Showing papers on "Moving target indication published in 1981"

Low target velocity interferometric AMTI radar

Abstract: 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-τ), C(t) and R(T-τ) which represents samples taken over multiple pulse repetition intervals for each range interval or bin of interest. The data is processed by both adjacent array processing and outer array processing, the latter only requiring a minimal amount of additional capacity. Compensation phase is further adjusted in a clutter/clutter-free 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/enhancement unit, maximum clutter cancellation is achieved in the clutter region and optimal moving target response is obtained in the clutter-free region. The two-range maps that result after subtraction of the doppler filter outputs are presented to a detection and validation processor to determine range, doppler, amplitude and angle measurements to the moving targets with a high degree of accuracy.

Method and system for tracking targets in a pulse doppler radar system

Abstract: A medium to low PRF pulse doppler radar wherein the effect of the clutter notch filter is eliminated at times when the doppler frequency of the target approximates the doppler frequency of the clutter to continue tracking the target provided that the doppler frequency of the target and clutter are at different ranges.

Apparatus for control of clutter breakthrough in MTI radar

Abstract: An apparatus for control of ground clutter breakthrough in MTI radar which remove hard limited clutter signals while allowing increased detection sensitivity to moving targets when such strong clutter returns are not present. Logic is provided to prevent the removal of strong moving target return even in the presence of hard limited clutter.

Suppression of ground and weather clutter

Abstract: It is shown that Weibull-distributed weather clutter obeys a Weibull distribution after passing through a moving target indicator (MTI) processor realised by a double canceller. Both ground and weather clutter can be thus suppressed by using the method of MTI and new Weibull constant false alarm rate (CFAR) systems.

Interference suppressor for radar MTI

Abstract: An impulse interference suppression circuit for use in combination with an-pulse Moving Target Indicator system comprising a gate connected to block the output signal from the MTI system when energized, and a circuit for taking the magnitudes of successive echo return signals, subtracting the magnitudes of consecutive echo signals to remove clutter, comparing the consecutive difference signals from such subtractions against each other, and generating and applying a blocking signal to the gate if the difference between the subtraction difference signals is above a given threshold level

Optimal Target t Designation Techniques

Abstract: Studies of signal processing techniques are presented for achieving optimal autonomous acquisition of stationary targets located in a moderately intense nonhomogeneous radar ground clutter background. The process of target acquisition comprises three basic functions: 1) target detection, 2) target selection or designation, and 3) reacquiring the target for tracking. It is the second of these functions, i.e., autonomous designation of a target, that is the subject of this discussion. Theoretical analyses and predictions of the probability of correct target designation for two acquisition search methods are presented and compared with results achieved using real radar imagery.

Pulse-Doppler radar with a circuit for coherent integration

Abstract: The moving target indication circuit (MTI) in a pulse Doppler radar comprising an arrangement for coherent integration is the cause of partial correlation of the noise voltages. The noise voltages of the output pulses of the moving target indication circuit are therefore partially correlated which results in a loss in the integration gain of the signal/noise power ratio during the subsequent integration. To avoid this loss, a weighting of the signal pulses is carried out in a weighting multiplier between the moving target indication circuit and the coherent integration.

Radar signal processor

Abstract: PURPOSE:To remove unnecessary data without deterioration of the ability to quantitatively measure the weather data and the like by removing ground clutter and the like in a moving target indication (MTI) manner in order to detect the desired signals and controlling the gate of the output circuit. CONSTITUTION:The signal (a) received by a logarithmic characteristic reception circuit 32 is converted into a digital value in a quantizing circuit 33, processed in a delay circuit 34 and a subtracting circuit 35 in a moving target indication manner and becomes a signal (c) with ground clutter and the like removed substantially. When the desired signal 42 about weather data or the like in the signal (c) is detected, a detecting circuit 38 generates a gate signal (d) through an amplitude comparing circuit 382 in order to control the gate circuit 372 in an output circuit 37. Thereby, the unnecessary data in the output obtained by adding the signal (b) whose clutter fluctuation or the like is decided to be large by a logarithm converting circuit 36 and the output of the circuit 33 is removed and the quantitative data such as the weather data (e) or the like can be extracted without deterioration.

New moving target simulators for Doppler radar

Abstract: Two new methods of providing equivalent Doppler frequency shift of reflected microwave signals have been developed. One is a mechanical spiral ‘barber's pole’ type of device. The other produces a single upper or lower sideband by purely electronic modulation techniques.

Moving Target Detector/Airport Surveillance Radar (ASR-7) Field Evaluation.

Abstract: : The Moving Target Detector (MTD) II, a sophisticated radar processor, was evaluated to determine its capability to provide improved radar detection in an air traffic control (ATC) environment The MTD II was installed on one channel of an airport surveillance radar (ASR-7) at Burlington, Vermont The major objective of testing was to compare the performance of the MTD II with that of the ASR-7 Moving Target Indicator (MTI) This report concentrates on the comparative probability of detection, false alarm rate, MTI improvement factor, subclutter visibility, dynamic range, velocity response, and the simultaneous flight test results of the two systems Comparison of the MTD II to the MTD I system is made when necessary to show major improvements or deficiencies in the MTD II design The results of the tests have shown that the MTD II provides surveillance capabilities superior to those of the ASR-7/MTI (Author)