJT-X in all cases was the latest available version.

IO73RF WSPR listening.

I ran WSPR for 50 minutes (19:14-20:04UT) at the beach, during which time the received signals at any given antenna were broadly stable.

The difference between the vertical at the beach and the vertical at home was a median +8.25dB in favour of the beach, with a range of +3dB to +12dB, based on an analysis of ten randomly-selected stations heard.  This result is entirely consistent with previous findings during the late afternoon/evening period from the west coast.

Still a bit of a mess, but at least it all runs off a USB 5V battery, is lightweight, and fits in a backpack!

The Raspberry Pi/SDR backpack system, which makes a reasonably high demand on the Pi's processor, does not therefore appear to suffer from any problems and can be considered a reliable receiver.  Note that you do need to have RF sampling at its lowest setting of about 250kHz, and audio sampling down at 16kHz or even 8kHz.  This is perfectly fine for HF.

The difference between the home delta and home 1/4 wave vertical was a median +5dB in favour of the delta loop, range of -2 to +19.5dB.

So, an elevated vertical at the beach is outperforming an inland full wave vertical delta loop (essentially, a pair of close spaced verticals), by 3dB on average, remembering and accounting for the fact that the 1/4 wave vertical has ~5dB less inherent gain than the delta.

Nearly time to go home.

Of course, on certain paths, and certain times of day, the beach location makes a very much larger difference.  Also, the signal from OX3HI was heard at -28.5dB median signal at the beach, but was not heard at all by either of the home antennas.

Windows 7 - still updating.

Are you still using Windows 7?  Many of us are, because it was one of the better iterations of the Windows OS.

Still being updated in May 2020.

The official line is that updates and support for Win 7 ended in December last year. Yet, it's been obvious for a while that there were minor OS updates coming through during 2020.

Overnight, a major update for Win 7 took place, taking over an hour to complete on my fairly fast quad core desktop.

Clearly, Win 7 is not yet dead.  No doubt this is driven by the need to avoid large organisational users, who update software only very rarely, falling victim to vulnerabilities that led to disasters such as the 'Wannacry' ransomware attack that crippled the National Health Service in the UK a few years ago.

Lockdown Exercise

How's your Covid-19 lockdown going by now?  Here in the Disunited Kingdom, Government guidance has become hoplessly confused with what is actually law, leaving most of the population, police and even the ministers themselves, lost as to what we are and aren't allowed to do!

Worse, the guidance and laws are now increasingly divergent between England and the other nations of the UK.  For the first time in centuries, there is now, in a very real effect, an enforceable border influencing people's movements between England and the other nations.  You can now go out in your car to find a nice place to exercise in England, but fined by the authorities if you happen to stray into Wales or Scotland to do the same. The population is slowly deciding there is so much confusion that they will make their own minds up as to what they can and can't do.

Sticking to the laws of Wales, I took my exercise last evening for an hour or so on the most northerly point of our little country.  Whilst I went for a walk, I left my new Raspberry Pi-RSP1a SDR receiving system listening to the world's WSPRs.  On an evening where a brisk northerly breeze was coming straight from the North Pole, one could certainly feel that Anglesey is not so far from the Arctic!

Backpack SDR WSPR reception, from Wales' most northerly point.

I've previously tested this area with a WSPRlite transmitter, and found it isn't as good a place as one might imagine.  That's partly because the ground underneath the antenna is very rocky and therefore prone to high losses, and partly because, being a north coast, it is looking towards an area of the planet where signals are not, in general, coming from.

The SDR receiving system still amazes me for the fact of its operation from a handheld USB battery, and tiny, now ageing Pi 3B+ palm-sized computer.  The only difficulty I had with the whole thing was getting the audio input levels - far too high, but still decoding, - set properly from Cubic SDR into WSJT-X.

The answer was obvious, but not on a 7" screen in strong sunlight, with everything crammed into a very small space!  The audio gain setting, which I had to reduce dramatically, is found on the extreme top right of the panel, as indicated here:

Cubic SDR panel.  Image: CubicSDR.com

Once that was done, I could leave it to its own devices and complete my walk!

The results were largely as expected.  For signals from the far west US, the north coast location was 5-6dB worse than the delta loop back home (only ~3 km away).  Allowing for the delta's inherent better gain over a 1/4 wave vertical, this is, roughly, the two antennas hearing equally well.  I would have expected better for western US signals, because their path brings them in from a NNW direction, where the sea could be expected to yield a better result.

The one exception to this rule, when allowance is made for the different antenna gains, was AA7FV, who has a large rhombic pointed very narrowly at Europe.  The signal here was equal in both antennas, meaning the 1/4 wave vertical at the coast was, in effect, hearing him ~3-5dB stronger than the delta.

Looking at Scandinavian signals, the situation was much the same, with the coastal vertical matching the delta loop at home (in other words, potentially hearing ~3-5dB better from the coast, allowing for the different inherent gains of each antenna).  One station, SM3DTQ was different, showing a 7dB enhancement at the coast (potentially, ~10-13dB better than the delta, allowing for gain differences).

It's a shame this location doesn't yield better enhancements, as it's a beautiful and peaceful place to work from for an hour or two, only five minutes away from home.  It seems I'll have to eventually spend more time driving to the west and east coasts for the best enhancements, which are certainly worth the effort! 

Meanwhile, you can spend a few minutes of your lockdown watching this video from the US, which is pretty much exactly what I have done:

Spectacular Es

Es has broken out in very sure order over the past 24 hours, with strong propagation on 10m and 6m.

Beaming the Netherlands with the 12m, 3-ele LFA.

But on 12m, the situation has been nothing short of unbelievable.  Not because there was much DX to be had - there wasn't from this latitude - but because of the strength of signals between, in particular, Wales and the Netherlands.

I've seen short skip signals on 12m many times, but not to the extent that signals reach in excess of +20dB!  Presumably, some of the receivers were using simple stick or wire antennas, making the whole thing even more remarkable.

Incredible short-skip signals to the Netherlands on 12m yesterday.

10m showed strong Es activity all day long, and was still producing FT8 QSOs here at 23:30UT.  WSPR with 1W overnight was spotted in Italy until 01:46UT, and resumed (to Austria) just four hours later.

10m activity late yesterday afternoon.

Well, it's not surprising, given we're at roughly a month before midsummer - though you wouldn't think it, given we have winds coming directly down from the geographic North Pole this week, with temperatures about 12 degrees colder than last week!

Victory in Europe 75: who called?

VE Day at home.

Although the VE weekend is not yet over, an early analysis of who has been taking an interest in GB5VEP (Victory in Europe - Poland) reveals what one might say is an unexpected pattern:

Calls from top 9 countries to GB5VEP

Way out in front of callers was Germany - representing the aggressor nation that once saw itself as the 'Master Race' and overlord of Poland and much of the rest of Europe.  It is perhaps good that the oppressor and oppressed reflect, remember and regret together. 

Very disappointing to see so few Polish stations calling in, easily outnumbered by Spanish stations, whose own nation was rather divided and ambiguous on which side it lay in WW2.

Mr. Churchill, who came to defend Poland, then sacrificed her to keep Stalin happy.  Image RAF/MoD.

Propagation was tough going, with marginal conditions on many bands, but rarely strong conditions on any band, except for 60m.

Victory in Europe celebrations begin.

The 75th anniversary celebrations of Victory in Europe Day have started, including out on the ham radio bands.

Very nice to work PF75FREE with my own VE call - GB5VEP - on an otherwise empty 15m band this morning.

Screengrab of GB5VEP, active most of this month.

As is the case for many across Europe, my family was impacted significantly by WW2.  My paternal grandparents were both sent to forced labour from Poland to Germany.

The story of forced labour is without doubt the most ignored aspect of WW2 history.  Though it sounds relatively innocuous, it involved random abductions ('roundups'), terrible hardship, and murder of innocents, including infants.  Some 12 million people were subject to this system during the war.

A very large number of often well-known and still-existent German companies made use of forced labour.  A list is found here.

My grandfather went to coal mining in Essen, but had a friend inflict an ankle wound with a spade upon him, such that he seems to have escaped further labour.

My grandmother was sent to serve a German officer in Magdeburg.  Very unusually, she was treated very well by this man, the identity of whom is, sadly, now lost to us.

Collection of Polish 'P' (Petka) badges, designed to German precision dimensions that served to reduce the value of human life to very little. 

During the period, my grandmother had a more acute experience.  One day, probably immediately after being removed from school and before being assigned to her work, she tried to take some coal off the railway line in order to keep warm, but was caught.  Roughed-up and blindfolded, with a pistol held to her head, she started saying her last prayer and made the sign of the cross.  This was, miraculously, just enough for the Nazi soldiers to put the pistol down, and tell her to go away.

Polish RAF 303 Squadron.  Critical to the Battle of Britain, they were not invited to attend VE Day parade in London in 1946, for fear of angering Stalin.  One of only several double-crossing of Poland during the war by Churchill and Roosevelt.

We can and should remember VE Day.  But we should also remember the horrendous human suffering, military and civilian, and the utter devasatation of civilised nations that led up to it.

Raspberry Pi, SDRPlay RSP1a and WSJT-X

After a lot of testing of the new Raspberry Pi 4B, especially its power use (very little changed from the 3B+ for my applications), this is now my standard field radio computer.

That means I have a 3B+ spare, which I decided to use for experimental purposes - such as trying to get a SDR receiver going. This is so that I don't have to carry a heavy 12V battery and a full rig when all I want to do is receive from the beach.

Like many, I had expected to have a fight with the Raspberry Pi's audio, to get it from the SDR software into WSJT-X for signal decoding.  But it turns out that all this is taken care of by the nice people at SDRPlay, who have an image disk ready for us to download and insert into the Pi's socket.

It was evening before I got everything shorted out...

After downloading the image, this was flashed across to a new micro SD card, and after a bit of editing the config file (see here) to get the correct settings for use with my 7" screen, we were off!

I managed to get Cubic SDR to open up alongside WSJT-X.  But it took me a while to figure out why there were no decodes at all.

Firstly, I had to correct something that seems only to happen with the SDRPlay image - poor timekeeping of the Pi, probably because it hasn't got NTP time installed by default.  As it was, the Pi was out by 3-4 seconds, way too much for good decode rates.  A much earlier download of the NOOBS package for my portable operations resulted in excellent timekeeping - all very odd!

This correction is easy to do, and needs only a couple of commands, which are listed here, but reproduced for my own records below:

sudo apt install NTP

Next, force time updates:

sudo apt install ntpdate

Checking it all works, type the following to return the time offset.  You may need to reboot to see it all take effect first:

sudo ntpdate -q 0.us.pool.ntp.org

 

Then I discovered that I can listen to the audio feed, even though it's being routed to software, simply by connecting a pair of headphones to the jack on the Pi.  This makes things a lot easier, as you can hear what's going on.  I don't think you can do this with a Windows computer.

What was going on was very stuttery sound indeed.  Cubic SDR lets you choose a low RF sampling rate of 250kHz, and an audio sampling rate of 22.05kHz - much lower than the typical default settings. This combination provides nice clear and stable audio for HF reception on the Pi 3B+

Unfortunately, the alternative, and much nicer, faster software - GQRX - has a fixed audio sampling frequency of 48kHz, which is too high for the Pi 3B+ to cope with.  It can probably be changed with a bit of file editing, if you have the patience that I don't!

 

A very short test at 14MHz WSPR, showing timekeeping and sample rates all now working nicely.

After all this, WSJT-X settled down nicely into plenty of decodes with good timekeeping going on in the background.  Cubic SDR takes a bit of getting used to in terms of its irritating frequency changing windows, but it's simple enough, once you get used to it.

The Pi CPU does get quite warm running all this code, peaking at about 50 degrees Celsius.  It ideally needs a cooling fan or passive heatsink, although I had neither for this test, which lasted for about three hours.  I expect the system can run on a 20Ah USB battery for five hours or so.

It's quite amazing that such a small computer can run all this software without a glitch.  The 4B, with 4GB RAM, should find the whole experience much easier going, but that will have to wait another day.

Model matches the reality.

Nice to see a good agreement between 14MHz long path modelling by VOACAP and reality overnight:

VK3QN (Blue) and VK3MO (orange) LP WSPR (5W) 14MHz reception at MW1CFN (vertical delta loop)

VOACAP prediction.

Zambia surprise!

12m was certainly very alive first thing this morning, with huge signals from Europe.

Then, from nowhere, a weak signal, barely visible on the waterfall, from 9J2BS.

This adds to the two other QSO's I've made with Zambia, the most recent (9J2HN) back in November 2013 using what is now almost a totally forgotten mode - JT65A - and my then 12m antenna - a steerable 2-element vertical beam.

Other good news is that a very slow lifting of Covid-19 rules looks likely over the coming days and weeks.  A very good job, because everyone is really fed-up of being locked indoors now, and the government clearly concerned about social unrest as the summer approaches.