After 39 of my own WSPR recordings at 14MHz were analysed yesterday, it's now possible to say that the latest JTDX update, which is not generally available at the moment, has a 2.7% better decode rate than WSJT-X 2.1.2.
[UPDATE 1: after an overnight listening session on 40m, the 2.7% improvement fell to just 0.5% with a much larger (1049) sample of decodes. WSJT-X managed to decode 1044 of these.
UPDATE 2: a roughly 18 hour listening session at 14MHz resulted in 728 decodes, 717 of which were decoded by WSJT-X, yielding a 1.5% advantage to JTDX.]
I had a look at which signals WSJT-X was failing to decode. It's all a bit odd, because there were two signals of -25 and -26dB, and one of +3dB. None of the signals were very close to other traces, so I can't figure out what WSJT-X is doing. The difference appears from time to time, regardless of how strong propagation is at that moment.
UPDATE: -30 and -31dB signals are being decoded regularly by JTDX now. It is also getting down to -34dB so far, which is as low as the alternative WSJT-X goes:
This morning, I was out and about in the car, when I decided there was some time to do a little operating near the sea, simply by pulling up at the roadside.
Now, I know I've written about this before. But it is worth reminding those new, or not so new to the hobby that, if operating from home is difficult or impossible due to bad neighbours, housing association rules or, as so many of us now face, increasing RFI, then all is not lost.
Not lost at all, in fact. Some years ago, I remember the ARRL's magazine, 'QST', expressing some surprise and perhaps rather suggesting it was a very second-rate thing to be, when a survey found a good proportion of operators only ever operated away from the home.
About three quick cycles of 1W WSPR at 14MHz, during very poor propagation, from the car - brilliant!
Well, I have never forgotten the old saying: 'never put all your eggs in one basket'. Investing heavily in radio equipment based at home is almost inevitably going to lead to anger and disappointment when, one day, something causes RFI that you can't overcome. In domestic and urban settings, it's simply going to happen, sooner or later, and no regulator I know of is going to help you much.
Far better to keep a few whips in your car, together with a rig in the boot, and a Raspberry Pi for digital modes. I only need to switch the rig on and plug the Pi into 12V, and I'm up and running in a minute or so. It really is a great feeling of freedom, even if you don't have any imminent RFI problems back home.
Better still, if you can access the coast, there's a good 10dB extra gain to be had by operating from near the sea, which in my book is a much easier way to get a better signal than investing in an expensive tower, Yagi and all the maintenance those things need.
If you can't get to the sea, then anywhere with a less cluttered, open horizon than one typically gets at home is likely to be a big improvement.
So, if you have a thousand Chinese switch mode PSUs buzzing away, don't worry. Just get in the car and escape it all!
If you've ever heard of the radio navigation aids LORAN and/or eLORAN, then you may have heard of Professor David Last, who was heavily involved in these systems' development.
Sadly, news arrived yesterday afternoon that a Cessna-172SP aircraft had ditched into the sea off the coast of Anglesey, during calm, fairly clear weather.
Professor David Last.
This afternoon, it was confirmed the pilot, lost and presumed dead, was David. The flight recordings from his transponder showed he was in straight and level flight, when the plane suddenly entered a modest but sustained descent into the sea, hitting the surface at 134 knots.
David seems to have started suffering a heart attack or stroke just after 11:34UT whem the airspeed begins to vary before a descent, with increasing airspeed, into the sea (top right on map).
There was no indication at all that 79-year old David, an extremely experienced and instrument-rated pilot, tried to glide the aircraft towards land as would happen following an engine problem, presumably because he suffered a heart attack or stroke.
I last saw David at my father-in-law's funeral in the spring, which makes 2019 a rather more horrible year than one would wish for.
The services continue to look for the aircraft and David's body, with only small aircraft debris having been recovered thus far.
Very interested to be part of what the software modifier-author calls an 'internal assessment' of the latest JTDX candidate release, which doesn't seem to be publicly available at the moment.
WSPR is the mode receiving attention this time. A large number of WSPR test files with signals down to an astonishing minus 38dB have been made available for testing. The current edition of WSJT-X, on which JTDX is based, has a lower limit of -34dB.
It will be interesting to see how this works out under real world conditions. More particularly, I hope it won't lead to a larger number of false decodes.
Initial testing shows some improvement over the general release JTDX. There were fairly regular decodes down to -31dB at 10MHz last evening, perhaps more frequently than I've seen with WSJT-X so far. But there are no decodes down to -34dB and below yet, although those are always scarce, anyway.
We'll see what turns up during listening tests through the week.
[UPDATE: yet another release candidate version has been released just a couple of days later. This does appear to be returning more signals around the -29 to -30dB mark, but as of yet, nothing that goes beyond -31dB. Time will tell if there is any significant improvement in sensitivity over earlier versions and WSJT-X]
The geomagnetic field underwent some moderate disturbance to around G1 levels overnight. As is usual, some interesting effects on 14MHz WSPR took place.
First, the reception reports of my 1W by the excellent WSPR station, OE9GHV - the only station outside the UK to hear my signal through the night, showing a big, but brief increase of about 15dB in signal strength between ~20:10 and 21:25UT:
If we look at the Kiruna magnetogram, we can see the signal increase aligns nicely with the main disturbance for the evening. The horizontal component most clearly shows the signal increases - as we always find - as the field begins to restore to quieter conditions:
Well, it's been a while since I turned my attention to the RSGB and its monthly magazine, RadCom, often changed to AdCom by critics, as it has so much advertising within.
Someone astutely observed a while ago that RadCom book reviews are almost always positive, and have nothing bad to say about any aspect of the texts examined.
This is quite important, because book sales make up a very large fraction of the RSGB's annual income, and potential buyers of these texts deserve a proper, rather than just an always-positive review.
Let's have a look at the Christmas 2019 edition of RadCom. Before we get to the books, there's a review of the Ciro Mazzoni 'Baby' Loop, a magnetic loop antenna that will set you back £1229.95 at the time of writing. There is absolutely no hint in the review that, should you wish to, it's easily possible to build a magnetic loop antenna for 40-10m for less than £100, or a bit more if you bought a fancy vacuum, rather than air-spaced capacitor, which is by no means necessary.
OK, the reviewer has been asked to comment on the commercial product. But should the RSGB simply fail to mention a substantial amount of money could be saved through a simple homebrew project, and instead, give the impression, at least to those just starting in the hobby, that they have to find £1229 for an antenna, in addition to the £1000+ rigs advertised prominently in the same magazine? I think not and, moreover, that the RSGB has a duty to help its members and prospective members to save money and learn how to build things. After all, we are still in the throes of a severe economic crisis, where money is in short supply for many.
Onward to the books. Any evidence of negative comments? Not a bit of it!
First, Brixmis, a book about the Cold War:
"It is a gripping read...It's a truly remarkable and very lively account that I really enjoyed."
Next, How to survive and atomic attack:
"This book is quite fascinating. It will definitely bring back some not-entirely-welcome memories to some, and/or give you something to talk about with your grandchildren."[with a very RSGB-eqsue presumption that only grandparent-aged people are reading RadCom.]
Then, House of Spies:
"This book...does it in a very readable way...Fascinating stuff."
Next up, The Discovery of the Universe:
"There is a colour section [ooh!] with some breathtaking images...all of which aid understanding of the topic. The breadth of this book's coverage is enormous, and all of it is in a readily digestible form. I found it very interesting and stimulating and hope you will too."
Penultimately, XY and Z: "This book certainly opened my eyes to a whole new 'take' on the history of Enigma[not another one!] and if you have any interest at all in the subject[why else would anyone buy it?]you'll find this book contains a lot more of the story than is normally published."
And, lastly, Space Exploration: "Rather than try to be all things to all people, this book describes itself as a sort of 'executive summary' of the grand, glorious enterprise we call space. It's supported by an extensive set of appendices and references that contain more technical information in the express hope that it launches you into your own journey. I think it will."
So, every book anyone ever reviews in RadCom is brilliant and worth buying. Strange, that, when so much of the RSGB's income depends on book sales, especially around Christmas.
Meanwhile, here's a public message from the RSGB:
Well, I found a number of good-hearted and open-minded people on QRZ to discuss the ground loop antenna today.
Of course, there was also the usual contingent of people who turned the discussion into one about on-ground dipoles - which my antenna isn't - and model results not based on the correct antenna or ground types. Takes all sorts, on the internet...
Meanwhile, as some argue among themselves about the earth loop being a 'dummy load', I was busy making real (split operation) QSOs with JA-land, with signal reports at the same level as seasoned G4 operators on 160m using full dipoles:
The latest 'crazy idea' to hit my head has been earth loop antennas for 160m. Initially, I thought these would be good only for receive, but then found transmitting was a very real possibility.
If you've never heard of these, take a look at a July 1985 edition of New Scientist, all about earth antennas and submarine communications. If you click on a page number, you get full pages to read.
It's all very simple in theory. The schematic below summaries my set-up: two copper pipe electrodes about 30m apart, where the AC current takes a loop-like path through the ground between them. This effectively yields a vertical loop antenna in the ground that is ~ 4 x the distance between the electrodes. High soil conductivity might yield a shorter path and thus shorter antenna than lower conductivity ground.
A ground loop antenna for 160m.
Before you say this couldn't possibly work, then have a look at this 39 second-long video of a UK long wave commercial radio transmission being received by one of my sloper antennas (hint, it's the weaker signal by far), and the ground loop antenna:
Early results on 160m are just as astonishing. I've never seen such strong signals as the ground loop antenna produces. Here's a minute or two's worth of FT8 'CQ' reports received of my ~35W output; very happy to get a good signal report soon after sunset here into far eastern Russia at 6555km. As sunset approached Japan, the antenna confidently managed to cross the 10,000km, which is absolutely amazing, when you think the antenna is, deployment-wise only a transmission line and two copper electrodes. Note that it is necessary to operate during low Kp in order to see good results at 160m.
Well, no other antenna I'e tried at 160m managed this kind of DX, just one hour after sunset here!
Like many people, I sometimes enjoy OH8STN's blog, mostly about field-based operating. Julian often does some product reviews. I don't know if he gets paid to do these, or whether the payment is 'in kind', i.e. he gets to keep what he reviews - which is a common protocol with cheaper equipment reviews.
I rarely find anything to disagree with on OH8STN's blog. But today, I was really quite irritated by his brief review of the 'Packtenna', a multi-band end-fed wire attached to a 9:1 unun.
Now, an endfed antenna like this is, if you'll excuse me for my French, piss-easy to make yourself. There are countless YouTube videos and book articles that tell you how to wind the unun, whether it be a 9:1 or 49:1. Presumably, you don't need a video on how to connect a wire and coax connector to the unun.
How much is this end-fed wire? The Packtenna website, accessed 12/11/2019, gives the wonderful price of $89.99
Now, that's quite a high price for a shrink-wrapped ferrite core on a plastic winder with wire attached to it. A much more substantial, robust end-fed by UKAntennas is only £59 - nearly a third cheaper - with the added advantage for UK buyers of not having to import and potentially pay duty on the product when the customs men get hold of it.
My money, for what it's worth, is on the Hawaii Emergency Ham Radio Club's simple, quite well-made and effective EF antenna - for just $56 (plus the risk of any duty). If you want to make your own, EARCH are noble enough to provide free instructions. I've had two of these antennas for about 7 years, and they've taken the worst weather and 50-100W output without any problem whatsoever.
My recommendation for a multiband EF antenna - made by EARCH (see link above).
What really got me going was when OH8STN said he has only had the antenna for "a few weeks", and sings its praises, despite the fact that it has "burned up" with some modest-power digimode use. I think his assertion that the "near perfect SWR" of "1:2" is supposed to read 1.2:1. We can forgive his wrong-way round ratio, where SWR is always properly given as 'something-to-1'.
I fail to see why a $89.99 antenna that fails after "a few weeks" under modest power use is in any way worth recommending, except where the user may have been unduly rough in its use and its failure was his own fault. Even then, an antenna intended to be 'packed' should be built sufficiently robustly to last a few years, not a few weeks. The 'burning up' presumably means an inappropriate ferrite selection by the maker; Julian's review doesn't say where the failure occurred.
If something isn't very good, it's either best not to write about it at all (which is what many magazines will do if confronted with a negative review), or else report on it candidly.
Oh, and the title for this blogpost? It was inspired by the fabulous 'Derry Girls':
A lot of ships out there - and a small number of ham operators. Image:Libreshot.com
I had a brief listen to 15m this morning. The band was very alive!
I called a few FT8 'CQ's, whereupon I was picked up by F5MYK/MM, on board a merchant vessel. He was reporting Maindehead grid HJ01 - a grid that is probably quite rare to put in the log, although it is on a major shipping route off the coast of Brazil.
Grid HJ01
There's always a nice surprise waiting with amateur radio!
Ah! How I enjoyed using JT65A over the years. Now almost entirely forgotten, this used to be my bread-and-butter weak signal digital mode.
There was a little activity on 14Mhz today, but rather sad to see just how few stations were active across the globe. I think I might try to start a JT65A revival.
Over the past few days, long-path DX at 14MHz has picked up considerably.
From around 07UT until about 12UT, propagation to VK and ZL has been very good. Yesterday morning, VK stations on SSB were around S9, and the far rarer ZL stations around S6. Obviously, the weak signal digital modes extend the possibility and time available for a successful exchange considerably.
Earlier in the week, long-path propagation, even using low power and simple wire antennas, extended as high as 21MHz (to
far eastern Russia), which hasn't been seen for a very long time.
This is how JA was looking on FT8 (about 15W to a vertical delta loop) at around 08:15UT this morning, probably via long path.
Inspired yet again by Bas, PE4BAS, I've been looking this week at simple ways to get on 160m, without too much arranging of new supports, or buying new wire.
A solution I came across quite quickly for this long-wavelength band - and large antenna requirement - was the folded vertical.
I already have an old 10m fishing pole buried among a Yew hedge, which has little purpose these days.
So, I took an existing 20m length of 300-Ohm twin wire, and ran nearly 10m up the pole. The remaining 10m runs horizontally. In other words, a folded inverted-L antenna. The important bit is to join the ends of the twinwire together at the distal end (making a 40m-long radiator). One side of the balun is connected to a ground stake, from which several short radials run.
The basic concept - a folded Marconi, or inverted-L antenna.
The feed point is a 4:1 balun, with coax going back into the shack. I had to do some repair work here, as a rat had chewed the coax where it entered the house. This is the point they always attack coax, because they can smell the food and warmth, which they are trying to get to. For this reason, I no longer run coax feeds through walls at or near ground level,. but at head height. Luckily, rats don't seem interested in chewing coax anywhere else!
The antenna, which would fit most small UK gardens, certainly works at both 80m and 160m, matching down to about 1.2:1 on 160m, and 1:1 on 80m. It seems to be better at 160m, where I managed a few QSOs, and even managed to get a reasonable, -18dB report from a VO1 station at his greyline time.
More time needed to see how well it works DX in practice, but initial tests look promising. Curiously, I am again hearing better than most others are hearing me. That may well again be due to much higher noise levels at the receivers, which is a well-observed phenomenon on other bands, too.
Over the past couple of weeks, 14MHz propagation at night has closed to all but groundwaves from a very small number of other UK stations.
Unique dark-hemisphere spot, winter 2018/19.
This heralds the start of winter all-night WSPR listening for me. There are always a lot of surprises, including globally-unique spots as transient geomagnetic effects briefly open propagation to unexpected places.
Why not have a go at some WSPR listening yourself? There is certainly a lot to discover and, even better, anybody with a computer and cheap SDR unit can take part. No ham licence or expensive rig required!
