Patent ID: 7619554

Claim:
In a passive radar system including at least one space-borne transmitter broadcasting at least one wide-band digitally modulated signal over a region thereby illuminating said region, at least one receiver antenna oriented to receive radiation from at least one portion of said region, wherein said at least one portion is a viewed area viewed by said at least one receiver antenna, and at least one reference antenna oriented toward said at least one space-borne transmitter, wherein said at least one reference antenna receives at least one portion of said at least one wide-band digitally modulated signal, the method comprising the steps of (a) selecting a coherent processing time duration based on: (i) a radar cross-section of a target within said viewed area (ii) a bandwidth of said at least one wide-band digitally modulated signal, and (iii) at least one antenna viewing angle of said at least one receiver antenna, wherein said at least one antenna viewing angle is substantially equal to a dimension of said at least one receiver antenna divided by a range to said target; and (b) coherently processing at least one received signal from said at least one receiver antenna with at least one reference signal from said at least one reference antenna, over a time interval greater than said coherent processing time duration.