4,400km opening between Cape Verde Islands and the City of London on 144 MHz - 30th Dec 2019

On the afternoon and evening of Monday the 30th of December 2019, there was another amazing tropo opening on 144 MHz from the Cape Verde Islands off the west coast of Africa to the UK.

On previous occasions, the openings have been mostly confined to the western parts of the UK where there is almost a complete sea path to the Cape Verde Islands. On the 30th of December however, the opening was further east.

The map above and below shows the stations that heard the FT8 signals from D41CV or were heard by D41CV.

As you can see below, the opening seems to have been confined to a narrow corridor and had to cross over Brittany in France and the north-west part of Spain.

In a separate tropo opening a few months back, only the most westerly French station on the Brittany peninsula managed to work D41CV as they could just about clear the Spanish coast for a complete sea path. On the 30th of December however, more French stations got in on the action.

The most amazing reports however were those from around London. Up until the 28th of December 2019, the IARU Region-1 tropo record for 144 MHz stood at 4,431kms.

Now look at the map above. The distance from D41CV to the stations in London is...
G7LRQ (4,436kms), M0HRF & M0ICR (4,427 kms) and G7LXP (4,435kms).

In terms of making a two way contact, I believe G4DCV, G7LRQ and M0ICR were successful. Others may have been as well but I don't have any further info.

Now consider this. The distance from London to St.John's in Newfoundland, Canada is 3,735kms. The signal from Cape Verde Islands is an extra 1,000kms further.

It is really incredible that a signal a VHF signal at 144 MHz could travel 4,400+ kms from some islands off the west coast of Africa and get as far as the capital city of the UK.

Tropo ducting... The map below shows the tropo forecast from Pascal, F5LEN. As you can see, there is a maritime path from the west of Africa to the UK and Ireland.

Links... 
1) F5LEN Tropo Forecasts

Example of BBC TV signal at 45 MHz being heard in South Africa

The BBC recently released this old television clip from 1949 explaining how an amateur radio station in Cape Town, South Africa had received TV signals from the UK.

#OnThisDay 1949: England and South Africa were linked through the magic of radio. pic.twitter.com/BpTODBlaRZ

— BBC Archive (@BBCArchive) October 6, 2019

The map below shows the path which is about 9,700kms or 6,000 miles...

The TV transmitter mentioned in the video was a 405 line transmission from Alexandra Palace in North London. This was vertically polarised with a power of 500 kilowatts (ERP?).

This TV signal had a video carrier on 45.0 MHz and a sound carrier down at 41.5 MHz.

The reception report in 1949 was near the peak of solar cycle 18. As can be seen from the chart below, that was a really good sunspot cycle and conditions were probably excellent on all the HF bands and well up into the low VHF region.

The most likely mode of propagation at 45 MHz was probably multi-hop from the F2 layer in the ionosphere. The maximum usable frequency was probably above 50 MHz so the signals on 45 MHz should have been very good.

It's likely however that with a video signal spread out over three and a half megahertz, the picture was probably very distorted and constantly changing. It should have been possible however to have very good reception of the sound on AM on 41.5 MHz with a dedicated radio receiver.

The radio contact shown in the clip between G8IG in England and ZS1PK in Cape Town, South Africa was probably on 28 MHz AM (note the beam at the start of the clip).

The South African station mentioned that signal were better when things were calm which might infer some sort of tropo ducting. That is unlikely to have been the case as it was very probable that all propagation was via the ionosphere and the weather conditions would have no impact.

All the same, it's an interesting example of early low band VHF TV reception.