Abstract: In a passive radar system a space-borne transmitter broadcasts wide-band digitally modulated signals over a region and illuminates the region. A receiver antenna is oriented to receive radiation from at least one portion of the region. The portion is an area viewed by the receiver antenna. A reference antenna is oriented toward the transmitter, the reference antenna receives a portion of the wide-band digitally modulated signal. A coherent processing time duration is selected based on: a radar cross-section of a target within the viewed area, a bandwidth of the wide-band digitally modulated signal, and the viewing angle of the receiver antenna. The received signal from the receiver antenna is coherently processed with a reference signal from the reference antenna, over a time interval greater than the coherent processing time duration.

Abstract: In a passive radar system a space-borne transmitter broadcasts wide-band digitally modulated signals over a region and illuminates the region. A receiver antenna is oriented to receive radiation from at least one portion of the region. The portion is an area viewed by the receiver antenna. A reference antenna is oriented toward the transmitter, the reference antenna receives a portion of the wide-band digitally modulated signal. A coherent processing time duration is selected based on: a radar cross-section of a target within the viewed area, a bandwidth of the wide-band digitally modulated signal, and the viewing angle of the receiver antenna. The received signal from the receiver antenna is coherently processed with a reference signal from the reference antenna, over a time interval greater than the coherent processing time duration.