Transient interference suppression for high-frequency skywave over-the-horizon radar

Skywave over-the-horizon radar (OTHR) plays an important role in the out-of-sight surveillance. However, the operational performance will severely degrade due to transient interferences. Previous works concentrate on time-domain methods to achieve transient interference suppression. However, time-domain methods are usually time-consuming and suffer performance loss when several discontinuous transient interference segments occupy parts of coherent processing interval. In fact, most transient interferences are spatially structured and can be cancelled at adaptive beamforming stage. In this study, the adaptive beamforming is adopted and a space-time cascade processing procedure is proposed for transient interference suppression. In the procedure, the sidelobe transient interferences are cancelled by adaptive beamforming and the mainlobe transient interferences are suppressed by a modified time-domain method. The proposed procedure is in accordance with the regular processing procedure of skywave OTHR and can provide reliable performance with small extra computational costs. The performance of the proposed procedure is evaluated using experimental data recorded by a trial skywave OTHR and the results verify the feasibility and effectiveness of the proposed procedure.