During propagation measurements on the 3.555555 MHz beacon
from PA0RYL we found periods
At first we searched for a problem in the beacon. Although it
uses a Rubidium reference oscillator
As a follow up on this we used another reference and improved
the measurement method by adding a
Then we measured for a longer period the signal from the beacon. The result is the picture below.
In this measurement we can see a resolution of about 10 milli-Hertz
The pink line on the left side is the local GPS disciplined
oscillator at 3.555545 MHz,
In the middle we see the signal of the beacon with its
The beacon signal shows all kinds off small deviations, at
some periods not as strong but especially
This drift most probably (almost certain) is caused by Doppler caused by moving layers off ionisation in the ionosphere moving overhead at some speed relative to the trajectory between observer and the beacon.
Measured variations off plus and minus 0,2 Hz are visible in the plot.
I done some calculations on Doppler speeds needed to reach
this drift, and for a Doppler off 0,2 Hz the speed of the reflecting cloud layer
Although this measurement and explanations of the results look
quite acceptable this theory still is a bit pre-mature
Although existence off Doppler shift caused by atmosphere is well known, just listen to some short wave radio stations and you will hear it, I am not sure if it has been measured before like this measurement, by radio amateurs.
Most probably this will have some follow up measurements.
Then next picture is the measurement from 23-10
At about 16.00 UTC I place a small white line in the waterfall
representing the length of 1 Hz step.
In december 2018 I started using SBSpectrum software.
It will automatically store the BMP file when it is ready and will continue the measurement.
Take a look at the measurements I done using SBSpectrum