A Novel Ionospheric Oblique-Incidence Sounding Network Consisting of the Ionospheric Oblique Backscatter Sounder and the Parasitic Oblique-Incidence Sounder

In this letter, a novel ionospheric oblique-incidence sounding network consisting of the ionospheric oblique backscatter sounder and the parasitic oblique-incidence sounder is presented. With the new configuration, the oblique ionogram and the backscatter ionogram can be provided at the same time. Due to the usage of a novel waveform combining the pseudorandom phase coding and the chirp modulation, about 130-dB signal processing gain can be usually obtained to improve the signal-to-noise ratio for the low-power transmission. Furthermore, through choosing different types of pseudorandom sequences for each transmitter, many oblique ionograms that depict the information of different propagation paths can be simultaneously achieved at a single receiver site. In addition, the digital beamforming technique is implemented on the receiving antenna array to simultaneously receive the echoes produced by each transmitter, to achieve a good space isolation to enhance the echo discrimination, and to suppress the strong interferers appearing in the high-frequency band. Details of the system configuration, the ambiguity function of the sounding waveform, and the signal processing algorithm are described. The initial experimental results show that multiple oblique ionograms can be simultaneously obtained at a single receiver site with this sounding network.