Methods of and circuits for suppressing doppler radar clutter

Claim 1

A radar clutter suppressor comprising: radar transmitting means for transmitting pulsed radar waves; receiving means for receiving radar echoes of the pulsed radar waves and for providing a received signal with doppler frequency components in response to the radar echoes; doppler processor means for frequency filtering this received signal and for providing a filtered signal in response to the received signal; means of providing a first signal with a magnitude proportional to the magnitude of the received signal; means of providing a second signal with a magnitude proportional to the magnitude of the filtered signal; ratio processor means including comparator means, reference level means and logic circuit means wherein said ratio processor means compares the magnitude of the first and second signals and provides a ratio processor output signal of a first level when ratio of magnitudes of the first signal to the second signal exceeds a first ratio value or when the ratio of magnitudes exceeds a second ratio value which is less than the first ratio value if the magnitude of the first signal is within a predetermined range of levels and provides a ratio processor output signal of a second level when the ratio of magnitudes is less than the second ratio value less than the first ratio value or when the magnitude of the first signal is outside the predetermined range of levels and the ratio of magnitudes is less than the first ratio value; and radar output means responsive to the ratio processor output signal for selectively passing a radar output signal constituting a clutter suppressed radar output only in presence of the second level of the ratio processor output signal.

Claim 12

A method of suppressing radar clutter comprising the steps of: transmitting pulsed radar waves; providing a received signal with doppler frequency components in response to radar echoes of radar waves; frequency filtering said received signal and providing a filtered signal; providing a first signal with a magnitude proportional to magnitude of said received signal; providing a second signal with a magnitude proportional to magnitude of said filtered signal; providing at least one reference level; comparing the magnitude of said first signal with the respective magnitudes of said second signal and said at least one reference signal and providing a ratio processed output signal of a first level when ratio of magnitudes of said first signal to said second signal exceeds a first ratio value or when said ratio of magnitudes exceeds a second ratio value less than said first ratio value if the magnitude of said first signal is within a predetermined range of values, and provides a ratio processed output signal of a second level when said ratio of magnitudes is less than said second ratio value less than said first ratio value or when the magnitude of said first signal is outside said predetermined range of values and said ratio of magnitudes is less than said first ratio value; and selectively passing a radar output signal constituting a clutter suppressed radar output only in the presence of the second level of said ratio processed output signal.

Claim 13

A method of suppressing radar clutter comprising the steps of: transmitting pulsed radar waves; providing a received signal with doppler frequency components in response to radar echoes of radar waves; frequency filtering said received signal and providing a filtered signal; providing a first signal with a magnitude proportional to magnitude of said received signal; providing a second signal with a magnitude proportional to magnitude of said filtered signal; providing at least one reference level; comparing the magnitude of said first signal with the respective magnitudes of said second signal and said at least one reference signal and providing a ratio processed output signal of a first level when ratio of magnitudes of said first signal to said second signal exceeds a first ratio value or when said ratio of magnitudes exceeds a second ratio value less than said first ratio value if the magnitude of said first signal is within a predetermined range of values, and provides a ratio processed output signal of a second level when said ratio of magnitudes is less than said second ratio value less than said first ratio value or when the magnitude of said first signal is outside said predetermined range of values and said ratio of magnitudes is less than said first ratio value; and selectively passing a radar output signal constituting a clutter suppressed radar output only in the presence of the second level of said ratio processed output signal.