23 May, 2019

50 MHz Doppler shift from planes

This is the first time I have observed Doppler shift in the 6 meter band. It is not so hard to see on the waterfall display of FT8.

The two stations are LA9PJA (1415 Hz) and LB6D (2477 Hz). Both of them are located in the same square as me (JO59). The other weaker signals are British and French. One can see the direct signal which has a constant frequency, and then a time-varying frequency on top of that.

16 May, 2019

Morserino now supports Single Paddle Emulation

Picture credit Morserino-32
I was happy to see the other day that the nice-looking Morserino keyer with its modern display in its latest firmware, version 1.3, now supports a new mode. It is described as follows:
A new mode in addition to Iambic A, Iambic B and Ultimatic: Non-Squeeze. This "simulates" the behavior of a single lever paddle when using a dual lever paddle. 
Operators used to single lever paddles tend to have difficulties using dual-lever paddles, as they sometimes inadvertently squeeze the paddles, especially at higher speeds. The non-squeeze mode just ignores squeezing, making it easier for these operators to use a dual lever paddle.

13 May, 2019

More spurs than I had hoped for

My Just good enough 10 MHz reference based on the direct output of a Neo-7 GPS module, described in detail before on this blog, is good in keeping long-term frequency stability. Short-term stability and phase noise is as expected not so good. When connected to the reference input of my Elecraft K3 and listening to an outdoor antenna, I get quite a substantial amount of spurs around 10 MHz radiating from the GPS module. But since the K3 itself does averaging over a second or so, this is fine from the point of view of keeping accurate frequency.

02 May, 2019

Book rather than Blog

My blog has suffered in recent years and here is the reason. For three years now I have been writing a book entitled "Waves with Power-Law Attenuation". It is now in Springer's catalogue under classical and continuum physics and I'm also very happy that it is published in the Acoustical Society of America Press series.

The emphasis is on models for waves that experience attenuation that follows a power-law in frequency. Topic-wise it is more about mechanical than electromagnetic waves, but analogies are drawn between the two fields as many of the models are the same. Power-law models in electromagnetics are in particular useful for waves in biological tissue, which is indeed also the case for acoustic and elastic waves.