Showing papers on "Moving target indication published in 1986"

Radar target discrimination by convolution of radar return with extinction-pulses and single-mode extraction signals

Abstract: A new method of radar target discrimination and identification is presented. This new method is based on the natural frequencies of the target. It consists of synthesizing aspect-independent discriminant signals, called extinction-pulses (E-pulses) and single-mode extraction signals which, when convolved numerically with the late-time transient response of an expected target, lead to zero or single-mode responses. When the synthesized, discriminant signals for an expected target are convolved with the radar return from a different target, the resulting signal will be significantly different from the expected zero or single-mode responses, thus, the differing targets can be discriminated. Theoretical synthesis of discriminant signals from known target natural frequencies and experimental synthesis of them for a complex target from its measured pulse response are presented. The scheme has been tested with measured responses of various targets in the laboratory.

Multiple parameter doppler radar

Abstract: A multiple parameter doppler radar system transmits a radar signal which is alternated between a first and second frequency toward a target. The doppler shifted signals reflected from the target are received and processed to derive a pair of doppler signals related respectively to the first and second frequency signals. The frequency of one of the doppler signals is measured and scaled to a target speed. The phase magnitude between the two doppler signals is measured and scaled to a target range. The phase lead/lag relationship of the two doppler signals is detected to determine if the target is moving toward or away from the radar system. The components of the system are controlled by a microprocessor which is programmed to perform quality determinations on the data derived from the signals to assess the reliability of the data even in a multiple target environment prior to displaying the parameters of target motion.

Coherent radar detection in log-normal clutter

Abstract: The paper deals with the problem of radar detection of a target echo embedded in log-normal clutter and white Gaussian noise. Relevant features of this article, with respect to previous papers on the same subject, refer to the coherent model assumed for the clutter and the processing chain. In more detail, the in-phase and quadrature components of clutter have been modelled to give a log-normal amplitude distribution and a near uniform distribution of the phase. Any shape of the correlation among consecutive clutter samples is also allowed in the model. At the same time, the processing chain is also coherent, i.e. it operates on the two components of the signals. Two architectures have been considered for the processor. The first, used in current practice, is formed of a linear transversal filter (for the clutter attenuation and the target echo enhancement) cascaded with a quadratic envelope detector and a comparison with a suitable threshold. The second processor considered differs from the previous one in the filter for clutter cancellation. A nonlinear homomorphic filter has been conceived to obtain a better suppression of clutter. The detection performance of the two processing chains have been evaluated, by means of computer simulation, in a number of operational cases of intrest. The paper gives a first contribution to the problem of finding better models of disturbance and of deriving more efficient processing chains.

Pulse radar equipment

Abstract: PURPOSE:To detect stably a moving target by switching a transmission frequency and a radiation polarized wave at every transmission period. CONSTITUTION:Local oscillation signals of local oscillators 1 and 1' are switched by a switch 14 with a transmission frequency switching signal and applied to transmitting and receiving mixers 3 and 10. Then, the signal is mixed with the oscillation signal of a coherent oscillator 2 by the mixer 3 and the lower side band is removed by a filter 4 to obtain a transmit signal. Then, the signal is separated into a vertically and a horizontally polarized waves by a polarized wave switch 15 after being passed through a power amplifier 5, etc., then radiated from an antenna 9. A reflected wave from the target is received by the antenna 9 and uniformed by a switch 15 into the same polarized wave, which is passed through a switch 8 and supplied to a filter 4' to remove its image frequency, so that a phase detection video is obtained by a phase detector 12 through a mixer 10, etc. Then, the signal is applied to moving target indicator circuits 13 and 13' while having the opposite polarities through a switch 14' at every transmission period and a received signal from a fixed target is removed from received signals to extract the received signal from the moving target; and video addition 16 is carried out to obtain the video output of the moving target.

MTI Target Visibility

Abstract: The available target Doppler space over which the target-to-clutter lutter improvement factor is equal to or greater than a design value based on the conventional moving target indicator (MTI) improvement factor I is investigated. Quantitative results are given for case of a zero-mean Gaussian spectrum using binomial weighting.

Automatic discrete frequency-controlling system

Abstract: The utility model relates to an automatic discrete frequency-controlling system, belonging to the technical field of an electronic circuit and a radar. The utility model is mainly adopts a slope discriminator composed of a wideband amplification, a differential pair amplitude limiting, a low pass filter, and a pulse detector. Two voltage comparators plot the frequency deviation region to make the analog circuit and the digital circuit bonded organically to realize the control of the discrete frequency. The automatic discrete frequency-controlling system not only doesn't damage the phase-locked frequency stabilization work of leveling off the vibration source, but also automatically carries out the frequency tiny control when the signal or the vibration frequency changes in a large scope. The utility model has the advantages of simple circuit, small size, convenient adjustment, stabilization, and credibility. The automatic discrete frequency-controlling system can be used for a usual radar, and a communication and reconnaissance receiver, besides the moving target indication, the moving target detection, and the automatic frequency tiny control system of the pulse Doppler radar.

Two-port synthetic aperture radar system.

Abstract: A two-port (port 1, 2) radar system measures the amplitude and phase clutter of target returns at both ports during staggered time intervals when sliding window processing occurs. Clutter returns remain constant but target returns from a moving target, between successive intervals, generate a phase difference indicative of relative radial target velocity.

Simulation of an adaptive MTI in a monopulse FMCW radar sensor

Abstract: A range-doppler spread target model is modified to obtain a clut ter model by including the effect of beam and range gate shape. This clutter modeling is then applied in a simulation of an FMCW radar sensor that uses an adaptive moving target indicator (AMTI) and a monopulse antenna to detect slow-moving ground targets. The ability of the AMTI to discriminate a slow-moving point target from ground clutter is shown via simulation.