Northrop Grumman Systems Corporation

United Technologies Corporation

Robert A Guarino

John A Didomizio

Edward F Stockburger

Daniel N Held

John Henry Fitzgerald

Hugh D Holt, Jr

Herbert Green

An interferometric moving target radar imaging system includes a plurality of simultaneously operating apertures, receivers and processing channels which together coherently process RF return signals to image a moving vehicle. The system corrects for the different phase centers of the apertures and interferometrically combines the return signals from different apertures to attenuate the energy from stationary objects. The true azimuth location of the moving vehicle within main beam clutter spread is then determined which facilitates distinguishing between slow moving and stationary objects to detect the moving objects which are then tracked and imaged in the range doppler domain.

Interferometric moving vehicle imaging apparatus and method

An AMTI radar employs a dual cancellation format to cancel the clutter in the radar returns received by the apertures of an interferometric radar antenna. The three-aperture antenna presents the radar returns to three receivers which demodulate the returns to a complex in-phase signal I and a quadrature signal Q which are sampled at a pulse repetition interval at all ranges of interest. After conventional motion compensation four data sets are derived from the returns of the three apertures, L(t), C(t-.tau.), C(t) and R(T-.tau.) which represents samples taken over multiple pulse repetition intervals for each range interval or bin of interest. Fast Fourier transforms change the data sets into the frequency domain and phase compensations for the data sets are calculated in a triple interferometric signal calibration unit. Compensation phase is further adjusted in a clutter phase calculator allowing a much reduced phase quantity to be applied to the delayed data sets as the second part of the dual cancellation signal. Following subtraction of doppler filter outputs of the delayed data sets from the undelayed data sets in the cancellation unit, maximum clutter cancellation is achieved. The resulting clutter-cancelled signals are presented to a detection and validation processor to determine range, doppler, amplitude and angle measurements to the moving targets with a high degree accuracy.

Dual cancellation interferometric AMTI radar

The range bin width of a range gated moving target indicator (RG-MTI) is expanded to decrease the sensed range resolution to that which is compatible with the displayable range resolution, without limitation by the pulse width of the transmitted radar pulse. A commensurate expansion in the width of the return video signals is provided to prevent loss of target return signal detection due to 'straddling' of the return signal by the expanded range bin width.

Expanded range gate moving target indicator

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Monroe, CT, United States of America

Robert A Guarino