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Multifrequency Doppler Software-Controlled Receiving System for Space Weather Monitoring

The ionosphere has been and remains the main channel for the propagation of radio waves of different frequency bands. The dependence of this channel parameters on the state of space weather is its main feature. To monitor the dynamic processes acting in the ionosphere, the V. N. Karazin Kharkiv National University operates the multifrequency multiple path radio system receiving high frequency (HF) and low frequency (LF) signals. The purpose of this paper is to describe the multifrequency multiple path radio system for oblique-incidence sounding of the ionosphere and to provide illustration of its performance. The system is comprised of the LF and HF synthesizer-type radio receivers synchronized to the rubidium frequency standard and two active loop antennas. The operating frequency settings, modes of operation, and the software control are performed remotely. The system is capable of revealing electron density disturbances with greater than ~0.01% amplitude, which move in vertical direction with a speed of greater than ~0.02-0.05 m/s. The system delivers excellent performance when investigating dynamic processes arising in the ionosphere under the influence of various sources of energy release.