Tuesday, January 31, 2023

Station Automation: First Contest

I've described or mentioned my home brew station automation system for well over a year. I've discussed the ups and downs, and how I changed direction when I ran into obstacles. It was only late last year that it first went into service.

It's been slow going. The reasons for the glacial pace were the large number of projects on my plate, reluctance to build stuff during the warm months, and uncertainty about what does and doesn't work for my style of operating and station design.

It's been in and out of use since that "first light" event as I've continued to work on it. The system has been used periodically on the air to test functionality and reliability, and to see whether it meets my objectives. In a few cases, experience from that usage motivated me to make changes. It is therefore with some pleasure to report that I have used the system for the first time in a contest. 

I chose a contest with modest demands on the system and where freedom from manual switching would prove particularly rewarding. That contest is the CQ WW 160 meter CW contest that took place this past weekend.

Ugly, isn't it? I kept the switching hardware at hand so that I could monitor its operation and swap back to the manual switch in case of failure. It took a few minutes to arrange the desk so that I could comfortably operate the contest. It worked out better than you might guess from the photo.

The manual switch is visible below the right corner of the monitor. I used the same DB25 connectors and pin-out to ease swapping between manual and automatic systems. You can see that I added connectors to the separate manual stack switch panel (green jar lid) for the same purpose. Eventually the system will reside below the operating desk, out of sight and (hopefully) out of mind.

There are 3 layers of 2×8 relay boards connected by Dupont wiring harnesses to the Arduino Mega. The processor board has a USB connection to the PC. That will eventually be migrated to Wi-Fi. There is no need for the hardware to be pretty since it will not be visible. The open design eases maintenance and inspection. I will have to add a loose cover to prevent dust accumulation.

The software GUI (graphical user interface) is tightly integrated with N1MM. There are good reasons for me to do it this way and I have not regretted that decision. At this stage of development my software only runs on Windows and, for convenience, it is on the same PC as the N1MM Logger+. The UDP broadcasts from N1MM can be received across all computers on my local network.

When I'm running stations I typically have my left hand on the keyboard and my right hand on the mouse. That way I am ready to type if I'm answered or to hunt for weak callers by clicking the Beverage direction buttons. Below is a closeup of the GUI. Design and operation of the GUI was fully described in an earlier article.

Eventually the buttons will be arranged around a great circle map centred on my location. That was my approach on the physical controller that I abandoned in favour of software. Making the GUI pretty is lower priority than getting it working. The same will be done with the 80 meter vertical yagi direction buttons on the left, which also now work. Since this was a single band contest, there is only one transmit antenna and no BPF (band pass filters) to deal with.

I wish that I had a software control to switch the FTdx5000 receive antenna feature. There is no generic way to do that since the CAT commands are unique to each manufacturer, and N1MM doesn't provide a generic interface for it. 

It can be helpful in a contest to switch between receive and transmit antennas and, for that matter, change the pre-amp setting to equalize signal levels. Beverages are great but their signal level is low. Lucky hams with directional 160 meter transmit antennas typically use it for receiving except for particularly weak signals that would benefit from a higher RDF (receive directivity factor).

The GUI was a pleasure to use. It is easier and faster than twiddling knobs and switches, and I don't end the contest with sore fingers and wrist. Because it was easy I "tuned" in stations faster and I was more willing to hunt down elusive signals. That helped my score. I would often click on Beverage buttons 2, 3 or 4 times after every CQ because it was so easy to do.

No bugs were encountered despite continuous use over many hours. That's reassuring. The only glitch is one I knew about before the contest and it wasn't difficult to work around. The problem is this: when I click a button on my GUI, Windows transfer focus to my app and keeps it there. I have to transfer focus back to N1MM to type into its EW (Entry Window). 

You can do it manually by clicking on the EW with the mouse. That's very inconvenient in a contest. While not a problem in this contest, when operating SO2R clicking on an EW alters the receive and transmit focus and the stereo behaviour of headphone routing. That's disastrous. There are Windows APIs to transfer focus less obtrusively and I added this to my software before the contest. 

My method of transferring focus only works about 95% of the time. For the other 5% I need to click on the EW or click on another GUI button and hope that focus transfers on the second attempt. The latter was easier and always worked. Now that the contest is over I'll get to work on improving the focus code. The N1MM development team provided guidance on how I should do it.

You might think that having a bunch of clacking relays at my elbow would be annoying. To my surprise it wasn't. They are not so loud with headphones that fully enclose the ears with foam pads. It was reassuring to be able to monitor that everything was working as it should on this, its first use in a contest.

I may write an article on its construction. In case I don't it may be helpful to briefly describe what is shown in the photo at right. There are updates to the hardware shown in a previous article, with the addition of wiring and cables for the Beverages and 80 meter yagi.

The Arduino is powered by the USB cable. It is also powered by the external 13.8 VDC supply, using the 5 VDC regulator from one of the relay boards. When I go wireless and lose the USB cable, it will have the power it needs. Logic on the relay boards operates at 5 VDC but the relay coils require 12 VDC. I chose the boards for that reason. 

I included polarity protection for the external power supply but no RFI filtering. So far the latter has not been a problem. In part this is because the antenna switch control lines connect via the relay contacts to the power supply, bypassing the sensitive logic circuits. That provides a measure of RFI protection, but no protection against lightning. The latter will require additional work. 

I had to unify the grounds of the various DC circuits and keep inactive control lines open (not grounded) to avoid peculiar circuit behaviour. In one case a grounded inactive control line created a current pathway through tower-mounted equipment shorted the power supply. Lightning protection will, in most cases, require GDT (gas discharge tubes).

The vast number of control lines due to the large number of antenna switches in my station have to be terminated on the relay boards. I spent a lot of time with a crimp tool to make the Dupont connectors that plug into the Arduino GPIO jacks. There are daisy chains of relay connections for ground and 12 VDC to power low-side and high-side control lines, respectively. The many Cat5 cables are screwed to relay terminals and the other end soldered to DB9 and DB25 connectors. It's tedious and exacting work, and unavoidable.

There are at present no cables for the two sets of BPF. They will connect to the GPIO jacks at the bottom centre of the photo. This was deferred until I came up with a switching circuit that meets my requirements. Unlike the antenna control lines, these short distance connections are amenable to solid state switching and are largely isolated from RFI and lightning risks. BPF were not needed in the 160 meter contest and can be manually selected.

One curious problem arose when I wanted to shut the system down. Turning off the 13.8 VDC power supply did not release the energized relays. Coil voltages are nominal and they will operate over a wide range of voltages. The critical specs are the turn on voltage -- the minimum voltage for the relay to energize -- and the release voltage -- the maximum voltage at which the relay will remain energized. 

The circuitry on the relay boards routes the 5 VDC regulated supply through the relay coil switching electronics when the external supply is disconnected, and 5 volts appears to be higher than the release voltage. I have to either cut all power to the Arduino or click buttons on the GUI to guarantee that all the relays are idle.

On to version 2.2

I must choose the final design for BPF switching and build it. That's almost entirely hardware since the software is already tracking the band and will bypass the BPF for non-contest bands. This must be built in the next two weeks if the automated system is to be used in the ARRL DX contest.

Once the hardware is substantially complete, it can be moved off the desktop. Software development only requires that it be accessible, not visible.

Successfully using the system in an actual operating event gives me confidence that I am on the right track. CQ 160 was a good choice since the demands on the system were modest, the benefit high and the risk was low since my participation was casual rather than competitive. There were no nasty surprises while logging 750 QSOs and many more CQs during 10 hours of operating.

Thursday, January 26, 2023

2023: Exploring Options

By the end of 2021 the major antenna work on my station came to an end. That was marked by the raising of the gargantuan 3-element 40 meter yagi. 2022 had so little station work in comparison to the previous 5 years that it almost felt like a vacation. This year I plan to ramp up my activity to refine what I have and make judicious additions and deletions to improve contest and DX results.

Before delving into my 2023 plan, I will first look back on the year that was. I did not achieve all of my objectives of my 2022 plan. That's typical for me. My plans are somewhat aspirational and reality always gets in the way. That's intentional. Aiming high is a strong motivator. But amateur radio is not a job and I am easily distracted by non-ham activities. All I can do is smile and shrug and move onward. 

As I say every year when the very same style of blog article is published: I do this to keep myself honest and to re-calibrate station plans to my objectives and resources. For most readers this may be of minimal interest other than to gain insight into how a ham with a big station thinks, plans and acts. There are likely a few morsels of interest to many readers. I won't be offended if you choose to read no further.

2022 review

My plan for 2022 can be found in an article from last January. I'll quickly step through what did and didn't get done. Refer to that article for the details of each project.

First up was my list of unfinished projects from 2021:

  • Stack switch for the 10 meter yagis
  • More radials for the 160 meter antenna
  • Efficiency improvements for the 80 meter vertical yagi
  • VHF antennas: longer boom 6 meter antenna, and an antenna for 2 meter DXing
  • Antennas for the WARC bands: 30, 17 and 12 meters

Of these, only the 10 meter stack switch was completed in 2022. Oh well. I'll come back to these when I discuss the 2023 plan. Let's return to the other items on the 2022 plan.

  • Prop pitch motors: I did complete the rebuild and I redid both direction pots. What I didn't do was improve the controller in the shack. I did get as far as designing and bread boarding the direction pot circuits. I still have to build complete controllers for the two prop pitch motors.
  • 160 meters: Although I continued to evaluate alternatives I ended the year with the same shunt fed tower transmit antenna. It's a great antenna but it can be better yet.
  • VHF: No new VHF antennas were built and raised, and indeed were not even designed. I had so much fun last year on 6 meters that I didn't care all that much.
  • WARC band antennas: Again, nothing was done. 12, 17 and 30 meters get little priority since they're not contest bands and I pretty well only chase new countries and band-countries on those bands. Something will eventually have to be done.
  • 40 meter yagi matching network: With a couple of capacitance hats breaking off it seemed pointless to play with the feed point match. I found this project easy to defer.
  • 80 meters: About the only part of my plan to improve the 3-element vertical yagi was to acquire a tower so that I can make it more robust, remove the stinger and support an even better stinger to make the antenna more efficient on 160 meters. I am deferring other improvements until that is done. No horizontal antenna, yagi or otherwise, went up last year. I've been debating alternatives.
  • Station automation: I've made significant progress but I've yet to cross the finish line. I have used the system live on the air but not yet in a contest. The latter was too risky since I expected hardware and software bugs to arise. They have though nothing serious.
  • Station modernization: I am a trained procrastinator. Once again I failed to update the rigs. I did lots of shopping and evaluating alternative transceivers, and failed to click 'buy'. With station automation and other projects incomplete, and not quite ready to invite guest operators, I decided to defer the purchase. Who knows, a fancy new rig will hit the market and scream 'buy me!"
  • Receive antennas: I had enough of a struggle repairing lightning damage to the Beverages and clearing rapidly regrowing bush and deer damage to spend time on a second receive system for the low bands.

Among the reasons not everyone got done was maintenance. A station this size requires a lot of it and I really didn't plan for it in my schedule. These included difficulty with the repair of the faulty prop pitch motor, lightning damage to the Beverage system, cable problems, etc. 

As always I could allocate more time to my many projects but I don't and I won't. This is a hobby, not a job, and when I feel like doing something else or nothing at all, I do! No excuses necessary. Now it's time to look forward to 2023.

As the title says, 2023 is the year to explore options. The station is in pretty good shape at this stage, and most projects are improvements and refinements rather than major construction projects. I hinted at a few of the projects in a recent article.

40 meters

As hinted in a recent article, I am building models for a reversible 40 meter Moxon. Most of the compass that thus be covered on the rotatable side mount currently occupied by a TH6 tri-band yagi. I have most of the aluminum in my stock. By making it reversible I can easily use one antenna to quickly switch between Europe and much of the US. The height is ideal for the latter and pretty good for the former.

Disposition of the XM240 is uncertain. I may deploy it as a fixed side mount for, say, Caribbean and South America, which is a valuable source of multipliers but not QSOs. I am souring on the inefficiency of coil-loaded element. With the big push over I have more time to pursue 1 or 2 db of gain improvement, and with improved F/B and SWR across the full 300 kHz of 40 meters.

I might first purchase a NEC5 license for EZNEC so that the design can be accurately modelled. It is not possible with NEC2, not even as enhanced in EZNEC. That will save me the trial and error I went through with the 3-element yagi element design.

The design of the capacitance hats on the 3-element yagi must be improved. I should have done a better job so I have no one to blame but myself. I lost 2 arms (out of 24) to metal fatigue, and I would not be surprised to lose more. I have a new design and enough material to trial it on the driven element. The ends of the driven element are easily reached by rotating it on the boom. 

Accessing the capacitance hats on the other two element is far more difficult. Recall that the boom is 46' and the antenna weighs 300 lb! A friend and I have come up with a method to rotate the element tips in towards the tower for the repair. The work will easily occupy a full day. Hopefully it'll be done before the summer heat arrives.

80 meters

I have planned improvements to the 80 meter vertical ever since I built it. These include

  • Wire element shape to improve gain
  • More radials to improve efficiency
  • Taller tower for the driven element so that the fragile stinger can be removed and the supports for the wire elements moved higher

Of these, I only expect to do the last in 2023. I will probably wait until late summer to do the work. The existing tower must be taken down, the base widened and improved, new guy anchors buried, and the new tower raised. The work is straight-forward but will take time.

Once the new tower is up I can pursue the other improvements at my leisure. A switchable side-mounted stinger of up to 10 meters height may be added to improve its efficiency on 160 meters.

As time goes by, I am convinced that I must have a horizontal antenna on 80 meters. When operating lower power or QRP in a contest, the vertical yagi alone isn't good enough. Many of the stations I need to work are within 1000 km, and when I operate with 100 watts or QRP. I miss working many stations. I learned that lesson, again, in this month's NAQP CW contest, and Sweepstakes CW before that. With a kilowatt the problem largely vanishes.

The antenna doesn't need to have gain, just horizontal polarization. I intend to once again raise my trusty old inverted vee to an apex height of about 100' (31 m). There are deployment options that I am modelling and interactions with yagis on the tower to be assessed. That will be the subject of a future article.

160 meters

I have two 160 meter projects this year. One is more radials for the shunt-fed tower, which I never did get done last year in time for the winter season. What I'd really like to do is build a small "plow" to bury the radials. It needs to be mechanized, perhaps attached to my mower, since there are almost 500 meters of wire (16 × 30 meters).

Burying the radials means no more rolling them out in the fall and rolling them up in the spring. Farm equipment used for haying will be unimpeded and the antenna will be operational the entire year. I don't operate much in the summer but it would be nice to have an effective antenna for DXpeditions and the occasional summer contest.

Radial burial reduces the urgency of an enhanced 160 meter option for the 80 meter vertical yagi, as described above. In some respects, the latter may be more convenient except in contests when it is necessary to be on 80 and 160 meters at the same time. Winter nights are long and the low bands are unavoidable.

Phasing the two towers for added gain is unlikely to go far this year. However, if I make the radial plow I may bury a set of radials for the second tall tower in preparation for the phasing project in 2024.

High bands

I have plenty of antennas for 20, 15 and 10 meters. The problem is that I am not getting the most out of them. The side mount yagis either don't rotate or have limited rotation. The upper yagis of the 15 and 20 meter stacks rotate together, and they rotate slowly because the prop pitch motors turn close to half the speed of rotators most hams use.

I would like to use swing gates to rotate the (currently fixed on Europe) lower yagis for 10 and 15 meters. That is unlikely to progress far this year other than design and prototyping in the workshop. The operational and maintenance burden of additional rotators and control cables gives me pause.

As a nearer term alternative I would like a full rotatable tri-band yagi on a fast rotator. This is a contest requirement, and is not needed for daily operating. Hunting multipliers and testing propagation requires fast reactions while not conflicting with the use of the high band stacks, which are likely to be in heavy use.

Since I am increasingly averse to the inefficiency of trapped yagis, I would prefer a tri-bander without traps. These are commercially available, but I'd like to take a shot at designing and building one of my own. They are challenging antennas to design due to the element interactions. The antenna doesn't have to be extremely large. 3-elements on 20 meters, and 3 or 4 on 15 and 20 meters is enough.

Can I do it this year? Perhaps not. Assuming the XM240 is removed from the Trylon tower in favour of the prospective reversible 40 meter Moxon mentioned above, the TH6 could be put on the Trylon until I have a better option.

The TH7 remains on the ground and will probably be sold. It isn't doing any good buried under the snow.

WARC bands

The 80 meter inverted vee should work reasonably well on 30 meters, or at least it has in the past. The pattern has multiple lobes (as expected) and the SWR won't be too dreadful. That may be good enough for chasing DXpeditions and the like. 

Even if it's not the best antenna to use it will be better than the 80 meter vertical I'm currently using. None of my other low band antennas are effective on 30 meters, and I would prefer not to occupy valuable tower space with a dedicated 30 meter antenna.

My antenna objectives for 12 and 17 meters are modest. I want a resonant antenna with a little directivity. A dual band 2-element yagi would be enough for me. I could mount the elements on a 40 meter yagi boom or build an entirely new antenna. It isn't difficult to design and build from scratch. The problem is the tower space and coax. 

A 5-band Spiderbeam or a hex beam are alternatives that suit my objective of a trap-free tri-band yagi. Since neither antenna can easily coexist with a second yagi on the same mast due to their mechanical complexity, they are not at the top of my priority list.

Receive antennas

I am happy to report that the entire Beverage system is back in service. It took me a while to gather the parts needed to rebuild the last of the reversible Beverage electronics. It went smoothly, and this time there were no construction and testing errors.

The station automation system (see below) is far enough advanced that the Beverage directions control works. Just click the buttons with a mouse. 

This year I need to decide whether to disconnect and ground the Beverages during the summer months when lightning is likely. I can't easily reverse the decision because the hay fields and bush are difficult to get into and are full of Lyme carrying ticks. I prefer to wait until the end of summer to reconnect them. 

The alternative is to add effective lightning protection to the system. I've been researching the matter and pricing components. It's not as difficult or expensive as I once believed. It is worth pursuing. Whether I do so before lightning season arrives is uncertain. 

I would like to prototype a second receive antenna this year, made with short phased vertical. The objectives are to test performance and whether home brewing is viable. This could expand into a full sized vertical receive array or just a minimal system for use during the summer months and for the second operator position during contests. The Beverage system supports just one direction and receiver at a time.

Station automation

This is another carryover from 2022. Except that I'm pleased to say that I'm getting close to completion of the new software driven system. It's been used for casual operating but not yet for contesting. There are as yet too many gaps and inadequate testing to trust it in a contest. That will soon change.

Features still to be added include BPF (band pass filter) switching, 160 on the 80 meter yagi, manual operation when N1MM fails or isn't being used, and several other operational and failure-mode functions.

I was slowed by other projects and an unwillingness to stare at a screen or soldering iron when the weather was still fine. The mess of wiring and tiny connectors have been a psychological barriers: the work is not difficult but tedious and exacting, and old people like me have little patience.

I've run into puzzling problems with managing and bonding the DC grounds in my station which, when thrown together into a unified stack of hardware, cause a variety of electrical malfunctions. These have been mostly eradicated and I have a plan to deal with the rest. 

There were software integration problems that made the system difficult to use in a contest. Those have also, for the most part, been resolved. I had much to learn about other software systems (N1MM, Windows APIs, etc.) to make everything play together nicely.

Once I have it fully working I will further develop the software to make it easier on the eyes, improve multi-op support, and migrate the software to a separate computer with a touch screen. I'll have more to say about these and more in future articles.

Prop pitch motors

I have the circuit design for the direction indicators and I have the relays for motor control to build prettier and better rotator controllers for the two prop pitch motors. I have already mentioned that I want to adapt orphan Hy-Gain rotator controllers for this purpose. Many hams have done this and they look really (and work) really good.

There are other improvement planned this year. Last year I built new direction pot systems, and although they are working well there is room for improvement. The immediate need is the belt drive between the mast and pot on the tower with 20 and 15 meter stacks. I have gathered almost all the parts I'll need, but I will wait for warmer weather. It is not an emergency.

Tension on the chain for the chain drive prop pitch motor driving the 3-element 40 meter yagi and upper 10 meter yagi is difficult to adjust. Slack in the chain allows the antenna to rock back and forth, providing a longer runway for wind induced acceleration and thus more momentum to be absorbed by the motor and tower.

I have ideas on how to adjust the tension without altering the existing system. I would like to try one of them this year.

Station modernization

Transceivers are at the core of any station. I have deferred several decisions until I decide on what current generation rigs to purchase since they impact station automation and peripheral integration. I can say that at this point I am leaning strongly towards the Icom 7610.

If that's what I do, the 7610 would become the primary rig and the FTdx5000 relegated as the second rig. The FT950 will be disconnected and kept as a spare. The resale value is low enough that it makes more sense to keep it as insurance again rig failures during a contest.

It is unlikely that I will purchase a new amplifier this year. Then again, I might accelerate my plan. My next amp will be solid state with automatic band switching and tuning. There are several ways this is being accomplished in current products and I have no favourite at the moment. Quite a few innovative designs have been introduced in the last year or two and more are likely to appear.

Although I have no other modernization plans for 2023, I am biased in my assessments of equipment for their openness and ease of software integration. Hardware jacks for control functions will be rejected in favour of wireless and IP communication.

Back to work

I will try to use the software system in the CQ 160 contest this weekend. I hate the knob and switch on the manual antenna switch which are very hard on the fingers. Who knows, I might get a sore wrist and finger from excessive clicking of buttons on the screen instead!

Indoor projects will keep me busy during this coldest time of winter. There is time enough in the warmer weather to dive into my 2023 station plan. Or so I hope. I get distracted easily, and since I'm retired that rarely has negative consequences. Discipline fades over time without a externally imposed schedule, such as that from a job. I can live with that.

Tuesday, January 17, 2023

Proxy Measurements and Propagation

Why do we count sunspots?

It's an interesting question since many hams seem to pay close attention to it. However, as we'll see, it's of greater importance to science historians and solar physicists, but misleading to HF propagation expectation. 

In the beginning, sunspots were counted because they were there! That was a monumental discovery since in many cultures and religions the Sun was declared to be perfect, without blemish. At first only the largest spots could be observed because, without instruments, the Sun is too bright to look at. Eventually it was a simple pinhole projector that allowed scientific observation. I did this myself a few times when I was young and pursuing my interest in astronomy.

With these simple instruments it was possible to discover the rotation of the Sun, and its differential rotation with latitude. Sunspot birth and death, sunspot groups and, with longer observation, solar cycles were recorded and studied. Progress was slow at first. The relationship to the ionosphere and radio propagation were wholly unknown because both were undiscovered. Over a century ago that changed.

Every ham knows that there is a correlation between sunspots and ionospheric radio propagation. The correlation is loose and of little use for answering whether there is, say, propagation from here to Egypt at 21 MHz right now. Another way of putting it is that sunspots are a poor proxy for ionospheric propagation. They're just easy to see and count.

Although the correlation is poor it is better than nothing. We would listen to WWV (before the internet!) for the latest data: sunspot number, solar flux and A and K indices. For a long time we had little else. It was often easier and more reliable to turn on the radio and listen or transmit and see what would happen. That's a bit like stepping outdoors to check the weather rather than rely on a low accuracy weather forecast, or none at all. As with the weather, we now have better data, proxies and prediction methods to rely on, and the internet to access them in real time.

A chart like the one above shows how wildly the sunspot number swings. To get meaningful information from the raw data it is necessary to smooth the data. That involves weighted averaging over a moving window of data. When you do that the correlation to propagation is greatly improved. The correlation is backward looking since the "prediction" is for the past. That doesn't help us today. Sunspot number and SSN (smoothed sunspot number) are informative to solar physicists, but not to hams. We need current information.

Ionosondes can tell us with good accuracy the ionization above us at a single location and time. The data, good as it is, tells us only a little about ionospheric propagation. That's why ionosondes, like weather stations are placed in many locations. The network is full of gaps since the interest these days is scientific and not commercial. There's little money to be made in 2023 from observing and predicting HF propagation.

Why can't we directly measure the Sun's affect on ionospheric propagation? Why do we rely on a proxy like sunspots? The major factor is EUV (extreme ultraviolet radiation). EUV radiation is correlated to sunspot activity but poorly, yet EUV is largely responsible for F-layer ionization. We need to directly observe EUV, not sunspots, for reliable propagation predictions. The attention paid by many hams to sunspots more often leads to confusion than enlightenment.

The NASA sourced diagram found on Wikipedia shows that electromagnetic wavelengths shorter than near UV radiation are blocked by the atmosphere. The ozone layer is largely responsible, but so is the ionosphere. Well, that must be true since if the ionosphere were transparent to EUV the ionosphere wouldn't ionize! This is not only good for propagation: EUV and more energetic radiation is hazardous to life. 

The downside is that EUV can't be directly monitored from the ground. It can only be observed directly by satellites, and that comes at a price. Ideally we want a measurement we can do at the Earth's surface that correlates well with EUV. That is, a reliable proxy!

EUV is closely correlated to solar radiation in a portion of the microwave spectrum which the atmosphere is largely transparent to. The Sun's noise across a 100 MHz spectrum near a wavelength of 10.7 cm is measured from ground observatories. With smoothing on the order of hours it is a good predictor of F-layer ionizing EUV radiation. That is, it's a good proxy for a major influence on radio propagation. This is the solar flux index (F10.7) that hams are familiar with.

Unfortunately, the current EUV level is insufficient to determine the current propagation. Propagation is far more complex than that. I would be remiss to focus only on EUV and its proxies, despite its outsized contribution.

Ions form during daylight in response to EUV, then gradually recombine during nighttime. The cycle repeats every day. The rates of ionization and de-ionization are not equal and, indeed, vary with the seasons: by latitude and hours of daylight.

This is not unlike what happens with the cycle of the seasons. The coldest temperatures in most of the northern hemisphere occur in late January, 5 weeks after the solstice when solar irradiation is minimum. For most of January the average rate of cooling is greater than that of heating. Only after the rates cross in late January does the temperature begin to climb. The same process in reverse occurs in July.

Sustained high SFI improves F-layer propagation with a net positive ionization rate over many days. Since we can measure the SFI each day, consecutive series (daily, hourly) of SFI values are needed to predict propagation via the F-layer. There is more than one observatory so measurements are possible around the clock. However, a high SFI where the Sun is shining does not contribute to ionization on the nighttime half of the globe.

Of course there's more to predicting propagation than EUV. X-rays from solar flares temporarily cause the D-layer to absorb short wave signals. Density, composition and speed of the solar wind, especially as enhanced by CME (corona mass ejections) can make the E-layer opaque or reflective and also disturb the F-layer at high latitudes. Visible and radio auroras are a useful but imperfect proxy for the relevant geomagnetic activity. There are many factors at play. Even the stratosphere plays a role, such as its likely influence on sporadic E propagation. 

As I write these words the SFI has been above 200 for several days. With the X-ray flux staying high there is also attenuation of signals being propagated by the F-layer. There are lots of signals on 10 meters but the signal levels are not what they could be. 

Now that the X-ray flux is dropping, conditions should become more favourable, at least until the next flare! This is good because, ideally, we want lots of sunspots that are middle aged, not new, to have sustained high EUV flux and without the constant flaring of young spots. Sunspots are a two-edged sword: the good of increased EUV and the bad of flaring and CME.

When the SFI is high I leave WSJT-X running with the 6 meter yagi pointing east then south in the afternoon when I'm busy doing other things, in hopes of decoding a signal from the tropics or South America. No luck yet but I did hear a US station working the TN8K DXpedition. Our chances improve as the solar cycle progresses and a sustained high EUV flux becomes routine.

In the meantime, it is wonderful to hear and work the world on 10 meters. It will only get better and 6 meters is next. At this northerly latitude I watch as daylight, and therefore EUV exposure, increases as the calendar progress towards spring.

Credit: xkcd (Jan 16, 2023)

In closing, watch the sunspot number as a harbinger of improved high bands performance, but pay closer attention to the SFI since it is the far better proxy for what to expect on the bands, right now when you turn on the rig. SFI and SSN track well but only when the latter is smoothed over many many months. Don't be misled by the sunspot number.

Friday, January 6, 2023

Appreciate What You Get

I was motivated to say a few words about the ongoing FT8WW operation on Crozet Island by conversations with fellow hams and what others have written in public fora. There is a diversity of perspectives on this most unusual of DXpeditions. I am surprised and not surprised, sometimes in strong agreement and sometimes in strong disagreement with the discourse. It is worth a moment's reflection.

Back in the days of yore, so to speak, working rare DX was a rare treat. Communications of the DXpeditioners' plans and progress was often long arriving and incomplete or contradictory. Just figuring out when and where to listen could be an enormous challenge. Some of the one-man operations had no pile ups at all! They engaged in S & P and if you called CQ DX you might be in for a surprise. I know several old timers who worked P5 that way.

The objective was to get the DX in the log, on any band or mode, and that was it. You could put a check mark next to that entity and start hunting or waiting for the next one to appear on the bands. A smaller number would try to work them on both CW and SSB, or on a band that was a particular focus of theirs. Others worked the DX on the same band and mode multiple times as a way of bragging about their big signal. The DX often couldn't tell because computer logging was as yet unknown.

In many respects the Crozet Island DXpedition is a bit of a throwback. There is just one man, Thierry F6CUK, operating from a remote corner of the world and trying to sate the appetites of DXers worldwide. It's quite the challenge for him and for us. His challenges include:

  • Restricted antennas: low wires only are permitted
  • Restricted operating hours: enforced quiet hours to protect the work of the science team
  • Weather: winds in excess of 100 kph occur almost daily, and antennas are difficult to keep up
  • Restricted duration: total operating time of several weeks, yet his stay is months long

He is doing his best under trying conditions. That "best" includes getting into as many logs as possible for that highly valued ATNO (all time new one). FT8 gets the job done since it puts everyone in a more equitable position, giving those with a small station a better chance than in the CW and SSB pile ups. Rate is achieved using MSHV to run 2 or 3 concurrent QSOs.

I used to enjoy battling it out with the big guns in the pile ups with the small station I returned to the hobby with 10 years ago. That isn't for everyone, and I understand that. Another factor is that many hams in this era of no-code licensing no longer know CW, and SSB is less friendly to small stations. Despite my limited interest in the digital modes (6 meters most notably) I have to concede that he's doing the right thing.

I could not be certain when or for how long he would operate CW, which is how I wanted to work him. For insurance I made the effort to work him on both 20 and 30 meters FT8. I now have a lifetime total of 3 digital QSOs on the HF bands! Compare this to several thousand digital QSOs I've racked up on 6 meters and a few hundred on 160 meters.

Since those FT8 contacts I've worked him on 20 meters CW. I hope to eventually work him on other bands using CW or SSB. I can only wait to see what he does.

One thing his limited operating has encouraged is pirates. Where there's demand, someone will step up to supply that demand, or so economic theory tells us. In this case, it's like searching the internet for a good deal on a brand name item and then spending your money on what turns out to be a low quality knockoff. Or they take the money and run. DX pirates don't profit but they seem to enjoy playing jokes on the unwary.

In this modern era of DXing where large, well-financed teams put big signals on all bands and modes this DXpedition to Crozet is unusual. Yet it used to be the norm decades ago. You wait, worry, and commiserate with friends as all of you scour the bands, hoping to have that one shot at a new one. This is anathema to many DXers today. They want to work DXpeditions on every conceivable band and mode, and are more than ready to complain loudly when they don't get what they want. The anti-digital clique is particularly vociferous.

It is both disheartening and amusing. The complaints are not fair to Thierry and I hope they don't diminish his enjoyment of activating this rare entity. For myself, well, I laugh at the entitlement on display. The naysayers don't seem to realize how childish they sound. Life isn't fair and you don't always get what you want. The Rolling Stones put it to song many years ago:

"You can't always get what you want
But if you try sometime you find
You get what you need"

In other words, if you're among the dissatisfied, stop complaining and appreciate what you get. No one owes anyone an ATNO. Work Thierry however you can, and thank him for the QSO. 

Perhaps if the French authorities are encouraged by an operation that is respectful and doesn't disrupt their activities on Crozet we will, in time, see more operations like this or bigger on Crozet and also Kerguelen. That would be wonderful. 

In the meantime, happy hunting and I'll hopefully see you in the pile ups for the upcoming Bouvet Island DXpedition. I worked Bouvet a long time ago but there has been no activity since my return to the hobby 10 years ago. This is one where we very likely can get what we want. Best of luck to them and to us!