QMX+ mechanical improvements

My QMX+ has some minor mechanical improvements:

1. Slimmer knobs. I decided to replace the knobs as I often touched the bottom one while adjusting the top one and vice versa. The slimmer knobs solved that. I found knobs on AliExpress with the same looks, only a smaller diameter as the image shows. Unfortunately they don't have screws, so they aren't so well attached as the original ones.
2. Folding laptop feet which I first saw on the AE5X blog.

Speech coding in DMR, D-STAR and System Fusion

Example of a speech signal which transitions
from an unvoiced to a voiced sound

Digital VHF and UHF communications is increasingly popular among radio amateurs using DMR, D-STAR and System Fusion. 

Very few radio amateurs, however, have much understanding of the signal processing required to compress a speech signal so it can be transmitted with the low bit rates available. Here is an attempt at an explanation.

My favorite faces for the Multi Face GPS Clock

Weekly progress bar with Monday as day 1
in week 9 and yearly progress bar
as of day 56 in the year.

Among the 50 different faces (or screens) now implemented on the Multi face GPS clock, it is hard to select favorites. 

So I start with the latest one that was implemented, i.e. the progress bars for week and year shown to the right. It was new in version 2.3.0 dated 2025-02-04.

A QMX+ coming together

I got an unassembled QMX+ for Christmas this year, and here are pictures of it coming together. First the winding of toroids for the low-pass filters: