MTI Weightings

A comparison is made between optimum weighting, which maximizes Pd for a given ?, and several MTI weightings. It is shown that a special case of the optimal weighting is approximately equal to the MTI weighting which maximizes the MTI improvement factor.     

CTD MTI Radar Filter with Charge-Transfer Inefficiency Compensation

The design and implementation of a second-order nonrecursive moving target indication (MTI) radar filter using commercially available charge-transfer devices as delay lines are described. A simple technique is included to compensate for the device charge-transfer in-efficiency and its sensitivity is analyzed. Experimental laboratory tests and results in an operating radar system are reported showing the good performance of the realized MTI radar filter.     

Quantization Requirements in Digital MTI

To minimize hardware complexity, it is desirable to implement a digital moving target indicator (MTI) with the fewest number of quantization levels. The reduction of the clutter cancellation ability of single-and double-canceller MTI's is discussed with binominal weighting as a function of the number of levels and the spacing of the levels. The method of analysis is applicable to more complex MTI's as weil as nonuniform quantizers.     

MTI Target Visibility

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.     

Correlation Effects of MTI Filters

A frequency domain approach for determining the effective number of independent pulses at the output of a square law detector in a moving target indicator (MTI) system leads to a definition which gives the same asymptotic results as given by a previous definition.     

Airborne adaptive MTI scheme with preventing the whitening of thetarget

A new airborne MTI scheme that applies to non-homogeneous clutter environment is presented. Results of simulation have proved that the scheme has a superior ground clutter suppression performance and can effectively prevent the whitening of a target     

Constrained Improvement MTI Radar Processors

A new class of staggered PRF MTI radar processors is developed in this paper. These processors are constrained to achieve a specified value of MTI improvement and, subject to this constraint, minimize variations in processor response as a function of target Doppler frequency. The selection of both filter weights and PRF stagger sequences is discussed and a number of representative designs are presented.     

MTI Improvement Factors for Weighted DFTs

The use of the discrete Fourier transform (DFT) to enhance the detection of moving targets in ground clutter is examined. The improvement factor, defined as the signal-to-clutter ratio at the DFT processor output compared with that of the input, is given as a function of normalized clutter spectral width for various weighting functions on the DFT input. The effect of quantization of the weights on the improvement factor is also examined.     

MTI Processing and Weibull-Distributed Ground Clutter

It is shown that the Weibull-distributed ground clutter obeys a Weibull distribution after processing by the double canceler moving target indicator (MTI).     

Closed-Form Expressions for Noncoherent Radar Integration Gain and Collapsing Loss

Closed-form formulas allow rapid determination of noncoherent integration gain and integration loss when the single-sample IF signal-to-noise ratio (SNR) is known. In addition, if the required SNR is known for any number of integrated pulses, the required SNR for any other number is easily determined. A closed-form expression is given for radar collapsing loss, expressed in terms of the equivalent integrated signal-to-noise ratio required to produce a given combination of false-alarm and detection probabilities. Alternatively, the single-sample signal-to-noise ratio of a set of samples may be used together with the closed-form expression for integration gain to get the equivalent integrated signal-to-noise ratio.     

An Adaptive MTI for Weather Clutter Suppression

A digital realization of an adaptive clutter-locking loop is presented. The purpose of the loop is to estimate the mean Doppler frequency of the clutter. The clutter spectrum is then shifted toward the zero Doppler by this estimate. A fixed moving target indicator (MTI) canceler following the loop suppresses the shifted clutter. Experimental simulations illustrate the feasibility of the loop. Results indicate that the proposed canceler works significantly better than a fixed canceler, while not as well as the 10-pulse moving target detector (MTD) processor. However, the complexity of the MTD is significantly more than the relatively simple adaptive processor presented here.     

Clutter suppression using recursive and nonrecursive MTI filters

The author calculates the effectiveness of clutter suppression of a moving-target-indicator (MTI) filter in tandem with a fast-Fourier-transform (FFT) Doppler filter bank, taking into account the transient response of the MTI filter. Both recursive and nonrecursive filters are considered. The analysis is extended to the high-pulse-repetition-frequency (PRF) case with clutter fold over. The results can be used to select key design parameters, including the MTI filter, the window size, and the initial transient segment to be discarded. Numerical examples are included     

Battlefield awareness via synergistic SAR and MTI exploitation

“Battlefield awareness” is critical to the success of future military operations. Existing and new sensor platforms will provide the necessary surveillance data; DARPA is developing the systems needed to turn the sensor data into meaningful information for the commanders. A central thrust of these efforts exploits the synergistic relationship between SAR and MTI radar. Used together, they offer comprehensive coverage of the battlefield     

Weighting Factor and Transmission Time Optimization in Video MTI Radar

In an earlier paper by the author the problem of determining the optimum symmetrical weighting factors for a video MTI radar was discussed. This paper extends this work so as to remove the symmetrical restriction from the problem. In addition, for a staggered pulse system, optimum times of transmission are determined. In the earlier paper a global solution to the restricted optimization problem was achieved. In this paper only a locally optimum solution is achieved for the more general problem.     

The Susceptivity of MTI Systems to White Noise

The performance of various coherent MTI systems in the presence of white noise is investigated. The single-pulse signal-to-noise ratios at the output of the filters are presented for the case of large system bandwidth. Generalized results, calculated as a function of the system's bandwidth, are given. Finally, those results are compared to the optimum signal-to-noise acheivable by a matched filter.     

MTI Clutter Locking for Arbitrary Clutter Spectral Shapes

Clutter-locking criteria for various types of cancellers and clutter spectra are discussed. It is shown that the proper locking criterion for general asymmetric clutter spectra is different from that applicable to those spectra which have even symmetry or are very narrow.     

Clutter Residues of a Coherent MTI Radar Receiver

In moving target indicator radar receivers a saturation is always present in the IF stages in order to compress the dynamic range of large clutter inputs. This nonlinearity greatly affects the performances of the cancelling circuits, because of the spreading of the spectra. A quantitative analysis of this effect has been conducted, with an analytical expression chosen for the limitation characteristic. A high degradation of both single-and double-canceller improvement factors has been obtained. Losses of 20 dB for the double canceller are not uncommon. Clutter residue levels at the receiver output have also been computed in order to see how the performance compares with ideal constant false alarm rate behavior.     

Effect of timing jitter on performance of MTI filters

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     

Performance Compparison of Optimum and Conventional MTI and Doppler Processors

The performance of an optimum radar signal processor and more conventional techniques (such as MTI, adaptive MTI, and cqherent integration) are compared. A mathematical method is suggested and applied to several cases of practical interest. A number of operative conditions are discovered in which the conventional processing techniques give very poor performance and the optimum radar processor becomes necessary.     

On Increasing Usable MTI Filter Bandwidth by Removing Linear-Phase Constraint

It has been shown in the literature that the linear-phase constraint of finite-duration impulse-response (FIR) digital filters can, under certain circumstances, be effectively traded either for a better filter amplitude response or a reduction in the number of filter coeficients. It is shown that such a tradeoff can be exploited for moving target indicator (MTI) radar signal processors to increase the usable bandwidth for target detection. Although it is demonstrated that the increase is significant for narrowband (ground) clutter, it is negligible for wideband (weather) clutter.