WITH

using

James Watt

As some of you know I do some QRPp Parks on the Air activations using the QRP Labs QCX Mini. For the past couple of years I've had GREAT results using my 40 and 20 meter QCX Mini with what I call, "My Smoke Detector Battery" setup

QRP Labs QCXX Mini 20 Meters

 

A few days later on May 1, 2024; I decided to give it another try but this time on 40 meters when conditions were not quite optimal. And again, I was amazed with the number of stations picking up my signal with "My Smoke Detector Battery"

QRP Labs QCX Mini 40 Meters

As most of you may know, during the month of June 2024, the sun has presented several Earth facing regions which have been quite active with solar storms, solar flares, large sunspot regions, CME's and HF radio blackouts. These conditions have not been favorable for QRPp communications. Living in Kentucky, USA this time of year also represents days and weeks of hot, humid weather with potential for almost daily thunderstorms. So far in June 2024; we've seen record low morning temperatures of 82 degrees and several days of temperatures exceeding 95 degrees with heat indices well over 100 degrees.

Finally the Solar Space Weather forecast for the first few days of July 2024 looked like an excellent opportunity to try some Parks on the Air CW activations using QRPp. However, terrestrial weather was another issue. Heat advisories were forecasted for the last few days of June 2024 and first few days of July 2024.  It was time to take advantage of this brief window to do some QRPp operating.

QRPp Equipment Set Up

The antenna I was going to use was the Tufteln 40 / 20 Linked EFHW. I made this antenna specifically for my QRP Labs 40 & 20 Meter QCX Minis.

Tufteln 40 / 20 Meter Linked EFHW

As for a keyer, I was going to use the American Morse Equipment Ultra Porta Paddle. 

American Morse Equipment Ultra Porta Paddle

Upon awaking before daybreak, I checked the NOAA Space Weather Predication Center's website for Space Weather conditions. It all looked favorable. Terrestrial weather had a Heat Advisory forecasted for July 2, 2024, so I decided to head out for a near sunrise Parks on the Air activation at Beargrass Creek State Nature Preserve US-7956 which is less than 4 miles from my QTH.

Not knowing who would be hunting at 1130 UTC, I arrived on site; throw up my arborist line about 45 feet into a tree and pulled up my antenna in a sloper configuration, set up my 40 meter QCX Mini and was ready to go.

At 1142 I started sending CQ and 'BEHOLD" within a minute or two the hunters responded top my calls and kept me busy for the next 50 minutes. Below are the results of what a QRPp CW Parks on the Air activation yielded me.

The highlight of this day's activation was a QSO with Greg / VE3GSS  Port Carling, ON, Canada. A little over 920 km from my Kentucky POTA site with less than 1 WATT.

At 1235 UTC the temperature had risen to 84 degrees. It made no sense in pushing it as I had already achieved more than I expected. To say I walked away with a HUGE grin on my face is an understatement. It was a GREAT Parks on the Air activation.

                                                         

On July 3, 2024 my internal clock woke me at 0900 UTC with basically the same Space and Terrestrial conditions that were in play as the day before.  So why not make this "Ground Hog Day in July.  Same time, same set up on July 3, 2024. One difference; today I would try 20 meters.

Within less than a minute after my CQ on 40 meters at 1143 UTC, my activation began with hunters eagerly wanting to be acknowledged.  I didn't disappoint and neither did they.  QSOs were rapid fire for almost an hour.

 At 1240, I switched over to my 20 meter QCX Mini to see what I could garner, knowing that at time time of morning in the U.S., the likelihood of getting any action on 20 meters was suspect.   I did manage one 20 meter QSO.  Here was my catch for a July "Ground Hog Day"

  

The highlight of this day was as try for a Park-to-Park QSO with a station in Japan. I tirelessly tried for several minutes to make a 40 meter contact with a Parks on the Air station JJVAS at JP- 0128. The QSB was pronounced and the strongest I could get was a 229.  The operator was kind enough to send AGN? a few times but I was just trilled for that reply with less than 1 WATT.

This day like many others brought greetings from people who have become familiar with my operations as they get in their daily walks, runs and cycling before the heat sets in.  Today though I met Dr. Tamekka Cornelius, Ph. D, who was out on her daily walk. She, like others are inquisitive about seeing a man sitting in a mostly open field connected to some wires, a bicycle close by and some weird equipment strapped to his legs.   Dr. Cornelius and I had a nice chat about Amateur Radio, brief history of my broadcast career and my bicycling activities.

 

Operating QRPp reminds me of the country music singer Kenny Rogers' song: 

"The Gambler"

You've got to know when to hold 'em

Know when to fold 'em

Know when to walk away

And know when to run

Once in your ham radio journey, try operating QRPp.

You might be surprised with YOUR results.

73

Jim

"Ham on a Bike"

]

 

    

Thank you to Ihar Yatsevich for writing in and sharing with us his open-source WSPR beacon project. The WSPR beacon consists of a custom PCB with ATMega328 microcontroller, GPS module, single transistor amplifier, and Si5351 with TCXO.

The result is a very simple, portable WSPR beacon that can be heard all over the world. However, it appears that no band filters are built into this, so you will need to add a bandpass filter for the WSPR band that you are using.

WSPR (Weak Signal Propagation Reporter) (pronounced "whisper") is an amateur radio digital HF mode designed to be decodable even if the signal is received with very low power. Because of this design, even low-power transmitters can be received from all over the world. It can also be used to help determine HF radio propagation conditions as WSPR reception reports are typically automatically uploaded to wsprnet.

If you are interested, Ihar has written about his project in more detail over on Reddit. 

Let’s start with the basics:

• WSPR stands for Weak Signal Propagation Reporter—a protocol implemented in a computer program used for weak-signal radio communication between hams.
• It lets users send and receive low-power transmissions for testing MF and HF propagation paths.
• Pronounced “whisper,” WSPR was designed and written initially by Nobel Prize winner and FT8 creator Joe Taylor, K1JT.
• The software code is now open source and updated by a small team.

If you’ve wondered if a band is open, WSPR can tell you.

As noted by Joe Taylor, K1JT, and Bruce Walker, W1BW, in their November 2010 QST article, “WSPRing Around the World,” WSPR transmits and receives but does not support normal types of on-the-air conversation. It sends and receives specially coded, beacon-like transmissions which establish whether particular propagation paths are open. Transmissions convey a callsign, station location, and power level using a compressed data format with strong forward error correction (FEC) and narrow-band, four-tone frequency-shift-keying (FSK).

K1JT notes that FEC greatly improves chances of copy and reduces errors to an extremely low rate. The signal bandwidth is only 6 Hz. Combined with randomized time-sharing, this assures that dozens of WSPR signals can fit into a 200 Hz segment of each amateur band. The WSPR protocol is effective at signal-to-noise ratios as low as -28 dB in a 2500 Hz bandwidth, about 10 to 15 dB below the threshold of audibility. On most bands, typical WSPR power levels are 5W or less (sometimes significantly less).

As the protocol has evolved, enhancements to WSPR have included upgrades in its decoder’s sensitivity, improved ability to handle larger numbers of signals in crowded sub-bands, and better detection of false decodes.

To take advantage of WSPR on the amateur bands, you’ll need a radio (one with USB audio is preferred) and a computer with an Internet connection. As users have pointed out online, you don’t need to transmit. Your system can still report what it hears.

The standard message is <callsign> + <4 character locator> + <dBm transmit power>. For example, “KE8FMJ EM89 37” is a signal from station KE8FMJ in Maidenhead grid cell “EM89,” sending 37 dBm, or about 5.0W.

Questions? Share them in the comments below or email me at KE8FMJ@gmail.com.

The post Ham Radio 101: What is WSPR? appeared first on OnAllBands.

So much for playing radio this weekend. In the last half hour my 200mW Zachtek WSPR transmitter, cycling from 80M to 10M every 15 minutes or so, managed to be heard in 2 places… Both in Boston and presumably by ground wave.

By comparison, here is a half hour block from a good propagation day:

Simply amazing! Enjoy the Aurora!

KM1NDY

Doing a little hammy ham ham research during the solar eclipse at the Ole Farm-O-La…Welcome to the first Technical Bulletin of the KM1NDY – Secret Amateur Radio Journal.

As we are now at the peak of the solar cycle, some radio amateurs are using WSPR on the 28 MHz band for their Pico-Balloons as they travel around the world.

Back in April of 2024, I had a post about reception of the KD9NGV pico-balloon as it made its way off the west coast of Ireland to the North Sea. See post HERE

I often see these pico-balloon on my receive list for 28 MHz WSPR but they're nearly all somewhere far away and the propagation mode is via the ionosphere. What I find interesting about the rare really close passes is that there is no propagation mode as such, the balloon is essentially line of sight to my location.

KJ7VBX-11... On the 8th of May 2024, I noticed that I was hearing the KJ7VBX-11 pico-balloon early in the morning just as it had woken up with the sun shining on it's solar panels. I was able to hear it pretty much all day from 07:40 UTC until 18:20 UTC.

During this time, it travelled from a spot off the west coast of Ireland, over the northern counties of Donegal, Derry and Antrim in Ireland, over the south-west of Scotland and then over Cumbria in England before falling silent for the night.

On the 9th of May, it woke up over the English Channel and then headed over the Netherlands.

The balloon is at an altitude of about 13,500 metres or 44,000 feet. The WSPR transmitter is supposed to be 20-milliwatts. As far as I know, it was launched on the 2nd of May 2024 but there seems to be very little information about it.

Format... Early on the morning of the 8th, I was the only person reporting it and it was the only signal I was hearing so I was able to do some tests without any confusion from other signals.

The WSPR transmitter on the balloon seems to have two formats. The first one is shown above. The transmitter turns on as a plain carrier for 30-seconds and then sends one WSPR transmission. I presume this carrier is to warm up the transmitter which is at or below 0 deg C and the 30 second carrier stops any drifting of the following WSPR signal.

The second format is shown below...

This time, there is a second WSPR transmission after the first one.

This is a sample of the decodes that I got in the space of about an hour...

The short format results in just a KJ7VBX decode.

The longer format results in an additional decode which are shown above in red.

At first sight, they look wrong. The callsign, locator and power levels seem to be nonsense. However note that the callsign field starts with a zero. This is a special data WSPR signal and contains the information about the location, altitude, temperature and battery voltage. It's just the WSJT-X receive software shows it in a format that doesn't seem to make any sense.

In conclusion... The balloon is currently heading over Europe so it's going to be line of sight to a lot of stations. Just listen on WSPR on 28 MHz and see if you can hear it.

On the 28th of November 2023, Perri Moore KD9NGV launched a Pico-Balloon from Illinois in the United States with a solar powered payload that transmits a WSPR beacon on 28.1246 MHz.

Most of the Pico-Balloons launched from the USA tend to take a path closer to about 30 degrees north of the equator and cross areas like the north of Africa and south Asia. In contrast,  the KD9NGV balloon seems to have covered a much wider area and has been reported at more northerly latitudes as shown on the map above.

By the 16th of December 2023, it had gone around the world once! By the 19th of February, it had gone around the world three times. By mid April 2024, it has gone around the globe multiple times and the red dots on the map show where it was when I received some of the WSPR signals over the last few weeks.

It then went silent as darkness fell. Once daylight broke again on the 8th of April, it was over the North Sea and GM4WJA started to report it.

At the time of the screen grab, LA3FY/2 in Norway was hearing it and it continued then over Scandinavia. It has since crossed over Russia and at the time of writing is up over the far north of Canada.

KD9NGV Payload... The actual payload pre-launch is shown below.

The 28 MHz WSPR signal is generated by a Si5351 clock generator and the power output is just 9 milliwatts... 0.009 watts!

The antenna is a vertical half-wave dipole made of #36 enamelled wire.  The top half is from the balloon to the U4B tracker (QRP Labs) and the lower half hangs below the tracker.  Three Powerfilm MPT 3.6-75  in a vertical triangle provide the power.  The complete payload weighs 12 grams.

The balloon is described as a "silver SAG Balloon with Helium.".

In conclusion... I have noticed these WSPR pico-balloons many times on the 28 MHz band before but they are nearly always flying over some exotic location. It was just unusual to have one pass so close and be line of sight.

I don’t need to explain the attraction of low power operation; if you’re reading this, the chances are that you are already a convert. I’ve been operating with low power ever since first being licensed in the UK in the late 70’s as G8RYQ, and then G4IFA. One of my first rigs was a homebrew VFO-controlled FM rig for 2M. I don’t remember how much power it put out, but it was at most only a few watts. Then there was an 80M DSB rig, built from a kit, that put out a watt or two. I had a series of 2M FM rigs, including an Icom IC-22A and a Trio TR2200 (1 watt out). I had a hand-rotated 5 element 2 meter beam. To change the beam heading, I leaned out of my bedroom window and twisted the aluminum pole that was supporting it. One of the PA transistors in my Icom IC-22A was blown, so the rig only put out 4 or 5W. I remember using that rig and the beam to talk regularly on simplex with a fellow young ham who was in Wales, 90-100 miles away. I think I used the TR2200 to talk with him as well, which was even more impressive, as the Trio only put out 1 watt of RF power.

My checkered amateur radio life did include one 100W rig. It was a TS520 that I owned for a couple of years in the early 1990’s. Other than that though, every rig I have ever built or owned has been 5 watts or less. After a while doing QRP, 5 watts becomes the norm. 5W is known as “the full QRP gallon”, and it does feel like it! I still run 5W as my default most of the time, on both CW and SSB. Recently though, I’ve been turning the power down, to see how lower power levels get out. A fun moment recently, was when I clearly heard the backwave from my little two-transistor transmitter on the KPH SDR, which is 41 miles away as the crow flies. That backwave was about 1mW, and being able to hear it on a remote receiver was something of a revelation. It was that moment that kickstarted my interest in even lower power levels than the mighty force of the full QRP 5 watts.

Once a day, I check into The Noontime Net on 7284KHz. It is virtually the only time I use SSB. They welcome check-ins from QRP stations. Once a year, they have a QRP day, when operators are encouraged (though not required) to check-in using QRP power levels. There is an honorable mention on their website for the station who checks in using the least power and this year, I took the prize for checking in with 10mW of SSB. The check-in was with Don KY7X in Wellington, NV. The distance between us is 168.5 miles as the crow flies. At an equivalent distance of 16,850 miles per watt, I think that would easily qualify for the QRPARCI 1,000 miles per watt award. Given that most members who apply for that award have achieved it with CW, I think that a QSO of 168.5 miles with 10mW of SSB is even more inspiring.

The lowest power I can turn my Elecraft K2 down to on SSB is 1 watt. I achieved the power of 10mW out by connecting an inline attenuator with a fixed attenuation level of 20dB in the antenna lead. It is one of those “barrel” attenuators, with a BNC connector on each end. With the success of a check-in with 10mW under my belt, I resolved to try for even lower power in next year’s QRP Day. This led me to a nifty little kit offered by QRP Guys. It is an inline attenuator, with switchable levels of attenuation of 10, 20, and 30dB. Also included is a bypass switch that allows the operator to easily switch the attenuator out of circuit when on receive. For $25 + shipping, it was the obvious solution to my QRPp needs. I was very close to pulling the trigger, when my “QRPp extreme sports” gene kicked in, and I thought it could be useful to be able to attenuate a signal by an extra 10dB, for a total of 40dB attenuation. This would reduce the 1 watt of SSB from my K2 down to the truly flea power level of 100µW, and the 100mW CW output to the mind-bogglingly low level of just 10µW! Granted, this extra 10dB of attenuation may never be needed, but if and when I succeed in making a QSO with 30dB of attenuation in the antenna line, I may always wonder if it could also have been made with an extra 10dB. It’s the desire to constantly push our achievements just that little bit further.

With that in mind, I decided to build my own attenuator box. There is no circuit design involved really, as it is simply a series of 50 ohm pi-attenuator pads and a few DPDT switches. I took the circuit from the QRP Guys’ attenuator and added an extra pi-section and switch –

All resistors are metal film 3W types. The 100 ohms ones are 1%, while the other values were 5%. If you can get 1% tolerance for all values, then all the better. If you want to calculate resistor values for any other degree of attenuation, you can use this online calculator.

There’s not much to the build. The diecast enclosure, switches, and BNC connectors all came from Tayda. I am not thrilled with the quality of the connectors and switches from Tayda. The terminals were hard to solder to, presumably due to the use of a cheaper alloy than the quality brands such as Kobiconn and Switchcraft use. Nevetheless, I persevered, and managed to obtain a reasonably satisfactory result.

The bypass/attenuate switch is useful when going from transmit back to receive, for ensuring that your reception is not also attenuated.

Daytime band conditions weren’t too good on first finishing this attenuator, though I did manage to just be heard by Don KY7X, 168.5 miles away, with an output power of 10mW SSB, using 20dB of attenuation from an original 1W signal. I’m not sure if it would have been enough for a positive ID of my signal if he didn’t already know who I was. Nevertheless, band conditions were poor that day, so this was a good sign. I decided to hook it up to my VK3HN WSPR beacon (thanks Paul), which puts out 200mW. I applied 30dB of attenuation, for a 200µW WSPR signal – that’s just 0.2mW! Incidentally, to figure out the various attenuation levels, and what output power they give you, there are several online calculators. I found this one to be useful.

Unfortunately, the lowest power level that can be encoded into a WSPR signal is 0dBM, equivalent to 1mW. I’m not keen on misrepresenting the power level, but as I was so eager to see what a mighty 200µW of WSPR could snag me, and as I considered a power level of 20mW (10dB of attenuation of the 200mW signal) to be too high, I decided to WSPR for the night on 40M, and encode the signal at 0dBm. Check out the following results from a night of WSPR’ing. There were 486 spots in total. This is not a lot by normal standards but a good result, I think, for such a low power signal. In this screen grab, they are sorted in order of distance, so these are the most remote spots. AI6VN/KH6 in Maui tops the list, for a distance of 3778km = 2347 miles. That’s 11.735 million miles per watt! In a normal night of WSPRing on 40M with the relatively high power of 200mW, I would expect multiple spots from Hawaii, VK and ZL land, as well as a spot or two from DP0GVN in Antarctica. However, 0.2 mW is a whole new ballgame, and I was very happy to get just one spot from HI –

Here’s the attenuator sitting on my desk, on top of the VK3HN WSPR beacon. It would be nice to have a tidy desk and a nice, clean operating position but every time I tidy it, it slowly gets like this again (the 3rd law of thermodynamics in action!) At the bottom of the stack is the Sproutie SPT Part 15 Beacon, which is currently not QRV. DK, if you’re reading this, you may notice something familiar at the very bottom of this picture –

I want to be able to WSPR on a more regular basis, and have the encoded power information on my transmissions actually be fairly accurate, so the next step was to build an attenuator with a fixed attenuation level of 23dB, to reduce the output of the WSPR transmitter to 1mW. This way, when a spot from me shows up with a power level of 0 dBm, it actually is 0 dBm. This online pi-attenuator calculator was pressed into service, and yielded the following values. If you don’t have a 12 ohm resistor, then a single 330 ohm part will be close enough –

As this attenuator will only be used to attenuate the 200mW output of the WSPR beacon, I used 1/4 W resistors. The two 56 ohm resistors were left over from a cheap resistor kit that I bought years ago. They had short, thin leads, and were ostensibly 1/4W parts. The left-hand one (the one closest to the transmitter) dissipates the most amount of power, and was getting very warm during 2 minute transmissions from the 200mW transmitter. I do think it was sustainable, but would have preferred it to run cooler. I didn’t have any 1/2W or bigger resistors in appropriate values, so decided to parallel 2 x 1/4W parts. There are plenty of fresh sheets of white paper here, but drawing schematics on envelopes is more fun. A 100 ohm and 150 ohm resistor in parallel makes 60 ohms. Using 352 ohms as the “top” resistor (achieved with a 330 and a 22 ohm resistor in series) makes for an attenuation level of 22.7dB, which is pretty dang close –

The two resistors on the left-hand side run much cooler than the single 56 ohm did. The 56 ohm one was a cheapie resistor, and I suspect it’s stated power dissipation of 1/4W was being a bit optimistic. All the resistors in the final attenuator are 1/4W metal film types. The project box came in a pack of 5 from Amazon, for $7.50. I have used the same ones recently to build QRP baluns and ununs. There are all sorts of fun and novelty projects they would be useful for. The lid snaps on. I can supply the link to anyone who is interested –

The increase in power from 200µW was noticeable after the first night of WSPR’ing on 40M with 1mW. Here is a screen grab of the most distant spots received. In just under 10 hours, I had 1114 spots. It’s a lot fewer spots than what I would receive with 200mW, but that many spots with just 1mW sounds very encouraging. I love this little WSPR beacon (thanks to Paul VK3HN once again). Out of 1114 spots, all of the drift figures were a big honking zero, with the exception of a single 1 and a single -1. Instead of the single spot from AI6VN’s remote listening station in Maui, I now had 7. Sure, propagation on different nights could be some of it, but I’m pretty sure the 7dB power increase from 200µW to a gigantic 1 milliwatt was a significant factor.

This QRPp experiment has been a huge success so far, and I haven’t even begun to work on the goal that I had in mind when beginning this. That was to use the switched step attenuator to see how far I can go with very low power on CW, my mode of choice. WSPR is very instructive and interesting, but an actual QSO, even a brief one, carries the extra appeal of contact with a distant person, with all the unpredictable intangibles that come along with that. I do wish there was a way of encoding lower powers than 0 dBm (1mW) into a WSPR transmission, as I would then be WSPR’ing with successively lower powers. I’ve already received a significant number of spots with 200µW of transmitted power. It would be great to see what could be done with, say, just 10µW (0.01mW), if anything. In the meantime though, there will be a lot of 1mW WSPR’ing emanating from the AA7EE radio ranch, as well as some extreme QRPp CW too, with the help of the switchable step attenuator.

VY0ERC is an amateur radio station located at a weather station on Ellesmere Island at 80 degrees north in the Canadian Arctic. They operate a WSPR beacon on several HF band including one on 10m on 26.1246 MHz.

I noticed that this was one of the unusual stations that I had heard on the WSPR mode on 28 MHz recently so I checked to see what stations reported hearing this Arctic beacon on 10m over the last 5-weeks. The results are shown above.

Some observations...

1) Over the 5-week period, just 101 stations reported hearing VY0ERC on 28 MHz. In the same time period, I heard 1224 stations here on the south coast of Ireland. G0PKT near London runs a similar power (0.2w) but was reported by 1224 stations.

2) The closest reporting station to VY0ERC was TF3HZ in Iceland at 2583kms. My location is 4134kms. The best DX was EA8BFK in the Canary Islands at 6545kms.

3) From what I could tell, VY0ERC was reported somewhere on nearly every day during the 5-week period. 

4) These are my decodes of VY0ERC and I would have been listening nearly every day for the 5-weeks on 10m.

All of my decodes were on the 11th of March and were between 13:58 and 15:38 UTC. The signal strength ranged from -13dB to -24dB so it was really buried in the noise.

In conclusion... I included this report of VY0ERC because it's a good example of how different propagation is just 10 degrees from the North Pole. While we're all enjoying worldwide propagation on 28 MHz at more southerly latitudes, it's a very different story in the Arctic region.

The two primary reasons for the lack of signals are a) the maximum usable frequency (MUF) drops are you head towards the polar regions and b) VY0ERC is in the auroral zone and this can severely distort digital signals like FT8 & WSPR.

The lack of signals coming from VY0ERC might also suggest that some of those long distance paths we see on 10m going over the polar regions are in fact not direct at all and might be skewed further south?

Over the last few weeks, I have been listening on the WSPR frequency of 28.1246 MHz and feeding the decoded WSPR signals to the WSPRnet website. As we're near the peak of the sunspot cycle, I was  hearing stations all over the world on the 10m band. I know when I see east-west paths open to the west coast of the USA and to Japan then conditions must be good.

One unusual signal though was the club station KH6EJ in Hawaii. The power output is just 0.2 watts into a MFJ 1982-LP antenna and it transmits on 80m, 40m, 30m, 20m, 17m, 15m, 12m & 10m. The 28MHz transmissions are at 18, 38 & 58 minutes past the hour. 

The received signals were in the range of -23dB to -29dB which means they were buried in the noise. These are the four decodes...

Why is it unusual?

1) I was the only station in Europe to decode the KH6EJ 10m WSPR signal over a 4-week period. Obviously my location in the north-west of Europe helps but I'm only using a simple vertical half-wave antenna for receive. Why didn't other stations in Europe decode the signal?

2) The short time window. I got just four decodes over the space of three days and they are all in the 18:38 to 18:58 UTC time window. This is close to the sunset times for my location.

3) The northerly path. The auroral zone in the Arctic can and does distort signals. If the signals are on  SSB or CW then they can sound a bit rough but for digital signals like WSPR or FT8, it can often mean that the signals are not decoded at all. 

In conclusion... I've worked Hawaii on 28 MHz a long time ago but if I was looking for it now as a new country on 10m then I'd be checking the band at sunset in March.

Conditions on the 28 MHz band have been really good for the last few weeks as can be seen from the map above which shows all of the WSPR stations that I heard from the 23rd of January to the 19th of February 2024.

In total, there are 1334 individual stations which is a lot for a mode like WSPR which after all is just a beacon mode and not designed to make two way contacts. There are a lot of interesting paths in the map but the one I will focus on here are the ones to Australia.

My location in north-west Europe is in the region of 15,000 to 17,500 kms from Australia. While it's not exactly the 'other side of the planet' i.e. 20,000kms, it's still a long way for a 28 MHz signal to travel.

In total, I heard 28 stations from Australia over the 4-week period on 28 MHz. The list is shown below...

It should not have escaped your attention - at least if you live in North America - there there have been/will be two significant solar eclipses occurring in recent/near times:  One that occurred on October 14, 2023 and another eclipse that will happen during April, 2024.  The path of "totality" of the October eclipse happened to pass through Utah (where I live) so it is no surprise that I went out of my way to see it - just as I did back in 2012:  You can read my blog entry about that here.

Figure 1: The eclipse in progress - a few minutes before "annularity". (Photo by C. L. Turner)

The October eclipse was of the "annular" type meaning that the moon is near-ish apogee meaning that the subtended angle of its disk is insufficient to completely block the sun owing to the moon's greater-than-average distance from Earth:  Unlike a solar eclipse, there is no time during the eclipse where it is safe to look at the sun/moon directly, without eye protection.

The sun will be mostly blocked, however, meaning that those in the path of "totality" experienced a rather eerie local twilight with shadows casting images of the solar disk:  Around the periphery of the moon it was be possible to make out the outline of lunar mountains - and those unfortunate to stare at the sun during this time will receive a ring-shaped burn to their retina.

From the aspect of a radio amateur, however, the effects of a total and annular solar eclipse are largely identical:  The diminution of the "D" layer and partial recombination of the "F" layers of the ionosphere causing what are essentially nighttime propagation conditions during the daytime - geographically limited to those areas under the lunar shadow.

In an effort to help study these sort of effects - and to (hopefully) better-understand the propagation effects, a number of amateurs went (and are) going out into the field - in or near the path of "totality" - and setting up simultaneous, multi-band transmitters.

Producing usable data

Having "Eclipse QSO Parties" where amateur radio operators make contacts during the eclipse likely goes back nearly a century - the rarity of a solar eclipse making the event even more enigmatic.  In more recent years amateurs have been involved in "citizen science" where they make observations by monitoring signals - or facilitate the making of observations by transmitting them - and this happened during the October eclipse and should also happen during the April event as well.

While doing this sort of thing is just plain "fun", a subset of this group is of the metrological sort (that's "metrology", no "meteorology"!) and endeavor to impart on their transmissions - and observations of received signals - additional constraints that are intended to make this data useful in a scientific sense - specifically:

• Stable transmit frequencies.  During the event, the perturbations of the ionosphere will impart on propagated signals Doppler shift and spread:  Being able to measure this with accuracy and precision (which are NOT the same thing!) adds another layer of extractable information to the observations.
  

• Stable receivers.  As with the transmitters, having a stable receiver is imperative to allow accurate measurement of the Doppler shift and spread.  Additionally, being able to monitor the amplitude of a received signal can provide clues as to the nature of the changing conditions.
  

• Monitoring/transmitting at multiple frequencies.  As the ionospheric conditions change, its effects at different frequencies also changes.  In general, the loss of ionization (caused by darkness) reduces propagation at higher frequencies (e.g. >10 MHz) and with lessened "D" layer absorption lower frequencies (<10 MHz) the propagation at those frequencies is enhanced.  With the different effects at different frequencies, being able to simultaneously monitor multiple signals across the HF spectrum can provide additional insight as to the effects.
  

To this end, the transmission and monitoring of signals by this informal group have established the following:

• GPS-referenced transmitters.  The transmitters will be "locked" to GPS-referenced oscillators or atomic standards to keep the transmitted frequencies both stable, accurate - and known to within milliHertz.
  

• GPS referenced receivers.  As with the transmitters, the receivers will also be GPS-referenced or atomic-referenced to provide milliHertz accuracy and stability.

With this level of accuracy and precision the frequency uncertainties related to the receiver and transmitter can be removed from the Doppler data.  For generation of stable frequencies, a "GPS Disciplined Oscillator" is often used - but very good Rubidium-based references are also available, although unlike a GPS-based reference, the time-of-day cannot be obtained from them.

Why this is important:

Not to demean previous efforts in monitoring propagation - including that which occurs during an eclipse - but unless appropriate measures are taken, their contribution to "real" scientific analysis can be unwittingly diminished.  Here are a few points to consider:

• Receiver frequency stability.  One aspect of propagation on HF is that the signal paths between the receiver and transmitter change as the ionosphere itself changes.  These changes can be on the order of Hertz in some cases, but these changes are often measured in 10s of milliHertz.  Very few receivers have that sort of stability and the drift of such a receiver can make detection of these Doppler shifts impossible.
  

• Signal amplitude measurement.  HF signals change in amplitude constantly - and this can tell us something about the path.  Pretty much all modern receivers have some form of AGC (Automatic Gain Control) whose job it is to make sure that the speaker output is constant.  If you are trying to infer signal strength, however, making a recording with AGC active renders meaningful measurements of signal strength pretty much impossible.  Not often considered is the fact that such changes in propagation also affect the background noise - which is also important to be able to measure - and this, too, is impossible with AGC active.
  

• Time-stamping recordings.  Knowing when a recording starts and stops with precision allows correlation with other's efforts.  Fortunately this is likely the easiest aspect to manage as a computer with an accurate clock can automatically do so (provided that one takes care to preserve the time stamps of the file, or has file names that contain such information) - and it is particularly easy if one happens to be recording a time station like WWV, WWVH, WWVB or CHU.

In other words, the act of "holding a microphone up to a speaker" or simply recording the output of a receiver to a .wav file with little/no additional context makes for a curious keepsake, but it makes the challenge of gleaning useful data from it more difficult.

One of our challenges as "citizen scientists" is to make the data as useful as possible to us and others - and this task has been made far easier with inexpensive and very good hardware than it ever has been - provided we take care to do so.  What follows in this article - and subsequent parts - are my reflections on some possible ways to do this:  These are certainly not the only ways - or even the best ways - and even those considerations will change over time as more/different resources and gear become available to the average citizen scientist. 

* * *

How this is done - Receiver:

The frequency stability and accuracy of MOST amateur transceivers is nowhere near good enough to provide usable observations of Doppler shift on such signals - even if the transceiver is equipped with a TCXO or other high-stability oscillator:  Of the few radios that can do this "out of the box" are some of the Flex transceivers equipped with a GPS disciplined oscillator.

To a certain degree, an out-of-the-box KiwiSDR can do this if properly set-up:  With a good, reliable GPS signals and when placed within a temperature-stable environment (e.g. temperature change of 1 degree C or so during the time of the observation) they can be stable enough to provide useful data - but there is no guarantee of such.

To remove such uncertainty a GPS-based frequency reference is often applied to the KiwiSDR - often in the form of the Leo Bodnar GPS reference, producing a frequency of precisely 66.660 MHz.  This combination produces both stable and accurate results.  Unfortunately, if you don't already have a KiwiSDR, you probably aren't going to get one as the original version was discontinued in 2022:  A "KiwiSDR 2" is in the works, but there' no guarantee that it will make it into production, let alone be available in time for the April, 2024 eclipse. 

Figure 2: The RX-888 (Mk2) - a simple and relatively inexpensive box that is capable of "inhaling" all of HF at once. Click on the image for a larger version.

The RX-888 (Mk2)

A suitable work-around has been found to be the RX-888 (Mk2) - a simple direct-sampling SDR - available for about $160 shipped (if you look around).  This device has the capability of accepting an external 27 MHz clock (if you add an external cable/connector to the internal U.FL connector provided for this purpose) in which it can become as stable and accurate as the external reference.

This SDR - unlike the KiwiSDR, the Red Pitaya and others - has no onboard processing capability as it is simply an analog-to-digital coupled with a USB3 interface so it takes a fairly powerful computer and special processing software to be able to handle a full-spectrum acquisition of HF frequencies.

Software that is particularly well-suited to this task is KA9Q-Radio (link).  Using the "overlap and save" technique, it is extraordinarily efficient in processing the 65 Megasamples-per-second of data needed to "inhale" the entire HF spectrum.  This software is efficient enough that a modest quad-core Intel i5 or i7 is more than up to the task - and such PCs can be had for well under $200 on the used market.

KA9Q-Radio can produce hundreds of simultaneous virtual receivers of arbitrary modes and bandwidths which means that one such virtual receiver can be produced for each WSPR frequency band:  Similar virtual receivers could be established for FT-8, FT-4, WWV/H and CHU frequencies.  The outputs of these receivers - which could be a simple, single-channel stream or a pair of audio in I/Q configuration - can be recorded for later analysis and/or sent to another program (such as the WSJT-X suite) for analysis.

Additionally, using the WSPRDaemon software, the multi-frequency capability of KA9Q-Radio can be further-leveraged to produce not only decodes of WSPR and FST4W data, but also make rotating, archival I/Q recordings around the WSPR frequency segments - or any other frequency segments (such as WWV, CHU, Mediumwave or Shortwave broadcast, etc.) that you wish.

Comment:  I have written about the RX-888 in previous blog posts:

• Improving the thermal management of the RX-888 (Mk 2) - link 
• Measuring signal dynamics of the RX-888 (Mk 2) - link
  

Full-Spectrum recording

Yet another capability possible with the RX-888 (Mk2) is the ability to make a "full spectrum" recording - that is, write the full sample rate (typically 64.8 Msps) to a storage device.  The result are files of about 7.7 gigabytes per minute of recording that contain everything that was received by the RX-888, with the same frequency accuracy and precision as the GPS reference used to clock the sample rate of the '888.  

What this means is that there is the potential that these recordings can be analyzed later to further divine aspects of the propagation changes that occurred during, before and after the eclipse - especially by observing signals or aspects of the RF environment itself that one may not have initially thought to consider:  This also can allow the monitoring of the overall background noise across the HF spectrum to see what changes during the eclipse, potentially filling in details that might have been missed on the narrowband recordings.

Because such a recording contains the recordings of time stations (WWV, WWVH, CHU and even WWVB) it may be possible to divine changes in propagation delay between those transmit sites and the receive sites.  If a similar GPS-based signal is injected locally, this, too, can form another data point - not only for the purposes of comparison of off-air signals, but also to help synchronize and validate the recording itself.

By observing such a local signal it would be possible to time the recording to within a few 10s of nanoseconds of GPS time - and it would also be practical to determine if the recording itself was "damaged" in some way (e.g. missed samples from the receiver):  Even if a recording is "flawed" in some way, knowing the precise location an duration of the missing data allows this to be taken into account and to a large extent, permit the data "around" it to still be useful.

Actually doing it:

Up to this point there has been a lot of "it's possible to" and "we have the capability of" mentioned - but pretty much everything mentioned so far was used during the October, 2023 eclipse.  To a degree, this eclipse is considered to be a rehearsal for the April 2024 event in that we would be using the same techniques - refined, of course, based on our experiences.

While this blog will mostly refer to my efforts (because I was there!) there were a number of similarly-equipped parties out in the fields and at home/fixed stations transmitting and receiving and it is the cumulative effort - and especially the discussions of what worked and what did not - that will be valuable in preparation for the April event.  Not to be overlooked, this also gives us valuable experience with propagation monitoring overall - an ongoing effort using WSPRDaemon - where we have been looking for/using other hardware/software to augment/improve our capabilities.

In Part 2 I'll talk about the receive hardware and techniques in more detail.

Stolen from ka7oei.blogspot.com

[END]

Bartgeier: mit bis zu 2.9m Flügelspannweite der grösste Vogel, denn man hier in den Alpen beobachten kann.

FT-8 ist heutzutage die dominierende Betriebsart im Amateurfunk. Sie hat SSB und CW zu einem grossen Teil verdrängt. Das geht so weit, dass man glaubt, dass die Ausbreitungsbedingungen miserabel sind, weil auf dem Band nichts zu hören ist. Bis man dann auf den FT-8 Kanal stößt: fröhlich zwitschern die FT-8 Signale um die Wette. Ganz besonders ist mir das bei der diesjährigen Es-Saison aufgefallen. Ohne FT-8 hätte ich oft gar nicht bemerkt, das das 6m Band offen ist. Beim neuen 4m Band war es noch ausgeprägter. Ich kann mir nicht vorstellen, wie ich in SSB oder CW innert der wenigen Stunden, die ich QRV war, 23 Länder hätte erreichen können. Und das nur mit einem auf den Dachbalken genagelten Drahtdipol und 20W. FT-8 ist für den Sporadic-E Funker ein Segen.

Aber auch auf KW hat sich die DX-Landschaft dank Joe Taylor dramatisch verändert. Wenn nicht gerade ein Contest läuft, findet man wieder Platz, um ein längeres Gespräch in SSB zu führen oder zu telegrafieren.  

Für FT-8 braucht es keinen guten Standort mit Platz für grosse Alugebilde und lange Drähte. Die teure Kilowatt Endstufe kann man sich auch abschminken. FT-8 ist eine QRP-Betriebsart. Sprachkenntnisse braucht es auch keine und man läuft nicht die Gefahr von Bandpolizisten und Besserwissern dumm angemacht zu werden.

Aber es gibt eine Betriebsart, die noch besser ist und weitere zusätzliche Vorteile bietet. Sie heisst WSPR und ist im Digitalpaket von WSJT-X enthalten. WSPR, gesprochen "Whisper" (Flüstern) ist nochmals effizienter als FT-8 - d.h. etwa 10 mal empfindlicher. Man braucht noch weniger Leistung und Antennenpower um ferne Stationen zu erreichen. Zudem sind viele der Stationen, mit denen man eine Verbindung herstellen kann, rund um die Uhr QRV. Auch braucht man während dem "QSO" nicht unbedingt an der Station zu sitzen. Der Computer macht seinen Job auch ohne Funker. Ja, ich weiss: Um eine unbediente Station zu betreiben, braucht es ein Bewilligung. Der Funker muss vor dem Sender sitzen und diesen kontrollieren können. Doch wie bei vielen Dingen im Leben gilt auch hier das Rumpelstilzchen-Prinzip: "Ach wie gut, dass niemand weiss, dass ich Rumpelstilzchen heiss." 

WSPR ist die ideale Betriebsart für den introvertierten Funkamateur. Dieser braucht sich nämlich nicht mit Stationen herum zuschlagen, die ihm auf seine Aussendungen antworten. Die Antworten treffen nämlich alle automatisch ein: über den heimischen Computer. Man kriegt auch nicht unverlangt diese Pappkärtchen, QSL genannt. Und trotzdem kann man sich an den vielen Verbindungen und dem DX freuen und interessante Weltkarten ausdrucken, welche diese Verbindungen dokumentieren.

Aber es macht nicht nur Spaß zu testen, wie weit man mit seiner QRP Station kommt. WSPR ist auch die ideale Betriebsart, um Antennenvergleiche anzustellen. "Ist jetzt die Magnetloop besser oder die T2FD?" Man stört dabei niemand und muss auch keine CQ-Rufe absetzen, auf die jemand antworten könnte.