System for minimizing multiple time around echos in a coherent-on-receive-doppler radar

Claim 2

A radar system comprising: a pulsed transmitter for transmitting pulses to intercept targets; a receiver for detecting target echo signals; a phase corrector circuit coupled to said transmitter and receiver for developing a coherent video output by establishing a phase coherency between each transmitted pulse and all first time around target echo signals; a first circuit, coupled to said phase corrector circuit, being responsive to the coherent video output therefrom for providing video target signals containing no first time around stationary targets; a control circuit coupled to said first circuit for providing an inhibit signal when a video multiple-time-around target signal is sensed; and a gate circuit, coupled to said control circuit and to said first circuit, being responsive to the inhibit signal from said control circuit for preventing the passage of video target signals therethrough only during the time that the inhibit signal is applied thereto.

Claim 3

A radar system comprising: a pulsed transmitter for periodically transmitting a pulse of RF power at the beginning og each interpulse period of the radar; a receiver for detecting target echo signals; a phase correcting circuit coupled to said receiver and to transmitter for developing a coherent video output by establishing a phase coherency between each transmitted pulse and all target echo signals returned within the interpulse period following the transmission of the transmitted pulse; first means, coupled to said phase correcting circuit, being responsive to the coherent video therefrom for providing video target signals containing no fixed target signals returned within the interpulse period following the transmission of the transmitted pulse causing the fixed target signals; a control circuit coupled to said first means and being responsive to the video signals therefrom for providing an inhibit signal when a video target signal is sensed as being returned beyond the interpulse period following the transmission of a transmitted pulse; a display unit for displaying video target signals; and a gating circuit, coupled between said first means and said display unit, being responsive to the inhibit signal for preventing video target signals from being displayed on said display unit only during the time that the inhibit signal is applied thereto.

Claim 4

A radar system comprising: a pulsed transmitter for periodically transmitting a pulse of RF power at the beginning og each interpulse period of the radar; a receiver for detecting target echo signals; a phase correcting circuit coupled to said receiver and to transmitter for developing a coherent video output by establishing a phase coherency between each transmitted pulse and all target echo signals returned within the interpulse period following the transmission of the transmitted pulse; first means, coupled to said phase correcting circuit, being responsive to the coherent video therefrom for providing video target signals containing no fixed target signals returned within the interpulse period following the transmission of the transmitted pulse causing the fixed target signals; a control circuit coupled to said first means and being responsive to the video signals therefrom for providing an inhibit signal when a video target signal is sensed as being returned beyond the interpulse period following the transmission of a transmitted pulse; a display unit for displaying video target signals; and a gating circuit, coupled between said first means and said display unit, being responsive to the inhibit signal for preventing video target signals from being displayed on said display unit only during the time that the inhibit signal is applied thereto.

Claim 5

The radar system of claim 2 wherein said gating circuit includes: a video circuit coupled to said first means for delaying the video target signals therefrom for a predetermined time sufficient to allow said control circuit to generate the inhibit signal when a video target signal is sensed as being Returned beyond the interpulse period following the transmission of a transmitted pulse; and a first gate coupled between said video circuit and said display unit for preventing video target signals from being displayed on said display unit during the time that an inhibit signal is applied thereto.

Claim 6

The radar system of claim 3 wherein said control circuit includes: a second gate coupled to said first gate; and a plurality of gating circuits coupled between said first means and said second gate, being responsive to a plurality of signals from said first means, for respectively generating first signals to cause said second gate to generate an inhibit signal.

Claim 7

The radar system of claim 4 wherein said control circuit further includes a plurality of circuits respectively coupled to said plurality of gating circuits and being further coupled to said second gate for increasing the length of time that each first signal is applied to said second gate.

Claim 8

The radar system of claim 5 wherein said control circuit further includes a plurality of comparison circuits respectively coupled to said plurality of gating circuits and being adapted to receive the plurality of signals from said first means, said comparison circuits allowing those ones of the plurality of signals which exceed a predetermined threshold level to be applied to said plurality of gating circuits.

Claim 9

In a coherent-on-receive doppler radar adapted to receive fixed and moving target echo signals from both within and beyond the maximum unambiguous range of the radar and which includes a first unit for producing coherent-on-receive video from all echo signals returned from targets within the maximum unambiguous range of the radar, a doppler analyzer coupled to the first unit for preventing the passage therethrough of fixed target echo signals returned within the maximum unambiguous range of the radar while allowing moving target echo signals and any multiple time around target echo signals to be passed therethrough, and a display unit for displaying video target signals, a system for substantially preventing multiple-time-around target echo signals from being displayed on the display unit, said system comprising: a control circuit coupled to the doppler analyzer for generating an inhibit signal when the doppler analyzer produces an output indicative of a multiple time around target echo signal; and an inhibit circuit, coupled to the doppler analyzer and to the display unit, being responsive to an inhibit signal from said control circuit for preventing video target signals from being displayed on the display unit while the inhibit signal is present and for allowing video target signals to be displayed on the display unit while the inhibit signal is not present.

Claim 10

In a coherent-on-receive doppler radar adapted to receive fixed and moving target echo signals from both within and beyond the maximum unambiguous range of the radar and which includes a first unit for producing coherent-on-receive video from all echo signals returned from targets within the maximum unambiguous range of the radar, a doppler analyzer coupled to the first unit for preventing the passage therethrough of fixed target echo signals returned within the maximum unambiguous range of the radar while allowing moving target echo signals and any multiple time around target echo signals to be passed therethrough, and a display unit for displaying video target signals, a system for substantially preventing multiple-time-around target echo signals from being displayed on the display unit, said system comprising: a control circuit coupled to the doppler analyzer for generating an inhibit signal when the doppler analyzer produces an output indicative of a multiple time around target echo signal; and an inhibit circuit, coupled to the doppler analyzer and to the display unit, being responsive to an inhibit signal from said control circuit for preventing video target signals from being displayed on the display unit while the inhibit signal is present and for allowing video target signals to be displayed on the display unit while the inhibit signal is not present.

Claim 11

The system of claim 7 wherein said control circuit includes: a plurality of comparison means coupled to the doppler analyzer for selectively comparing levels of associated signals therefrom with a predetermined threshold level, each of said plurality of comparison means generating an output signal when the level of its associated signal exceeds the predetermined therehold level; a first gate circuit coupled to said inhibit circuit; and a plurality of gating circuits, each coupled to selected ones of said comparison means and to said firat gate circuit, said gating circuits being responsive to a sufficient number of output signals from selected ones of said plurality of comparison means for developing first signals to cause said first gate circuit to generate an inhibit signal.

Claim 12

The system of claim 8 further including means coupled between said first gate circuit and said plurality of gating circuits for increasing the length of time that a first signal is applied to said first gate circuit.

Claim 13

The system of claim 8 wherein said inhibit circuit includes: a second gate circuit coupled between said first gate circuit and the display unit for preventing video target signals from being displaYed by the display unit only when the inhibit signal is applied thereto; and means coupled between said first unit and said second gate circuit for delaying the application of all video target signals to said second gate circuit to allow said control circuit sufficient time to generate the inhibit signal after a multiple-time-around target echo signal is sensed.

Claim 14

The system of claim 10 further including means coupled between said first gate circuit and said plurality of gating circuits for increasing the length of time that a first signal is applied to said first gate circuit.