Continuous Doppler Sounding System
The continuous Doppler sounding system (CDSS) works by transmitting a continuous radio wave, which is reflected by the plasma in the ionosphere. The reflected signal is received, and the frequency compared with that of thetranmsitted wave. The Doppler shift between both signals provides information about the movement of the reflecting plasma. By making simultaneous measurements on differnet soundngs paths, meaning the signal is reflected in different locations, allows reconstruction of the travel speed and direction of ionospehric disturbances
The Belgian CDSS system comprises a single reception point, located at the RMI headquarters in Ukkel, and three transmitter antennas, located in Dourbes (shown in the icture), Jabbeke, and Manhay.
The above picture shows the signal from only the Dourbes transmitter, received in Ukkel, on Ferbuary 6, 2023. The sudden disturbance seen at 10:45 UT, followed by a longer disturbance after 10:45 UT, are signatures of the infrasound produced by the Earthquake in Turkey on that they.
Spectrograms can be viewed at the Doppler data repository maintained by the Czech Academy of Science: datacenter.ufa.cas.cz.