Lockheed Martin Corporation

Lockheed Martin Mission Systems

Kevin W Baugh

Robert H Benner

Richard A Lodwig

A system and method for narrowband pre-detection signal processing in passive coherent location applications is disclosed. A receiving subsystem receives a reference signal and a target signal from an uncontrolled transmitter. The target signal is reflected from a target. The passive coherent location system includes subprocessors that perform pre-detection operations on the reference and target signals. The functions include zero-doppler cancellation, quadrature demodulation, reference beam regeneration, coherent processing interval selection, power spectral density estimation, cross ambiguity function formation, and the like. Within these operations, the reference signal is filtered with respect to the target signal to form a first output reference signal. The first output reference signal is combined with the first target signal to form a first output target signal. The output target signal then is used for subsequent passive coherent location processing operations. The filter is updated with respect to a difference between the target signal and a subsequent target signal. Further, two paths are used for correlation processing of the reference and target signals.

System and method for narrowband pre-detection signal processing for passive coherent location applications

A civil aviation passive coherent location system and method is disclosed. A receiver subsystem receives reference transmissions from an uncontrolled transmitter. The receiver subsystem also receives scattered transmissions originating from the uncontrolled transmitter and scattered by an airborne object. The received transmissions are compared to determine measurement differentials, such a frequency-difference-of-arrival, a time-difference-of-arrival and an angle of arrival. From the measurement differentials, an object state estimate is determined. A previous state estimate may be updated with the determined state estimate. Processing subsystems determine the measurement differentials and state estimates.

Civil aviation passive coherent location system and method

A system and method for narrowband pre-detection signal processing in passive coherent location applications is disclosed. A receiving subsystem receives a reference signal and a target signal from an uncontrolled transmitter. The target signal is reflected from a target. The passive coherent location system includes sub-processors that perform pre-detection operations on the reference and target signals. The functions include zero-doppler cancellation, quadrature demodulation, reference beam regeneration, coherent processing interval selection, power spectral density estimation, cross ambiguity function formation, and the like. Within these operations, the reference signal is filtered with respect to the target signal to form a first output reference signal. The first output reference signal is combined with the first target signal to form a first output target signal. The output target signal then is used for subsequent passive coherent location processing operations. The filter is updated with respect to a difference between the target signal and a subsequent target signal. Further, two paths are used for correlation processing of the reference and target signals.

A system and method for wideband pre-detection signal processing for PCL applications is disclosed. The method includes receiving an input signal, implementing a transformation operation on the input signal, compensating the input signal for channel distortion, demodulating and forming complex-valued representations of the compensated input signal, estimating a reference signal and a target signal from the demodulated input signal, reducing a portion of the reference signal in the target signal, wherein the reference signal is adaptively filtered with respect to the target signal and combined with the target signal to form an output target signal, implementing an inverse transformation operation on the output target signal and the reference signal, forming a plurality of target beams for the output target signal, forming a plurality of decimated lag products for each of the plurality of target beams, forming a plurality of decimated lag products for the reference signal, estimating a cross ambiguity function for the each of plurality of target beams using the plurality of decimated lag products for each of the plurality of target beams, and estimating an auto ambiguity function for the reference signal using the plurality of decimated lag products for the reference signal.

System and method for wideband pre-detection signal processing for passive coherent location applications

A system and method for detection and feature extraction in a passive coherent location system is disclosed. During a coherent processing interval, detection and feature extraction operations are performed to determine peak detections and target parameters for targets. The system forms an ambiguity surface that has ambiguity surface data or the coherent processing interval. Bins from a previous ambiguity surface are associated with the ambiguity surface data. New bins are identified for new target echoes within the ambiguity surface. Peak detections are formed from the bins. The peak detections correlate to the target echoes of the coherent processing interval. Target parameters for the targets are estimated from the peak detections.

System and method for detection and feature extraction in passive coherent location applications

A system and method for mitigating co-channel interference is disclosed. A radar system detects targets from received signals at an antenna array. The received signals include direct signals and target signals transmitted from remote transmitters. An antenna array receives the signals. A signal processing system is coupled to the antenna array to perform processing operations on the received signals. The processing system includes a primary cancellation component and a secondary cancellation component. A primary illuminator signal is cancelled from the received signals by the primary cancellation component. An adaptive beam former obtains a secondary illuminator signal from the received signals. A reference regenerator regenerates the secondary illuminator signal. An adaptive cancellation filter removes noise from the secondary illuminator signal. The secondary cancellation component mitigates co-channel interference by canceling the secondary illuminator signal from the received signals.

System and method for mitigating co-channel interference in passive coherent location applications

A system and method for enhancing object state awareness is disclosed. The system includes a receiver subsystem that receives reference signals from an uncontrolled transmitter and scattered transmissions originating from the uncontrolled transmitter and scattered by an object. The system also includes a front-end processing subsystem that determines a radial velocity of the object based on the received transmissions. The system also includes a back-end processing subsystem that determines object state estimates based on the determined radial velocity.

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Gaithersburg, MD, United States of America

Kevin W Baugh