February 28, 2005

Brazil to Barbados on 144MHz....

Congratulations to the JAPY Dx Group for the recent VHF expedition. The write up is excellent and audio's are available too. The detail and audios are proof enough of a genuine communication at 144MHz over a 4400km path.

I do think this is fascinating as it is apparently quite a different experience to TEP as reported in Europe....

The contact was via FM modulation and many FM broadcasts were also heard. From the audio's there seems to be no noticable frequency modulation of the received signal, this appears to be very much unlike the well reported southern Europe to Southern Africa path reported by EA6VQ I discussed (via Skype ) this contact with IK0BZY who personally experienced a major TEP opening in 1989 over a 7000km path to South Africa. The contact was possible only by CW due to the FM and AM nature of the channel distortion.

I also find the contact interesting as the group set out to look for TEP, had just a few days, the solar cycle and time of the year were far from what is considered "optimum" by traditional TEP understanding and yet they made it, it seems it might be quite a reliable channel!.

The path does seem from the map to be symmetrical about the geomagnetic equator as expected for TEP. Looking at the Broadcast log a large number of the stations reported seem to be from Barbados i.e. just one TINY island in the Carribean. TEP or Es may also produce this effect. I am sure many VHF ops have experieced sporadic E openings where the same station appears to be strong for a long time with sometimes no other stations heard.

The FM contact is also interesting as the Barbados station was mobile (was his antenna a vertical whip?) I have sent 8P6JB an e-mail so I hope he can provide a perspective from the Barbados side. Enrico IK0BZY was convinced that when he was working South Africa, that the signal strength was good enough for CW with modest power and reasonable yagi but no way it would have supported 12kHz bandwidth and omni antennas. I guess that this may be explained by the lack of FM distortion.

I guess all of the differences between these contacts and the Europe to South Africa contacts can be explained if shorter TEP paths experience far less FM distortion hence stronger signals in narrow bandwidths....not much 144MHz activity in Central Africa to test this theory though!!

Anyway, I'm very impressed and I hope more tests will now be made. Listen to the audio's on JAPY site, I know if it had been me I would have sounded much more excited!!

Posted by Tim at February 28, 2005 05:43 PM
Comments

Hello tim

Like you I spent a week ago long time on the japy side. I was at qrl and had spare time cause of deleted lessons.
The last month I do a lot of reading on the internet on 6m propagation and history and also on tep.
I remember in 1979/1980 I was listening on a Barlow reciever on 28.885 to all the test they did from 5B,SV,ZS, ZE and namibie crossband to 6m and 2m.
I also do remember that the tv vhf band 3 in south africa reaches to a higher frequency than in europe. There were transmitters on 238 or 236 MHZ I am not sure. That frequencies are completely free in Europe.
We have to wait till the next good sunspotmaximum for the tremendous TEP.

Tim look for us in the coming weekend the VHF,UHF,SHF contest. On 2 meter we are normally around 260. Call sign PI4GN JO33II(also WW-convers)
On 70 cm we are sure on 260 but You haven't anything on that band I reckon..

We are qrv on all band till 24 GHz.
On 24 G we have a new set up of 8 watt HF (collossal power), but not yet possible in the mast. (30 kg extra) is to much. So were are doing the tests from ground to some portable stations at distances of 40 to 60 km.

So thats all for now.
PS: Had 20 cm of snow this morning. Hope it doesn't interfere with the building op of antennes on friday and saterday.

73 Gerard

Posted by: gerard at March 2, 2005 02:08 PM