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 »
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 »
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 »
Mostly during the morning hours around sunrise, FT8 beacon transmissions can be heard on the 60 metre band. The purpose of these transmissions is to collect data for a propagation study. This is an ongoing project. An article which was published April 2021 is found here. Examples of graphs are found on page 5. An… Continue reading »
Last week an electrolytic Capacitor had failed in a 70’s measuring instrument (HP 8445B preselector). The capacitor in question is a smoothing capacitor in the power supply assembly. It stopped smoothing, but shorted the whole supply out. Poof, fuse blown. Thank goodness for that! Not much time that moment, so something for the next day…. Continue reading »
Similar to the recent retraction of the permits in New Zealand, the ACMA decision not to support amateur use of the 60 m band in Australia is a slap in the face. Invalid arguments and even secrecy were brought forward to support the decision. Why is 15 kHz of spectrum with only 15 Watts radiated… Continue reading »
Today, I received very sad news about expiry of the 60 m trial licenses in New Zealand. On October 24th, the 60 metres band in New Zealand will become silent. I very well remember the first contacts back in January 2018 and at the time, I did not know about the very good propagation between… Continue reading »