The Effect of Constant Velocity Error on SAR Focus

The usual analyses of the effect of constant radar velocity error on synthetic aperture radar (SAR) focus generally yield the result that the cross-radial component of velocity error is primarily responsible for image defocusing. A simple argument is given demonstrating that image focus depends on accurately estimating radar speed, in which the along-track (AT) component of velocity error is most important.     

Computationally Efficient Bank of Rectangular Digital Filters

A computationally efficient scheme for forming a bank of identical contiguous rectangular digital filters is described. The data processing is organized in a sequential form allowing use of the FFT algorithm as the first stage. An example is given in which a bank of 256 rectangular filters is formed using only a few percent of the number of complex multiplies required by straightforward procedures. The steepness of cutoff is unaltered and the inband ripple is only slightly affected, but the sidelobe level suffers some degradation.     

Performance of a Two-Sample Mann-Whitney Nonparametric Detector in a Radar Application

The detection of signals in an unknown, typically non-Gaussian noise environment, while attempting to maintain a constant false-alarm rate, is a common problem in radar and sonar. The raw receiver data is commonly processed initially by a bank of frequency filters. The further processing of the outputs from the filter bank by a two-sample Mann-Whitney detector is considered. When the noise statistics in all filters are identical, the Mann-Whitney detector is distribution free, i. e., the false-alarm probability may be prescribed in advance regardless of the precise form of the noise statistics. The primary purpose of this paper is to demonstrate the potential advantage of nonparametric detectors over conventional detectors. The signal detection performance of the Mann-Whitney detector is compared to that of an ordinary linear envelope detector plus integrator in the presence of Gaussian and several hypothetical forms of non-Gaussian noise. This comparison is made for both uniform and nonuniform distributions of noise power across the filter bank. Besides providing a much more constant false-alarm rate than the conventional detector, the Mann-Whitney detector's signal detection performance is found also to be much less sensitive to the form of the noise statistics. In one case, its detection sensitivity is found to be 11 dB better than that of the conventional detector. Even when the noise power density is made moderately nonuniform across the filter bank, the detection performance of the Mann-Whitney detector is found not to be significantly affected.     

Some Results on Pulse-Burst Radar Design

Pulse-burst radar attempts to capitalize on the advantages of both low and high PRF radar while minimizing their disadvantages. Optimization procedures are applied to the choice of transmitter signal and receiver weighting. The results are compared to the use of Tschebyscheff transmitter weighting with an optimized receiver. The effects of various design and operational parameters are indicated. The performance of pulse-burst radar is qualitatively compared to that of conventional low and high PRF Doppler radar. It is concluded that pulse-burst radar offers the possibility of achieving a solution to the MTI problem under operational conditions where conventional Doppler radars fail.