Multiplatform GMTI radar with enhanced SNR, monopulse

摘要

The present invention is directed to a ground moving target (GMTI) radar that can detect targets, including dismounts, with very small minimum detectable velocities by combining signals from antennas on different spatially separated platforms in a main beam clutter-suppressing spatially adaptive process without requiring that the relative positions of the antenna phase centers be accurately tracked. The clutter nulling is in addition to that provided by the Doppler filters. The spatial displacement provides a narrow mainbeam clutter null reducing undesired target suppression. The clutter-suppressing spatially adaptive structure is used in both the sum and delta channels of the monopulse processor so that the beam distortion caused by the spatial nulling is compensated for, and the monopulse look-up process is preserved to maintain angle accuracy. Noncoherent integration is employed to recover signal to noise loss resulting from the uncertain relative locations of the platforms.

主权项

1. A GMTI radar system comprising:
a signal input portion configured to receive first main channel radar return signals and second main channel radar return signals from a first main radar receiver and a second main radar receiver, respectively, both being disposed on a main airborne platform, the data input portion also configured to receive first auxiliary channel radar return signals and second auxiliary channel radar return signals from at least one first auxiliary radar receiver and at least one second auxiliary radar receiver, respectively, both being disposed on at least one auxiliary airborne platform, the main airborne platform being independent and spatially separated from the auxiliary airborne platform; a plurality of Doppler filters coupled to the signal input portion, the plurality of Doppler filters being configured to derive: a first main clutter signal and a first main target signal from the first main channel radar return signals; at least one first auxiliary clutter signal and at least one first auxiliary target signal from the first auxiliary channel radar return signals; a second main clutter signal and a second main target signal from the second main channel radar return signals; and at least one second auxiliary clutter signal and at least one second auxiliary target signal from the second auxiliary channel radar return signals; a first adaptive cancelation circuit coupled to the plurality of Doppler filters, the first adaptive cancelation circuit being configured to generate a first weight vector that is a function of the first main clutter signal and the at least one first auxiliary clutter signal and apply the first weight vector to the at least one first auxiliary target signal to obtain a first weighted auxiliary target signal, the first adaptive cancelation circuit being further configured to combine the first weighted auxiliary target signal and the first main target signal to provide a first clutter suppressed target signal; a second adaptive cancelation circuit coupled to the plurality of filters, the second adaptive cancelation circuit being configured to generate a second weight vector that is a function of the second main clutter signal and the at least one second auxiliary clutter signal and apply the second weight vector to the at least one second auxiliary target signal to obtain a second weighted auxiliary target signal, the second adaptive cancelation circuit being further configured to combine the second weighted auxiliary target signal and the second main target signal to provide a second clutter suppressed target signal; and a monopulse angle estimation circuit coupled to the first adaptive processing circuit and the second adaptive processing circuit, the monopulse angle estimation circuit being configured to provide a monopulse angle estimation ratio that is a function of the first clutter suppressed target signal and the second clutter suppressed target signal, but not a function of the first weight vector or the second weight vector.