Ionospheric Doppler and echo phase measured by the Wuhan Ionospheric Oblique Backscattering Sounding System

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Abstract

[1] Wuhan Ionospheric Oblique Backscattering Sounding System (WIOBSS) is a high-frequency (HF) sky wave over-the-horizon radar developed for ionospheric research and HF channel management. This radar, located in Wuhan (30.35°N, 114.33°E) has been under construction by the Ionosphere Lab of Wuhan University since 2002. WIOBSS uses long coded pulses and pulse compression to achieve good sensitivity and measures the bitemporal ionospheric response, channel scattering function, and phase of echoes simultaneously and then displays the processed data as ionograms and Dopplionograms in real time. Bitemporal ionospheric response is a matrix composed of the ionospheric transmission function with delay and time variables, while the scattering function shows the spectrum of the received signals as a function of the delay and Doppler coordinates, and is obtained by the Fourier Transform of the bitemporal ionospheric response over the time variable. The application of pulse compression and coherent integration allows WIOBSS to measure ionospheric Doppler with high resolution and very low power. A method is developed to get phase data directly from the bitemporal ionospheric response. The measured phase is strung in a series and then divided into linear and nonlinear components. The angular frequency of the linear component is in direct proportion to ionospheric Doppler velocity while the fluctuation of the nonlinear component includes the information of Doppler velocity spread. The phase method based on pulse impression is able to obtain the statistic Doppler information from weak backscattered echoes in short detection time.

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