Showing papers on "Moving target indication published in 1989"

Detection performance in K-distributed and correlated Rayleigh clutters

Abstract: Performance prediction for a detection system employing noncoherent integration is carried out for a chi-square family of fluctuating targets in K-distributed clutter plus noise. The detection performance for Swerling 11 targets in the K-distributed clutter plus noise is compared with that in exponentially correlated Rayleigh clutter. The results show that the performance prediction based on N pulses integrated in clutter plus noise using the K-distributed clutter model may be approximately equivalent to that using the exponentially correlated Rayleigh-distributed clutter model. >

Blind speed elimination for dual displaced phase center antenna radar processor mounted on a moving platform

Abstract: A radar system mounted on a moving vehicle uses a displaced phase center antanna (DPCA) and associated processing for taking the difference between the two signals received by the displaced antennas to provide moving target indication (MTI) by cancellation of the returns from stationary targets The presence of moving targets is identified by threshold processing within discrete frequency bands DPCA processing ordinarily results in amplitude nulls or "blind speeds" for targets moving at particular radial velocities According to the invention, the two signals received by the displaced antennas are summed, weighted and divided into frequency bands which extend through the expected null region in a form of Doppler processing Threshold processing is performed on DPCA processed signals within certain frequency bands outside of the null regions and on Doppler processed signals within other frequency bands, thereby substantially eliminating the blind speeds

Doppler-Rate Filtering For Detecting Moving Targets With Synthetic Aperture Radars

Abstract: The detection of moving targets with Synthetic Aperture Radars (SAR) is usually carried out by means of methods based on a Doppler filtering. The targets are detected if their Doppler frequency spectrum falls outside of the clutter spectrum, where the clutter consists, in this case, on the returns from the ground. These methods however present some drawbacks, namely: a) targets with low radial velocity, with respect to the radar, are not detected and, b) in order to create a certain visibility region in the Doppler frequency domain, the Pulse Repetition Frequency (PRF) must be taken sensibly higher than the clutter bandwidth and this entails a reduction of the monitorable swath and then a loss on the possible radar coverage. In order to overcome the afore-mentioned shortcomings, a technique for detecting moving targets whose spectrum is embedded in the clutter spectrum is presented in this paper. The technique is based on the difference in the Doppler frequency rate and spatial correlation between moving and fixed targets. The received signal is first filtered in an adaptive way for improving the power ratio between moving and fixed target. The adaptive filter is then followed by a Doppler-rate filters' bank, each filter being matched to a particular Doppler-rate. The performances of the proposed technique are assessed by means of a simulation program.

Active phase quieting target highlight detector

Abstract: An active phase quieting target highlight detector using phase and magnitude detection can discriminate sets of spatially-ordered highlights due to a target, from clutter or multipath echoes, along with nonsmoothed magnitude or envelope detection, and can better discriminate target structure due to reception of echoes from shorter active pulses. False target detection and multipath detection are reduced while detection of target structure is retained by a time domain detection scheme.

Moving target indication unit

Abstract: Moving target indication unit provided with a doppler filter bank (1) with n output channels Ai (i = 0, 1, 2, ..., n-1), several threshold circuits (24.i) connected to the output channels, a detection and registration unit (7, 14, 18, 23) provided with means (7, 14, 18) for the determination and registration, per azimuth cell, of a parameter for the amount: of clutter in an azimuth cell.The said means are further suitable for determining, based on the output signals of the filter bank (1), k (k ? 2) parameters per azimuth cell and processing per azimuth cell the combination of k parameters to obtain n threshold values, used to set the n threshold circuits.

Target identifying device

Abstract: PURPOSE: To accurately identify a target by identifying target in consideration of the absolute size of the target and its shape change with an aspect angle CONSTITUTION: The radio wave 8 reflected by the target 2 is received by a radar device 9 and a radio wave signal processor 10 detects the distance from the target 2 and moving direction of the target according to the signal obtained from the radar device Further, the radio wave signal processor 10 calculates the aspect angle from target moving direction information and calculates the position of a light wave sensor 4, ie the position of a view point to the target from the aspect angle information and information on the distance from the target 2 Then feature parameters stored in a storage device 12 previously are coordinate-converted by a corrector 11 by using the aspect angle information and distance information to project the target 2 so that the direction of the target is equal, and then the distance is corrected by enlargement or reduction so that the absolute size is equal COPYRIGHT: (C)1991,JPO&Japio

False alarm control using ambiguous velocity

Abstract: A novel technique for rejecting clutter residues is proposed. The technique uses maximum-likelihood estimates of the target Doppler and target amplitude generated from consecutive pulses out of an MTI (moving target indicator). Multiple estimates are made and consistency checks are applied to the estimates. Simulation results indicate that for large clutter-to-noise ratios (>or=55 dB) the probability of false alarm from clutter residues is reduced from 1.0 to below 0.01. >

Effect of timing jitter on performance of MTI filters

Abstract: The effect of transmitting timing jitter and sampling jitter on a multipulse clutter cancellation system is analyzed, and explicit expressions are obtained for the net increase in the residue clutter power due to timing jitter. The increase in mean-square error is found to be proportional to the jitter variance, with the two jitters contributing almost equally. The system analyzed can have either a recursive or nonrecursive MTI filter, and the latter includes the familiar two- and three-pulse canceller as special cases. The increase in residue clutter power for a three-pulse canceller is about 4.8 dB worse than that for a two-pulse canceller. >

Area MTI - A Multiple Scan Signal Processing Technique

Abstract: This paper presents Area Moving Target Indication (Area MTI) as a signal processing technique for the detection of slow moving or tangentially moving targets The work was performed by the Rome Air Development Center (RADC) in their study of the Bird/Aircraft Strike Hazard (BASH) problem at Dover AFB A radar for bird hazard warnings was necessary to cope with the large numbers of birds wintering at several wildlife refuges located near the base Such a radar presents a formidable surveillance/tracking problem, and Area MTI has the potential to provide a solution to this problemAlthough the improvement obtained was less than the ultimate rejection capability of conventional MTI, the Area MTI did result in a relative enhancement for the detection of slow and tangential moving targetsAdditional techniques to improve performance are currently being investigated, for example, integration of conventional MTI and Area MTI It is expected this technique will enhance the detection of target returns suppressed by conventional MTI while retaining Area MTI's high "average" improvement factor

Adaptive order recursive lattice for optical target detection using correlated frames

Abstract: An adaptive order-recursive least-squares procedure for the detection of an optical target in a heavy clutter environment is introduced. The procedure makes use of the correlated noise (clutter) in the adjacent frames of a scene to suppress the clutter and to detect efficiently the optical target embedded in one of the frames. It does not require much information about the sequence of images, the statistics of the clutter and noise, or the intensity and position of the target. The only requirement is that the background clutter in the two adjacent frames of a scene be partially correlated. The performance of the proposed detection procedure is evaluated using real images with artificially implanted targets. >

Moving Target Indication And Position Estimation With Autodyne Detection

Abstract: Detection and position estimation of targets in the presence of strong scattering background clutter with an opticalDoppler Autodyning Tracking (DAT) technique is proposed for the first time. The DAT technique is based on measuring relative Doppler shifts introduced by different velocities of target and background scatterers with a direct detection method.I. INTRODUCTION In this paper we propose a novel ladar technique for detecting and estimating angular position of targets in the presence of strong scattering background clutter. The technique uses a method related to self -beating light spectroscopy1,2 to detect and precisely locate targets moving relative to the background. This is accomplished by mixing together thelaser radiation scattered by the target and background with a photodetector. The resulting photocurrent has a spectrumwhich is analyzed for a target presence.The problem of detecting a moving target relative to a strong background has received considerable attention in theliterature dedicated to both passive3'4 and active sensors5,6,10 Moving Target Indication (MTI) methods developed foractive systems are based on exploiting the difference between the background and target induced Doppler frequency shifts.