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Showing papers on "Moving target indication published in 1984"


Patent
20 Jul 1984
TL;DR: In this paper, the authors discuss suppressors and methods of clutter suppression for cw doppler, pulse Doppler and MTI (moving target indication) radars.
Abstract: Clutter suppressors and methods of clutter suppression for radars which employ the doppler effect for enhancing signals due to moving targets relative to signals due to clutter caused by land, sea or rain. Specifically, the disclosure concerns suppressors and methods of clutter suppression for cw doppler, pulse doppler and MTI (moving target indication) radars. The suppressors reduce the occurrence of radar output due to clutter by permitting and prohibiting radar output on the basis of the strength of signals that contain doppler frequency components of the radar echo.

67 citations


Patent
20 Jul 1984
TL;DR: In this paper, a digital filter with cascaded digital delays or memories (311-1-311-(N-1)), weighting multipliers (331-1 -331-N) applying weights to the output signals from the memories and adder (380) for combining the weighted signals.
Abstract: The apparatus comprises a digital filter with cascaded digital delays or memories (311-1 -311-(N-1)), weighting multipliers (331-1 -331-N) applying weights to the output signals from the memories and adder (380) for combining the weighted signals. A region discriminator (360) discriminates between different return signal regions and the weighting coefficients are correspondinglv switched by a control signal generator (350) and a weighting coefficient generator (340). The filter characteristics are thereby switched for individual regions so that the optimum characteristics can be obtained for the stationary clutter region, moving clutter region, clear region, etc, thereby providing suppression of undesired signals which is adapted for each region.

33 citations


Journal ArticleDOI
R. Fante1
TL;DR: In this article, the probability of single-pulse detection of an N -glint target immersed in K-distributed clutter is investigated for low-grazing angle detection of realistic targets in heavy ground and sea clutter.
Abstract: Results are obtained for the probability of single-pulse detection of an N -glint target immersed in K -distributed clutter. The results are applicable to low-grazing-angle detection of realistic targets in heavy ground and sea clutter.

24 citations


Patent
07 Jun 1984
TL;DR: In this article, a modified coherent integration is proposed for a pulse Doppler radar system with variable pulse repetition frequency, where the reflected pulses are subject to a simplified vectorial addition by the use of a number of filters.
Abstract: A pulse Doppler radar system with variable pulse repetition frequency has a coherent integrator to which the reflected pulses are supplied in order to avoid deterioration of the indication of a moving target given over-the-horizon reception. The coherent integrator subjects the reflected pulses to a simplified vectorial addition by the use of a number of filters. A precondition for the modified coherent integration is a staggering of the pulse repetition periods such that their sums formed over successive pulse repetition periods are constant, and a phase reference for the signal amplitudes is obtained such that the phase difference is equal to zero after every second pulse repetition.

23 citations


Journal ArticleDOI
TL;DR: In this paper, a technique for implementing moving target indication (m.t.i.) in an independent bistatic radar receiver is described, where an oscillator at the receiver is primed at the instant of switch-on at the beginning of each p.r., such that its phase is determined by the clutter echo.
Abstract: The paper describes a technique for implementing moving target indication (m.t.i.) in an independent bistatic radar receiver. Conventional techniques for m.t.i., and the particular features and advantages of the bistatic radar configuration are also reviewed.The technique of phase priming by clutter echoes is suggested as a means for providing a coherent reference at the receiver, without need for any link between radar transmitter and receiver. An oscillator at the receiver is primed at the instant of switch-on at the beginning of each p.r.i. with a small sample of echo signal from close-in stable clutter, such that its phase is determined by that of the clutter echo. This enables m.t.i. processing to be obtained, just as with a conventional monostatic radar system.An experimental system using this principle is described, and results demonstrated and discussed.

16 citations


Journal ArticleDOI
TL;DR: In this article, a 0.5 ms delay line with a time-bandwidth product of > 105 was demonstrated by recirculating a 2 ns pulse around a 20.4 km single-mode fiber five times.
Abstract: A 0.5 ms delay line with a time-bandwidth product of > 105 is demonstrated by recirculating a 2 ns pulse around a 20.4 km single-mode fibre five times. Analogue signal regeneration is employed after each recirculation. System dynamic range, signal/noise ratio and cancellation ratio for a noncoherent moving target indicator radar application are given.

11 citations


Patent
31 Jan 1984
TL;DR: In this paper, a radar channel is included for doppler processing the received N+1 pulse echo signal bursts, where the radar is operative to change the transmitted carrier frequency from one pulse burst to another.
Abstract: In a radar operating in a moving target indication (MTI) mode with frequency diversity by transmitting N+1 pulse bursts and receiving echo signalling therefrom, a radar channel is included for doppler processing the received N+1 pulse echo signal bursts. Each pulse of the same burst envelopes a fixed carrier frequency. The radar is operative to change the transmitted carrier frequency from one pulse burst to another. The radar channel comprises an MTI filter operative as two different orthogonal MTI filters, each having a frequency response similar to an N-pulse MTI filter, to process functionally in parallel a received N+1 pulse echo signal burst to generate a filter signal from each functional filter. Also included is apparatus for combining the two filter signals non-coherently to generate a composite signal corresponding to the N+1 pulse echo signal burst for target detection. The radar channel is operative to process N+1 pulse bursts with either fixed or variable interpulse periods. The two functionally operative filters have frequency response characteristics substantially similar to each other for target echo signals, but effect uncorrelated noise output signals corresponding to a common N+1 pulse echo signal burst.

10 citations


Proceedings ArticleDOI
04 Dec 1984
TL;DR: The Pipelined Resampling Processor was presented to this conference in 1983 in concept as a practical solution to real-time high resolution geometric image rectification needs and performance results obtained from the development unit completed in late 1983 are presented.
Abstract: The Pipelined Resampling Processor (PRP) was presented to this conference in 1983 in concept as a practical solution to real-time high resolution geometric image rectification needs. In the present report we present performance results obtained from the PRP development unit completed in late 1983. The small size, weight, and power requirements of the PRP and its high throughput make it very well suited for space and airborne applications where goemetric correction of image data must be done autonomously in real-time. This high resolution geometric correction is a necessary adjunct to applications using frame differencing or frame averaging for motion compensation, moving target indication, noise suppression or data compression as well as applications requiring precise correction of focal plane sampling distortions. By equipping the PRP with manual controls, image geometry can be manipulated at video rates from a console to achieve a much higher image analysis throughput than is possible for more general purpose processing facilities. In mapping, merging, classifi-cation and registration applications, interactive video rate processing will be important in bringing these and other image analysis techniques out of the laboratory and into an operational environment.

4 citations


06 Apr 1984
TL;DR: In this article, the authors used six integrators used in long-term radar integration and found that there was significant improvement in target detection due to the long term integration and that the false target generation could be controlled.
Abstract: : Six integrators used in long term radar integration were studied. Generally, we found, even in fairly dense background of targets, that there was significant improvement in target detection due to the long term integration and that the false target generation could be controlled. The mechanism that allowed this result is based on removing a small percentage of the strongest signal in each integrator. This mechanism removed the few true target signals in many of the integrators which could cause ghost detections that were not valid targets. Using this technique, the false detections were easily controlled at only a very small expense in true target detectability.

2 citations


Patent
20 Jan 1984
TL;DR: In this paper, the output picture of an image pickup device is stored in a frame memory and the readout timing at which the picture is read out of the memory is varied according to the output of a gyro detecting the motion of a turntable.
Abstract: PURPOSE:To cancel picture blurring and extract only the movement extent of a moving target, and to display the moving target with high precision by storing the output picture of an image pickup device temporarily, and varying the readout timing of the picture according to the output of a gyro detecting the motion of a turntable. CONSTITUTION:The output picture of the image pickup device 5 is inputted to a frame memory 12 and stored therein temporarily. The output of the gyro 8 detecting the motion of the turntable 4, on the other hand, is inputted to the memory 12. The readout timing at which the picture is read out of the memory 12 is varied according to the output of the gyro 8. Consequently, picture blurring due to the deviation of the turntable 4 is canceled and only the movement extent of the target is extracted.

1 citations


Proceedings ArticleDOI
01 Mar 1984
TL;DR: Close form analytical expressions, maximising detection probabilities for given false alarms, are presented which allow the use of a lattice as a detector by setting thresholds on the associated reflection coefficients in order to identify a signal from background noise.
Abstract: Conventional processors for analysing pulsed Doppler returns employ either fixed digital filter schemes for target location, or FFT processors for identifying target velocities. In this paper a new configuration is proposed for processing radar returns which employ a lattice structure. Based upon the underlying probability distribution of the complex reflection coefficients; closed form analytical expressions, maximising detection probabilities for given false alarms, are presented which allow the use of a lattice as a detector by setting thresholds on the associated reflection coefficients in order to identify a signal from background noise. Using clutter models for ground clutter and weather clutter it is shown that in some circumstances the lattice can be used to identify a target in clutter environment.

Patent
13 Apr 1984
TL;DR: In this article, a memory for storing data on the atenuation quantity of the received signal of radar for every fractionized range and azimuth sections is proposed. And the memory is accessed with addresses obtained by a range address counter.
Abstract: PURPOSE:To vary a radar received signal not only in a range direction, but in an azimuth direction and to remove clutter excellently by providing a memory for storing data on the atenuation quantity of the received signal of radar for every fractionized range and azimuth sections. CONSTITUTION:The data on the radar received signal from a data input circuit 10 which is attenuated stepwise or according to a specific function is written in the memory 13 sectioned by the range and azimuth. The contents of this memory 13 are accessed with addresses obtained by an azimuth address counter 15, range address counter 16, etc., and outputted through a D/A converter 12, etc., and then received signal is attenuated not only; in the range direction, but also in the azimuth direction, so that clutter generated on the video signal on a moving target indicator owing to abrupt variation in clutter reception level at the boundary part of an attenuation quantity setting area disappears and the remainder is also removed.

ReportDOI
31 Dec 1984
TL;DR: This report uses a simplified clutter return model for MTI simulation and shows how this model produces the same correlation function and spectral density function as the ones measured from an actual radar return.
Abstract: : A radar return form a patch of clutter usually consists of a large number of echoes from individual scatterers. Each of these scatterers moves randomly and introduces a randomly distributed doppler spectrum. Therefore, to simulate the performance of a MTI (Moving Target Indicator) system, we must sum a large number of randomly distributed samples from each radar pulse return. The computer-time required in this case is very lengthy, and therefore it is not feasible for us to use this approach in a large-scale simulation. In this report we use a simplified clutter return model for MTI simulation. We show how this model produces the same correlation function and spectral density function as the ones measured from an actual radar return. We then use this simulation program to compute the statistical distribution of the improvement factor of a MTI system with binomial weights. Originator-supplied keywords include: Signal processing.

Proceedings ArticleDOI
09 Jan 1984
TL;DR: In this article, an infrared search and track system with optical processing to support background rejection and moving target indication is described, where background rejection consists of a spatial filter to eliminate large distributed sources on which a small target is superimposed, and optical image subtraction to remove small stationary targets.
Abstract: As modern infrared sensing systems become smarter and able to collect more data at faster rates, the complexity of on-board data processing systems becomes greater. While V HSIC and VLSI digital systems offer a great amount of support for the on-board processing, there is a place for optical data processing. This paper discusses one processor architecture which performs several on-board analysis functions optically as well as reduces the data processing load which the electronic digital processing portion must address. The application exemplified is an infrared search and track system with optical processing to support background rejection and moving target indication. Backgrounds to be rejected in this application do not generally exceed the target intensity; that is, the targets are typically as bright as or brighter than the background. Background rejection consists of a spatial filter to eliminate large distributed sources on which a small target is superimposed, and optical image subtraction to remove small stationary targets. Moving target indication is performed with a spatial filter and a wedge detector array. Techniques for target characterization and identification have been developed but will not be discussed in this paper; nor will techniques for ballistic target impact point prediction be presented. One of the more difficult aspects of optical processing is the interconnect between the infrared detector array and the optical processor; candidate technologies for this optical interconnect will be reviewed.