Guest Post: Example of Lightning Scatter at 144 MHz ...by Kadri, TA1D

In a follow up to my recent post about lightning scatter at 1296 MHz, Kadri TA1D got in touch to say that he saw another example at 144 MHz. He wrote a post about it on his blog in Turkish and that is linked from the bottom of this post. 

He has kindly given me permission to publish a version in English here. I'm using Google Translate for most of this post with a few corrections so a few errors may creep in.

John, EI7GL

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Contribution of lightning to Radio Communications at 144 MHz ...by TA1D

Towards the end of summer 2021, I was operating from my summer QTH station in the North Aegean in Turkey / Turkiye. It was raining with lightning one day when I was communicating with Meteor Scatter on 144 MHz and I decided to check if the SV2JL/B beacon station in Greece on 144.450 MHz could be heard during the hours when lightning was concentrated in the middle of the Aegean Sea.

I turned my antenna to the west and started listening on 144.450 MHz. At that time, the sound of the CW beacon could be very faintly heard with some fading (QSB). Sometimes it became  unreadable and rose again, but overall, the signal level was very poor.

While I was listening, I also had the computer monitoring with the MSK144 mode and sometimes, the morse signal appeared clearly on the screen as short and long lines.

I noticed that I was also hearing the static crashes from the lightning and these can be seen on the screen shot above.

I noticed that I could hear the radio signals of SV2JL/B very faintly during each lightning strike. When the static crash was at a red level, the morse signals became loudly audible before dropping back down to a lower level.

I realised that I had witnessed an interesting physical event and it was possible due to my position and situation.

Is it of any use to radio amateurs? Yes, it can be useful. We can make use of meteor scatter with the MSK and FSK modes to make contacts using short pings and bursts. We could also make use of the short scatter signals from lightning strikes.

Thanks to lightning, we are listening and sending like meteor scatter communications. Lightning strikes at the appropriate angle between the two stations during our meteor scatter style QSOs may help us communicate.

In conclusion; This physical phenomenon that I have noticed and determined can be effective in amateur radio communication.

There may be articles written by people who witnessed similar events on different web pages, but I have not come across them yet.

Meteorite: Pieces of Stone, Soil, mineral and ice floating or orbiting in space.

MS: Meteor Scatter, bouncing off meteor trails, reflection.
MSK and FSK: Digital communication mode
Beacon: Radio Beacon, Robot station that sends Morse or digital signals at certain intervals.
CW: Morse signal, carrier wave
RF: Radio Frequency
SV2JL/B: Robot Beacon station installed in Greece
APS: Airplane Scatter: Reflection and scattering from the aircraft surface.

TA1D Kadri K.Mehmet Başak

Links...

1) The full original article is on the TA1D website... http://ta1d.com/?p=226

Lightning Scatter contact on 1296 MHz in Australia - 13th Feb 2024

Lightning scatter is one of those exotic propagation modes that sometimes get a mention in books and articles but there seems to be very few examples. I think most people would expect this mode to be perhaps seen in the VHF part of the spectrum so it was a surprise to read that VK7MO and VK3MAP in Australia claimed to have made an lightning scatter contact on 1296 MHz!

They report that on the 13th of February 2024, there was a severe lightning storm between them and they attempted to make contact on 1296 MHz using the MSK144 mode. 

They write... "The distance between us is 505 km and we ran 33 & 36 element single yagis with power levels of 120 and 50 watts. We were surprised that at this distance it was also possible to receive MSK144 decodes on aircraft scatter. However, we found it was possible, by replaying the files and examining the MSK144, Fast Graph window, to clearly identify the difference between both types of propagation. While at the time we completed three QSOs on 1296 MHz using MSK144, examination of the files shows that only one QSO was completely on lightning scatter and the other two were partly on aircraft scatter. Still, we can report the completion of a QSO using lightning scatter on 1296 MHz."

After their tests, they came to the following conclusions...

• We are confident that we achieved 50 lightning scatter decodes and one QSO at 1296 MHz.
• We used 15 second periods and auto sequencing to respond quickly enough.
• If aircraft are present, it will be difficult to confirm that a QSO is completely via lightning scatter until files are subsequently decoded.
• The durations of lightning pings between 0.1 and 0.3 seconds are ideally suited to MSK144.
• We are somewhat surprised that no corresponding pings were detected on 2 metres but conclude that 1296 MHz is a better band. Even if lightning pings can be detected on 2 metres it will be difficult to discern them from meteor pings.
• We think 1296 MHz is probably the optimum band for lightning scatter. 
• Stations in the tropics should have a much better chance of seeing such events.

Commentary: Aircraft scatter is a very common mode of propagation and its effects are often seen on signals in the VHF, UHF & Microwave bands.

At 10kms above the ground, an aircraft has a visible horizon of about 400kms (800km circle).

Looking at an airplane pilots forum, cloud to cloud lightning is most common at about 3kms above the ground. This means the visible horizon from that height is about 200kms (400km circle).

Doing a quick check, it seems that the lightning would need to be at least 4.5kms above the ground for it to be visible to both stations for a 500km path.

It would be interesting to see if others could replicate these results? Some locations in the Mediterranean or the SE of the United States are possible locations during the summer months?

I'd expect it won't be easy to stations to pick out any possible lightning scatter signals from the many aircraft scatter reflections and tropo-scatter signals present.

If you would like to read the article from VK7MO and VK3MAP, then click on this LINK

Addendum: In this video, VK7MO talks about the contact and some of the background information.

In the video, VK7MO makes the valid point that at lower frequencies like 144 MHz, the RF noise from the lightning discharge may actually interfere with the actual MSK144 signal that is being propagated. 

Follow up video...