Geodesy

Quantum mechanics

Terminator (solar)

Solar eclipse

China

Archaeology

Radio wave

Geology

Ionosphere

Physics

Sunset

Amplitude

Optics

Astronomy

Geography

Eclipse

Environmental science

Remote sensing

Geophysics

Meteorology

Doppler effect

Radio Science

We briefly describe the multifrequency multiple‐path radio system and illustrate its observational capabilities by performing, as an example, the study of dynamic processes that occurred in the ionosphere over China during the partial solar eclipse on August 11 2018. This system, based on the software‐defined radio technology and capable of operating in the 10‐kHz to 30‐MHz band, has been developed jointly by Harbin Engineering University, the People's Republic of China, where it is located, and V. N. Karazin National University, Ukraine. The principle of the system operation is based on measurements of a Doppler shift of frequency. The implementation of Marple's algorithm for autoregression spectrum analysis has permitted an increase in a Doppler resolution down to 0.02 Hz and in a temporal resolution down to 7.5 s. The number of radio propagation paths and their orientation depend on the specifics of problems being solved. The interpretation of the eclipse effects is complicated by processes launched by the dusk terminator. The eclipse was associated with an increase in the number of rays, the generation of oscillation processes in the atmospheric gravity wave range of periods, and with a negative Doppler shift of frequency at first and a positive shift of smaller magnitude subsequently. The solar eclipse launched ~9–14% amplitude quasiperiodic oscillations in the electron density, while a maximum decrease of order 26% was observed over the Hailar–Harbin path in the ionospheric E region. The latter value does not virtually differ from theoretical estimates.

Radio Monitoring of Dynamic Processes in the Ionosphere Over China During the Partial Solar Eclipse of 11 August 2018