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 »
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 »
Over time, items were added to the inventory of measurement instruments. But it all started with some simple things, because professional instruments were way out of reach at the time I was licensed in 1976. We had to cope with uncomplicated equipment to be able to “guesstimate” what we were doing. The grid dipper One… 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 »
About two weeks ago, my Alpin 100 suddenly failed whilst transmitting. Shutdown with error 52. The manual stated that the high voltage was less than 1500 V or over 3300 V. I tried to restart and immediately went to the HV menu, the voltage was about 2100 V, which was much lower than the expected… Continue reading »
Having read about WSJT-X version 2.3.0 with the new FST4 protocols, curiosity drove me to perform some tests. In the past, I wrote about FT8 and the fact that its sensitivity is considerably less than JT65 or JT9, leading to lost DX opportunities. Especially on 60 metres, the restricted power levels pose an additional challenge… Continue reading »