Down under – 3 days in a row

By   13 November 2016 08:47

The 12th November 2016, another opening to VK7BO occurred. As I wanted to analyse the openings, I transmitted every other minute, mostly CQ’ing and making some QSO’s just as well.

All spots were visible on and to be on the safe side, I took notes in my little booklet, that has a lot of notes about observations anyway.

The signal strength was excellent, with -5 dB at best. I have to add, that I replaced my 60 m dipole with a doublet, that might have a little different performance. It is fed with a balanced feeder with a tuner. The legs are a bit longer than the dipole, about 16 metres, which could add a tiny bit of gain.

As I started the transmissions earlier than before, a nice data series was gathered. The graph below shows the SNR’s for 3 days, Nov10, 11 and 12.

Nov 2016 - 3 days JT65 reception @VK7BO

Nov 2016 – 3 days JT65 reception @VK7BO

The data from 3 days were put in a table, rounding times to 2 minute increments (odd minutes were changed to even minutes). On Nov 10 and 11, I did not transmit all the time, so there are missing points. The grid lines are 10 minutes apart. Times are UTC.

The first spots from Europe to VK7BO appeared around 18:15 on Nov 12. At that time, I was finishing my dinner… My first transmission was around 18:30.

Looking at the graph, some aspects a remarkable. There seems to be a double maximum, the first around 19:10 and the second around 19:45. The decay on Nov 11 and 12 was about 4 dB per 10 minutes, on Nov 12, the decay was a bit slower. More data is needed to get more reliable values, but the overall picture is clear.

The symmetry on the 12th is also clearly visible, indicating that the rise is also at about 4 dB per 10 minutes. If the double maximum would be characteristic for these occurrences, one might expect a period where signal strengths remain fairly constant for a period of time.

More information will follow, as I am gathering data about the ionosphere and magnetosphere. This will have to wait, as my daughter celebrates her birthday today. Many happy returns, my girl!