Ooooh! Aurora!

Thanks to an UK-based aurora text alert, I was made aware of a Kp=5 event mid-morning today.

By tea time, the event had grown to G3 levels.  I could hear echoey FT8 signals when pointing south with my 2-ele beam, so a good indication it should be turned north! 

Significant 50MHz FT8 signal spread due to aurora.

 

Wow!

 

Sure enough, there was MM5DWW busy working an aurora scatter pile-up.  He wasn't very strong, but was certainly stable and perfectly readable, even at a normal speaking speed.

All turn to the north!  12m Yagi and 6m quad eagerly await aurora scatter.  The quad is lower than the Yagi, and only shows a small degree of interaction when up.

 

I put in a number of calls, but no joy for a while amongst others in Scotland who were catching stronger conditions than in Wales.

Just before I had to get the kids, I managed to get through, taking a couple of repeat efforts to get the complete callsign across.  Here's the HRD recording:

Mesospheric · 50.155.000, USB

Very happy with that QSO - the first aurora SSB contact since January 01, 2016!

A couple of hours later, aurora-Es kicked in, with spectacular signal strengths to the east and northeast:

 

 

 

Is it goodbye, ZLP?

I've been complaining a lot recently about ZLP Electronics' interfaces no longer having on-board volume controls for input and output.  These are a much faster, more convenient way to adjust levels than having to do it from the computer.  The ZLP also had connections for two rigs, which means no swapping cables or separate units when there is a HF and VHF radio sitting side-by-side.

A perfect ZLP interface (with conections for two rigs), spoiled by abandoning on-board level controls.

 

So, with little prospect of ZLP changing things back, and there being a very limited choice of good quality soundcard interfaces, I semi-gave up on moving beyond the two ZLP units I have for now.  But in the end, something will fail and change must happen.

Then, a chance contact with a reader of this blog told me about the HB9ZHK DigiLink Nano.  Unlike the ZLP units, this is much smaller, also has no volume controls - something we seem to be largely stuck with now - and sells for about the same price as a ZLP, when international currency and postage charges are taken into account.

A new, smaller way forward?  The DigiLink Nano.  Image: HB9ZHK.

 

So, this morning, I decided to buy one, and see how well it does compared to my existing interfaces.  Delivery is, of course, likely to be slow in the current environment of pandemic and Brexit in the UK; we like things as difficult as possible, apparently!

At least volume adjustment via alsamixer on Raspberry Pi is pretty easy, using a text-based graphical interface that is similar in use and effect to a Windows machine.

No doubt there will be a period of careful WSPR monitoring to come in the coming weeks...

 

JS8 Call. Hmm...

I've downloaded the JS8Call package - which is a very nicely presented piece of software - a couple of times in the past year or so.  But I never advanced to using it, as (a) I was a bit unsure if I would want a messaging service and (b) I don't like messing about with CAT settings without very good cause!

 

Anyhow, prompted by PE4BAS and his working of a Finnish OHFF station this wekeend by JS8, I decided to have another go.

The software is really nice.  Very clearly laid-out, obviously with tablets and other such devices in mind.  It even responded well to CAT settings!

It's also nice to be able to send a command - the so-called 'Heartbeat' signal - such that others hearing you will send a SNR transmission in return.  That does pose a risk of some idiot one day sending Heartbeat requests endlessly, forcing others to transmit permanently. 

Very nice layout, but the message box text is pretty small. 

The JS8 mode is potentially attractive to newcomers to the hobby, as they will inevitably already be instantly familiar with the JT modes now forming most of ham radio activity.  So it is fairly easy to adopt JS8, which 'feels' much the same as JT modes.

Where I think JS8 fails, and won't stand the test of time, is in the fact that it's very limited indeed in its data rate and, therefore, takes a long time to send even very short messages - about a minute is typical.  If you want to introduce a small amount of personality into your messages, you will be waiting at least two minutes for each to be sent.  

Even with this glacial rate, sensitivity for JS8 is nowhere near as good as some alternatives.

Modest volume of users of JS8 last evening.

 

If you've ever used modes like OLIVIA, where the data rate can be adjusted from quite fast to pretty slow, according to conditions, or even something more arcane like Hellschreiber, then you quickly start wondering: what the hell is the point of JS8?  It's just not very good at all, other than as, I guess, a freetext beacon of sorts.  

I know some, like OH8STN, will defend JS8 precisely on that basis - a means to quickly send an 'I'm OK out here in the snow and wind in my tent!' message.  But let's be realistic: how many of us undertake that kind of activity, and would we really rely on a ham radio set if we were in trouble?  Maybe.  Or maybe our fingers would be so cold as to make using anything pretty much impossible. Yes, I've experienced that, many times!

So, although the novelty will hang around for a while longer, JS8 is the wrong and monumentally retrograde answer to the question of effective, efficient keyboard-to-keyboard radio.  

6m - Alive!

Here we go.  As PE4BAS just predicted due to his unfortunate, but thankfully repairable damage to an antenna, 6m opened up strongly today!

Hurrah!

RF Exposure limits - worked example

Here in the UK, our regulator, OFCOM, recently introduced mandatory compliance with RF safety limits.

I'm not a member of the RSGB, but I gather that there has been a large amount of criticism of OFCOM about the rationale for these rules, and the manner in which amateurs with no knowledge, experience or apparatus in assessing RF safety can, in fact, assess it.

In any case, the ship has now sailed, and we have to demonstrate compliance, "if required".  I doubt most of us will ever be contacted about this in practice.

RF 'safe' distances at 144MHz are very different to 24MHz.

 

But if you are asked to show compliance, how do you do it?  OFCOM have a very simplistic applet that runs under a spreadsheet.  This has also, rightly, come in for a lot of criticism, and even my untrained eyes can see it misses out a lot of important detail.  Nothing on ground reflections, absorption, mast height, etc.

So I was interested to come across G1KQH's recent post about a much more comprehensive calculator.

I was interested in the obvious, worst-case antenna that I use, which is an 8-element, 144MHz Yagi.  It's only 4 metres above ground, as I am already at over 100m up, with a clear line of sight in most directions.  I also use an amplifier, typically pushing out about 110W or so.  As there is a public footpath running very close to it, a computation of RF exposure is a good idea, even if, in practice, nobody ever uses that path.  If they did, they would only be present for a few seconds.  

No allowance is made for exposure time, as the whole thing seems to be based on permanent exposure at the selected power, antenna, and duty cycle values, such as might loosely apply in the case of a close neighbour or something like that.  For transient public presence, I suppose it would be justifiable to reduce the 'effective duty cycle' to near zero.

This is a grab of the output, suggesting that I shouldn't have to change anything, showing that even a close passage to the mast would remain 'safe' (noting that there is no scientific literature to determine what is unsafe at HF - I asked ICNIRP, OFCOM, PHE and the rest to check).  If I raised the antenna by just 0.5m, it would be 'safe' directly next to the pole, at zero distance.

An attempt to compute RF exposure for my 8-ele, 144MHz Yagi.

Now, it's important to stress that, just like OFCOM's applet, nobody can see what equations and assumptions any of these calculators are using in the background.  OFCOM would have to tell us if we asked, but software written by others - especially if they have since died - will remain an unkown 'black box', unless it's open source.

The real test would come if someone complaining about RF exposure went to town and took up a case in law.  I expect that would be an incredibly technical, very expensive and hotly contested case, because there is (a) no peer-reviewed evidence for harm advanced by any of the authorities at present (b) methods of assessment may be flawed, and (c) different experts may well reach different conclusions. 

But I guess more, and perhaps more accurate calculators will now start appearing, as people worry about compliance, ridding themselves of the inevitable malicious complaints some will get, or just from the underlying feeling of duty to comply that such rules bring.

End of week round-up

Been a busy week with non-radio matters!  Even so, the Es season is getting going, with plenty of activity on 10m on many of the past days.  12m is also pretty active now.  Not so much on 6m yet, though.

With persistent northerly winds and cold air, we've seen very energetic convection recently, which always threatens to produce the unexpected bolt of lightning.  Luckily, none has yet occurred!  But it makes for exciting times when I go out flying!

Lots of energy!

A troubling development, down at 14MHz, has been the sudden appearance of very long periods of OHR intereference, which can be very severe.  It seems to be at considerable distance, and is probably Chinese or Russian.

So much for international laws!  OHR interference on 14MHz 07/05/2021.

 

As for the 12m activity, Es persisted beyond 22UT last evening, with good signals into most parts of Latin America, including fairly rare signals from Bolivia.

Not a bad end to the day on 12m!  Terminator correct for time of spots.

In between the radio came walks in our beautiful mountains, made even more spectacular by cold, clear weather:

Above Stwlan hydroelectric dam and upper lake.

Don't forget the muons!

If you've any interest, as no doubt many amateur radio enthusiasts do, in the physics of the universe, then you can do a lot worse than get involved with the MuonPi project, which I highlighed first at the end of last year.

At this page, you can see coincidental muon detections occurring in real time.  It's amazing that, using just a Raspberry Pi and GNSS data, timing resolutions of 22 microseconds are consistently realised.

Here's my dector running under the wardrobe; the flashing blue light at bottom left is the muons being detected by the plastic scintillator slab at top:

 

So why not drop the team an e-mail, and book yourself a kit?  Getting it all going is pretty straightforward.