General Dynamics Advanced Information Systems, Inc.

Erim International, Inc.

Other

Ron S Goodman

Edward F Gabl

Mark A Ricoy

Elizabeth T Batteh

Scott D Connell

Walter G Carrara

Terry Goodman

Ronald A Schneider

Provided are two-dimensional autofocus methods in a synthetic aperture radar (SAR) system which include: (1) two-dimensional pulse pair product algorithm including shear PGA, eigenvector phase history ('EPH'), shear PGA/EPH); (2) two-dimensional optimization algorithms including parametric one-dimensional estimate/two-dimensional correction, parametric two dimensional estimate/two-dimensional correction, unconstrained two-dimensional nonparametric and constrained two-dimensional nonparametric methods; (3) a two-dimensional geometry filter algorithm; (4) a two-dimensional prominent point processing algorithm; (5) a one-dimensional phase estimate of higher order two dimensional phase errors; and, (6) a fast SHARP parametric autofocus algorithm.

Methods for two-dimensional autofocus in high resolution radar systems

A lifting device adapted to be fitted to a tracked vehicle which is configured to operate in snow-covered terrain. The lifting device has an interface member which in one form allows for an interface portion of the mast region to fit to a plurality of commercially available tracked snow vehicles. Further, in one form, the lifting device interfaces with the existing hydraulics of conventional tracked snow vehicles.

Detachable lifting mechanism for a tracked snow vehicle method and apparatus

A method of performing the computer-intensive initial steps of the range migration algorithm, or RMA, produces radar imagery of higher quality than the current polar format (PF) processing approach, while operating faster and more efficiently than the standard RMA. The new method is advantageous when the synthetic aperture length required to achieve azimuth resolution is significantly larger than the azimuth extent of the processed scene. The method subdivides the signal history into a plurality of non-overlapping subapertures, adds a low bandwidth azimuth chirp across each subaperture and applies a fast Fourier transform separately to each subaperture. The results are coherently combined, after which the remaining steps of the conventional RMA may be completed with minor modifications to the subsequent two-dimensional phase compensation. The invention is applicable to spotlight, stripmap and scan-mode SAR image formation, and the separate, subaperture Fourier transformations may be performed simultaneously.

Subchirp processing method

The sensitivity of a synthetic aperture radar (SAR) system employing stretch processing is improved in the presence of radio-frequency interference (RFI). The sequence of data processing operations initially uses a high number of bits to digitize radar echoes plus RFI, then uses floating-point arithmetic to perform range deskewing to 'compress' RFI tones, followed by threshholding and nulling the primary RFI contributors, and finally re-quantizes the resulting radar signal to a lower number of bits and appropriately allocating these bits over the range of signal levels.

Growing community of inventors

Novi, MI, United States of America

Ron S Goodman