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...

Lightning detected on the 28 MHz band - 23rd July 2021

 

Friday 23rd July 2021: During the afternoon of the 23rd, I noticed what sounded like a continuous stream of static crashes on the 28 MHz band. I checked the Irish weather website Met Éireann and sure enough, there was a huge thunder storm crossing Ireland about 130-150kms to the north of me.

I have heard static crashes from lightning before but never on this scale. It's usually a static crash every 10-20 seconds but this one was almost continuous.

I was wondering at first if it was some local noise source but I could hear the number of static crashes reduce as the storm moved west.

Even though I am using just a basic CB type half-wave vertical on 28 MHz, I do have a good view to the north. If some of these strikes were from cloud to cloud at a km or two above the ground then I was probably line of sight to some of them.

Noise from Lightning Strikes detected on the 40 MHz band

On the 3rd of June, I was on the 40 MHz band listening for the new EI1CAH beacon in the west of Ireland when I noticed some very distinctive static crashes. When I checked the rainfall radar map, sure enough there were plenty of lightning strikes just over 100kms from my location.

I was surprised just how strong they were considering they were so far away.

It's worth getting to know that these sound like as they give you plenty of time to unplug your antennas before the lightning reaches your location.

Detecting lightning strikes on 28 MHz - 4th Apr 2019

While monitoring the FT8 frequency on 28 MHz, I noticed the tell tale crackle of a lightning strike. They are usually less than one second long and are pretty distinctive once you get used to hearing them.

There was no sign of any lightning where I live so I knew it had to be some distance away.

The dots shown above are those I heard on SSB on 28 MHz.

I have heard lightning before on 28 MHz but they were about 70 kms away. This time however, I was hearing lightning strikes which were up to 130 to 160 kms away (80-100 miles).

Pretty amazing considering that the radio energy is spread out over all of the LF and HF spectrum and up into VHF as well.

One obvious advantage of this reception is that you can hear a lightning storm approaching on the radio long before it actually arrives at your location.

It also raises the question... what is the maximum distance a lightning strike can be heard on 28 MHz???

If anyone would like to give it a go then there are some links below for tracking the lightning strikes. Just be careful to make sure the delay on the websites is low and what you seen on the screen is actually the lightning strike that you heard. You should hear the crackle and then see the dot appear on the screen a few seconds later.

By the way, this will also work with a simple medium wave radio as well. Just tune to a quiet frequency during daylight hours and you should heard the crackle from the distant lightning strikes.

Links...
https://www.lightningmaps.org/
http://en.blitzortung.org/live_lightning_maps.php?map=10