Meteor scatter experiment with the 2023 Geminid shower

In this post, I'll outline how I used an amateur radio beacon 500kms away to find the peak of the 2023 Geminids meteor shower and what else I noticed.

Introduction... Back in 2022, a new radio beacon called GB3MBA was put on air on the 50 MHz band and its primary purpose was carrying out meteor scatter experiments. Located near the town of Mansfield in the centre of England, the beacon runs 75-watts into a small Moxon antenna which beams straight up.

Unlike most amateur radio beacons, this one is basically a carrier that is on nearly all of the time which is exactly what is needed for meteor scatter experiments. The main coverage area is the UK itself but as I'm 502 kms from the beacon, I'm close enough for it to be of use.

I expected that most of the signals that I would hear would be from meteors burning up over Wales and would be arriving at my location about 20 degrees above the horizon.

Experiment Objectives... This is what I wanted to do...

• Carry out an experiment as a 'proof of concept', take measurements, gain experience and see how I could improve on it.
• Take 'hard measurements' with real data as opposed to just forming an opinion.
• See if I could plot and find the peak of the 2023 Geminid meteor shower as a form of 'citizen science'.

Methodology & Equipment... For the previous few days before the peak, I was listening to meteor bursts from the beacon to establish the best method to carry out the experiment.

Radio... I was using an old Kenwood TS-690 amateur radio transceiver which still works fine and is pretty sensitive. I tuned it to 50.408 MHz and set the mode to CW. It drifts a few Hz with the changes of temperature in the shack but it was fine for this experiment. I just needed to be careful to make sure I was always on frequency.

Antenna... In the run up to the experiment, I used a 2-element Yagi in my attic beaming 120-degrees (east-south-east) to get ready. This was beaming about 45 degrees away from the beacon and being indoors, it wasn't optimum. Just before the experiment, I built a vertical T2LT (flowerpot) half-wave antenna and mounted it about 6-metres above the ground. It had a clear view of the sky towards Wales and the beacon.

Software... I used the SpectrumLab programme to look at the audio spectrum so that I could see any bursts and pings of signal. Under the 'Quick Settings', I used Slow Morse Reception ("QRSS") and I then selected 'Slow CW, 30 sec/dot'. 

I knew it wasn't practical to look at a screen for hours on end. At this setting, the audio spectrum is about 30 Hz wide and it takes about 1h 20m for the signals to drift from right to left across the screen. What this meant in reality was that I could look at the screen every 60-80 mins, count the signals on the screen and record the number of pings and bursts.

What to record?... I knew whatever I did, it had to be consistent for the observing period. I decided to use the number of signals seen in a 30-minute period. If it was a long burst or a short ping, I counted it as one signal. 

This raises the obvious question... should I count the number of pings and bursts, should I record the strong signals versus the number of weak signals? The problem is where do I draw the line? I knew I'd see long bursts, short pings and everything in between. It was the same for the signal strength... what's a 'strong signal'? 

I decided I just wanted 'hard data'. Was there a meteor scatter signal present on the screen... Yes or No. It's simple and there's no ambiguity.

Time period... For the experiment, I counted the number of meteor scatter signals from 17:30 UTC on the 14th of December to 22:00 UTC on the 15th of December 2023...a period of 28 hours and 30 minutes. This time frame coincided with the predicted peak of the Geminid meteor shower.

Results... This is the chart that I generated for the 28.5 hour period.

The recording period starts at 17:30 UTC on the 14th of December when the Geminid constellation and radiant point would be just above the horizon. I'll break down the chart in more detail below but the key thing to note is the peak at about 20:00 UTC on the 14th of December.

I had intended to stop recording early in the morning of the 15th but I was wondering if the peak was really the peak? Would there be another peak 24-hours later when the radiant point would be at the some position in the sky? As you can see, there was no peak 24-hours later. I had actually recorded the peak of the Geminids on the 14th.

Results - Time Frame - 17:30 UTC 14th Dec to 05:30 UTC on the 15th of December... The peak, the dip and the highest radiant...

The first 12-hours is shown above in more detail.

The start... I did a search on Google and it said that the constellation Gemini would rise above the horizon in London at 17:23 UTC. I'm 8.5 degrees west which means it would be 33 mins later... 17:56 UTC. The mid point might be say 17:39 UTC? I found another website which said that the radiant point would rise around 16:07 UTC??

This is further complicated by the fact that we're really looking at a time when meteors from radiant point in the Geminids would be hitting the atmosphere 100kms about Wales? I think 17:30 was a good enough time to start.

The peak... Between 19:00 and 20:30 UTC, I had counts of 15, 19 & 21 for each of the 30-minute intervals.

This is a screenshot I took during this period.

First, I'll explain what you are looking at. The vertical axis is a 30 Hz wide segment of the audio spectrum. The screen is moving from right to left and the white dotted lines are the 5-minute time intervals.

If I was hearing the beacon signal directly, it would be a solid yellow line running from right to left across the centre of the screen.

What you are looking at are the pings and bursts of meteor scatter signals which are spread out across the audio spectrum due to doppler shift.

Prior to the shower, I had seen that the peak was expected at 19:30 UTC on the 14th of Dec. Looking at my screenshot, I think the peak of the 2023 meteor shower occurred between 19:55 and 20:20 UTC on the 14th of December.

The dip??... I did make a note of how weak the reflections were from 22:30 and 00:00 UTC and this can be clearly seen in the chart above. 

As the meteor shower radiant moves slowly across the sky, the angles between the transmitter, receiver and the trails of the meteors will change. At some points, the meteor trails will be parallel between my location and the beacon and at other points, the trails will be perpendicular.

I suspect the dip is due to the geometry of the meteor trails but I'm not sure. It could also be just a statistical error. I would need to repeat the observations on several days around this time period to see if it repeats.

Maximum elevation... At about 01:30 UTC, the radiant point was supposed to be at its highest elevation which was about 71 degrees above the horizon.

Before the experiment, I was wondering if this mattered? Would there be some sort of peak when the radiant peak was at its highest point in the sky? The answer seems to be no, there is no peak.

Results - Time Frame - 01:30 UTC to 11:00 UTC on the 15th of December... The daily morning peak...

When it comes to random meteors entering the atmosphere, the best time for signals tends be around 6am local time. This is because the speed of the earths rotation is added to the speed of the meteors resulting in more energy to dissipate.

This enhancement can be clearly seen in the chart above. It increases after 02:00 UTC and decreases after 10:00 UTC. For me at least, it seemed to be an eight hour window.

The converse is also true. At 6pm local time, the speed of the earth's rotation is subtracted from the original speed of the meteors.

This means that the peak of the 2023 Geminids at about 20:00 UTC happened just two hours after 6pm for me which isn't a great time.

As I was looking at the original chart with the 28.5 hour display, I realised that I was looking at two peaks but both were completely different. One is a fixed peak and the other is a variable peak.

The fixed peak was the peak of the Geminids at about 20:00 UTC on the 14th of December. That's fixed, the peak is the peak.

The morning peak however will depend on where you are. Somewhere in the world, the peak of the Geminids meteor shower will coincide with 6am local time. That turns out to the western half of the Pacific. Anyone in say Hawaii, Alaska, Korea, Japan, east China and the Philippines should have seen some very good meteor bursts and pings. That is of course conditional on having the radiant point above the horizon and that will depend on the location.

Results - Time Frame - 09:00 to 22:00 UTC on the 15th of December... This is the last 13 hours of the plot in more detail...

The radiant point for the Geminids sets about 10:00 UTC and a drop in numbers can be seen. The signals from about 10:00 to 17:30 UTC are random meteors and are not Geminids as the radiant point is below the horizon.

You can see it was particularly poor from 16:30 to 17:30 UTC. Then the Geminids radiant point comes above the horizon and the numbers increase again.

Other observations... Aircraft Scatter... I've seen plenty of aircraft scatter on signals before but I was really surprised to see it on a signal from 500kms away.

These can be very easy to miss. On the QRSS 3 setting, these appear as almost horizontal lines due to the larger vertical scale and faster scrolling speed. On QRSS 30 as used above, the slant becomes a lot more obvious.

As you can see, the doppler shift is in the region of 5-7 Hz. When I was seeing these signals appear, I would check FlightRadar 24 and sure enough, there was often a large plane to the west of Aberstwyth on the west coast of Wales. This is around the halfway point from the beacon to my location.

This suggests to me that while the GB3MBA beacon is 'beaming straight up', there is plenty of RF heading towards the horizon as well.

You'll notice as well that the trails last for about 90 seconds which should be enough for digital modes like MSK144 or possibly FT4? I'd have no doubt that a lot of those one off FT8 decodes on the 10m and VHF bands that people get are due to aircraft scatter like this.

Additional Notes...

• I couldn't tell if any meteor heard was a Geminid or not for the time the radiant was above the horizon.
• Despite all of the 'streaks' visible on the screen, the signals were actually pretty weak. Many were not audible to my ear and I'd say the strongest signals were probably something like 519. 
• The process that I used was very labour and time intensive. I literally had to set an alarm to wake up every 60-80 mins overnight and take the measurements.
• My resolution was 30 mins which may have limited the resolution in that I couldn't tell if two very close bursts were one or two.

In Conclusion... I think the experiment overall was a success. I was able to see the peak of the 2023 Geminid meteor shower which was from 19:55 to 20:20 UTC on the 14th of December.

I'm sure there is room for improvement but I think this is a useful 'citizen science' project which can be done by anyone with a good receiver and antenna. This method is also easy enough that it's not restricted to those from a radio background. 

Anyone with a serious interest in astronomy and meteor research could do this and consider it as an additional tool. This system works regardless of the weather. While 'visual' amateur astronomers need clear skies, the 'radio' based amateur astronomer can carry on regardless.

It might make an excellent project for an astronomy or radio club and maybe give a presentation to students as part of a STEM outreach programme

I think it proves that GB3MBA is indeed a very useful beacon for meteor scatter research and I think the challenge now is for them to make more people aware of it.

You can tell from the length of this post that this was a deep dive down the rabbit hole for me. As soon as I had one question answered, I thought up of two more additional questions.

The future??.. I'd see these as areas for improvement.

1. My antenna was a vertical half-wave which is omni-directional. I think something like a 3-element Yagi would give me at least 6dB more gain, reduce noise and result in more pings and bursts.
2. My experiment was for 28.5 hours with a resolution of 30 mins. I think in the future, I would use QRSS 3 with a finer resolution of 10 minutes and plot the period around the predicted peak in more detail.

More information...

For more information on the GB3MBA beacon, go to https://ukmeteorbeacon.org/

There is also the BRAMS beacon in Belgium on 49.970 MHz which might be of interest... https://brams.aeronomie.be/

WSPR activty report for the 28 MHz band - Nov 2023

Every day for the last few months, I have left the radio listening on the WSPR frequency of 28.1246 MHz and I feed the spots up to WSPRnet. Most days, I don't even check what the radio heard, I just leave the radio on so that others can see how far their 10m WSPR transmitters are reaching.

I had a look today at what I heard for the last 5-weeks which is from the 26th of October to the 29th of November 2023. Considering that we're near the peak of the sunspot cycle, this post gives an idea of what what the band was like.

Totals & Distribution... In total, I heard about 1200 individual stations on 28 MHz during the 5-week period. This is a huge change from a few years ago when I would hear relatively few. It's not that conditions just got good but I think a lot of WSPR users came up to 28 MHz from the lower bands. 

There are a few false reports in the 1200 from strange callsigns out in the middle of nowhere but the vast majority of them are genuine.

The map above shows the distribution and it's obvious most of the WSPR activity is centred on North America and Europe. South America is surprising low and there is almost nothing from Africa outside of South Africa. There is however a good amount of activity from Australia.

DP0GVN... I heard the German Antarctic research station DP0GVN a total of 47 times during the 5-weeks. The best times seem to be in the afternoon but I heard it as early as 07:48 UTC and as late as 18:48 UTC.

Japan???... Where is everyone? I know there have been paths from Ireland to Japan on 28 MHz for people using FT8 but I heard nothing on WSPR. I checked some of the reports for some of the Australian stations and these seem to confirm that there seems to very little interest in WSPR in Japan.

North America... This is the distribution of stations in North America. For the USA, this pretty much mirrors the level of activity and population in the country. You can draw a line north from Houston, Texas and a lot of the radio amateurs are to the east of that.

From Ireland, it's pretty easy to hear the eastern half of the USA so it's nice to see all of those more difficult northerly paths to the west coast. This is especially true when I start seeing those VE6's and VE7's in the north-west.

I do have one report of hearing KL2OF in Alaska but I think it was bogus. I only heard it once, QRZ says the call has expired and the signal was only sent for one 2-minute period. 

I'm not even sure if a WSPR path is likely to Alaska from Europe considering the polar flutter on the signal at 28 MHz?

The UK on Backscatter... There are quite a number of stations in England using WSPR on 28 MHz and most of these stations shown above are about 400-700kms from my location. This is too short for single hop F2 layer and they are in my 'skip zone' according to usual propagation textbooks.

There might be some Sporadic-E in there but it's likely the vast majority are F2 layer backscatter. The 10m signal is being reflected off distant objects like mountains and ocean waves 1000's of kms away. It's certainly not aircraft scatter.

France - Où êtes-vous???... The map above shows the distribution of signals from western Europe. WSPR is popular in the Netherlands and Germany but where is all the WSPR activity from France???

It doesn't seem to be just a lack of transmitters either. There seems to be a equal shortage of people in France listening on the band and reporting.

Australia on 10m... It's always nice to see the 28 MHz WSPR signals from Australia coming through and I heard 29 VK stations in the 5-week period. For whatever reason, I didn't hear any VK7 stations from Tasmania.

As can be seen from the chart below, most of these stations are about 15,000 to 17,500 kms from my location.

Note the Signal to Noise reports (SNR). Most are these signals are buried in the noise and below what can be heard by the human ear. That's the magic of the WSPR mode.

WSPR seems to have a niche following in Australia and those guys are doing some interesting work investigating propagation paths on the 50 MHz and 144 MHz VHF bands.

Polar Stern... Nearly all of the WSPR signals are from stationary stations but a few are on the move. The map above shows my reception reports of the German polar research ship Polar Stern which uses the call DP0POL. It went through the English Channel a few weeks ago and made it's way down to South Africa.

Some days, propagation is good and I get a string of reception reports resulting in a blurred line. Some days, I heard it only a few times if t all.

Path of pico-balloon AF6IM

Pico-Balloon AF6IM... The very small balloon AF6IM was launched from California a number of weeks ago and it has gone around the world at least once. See my previous post.

The map above shows where I heard it over the last few weeks.

In summary... As a beacon mode, WSPR won't be of interest to everyone but it's nice to see a good level of interest in the mode especially on the 28 MHz band.

Just for reference, I was using a simple CB type half-wave antenna for this test so nothing special on my side.

Link...
1) The best website to check WSPR reports is http://wspr.rocks/

Did each contact from 3Y0J on Bouvet Island cost $38?

One of the biggest and most expensive expeditions in recent times was the 3Y0J activation on Bouvet Island in the South Atlantic. The initial plan was to be have 12 stations active for most of the month of February 2023 with a target of 200,000 contacts.

The reality was that they had a lot of difficulty getting the equipment onto the island due to the rough seas and they only managed to operate a few stations for a week which left many disappointed.

What intrigued me was the overall cost of the expedition. Unless I am missing something, I work out that each contact made cost in the region of $38!

Let's have a look...

According to the 3Y0J website, they raised $715,000 USD to fund the expedition which I find incredible in itself. A breakdown of the funding sources can be found on the 3Y0J website.

It just seems like a huge amount of money just for people to say that they made a contact with someone on this remote island. I don't know if all of this money was spent but for now, let's assume the bulk of it was.

Then we have the number of contacts that were actually completed... 18,833... which is 9.4% of the target planned.

If we divide $715,000 by 18,833 then we get an average cost of $37.965 which we can round up to $38 USD per contact.

No doubt there were quite a number of people who had more than one contact so the cost of each contact per person is even higher. 

If the initial target of 200,000 contacts had been achieved then the average cost per contact would be $3.58 USD.

I can't help wondering if a time will arrive in the next few years where an expedition will no longer be viable because of the costs involved? How much is too much?

Opening on the 50 MHz band between Europe and Australia - 16th Jan 2023

 

On the 16th of January 2023, there was an opening on the 50 MHz band between Australia and Europe. Tom, SP5XMU supplied the screenshot above which suggests that there was plenty of activity.

I had a closer look at this opening and what I present below is an overview of what it was like. It's not an extensive list of all the contacts or paths but I feel it gives a good representation.

While the image above suggests an extensive opening, it would seem that the footprint of the opening in Europe and Australia was confined to certain geographical areas.

The map above shows the FT8 paths from VK6KXW in the west of Australia. The number of European stations is quite low and the main footprint is in Portugal, Spain and the west of France.

VK6IR is also in the west of Australia and the image above shows the FT8 paths in Europe. Again, it's a relatively small geographic area in Europe. Notice how the F2 signals seemed to have jumped over Italy and Greece.

The image above shows the 6m paths from VK5BC near Adelaide. Note the little cluster of signals from the west of France.

This image shows the paths from VK3WK near Melbourne. Same pattern again. From what I can tell, the stations near Sydney and the VK4 stations further up the coast near Brisbane were not able to access this particular opening.

The longest path that I saw was 17,875kms between CT1IUA in Portugal and VK3DUT in the SE of Australia.

These are the spots from the DX cluster which seems to concur with the observations above...

de dx freq obs time
VK6KXW  EA7KLL 50313  [LoTW] FT8 -20 dB 1220 Hz 1033z 16 Jan
VK3OTR  F4BKV 50314.5  [LoTW] FT8 QF02WH19<>IN96GG Tnx call ft8 1010z 16 Jan
VK3OTR  F1IXQ 50314.5  [LoTW] FT8 QF02WH19<>IN95PP Tnx qso 1009z 16 Jan
VK6FLVV  EC4TR 50313  [LoTW] 1006z 16 Jan
VK6KXW  EC4TR 50313  [LoTW] tu qso 1000z 16 Jan
VK6KXW  EC4TR 50313  [LoTW] FT8 -17 dB 545 Hz 0948z 16 Jan
VK6KXW  EA3CA 50313  [LoTW] FT8 -14 dB 1601 Hz 0947z 16 Jan
VK6KXW  9H1TX 50313  [LoTW] wkd, vk3/5/6 tu david 0921z 16 Jan
VK5PO  F4BKV 50313  [LoTW] 200w res dipole at15ft 0915z 16 Jan
VK6KXW  9H1TX 50313  [LoTW] FT8 -17 dB 716 Hz 0900z 16 Jan
VK6KXW  9H1TX 50313  [LoTW] FT8 -7 dB 714 Hz 0835z 16 Jan
EA7HG  VK6KXW 50313  [LoTW] FT8 -19 dB 672 Hz 1021z 16 Jan
EA5WU  VK3KJ 50314  [LoTW] FT8 IM99WU<>QF21 0954z 16 Jan
EA5WU  VK3FZ 50313  [LoTW] FT8 IM99WU<>QF22 0952z 16 Jan
9H1TX  VK5AKK 50313.7  JM75FU<F2>PF94HK FT8 0920z 16 Jan
9H1TX  VK3GA 50313.7  [LoTW] JM75FU<F2>QF22 FT8 0914z 16 Jan
9H1TX  VK3FZ 50313.7  [LoTW] JM75FU<F2>QF22 FT8 0913z 16 Jan
9H1TX  VK5BC 50313.7  [LoTW] JM75FU<F2>PF85 FT8 0906z 16 Jan
9H1TX  VK6KXW 50313.7  [LoTW] JM75FU<F2>OF87 FT8 0904z 16 Jan
9H1TX  VK3BD 50313  [LoTW] CQ SECOND ALL WAY GL 0900z 16 Jan
9H1TX  VK3BD 50313.7  [LoTW] JM75FU<F2>QF22 FT8 0857z 16 Jan

All the activity seems to have been FT8 on 50.313 MHz.

Analysis... Over the last few years, we've seen some multi-hop Sporadic-E or something similar during the months of June and July. In this case, it would seem to have been a genuine F2 layer opening on 50 MHz with the solar flux up over 230.

As we get closer to the equinox, I suspect we might see more 6m openings like this. The question is if they will reach further north in Europe and further south to the likes of Tasmania and New Zealand?

The huge difference with this solar cycle is that there are a lot more people using a weak signal mode like FT8 on one frequency i.e. if there is any sort of opening, the signal will be heard and reported.

That may bring it's own problems if the opening is too good though with everyone on the same frequency.

Australia to Europe FT8 paths as reported by PSK Reporter.