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Comparision of devices for monitoring of the ionosphere at the observatory Průhonice
Beran, L. ; Chmelař, P. ; Rejfek, Luboš ; Chum, Jaroslav ; Mošna, Zbyšek
This document is about comparison of the methods ad systems for the measurement of the ionosphere used at the geophysical observatory Pruhonice (50N, 14.5E). Three systems for ionospheric monitoring are installed at the station. The first system for the monitoring of the ionosphere is Digisonde, the second system is countinuous Doppler sounding. Each system has its banefits and weaknesses which are compared in this paper.
HF Doppler Radar Observations of Geomagnetic Pulsations
Fišer, Jiří ; Chum, Jaroslav
Geomagnetic pulsations interact with the ionosphere, which influences the propagation properties of high frequency (HF) radio waves. In this work we present results of an experimental study focused on investigation of relations between the geomagnetic pulsations observed on the ground and the Doppler frequency shift oscillations observed remotely in the ionosphere by a Doppler sounding system in the Czech Republic. We study mainly the dependence of phase shift between them on various parameters.
LHR associated oblique noise bands
Chum, Jaroslav ; Jiříček, František ; Shklyar, D.
Observations onboard the Magion-5 satellite revealed oblique noise bands above the local Lower Hybrid Resonance (LHR) frequency - wave phenomena, which (to the best of authors' knowledge) have not been discussed yet. Examples of such oblique bands, both in review (large time-scale) spectrograms, and in detailed (small time-scale) spectrograms are presented. Based on ray-tracing simulations, an explanation of these oblique bands is suggested.

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2 Chum, Jan
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