Jammer reference target measurement system

Claim 1

A system for cancelling signals from a jammer entering the mainlobe of the antenna of a monopulse radar and for providing target locations with respect to the location of the jammer comprising: means for notching the antenna response at the jammer location with the antenna pointing so that the jammer is positioned within the 3 dB points of the mainlobe of the antenna; means for shifting the effective orientation of said antenna by a small amount and notching the antenna response at the jammer location at the new effective orientation, said new orientation being such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation; and means for determining the ratio between echo signals from the same targets in these two notched antenna responses, said ratio being proportional to the angle separating the target in the response from the jammer.

Claim 2

A system for cancelling signals from a jammer entering the mainlobe of the antenna of a monopulse radar and for providing target locations with respect to the location of the jammer comprising: means for notching the antenna response at the jammer location with the antenna pointing so that the jammer is positioned within the 3 dB points of the mainlobe of the antenna; means for shifting the effective orientation of said antenna by a small amount and notching the antenna response at the jammer location at the new effective orientation, said new orientation being such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation; and means for determining the ratio between echo signals from the same targets in these two notched antenna responses, said ratio being proportional to the angle separating the target in the response from the jammer.

Claim 3

A method for cancelling signals from a jammer entering the mainlobe of the antenna of a monopulse radar and for providing target locations with respect to the location of the jammer comprising the steps of: notching the antenna response at the jammer location with the antenna pointing so that the jammer is positioned within the 3 dB points of the mainlobe of the antenna; shifting the effective orientation of the antenna and notching the antenna response of the jammer location at this new effective orientation, said new orientation being such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation; and determining the ratio between any echo signals from the same targets in these two notched antenna responses; said ratio being proportional to the angle separating the target in the response from the jammer.

Claim 4

A method for cancelling signals from a jammer entering the mainlobe of the antenna of a monopulse radar and for providing target locations with respect to the location of the jammer comprising the steps of: notching the antenna response at the jammer location with the antenna pointing so that the jammer is positioned within the 3 dB points of the mainlobe of the antenna; shifting the effective orientation of the antenna and notching the antenna response of the jammer location at this new effective orientation, said new orientation being such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation; and determining the ratio between any echo signals from the same targets in these two notched antenna responses; said ratio being proportional to the angle separating the target in the response from the jammer.

Claim 5

A method for cancelling signals from a jammer entering the mainlobe of the antenna of a monopulse radar and for providing target locations with respect to the location of the jammer comprising the steps of: receiving a first set of echo and jamming signals and determining the position of the jammer therefrom; effectively orienting the boresight axis of said monopulse radar antenna to point so that the jammer is positioned within the 3 dB points of the antenna mainlobe; receiving a second set of echo and jamming signals reflected from the next radar transmission after said orienting step; adaptively cancelling the jammer signal from the second set of received echo and jamming signals; storing this second set of adaptively cancelled echo signals in time sequential order; effectively changing the orientation of the boresight axis of said monopulse radar antenna by a small arbitrary angle θ such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation of the antenna; receiving a third set of echo and jamming signals reflected from the next radar transmission after said orientation changing step; adaptively cancelling the jamming signals from this third set of received echo and jamming signals; reading-out said second set of stored adaptively cancelled echo signals in time coincidence with the occurrence of the adaptively cancelled echo signals in said third set reflected from the same targets; and dividing the adaptively cancelled echo signals in one of the second or third sets, e.g., the second set, by the time coincident adaptively cancelled echo signals in the other of the second or third sets, e.g., the third set, to obtain a set of ratio signals which are proportional to the angles separating the individual targets from the jammer.

Claim 6

A method for cancelling signals from a jammer entering the mainlobe of the antenna of a monopulse radar and for providing target locations with respect to the location of the jammer comprising the steps of: receiving a first set of echo and jamming signals and determining the position of the jammer therefrom; effectively orienting the boresight axis of said monopulse radar antenna to point so that the jammer is positioned within the 3 dB points of the antenna mainlobe; receiving a second set of echo and jamming signals reflected from the next radar transmission after said orienting step; adaptively cancelling the jammer signal from the second set of received echo and jamming signals; storing this second set of adaptively cancelled echo signals in time sequential order; effectively changing the orientation of the boresight axis of said monopulse radar antenna by a small arbitrary angle θ such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation of the antenna; receiving a third set of echo and jamming signals reflected from the next radar transmission after said orientation changing step; adaptively cancelling the jamming signals from this third set of received echo and jamming signals; reading-out said second set of stored adaptively cancelled echo signals in time coincidence with the occurrence of the adaptively cancelled echo signals in said third set reflected from the same targets; and dividing the adaptively cancelled echo signals in one of the second or third sets, e.g., the second set, by the time coincident adaptively cancelled echo signals in the other of the second or third sets, e.g., the third set, to obtain a set of ratio signals which are proportional to the angles separating the individual targets from the jammer.

Claim 10

A method for cancelling jammer signals entering the mainlobe of a monopulse radar having two effective antenna apertures, and for providing target locations with respect to the location of the jammer comprising the steps of: receiving a first set of echo signal pairs from a first radar transmission along with jamming signals from said two effective antenna apertures; generating a first set of sum and difference signals from said first set of signal pairs; determining the angular position of the jammer with respect to the boresight axis of the two effective antenna apertures utilizing said first set of sum and difference signals; orienting the boresight axis of the two effective antenna apertures to point so that the jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; receiving a second set of echo signal pairs from a second radar transmission along with jamming signals from said two effective antenna apertures after said orienting step; generating a second set of sum and difference signals from said second set of received echo signal pairs; generating a third set of sum and difference signals from said second set of sum and difference signals; adaptively cancelling the jamming signal by utilizing either the third set of sum or the third set of difference signals as the main signal, e.g., the third set of sum signals, and the other set, e.g., the third set of difference signals, as the auxiliary signal in an adaptive cancelling process; storing this adaptively cancelled set of echo signals in time sequence; changing the orientation of the boresight axis of the two effective antenna apertures by an arbitrary angle such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation of the antenna; receiving a third set of echo signal pairs from a third radar transmission along with jamming signals from said two effective antenna apertures; generating a fourth set of sum and difference signals from said third set of each signal pairs; generating fifth set of sum and difference signals from said fourth set of sum and difference signals; adaptively cancelling the jamming signal by utilizing the fifth set of sum and the fifth difference signals in an order reversed from that used in the first adaptive cancelling step process, e.g., with the fifth set of sum signals utilized as the auxiliary signal and the fifth set of difference signals utilized as the main signal in an adaptive cancelling process; reading-out the adaptively cancelled stored echo signals from said second radar transmission in time coincidence with the occurrence of the adaptively cancelled echo signals reflected from the same targets from said third radar transmission; dividing the sequentially read-out adaptively cancelled echo signals from said second radar transmission by the adaptively cancelled echo signals from said third radar transmission to obtain a ratio signal which is proportional to the elevation angle separating the target from the jammer; and applying this ratio signal to a look-up table to determine the target location with respect to the jammer.

Claim 11

A method for cancelling jammer signals entering the mainlobe of a monopulse radar having two effective antenna apertures, and for providing target locations with respect to the location of the jammer comprising the steps of: receiving a first set of echo signal pairs from a first radar transmission along with jamming signals from said two effective antenna apertures; generating a first set of sum and difference signals from said first set of signal pairs; determining the angular position of the jammer with respect to the boresight axis of the two effective antenna apertures utilizing said first set of sum and difference signals; orienting the boresight axis of the two effective antenna apertures to point so that the jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; receiving a second set of echo signal pairs from a second radar transmission along with jamming signals from said two effective antenna apertures after said orienting step; generating a second set of sum and difference signals from said second set of received echo signal pairs; generating a third set of sum and difference signals from said second set of sum and difference signals; adaptively cancelling the jamming signal by utilizing either the third set of sum or the third set of difference signals as the main signal, e.g., the third set of sum signals, and the other set, e.g., the third set of difference signals, as the auxiliary signal in an adaptive cancelling process; storing this adaptively cancelled set of echo signals in time sequence; changing the orientation of the boresight axis of the two effective antenna apertures by an arbitrary angle such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation of the antenna; receiving a third set of echo signal pairs from a third radar transmission along with jamming signals from said two effective antenna apertures; generating a fourth set of sum and difference signals from said third set of each signal pairs; generating fifth set of sum and difference signals from said fourth set of sum and difference signals; adaptively cancelling the jamming signal by utilizing the fifth set of sum and the fifth difference signals in an order reversed from that used in the first adaptive cancelling step process, e.g., with the fifth set of sum signals utilized as the auxiliary signal and the fifth set of difference signals utilized as the main signal in an adaptive cancelling process; reading-out the adaptively cancelled stored echo signals from said second radar transmission in time coincidence with the occurrence of the adaptively cancelled echo signals reflected from the same targets from said third radar transmission; dividing the sequentially read-out adaptively cancelled echo signals from said second radar transmission by the adaptively cancelled echo signals from said third radar transmission to obtain a ratio signal which is proportional to the elevation angle separating the target from the jammer; and applying this ratio signal to a look-up table to determine the target location with respect to the jammer.

Claim 12

A system for cancelling jammer signals in the mainlobe of a monopulse radar and providing target locations with respect to the location of the jammer comprising: a monopulse radar including an antenna with two effective apertures and a boresight axis for receiving echo signals from a radar transmission at each effective aperture along with jamming signals and generating signals A' and B' therefrom; means for converting said received echo signals A' and B' into sum and difference signals; means for determining the angular position of the jammer with respect to the boresight axis of said monopulse radar antenna by utilizing said sum and difference signals and then effectively orienting said boresight axis to point so that said jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; adaptive canceller means with main and auxiliary inputs; a memory means for amplifying the received echo signals A' and B' from said two effective antenna apertures prior to conversion to sum and difference signals and applying these amplified signals to the main and auxiliary inputs of said adaptive canceller means, e.g., the A' echo signal to the main input and the B' echo signal to the auxiliary input, such that the jamming signal is cancelled from the output of said adaptive canceller means; wherein said adaptive canceller means cancels the jamming signal from a first set of echo signals received from the next radar transmission after said monopulse antenna axis has been effectively pointed so that the jammer is within the 3 dB points of the antenna mainlobe and applies this adaptively cancelled first set of echo signals in time sequence to said memory; means for changing the effective orientation of the boresight axis of said monopulse radar antenna by an arbitrary angle, such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation of the antenna; first switching means for reversing the application of the amplified echo signals A' and B' to said adaptive canceller means for the next radar transmission after the effective orientation of said monopulse antenna axis has been changed by said arbitrary angle, e.g., B' to said main input and A' to said auxiliary input; wherein said adaptive canceller means then cancels the jamming signal from a second set of echo signals received from the next radar transmission after the effective orientation of said monopulse antenna axis has been changed by said arbitrary angle; divider means with one input port connected to the output of said memory; second switching means for switching the adaptive canceller means echo signal output from said memory to a second input port of said divider means such that said second set of echo signals are applied thereto; wherein said first set of adaptively cancelled stored echo signals in said memory are read-out to said divider means in time coincidence with the occurrence of adaptively cancelled echos in said second set reflected from the same targets such that a ratio signal is obtained for each target which is proportional to the angle separating the target from the jammer position.

Claim 13

A system for cancelling jammer signals in the mainlobe of a monopulse radar and providing target locations with respect to the location of the jammer comprising: a monopulse radar including an antenna with two effective apertures and a boresight axis for receiving echo signals from a radar transmission at each effective aperture along with jamming signals and generating signals A' and B' therefrom; means for converting said received echo signals A' and B' into sum and difference signals; means for determining the angular position of the jammer with respect to the boresight axis of said monopulse radar antenna by utilizing said sum and difference signals and then effectively orienting said boresight axis to point so that said jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; adaptive canceller means with main and auxiliary inputs; a memory means for amplifying the received echo signals A' and B' from said two effective antenna apertures prior to conversion to sum and difference signals and applying these amplified signals to the main and auxiliary inputs of said adaptive canceller means, e.g., the A' echo signal to the main input and the B' echo signal to the auxiliary input, such that the jamming signal is cancelled from the output of said adaptive canceller means; wherein said adaptive canceller means cancels the jamming signal from a first set of echo signals received from the next radar transmission after said monopulse antenna axis has been effectively pointed so that the jammer is within the 3 dB points of the antenna mainlobe and applies this adaptively cancelled first set of echo signals in time sequence to said memory; means for changing the effective orientation of the boresight axis of said monopulse radar antenna by an arbitrary angle, such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation of the antenna; first switching means for reversing the application of the amplified echo signals A' and B' to said adaptive canceller means for the next radar transmission after the effective orientation of said monopulse antenna axis has been changed by said arbitrary angle, e.g., B' to said main input and A' to said auxiliary input; wherein said adaptive canceller means then cancels the jamming signal from a second set of echo signals received from the next radar transmission after the effective orientation of said monopulse antenna axis has been changed by said arbitrary angle; divider means with one input port connected to the output of said memory; second switching means for switching the adaptive canceller means echo signal output from said memory to a second input port of said divider means such that said second set of echo signals are applied thereto; wherein said first set of adaptively cancelled stored echo signals in said memory are read-out to said divider means in time coincidence with the occurrence of adaptively cancelled echos in said second set reflected from the same targets such that a ratio signal is obtained for each target which is proportional to the angle separating the target from the jammer position.

Claim 14

A system for cancelling jammer signals in the mainlobe of a monopulse radar and providing target locations with respect to the location of the jammer comprising: a monopulse radar including an antenna with two effective apertures and a boresight axis for receiving echo signals from a radar transmission at each effective aperture along with jamming signals and generating signals A' and B' therefrom; first means for converting said received echo signals A' and B' into a first set of sum and difference signals A'+B' and A'-B'; means for determining the angular position of the jammer-with respect to the boresight axis of said monopulse radar antenna by utilizing said first set of sum and difference signals and then effectively orienting said boresight axis to point so that the jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; adaptive canceller means with main and auxiliary inputs; second means for converting said first set of sum and difference signals into a second set of sum and difference signals G 1 A' and G 2 B', where G 1 and G 2 are constants, and applying the signals G 1 A' and G 2 B', in either order, to the main and auxiliary inputs of said adaptive canceller means, e.g., the G 1 A' signal to the main input and the G 2 B' signal to the auxiliary input, such that the jamming signal is cancelled at the output of said adaptive canceller means; wherein said adaptive canceller means cancels the jamming signal from a first set of echo signals received from the next radar transmission after said monopulse antenna boresight axis has been pointed so that the jammer is positioned within the 3 dB points of the antenna mainlobe and applies this adaptively cancelled first set of echo signals in time sequence to said memory; means for changing the effective orientation of the boresight axis of said monopulse radar antenna by an arbitrary angle such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation of the antenna; first switching means for reversing the application of the echo signals G 1 A' and G 2 B' to said adaptive canceller means for the next radar transmission after the effective orientation of said monopulse antenna axis has been changed by said arbitrary angle, e.g., G 2 B' to said main input and G 1 A' to said auxiliary input; wherein said adaptive canceller means then cancels the jamming signal from a second set of echo signals received from the next radar transmission after the effective orientation of said monopulse antenna axis has been changed by said arbitrary angle; divider means with one input port connected to the output of said memory; second switching means for switching the adaptive canceller means echo signal output from said memory to a second input port of said divider means such that said second set of echo signals are applied thereto; wherein said first set of adaptively cancelled stored echo signals in said memory are read-out to said divider means in time coincidence with the occurrence of adaptively canceled echos in said second set reflected from the same targets such that a ratio signal is obtained for each target which is proportional to the angle separating the target from the jammer position.

Claim 15

A system for cancelling jammer signals in the mainlobe of a monopulse radar and providing target locations with respect to the location of the jammer comprising: a monopulse radar including an antenna with two effective apertures and a boresight axis for receiving echo signals from a radar transmission at each effective aperture along with jamming signals and generating signals A' and B' therefrom; first means for converting said received echo signals A' and B' into a first set of sum and difference signals A'+B' and A'-B'; means for determining the angular position of the jammer-with respect to the boresight axis of said monopulse radar antenna by utilizing said first set of sum and difference signals and then effectively orienting said boresight axis to point so that the jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; adaptive canceller means with main and auxiliary inputs; second means for converting said first set of sum and difference signals into a second set of sum and difference signals G 1 A' and G 2 B', where G 1 and G 2 are constants, and applying the signals G 1 A' and G 2 B', in either order, to the main and auxiliary inputs of said adaptive canceller means, e.g., the G 1 A' signal to the main input and the G 2 B' signal to the auxiliary input, such that the jamming signal is cancelled at the output of said adaptive canceller means; wherein said adaptive canceller means cancels the jamming signal from a first set of echo signals received from the next radar transmission after said monopulse antenna boresight axis has been pointed so that the jammer is positioned within the 3 dB points of the antenna mainlobe and applies this adaptively cancelled first set of echo signals in time sequence to said memory; means for changing the effective orientation of the boresight axis of said monopulse radar antenna by an arbitrary angle such that the jammer is still located approximately within the 3 dB points of the new mainlobe orientation of the antenna; first switching means for reversing the application of the echo signals G 1 A' and G 2 B' to said adaptive canceller means for the next radar transmission after the effective orientation of said monopulse antenna axis has been changed by said arbitrary angle, e.g., G 2 B' to said main input and G 1 A' to said auxiliary input; wherein said adaptive canceller means then cancels the jamming signal from a second set of echo signals received from the next radar transmission after the effective orientation of said monopulse antenna axis has been changed by said arbitrary angle; divider means with one input port connected to the output of said memory; second switching means for switching the adaptive canceller means echo signal output from said memory to a second input port of said divider means such that said second set of echo signals are applied thereto; wherein said first set of adaptively cancelled stored echo signals in said memory are read-out to said divider means in time coincidence with the occurrence of adaptively canceled echos in said second set reflected from the same targets such that a ratio signal is obtained for each target which is proportional to the angle separating the target from the jammer position.

Claim 18

A system for cancelling jammer signals in the mainlobe of a monopulse radar and providing target locations with respect to the location of the jammer comprising: a monopulse radar including an antenna for receiving echo signals from a radar transmission along with jamming signals and generating a first set of sum and difference signals therefrom; means for determining the angular position of the jammer generating said jamming signals with respect to the boresight axis of said monopulse radar antenna by utilizing said sum and difference signals and then effectively orienting said antenna boresight axis to point so that the jammer is positioned within the 3 dB points of the antenna mainlobe; means for generating a second set of sum and difference signals from said first set of sum and difference signals; first adaptive cancelling means with main and auxiliary inputs; second adaptive cancelling means with main and auxiliary inputs; means for shifting the phase of said second sum signal; means for shifting the phase of said second difference signal; first means for adding said second sum signal to said second difference signal and applying this sum to the main input of said first adaptive canceller means and to said auxiliary input of said second adaptive canceller means; second means for adding said phase shifted second sum signal to said second difference signal to obtain a squinted signal and applying this sum to the auxiliary input of said first adaptive canceller means; third means for adding said second sum signal to said phase shifted second difference signal to obtain a squinted signal and applying this sum to the main input of said second adaptive cancelling means; and means for dividing the output signal from one of said adaptive canceller means by the output from the other of said adaptive canceller means in order to obtain a ratio signal which is proportional to the angle separating the target echo from the jammer position.

Claim 19

A system for cancelling jammer signals in the mainlobe of a monopulse radar and providing target locations with respect to the location of the jammer comprising: a monopulse radar including an antenna for receiving echo signals from a radar transmission along with jamming signals and generating a first set of sum and difference signals therefrom; means for determining the angular position of the jammer generating said jamming signals with respect to the boresight axis of said monopulse radar antenna by utilizing said sum and difference signals and then effectively orienting said antenna boresight axis to point so that the jammer is positioned within the 3 dB points of the antenna mainlobe; means for generating a second set of sum and difference signals from said first set of sum and difference signals; first adaptive cancelling means with main and auxiliary inputs; second adaptive cancelling means with main and auxiliary inputs; means for shifting the phase of said second sum signal; means for shifting the phase of said second difference signal; first means for adding said second sum signal to said second difference signal and applying this sum to the main input of said first adaptive canceller means and to said auxiliary input of said second adaptive canceller means; second means for adding said phase shifted second sum signal to said second difference signal to obtain a squinted signal and applying this sum to the auxiliary input of said first adaptive canceller means; third means for adding said second sum signal to said phase shifted second difference signal to obtain a squinted signal and applying this sum to the main input of said second adaptive cancelling means; and means for dividing the output signal from one of said adaptive canceller means by the output from the other of said adaptive canceller means in order to obtain a ratio signal which is proportional to the angle separating the target echo from the jammer position.

Claim 23

A system for cancelling jammer signals in the mainlobe of a monopulse radar and providing target locations with respect to the location of the jammer comprising: a monopulse radar including an antenna with two effective apertures for receiving echo signals from a radar transmission along with jamming signals; means for determining the location of said jammer; means for effectively pointing the boresight axis of said monopulse antenna so that the jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; first means for squinting the echo signals received from the two effective apertures of said monopulse antenna for a first angle of arrival; first means for adding the echo signals from each of said two effective antenna apertures; second means for squinting said echo signals from said two effective apertures of said monopulse antenna for a second angle of arrival; first adaptive cancelling means for cancelling the jamming signal from the received echo signals by utilizing the output signals from said first adding means and said first squinting means in an adaptive cancelling process; second adaptive cancelling means for cancelling the jamming signal from the received echo signals by utilizing the outputs from said adding means and said second squinting means in an adaptive cancelling process; and means for taking the ratio of the output signals from one of said adaptive cancelling means with respect to the output signals from the other adaptive cancelling means, said ratio signals being proportional to the angles separating the individual targets from the jammer.

Claim 24

A system for cancelling jammer signals in the mainlobe of a monopulse radar and providing target locations with respect to the location of the jammer comprising: a monopulse radar including an antenna with two effective apertures for receiving echo signals from a radar transmission along with jamming signals; means for determining the location of said jammer; means for effectively pointing the boresight axis of said monopulse antenna so that the jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; first means for squinting the echo signals received from the two effective apertures of said monopulse antenna for a first angle of arrival; first means for adding the echo signals from each of said two effective antenna apertures; second means for squinting said echo signals from said two effective apertures of said monopulse antenna for a second angle of arrival; first adaptive cancelling means for cancelling the jamming signal from the received echo signals by utilizing the output signals from said first adding means and said first squinting means in an adaptive cancelling process; second adaptive cancelling means for cancelling the jamming signal from the received echo signals by utilizing the outputs from said adding means and said second squinting means in an adaptive cancelling process; and means for taking the ratio of the output signals from one of said adaptive cancelling means with respect to the output signals from the other adaptive cancelling means, said ratio signals being proportional to the angles separating the individual targets from the jammer.

Claim 31

A method for cancelling jammer signals in the mainlobe of a monopulse radar which includes an antenna with two effective apertures and for providing target locations with respect to the location of the jammer comprising the steps of: receiving a first set of echo signals from a radar transmission along with jamming signals; determining the location of the jammer from said first set of echo and jamming signals; effectively orienting the antenna of said monopulse radar to point so that the jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; squinting the echo signals received from the two effective apertures of said monopulse antenna for a first angle of arrival; and simultaneously adding the echo signals received from the two effective apertures of said monopulse antenna; and simultaneously squinting the said echo signals received from the two effective apertures of said monopulse antenna for a second angle of arrival; adaptively cancelling the jamming signal from the received echo signals by utilizing the output signals from said first squinting step and from said adding step in an adaptive cancelling process; simultaneously adaptively cancelling the jamming signal from the received echo signals by utilizing the output signals from said adding step and said second squinting step in an adaptive cancelling process; and dividing the output signals from one adaptive cancelling step by the output signals from the other adaptive cancelling step to obtain ratio signals which are proportional to the angles separating the individual targets from the jammer.

Claim 32

A method for cancelling jammer signals in the mainlobe of a monopulse radar which includes an antenna with two effective apertures and for providing target locations with respect to the location of the jammer comprising the steps of: receiving a first set of echo signals from a radar transmission along with jamming signals; determining the location of the jammer from said first set of echo and jamming signals; effectively orienting the antenna of said monopulse radar to point so that the jammer is positioned within the 3 dB points of the mainlobe of said two effective antenna apertures; squinting the echo signals received from the two effective apertures of said monopulse antenna for a first angle of arrival; and simultaneously adding the echo signals received from the two effective apertures of said monopulse antenna; and simultaneously squinting the said echo signals received from the two effective apertures of said monopulse antenna for a second angle of arrival; adaptively cancelling the jamming signal from the received echo signals by utilizing the output signals from said first squinting step and from said adding step in an adaptive cancelling process; simultaneously adaptively cancelling the jamming signal from the received echo signals by utilizing the output signals from said adding step and said second squinting step in an adaptive cancelling process; and dividing the output signals from one adaptive cancelling step by the output signals from the other adaptive cancelling step to obtain ratio signals which are proportional to the angles separating the individual targets from the jammer.