Reception of the 50 MHz GB3MBA beacon during the Quadrantids meteor shower - 4th Jan 2024

Back in December, I carried out an experiment to find and record the peak of the Geminids meteor shower by listening to the GB3MBA 50 MHz beacon which is 500kms from my location. See post HERE

On the afternoon of 4th of January 2024, there was the peak of the Quadrantids meteor shower which tends to be very narrow but intense. This time, I just took some screenshots of the meteor reflections.

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.

For the Quadrantids meteor shower, I was using a Yaesu FT817 on USB as a receiver and the antenna was a 2-element Yagi in the attic of my house. The antenna was beaming about 120 degrees which is about 45 degrees off the beam heading for the beacon (The choice of beam heading is determined by the space in the attic and I wasn't trying to beam away from the beacon).

Quadrantids screen shots...

The image above shows the composite collection of seven different screenshots. As can be seen, there was plenty of evidence of pings and bursts from the GB3MBA beacon.

The images on the blog are quite small and a link to a larger version of the image is on Facebook HERE.

I'll use the more detailed example above to explain what you are looking at. The time is moving from right to left and you will notice the 30-second timestamps. As my receiver isn't GPS locked, I'm probably around 5 Hz off frequency which is ok. 

If I was hearing the beacon directly, it would show up as a solid yellow line going across the centre of the screen. Instead, you are looking at the signal reflecting / refracting off the trail of electrons left behind by the meteor as it burnt up. As these electrons are in motion in different layers of the upper atmosphere, there is some doppler shift on the signal.

In the example above, the 50 MHz signal lasted for about 90-seconds.

The signal on the far right of the image above is one of my favourites. This is called an 'epsilon' echo as it twirls around. What causes such a complex pattern as opposed to the other 'smudges'?

Link...
1) GB3MBA website

Geminid meteor shower peaks on the 14th of Dec 2023

The Geminid meteor shower is one of the biggest of the year and meteors from this shower should appear from the 4th to the 20th of December. The peak is predicted to be at 19:30 UTC on  Thursday 14th of December 2023.

The radiant of the shower is above the horizon from about 18:00 to 10:00 local time and will be highest above the horizon around 02:00 local time. As the sky will be dark with a new moon, it should be a good visual spectacle as well in clear skies.

From a radio point of view, there should be plenty of meteor pings and bursts with an hourly rate of 150 expected.

On bands like 40 MHz, 50 MHz & 70 MHz, signals that are 500-1000kms distant should give good signals. The higher bands like 144 MHz will need longer paths.

One of the best bands for meteor scatter is 50 MHz. See if there is a beacon about 500kms from your location and have a listen on SSB or CW. It can be useful to have a waterfall display like that used for FT8 so that you can visually see weak signals.

The best time for meteor scatter is usually around 6am local time. If you were to try around 6am on the 14th & 15th of December then you should see and hear plenty of meteor bursts and pings.

Meteor Shower Calendar - April 2021 to January 2022

 

While the Spring months tend to be the quietest in terms of meteor showers, things start to pick up at towards the end of April every year. The peaks of the various meteor showers are good times to check for bursts and pings of radio signals on the VHF bands.

I have put together a calendar which contains a list of most of the current meteor showers. The list below covers from April 2021 to January 2022.

144 MHz signal from the Faroe Islands heard 3000kms away in Bulgaria during Geminid Meteor Shower - Dec 2020

Every year, the Geminid meteor shower peaks around the 14th of December and many VHF radio amateurs make contacts by bouncing signals off the meteor trails left behind. The maximum distance tends to be similar to Sporadic-E i.e. in the region of 2300 kms.

During this years Geminids, Stamen LZ1KU announced a suprise reception on 144 MHz of Jon OY9JD on the Faroe Islands, a distance of 3075 kms!

A composite of the screenshot from LZ1KU is shown below...

As can be seen, the mode used was MSK144 and there is one decode from OY9JD.

On an online forum later, OY9JD did confirm that he was on air at that time...

According to info provided by SO3Z, Jon OY9JD is using an ICOM IC970 with 500W into an 8 el Yagi 3m long. LZ1KU is using an array of 4 x 12 elements and 1.7kW.

Even though there was no two way contact on this occasion, it is still an impressive distance for 144 MHz. Remember that 3075 kms is roughly the distance across the North Atlantic between Ireland and Newfoundland.

In fact, 3075 kms to the west from OY9JD actually reaches the remote areas of Labrador in NE Canada.

Mode of Propagation??? (Updated)... 

(Theory 1) Double Hop Meteor Scatter... Most meteor trails capable of supporting propagation of 144 MHz signals last for a fraction of a second at best with the occasional one lasting several seconds.

Was it a case that that on this particular occasion, two meteor trails were in just the right spot happened at the same time?

In other words, the MSK144 signal from OY9JD was reflected off the ionised trail of one meteor, then hit off another trail several hundred kms later and then was picked up in Bulgaria.

As you might imagine, this isn't that common as it requires there to be two meteor trails to be just in the right place and at just the right time.

(Theory 2) Tropo Assist?... As for did tropo play a part in the path? The conditions looked pretty poor as can be seen from the image below.

It seems unlikely that any sort of tropo ducting played any part in this reception report.

Theory 3... Refection from the International Space Station??? It would seem as if the International Space Station (ISS) was above the horizon at the same time.

In response to my original theory that it was double hop meteor scatter, Alejandro LU8YD from Argentina writes... 

"My opinion is that the QSO analysis is not correct. You have to check the location of the ISS space station at the time of the QSO and you will see that it was crossing the path between stations LZ and OY. In my opinion it is a QSO by Spacecraft scatter and not by meteor scatter. Reflections of amateur radio signals by the ISS as a passive reflector has occurred before. Despite this, it must be considered an extraordinary QSO and achievement by LZ1KU and OY9JD for which I congratulate them.

Please send my regards and congratulations to Stamen and Jon

Kind regards Alejandro LU8YD"

After receiving Alejandro's message, I checked out the position of the ISS on the morning of the 14th of December.

The beam heading from the Faroe Islands to Bulgaria is 147 degrees. The time stamp on the MSK144 signal was 11:03 UTC.

It's not a perfect match but the ISS was certainly in the same general area of sky at the time. The ISS reached a maximum elevation of 10 degrees during that pass and it was probably around 4-5 degrees at 11:03 UTC.

This is the view of the pass from Bulgaria...

From the Bulgarian perspective with a higher pass, the time and beam heading seem closer aligned. The Faroe Islands are on a beam heading of 327 degrees from Bulgaria.

Considering the size of the ISS and the size of the reflective surface, it has to considered a strong contender for the reception report.

However, I still have some questions. What about doppler shift? Would the doppler shift have moved the signals outside the receive passband of the receiver? What impact does doppler have on a MSK144 signal and the ability to decode it?

Conclusion (Updated)... My original thinking was that it was probably double hop meteor scatter. After all, there must be occasions when two meteors trails just happen to line up in the correct position at the same time.

The fact that the International Space Station was in the same area of sky at the same time must make this the most likely reason although in retrospect, I don't think we can be absolutely certain but it does seem likely.

I'd be inclined to say 90:10 in favour of refection off the ISS as opposed to double hop MS but others may have different opinions.

North Atlantic on 144 MHz??? ... Here is an intriguing thought: If the signal at 144 MHz can get 3075 kms from the Faroe Islands to Bulgaria was via double hop meteor scatter then why not across the North Atlantic from Ireland/UK to Newfoundland?