A bit like the fashion for middle aged men, my good old Hewlett Packard 8568B got new clothes. In my opinion, it is one of the masterpieces of Hewlett Packard spectrum analyser design. Even today, the specifications are hard to beat with new equipment in the “amateur price” range. I will return to that. The… Continue reading »
For some time, I suffer from tremendous interference from various sources. The worst one is LED lighting which generates very strong interference in the 50 MHz band. I wanted to see what the interference would be like we still had analogue television. We used to have CCIR system B on VHF and the channel 2… Continue reading »
Recently, I wrote some comments about the remainder of the current solar cycle. I am not overly optimistic about the possibility of good 6 m condx after this winter. A long time ago I came to the conclusion that predictions are unreliable at best. But it is nevertheless interesting to look at some data and… Continue reading »
A priori is a Latin phrase which – in the context of FT8 etc. – translates to prior knowledge. This article aims to explain what a priori decoding does. It also discusses how AP relates to a “valid QSO”. A little paragraph is dedicated to to information theory. The article also illustrates that AP is… Continue reading »
On the 31st of October 2024, we had a good opening to North America on 6 metres. Lots of stations active with FT8, but I checked classic modes as well. On about 50.110 just before 1300 UTC, N1BUG was working EU stations, initially rather weak. But the signal increased and reached S9 levels. After a… Continue reading »
Recently, I read about noise reduction with artificial intelligence. AI is quite fashionable and, in my view, is seen too much as a panacea. Here are some thoughts based on some theory. 1. Noise If there is “pure noise” (white noise) then you cannot filter out that noise. AI or no AI, it is impossible…. Continue reading »
April 2023 was less “productive” when compared with March. The F2 electron density at moderate to high latitudes is greater during winter than in summer, especially at times of enhance solar activity [1]. This implies that the F2 critical frequencies become lower towards the summer season in the northern hemisphere. During previous cycles, most openings… Continue reading »
March 2023 was an interesting month. It reminded me of March 1979, when first 6 metre amateur signals were heard. After many times trying, I was amazed to hear the ZS6PW beacon on the 12th of March. The station consisted of an indoor dipole on the attic, connected to a converter from 50 to 14… Continue reading »
There were times that reports were collected by editors of newsletters. PA0BN edited the Dutch VHF bulletin for many years and my observations were sent to him to merge with those of other active amateurs. The newsletters were a joy to read. Nowadays, there are many blogs and fora, resulting in a lot but distributed… Continue reading »
What the… are hash collisions? What has it to do with FT8? This article explains that the FT8 protocol can confuse call signs and the software seems to behave erratically. What is a hash? In short, a hash code is a number, usually calculated via bit operations. Hash codes are widely used in data storage… Continue reading »