Waveform Design for Multistatic Radar Detection

We derive the optimal Neyman-Pearson (NP) detector and its performance, and then present a methodology for the design of the transmit signal for a multistatic radar receiver. The detector assumes a Swerling I extended target model as well as signal-dependent noise, i.e., clutter. It is shown that the NP detection performance does not immediately lead to an obvious signal design criterion so that as an alternative, a divergence criterion is proposed for signal design. A simple method for maximizing the divergence, termed the maximum marginal allocation algorithm, is presented and is guaranteed to find the global maximum. The overall approach is a generalization of previous work that determined the optimal detector and transmit signal for a monostatic radar.     

Simple Procedures for Radar Detection Calculations

The literature of radar contains results of Rice, Marcum, Swerling, and Schwartz in several families of curves, which permit radar engineersto estimate the signal energy ratio required for a given level of detectionperformance. The variety of radar problems, however, makes itimpractical to construct curves for all combinations of radar and targetparameters. The concept of detector loss is used here to evaluate lossesattributable to integration and collapsing, with an accuracy of ±0.3 dBon steady targets. This is added to a separate fluctuation loss, modifiedfor diversity effects, to obtain results on all Swerling target modelsand also on partially correlated targets. The accuracy of the combinedlosses is ±0.5 dB for a wide range of detection and false-alarm probabilities.Starting from the basic single-sample detection curves, onlythree additional graphs are needed to find the energy ratio for givendetection performance in any of these cases. Examples are given whichshow the ease with which different radar options may be compared asto performance on an arbitrary type of target.     

UWB Radar for Human Being Detection

UWB radar for detection and positioning of human beings in a complex environment has been developed and manufactured. The novelty of the radar lies in its large operational bandwidth (11.7 GHz at -10 dB level) combined with high time stability. Detection of respiratory movement of a person in laboratory conditions has been demonstrated. Based on experimental results, human being radar return has been analysed in the frequency band from 1 GHz to 12 GHz. The novel principle of human being detection is considered and verified experimentally.     

A Method for Radar Turbulence Detection

A method is described whereby a conventional non-Doppler radar may be used in the measurement and detection of atmospheric turbulence. The technique involves the measurement of the average echo power and the variance of the fluctuation spectrum in each of two separated pulse volumes, and corresponding measure ments of echo power and variance of the detected signals in a channel representing the predetection sum of the signals from those two volumes. It is shown that the variance of the sum channel is the power-weighted sum of the variances in the independent channels plus a term dependent upon the difference in mean radial velocity of the associated pulse volumes. Accordingly, the difference in mean radial velocity can be measured. When the spacing of the sampled volumes is adjusted to represent distance along an aircraft flight plan, the measurement is a measure of the turbulence to be experienced in traversing the space between those volumes. Specific systems for accomplishing the measure ment are discussed.     

Simple Expressions for Determining Radar Detection Thresholds

The threshold value required to obtain a specified false-alarm probability, when postdetection integration follows a square-law or an envelope detector, is frequently needed in theoretical and practical studies of radar signal processor performance. The determination of such threshold values requires a substantial numerical computational effort. In this correspondence, simple expressions are presented with which these thresholds can be determined with excellent accuracy using only a scientific calculator.     

Performance Data for a Double-Threshold Detection Radar

A problem f requently encountered by radar systems analysts is the evaluation of the "double-threshold" or M out of N detection process. Detection probabilities of this process are binomially distributed, making it difficult to obtain exact results for large values of the number of samples and for low probabilities of false alarm. In this paper, the M out of N detection algorithm is defined and detection performance is calculated for the special cases of the nonfluctuating target and Swerling cases I and 11 for false alarm probabilities of 106, 10-8 and 10-10.     

Target Detection and Parameter Estimation for MIMO Radar Systems

We investigate several target detection and parameter estimation techniques for a multiple-input multiple-output (MIMO) radar system. By transmitting independent waveforms via different antennas, the echoes due to targets at different locations are linearly independent of each other, which allows the direct application of many data-dependent beamforming techniques to achieve high resolution and excellent interference rejection capability. In the absence of array steering vector errors, we discuss the application of several existing data-dependent beamforming algorithms including Capon, APES (amplitude and phase estimation) and CAPES (combined Capon and APES), and then propose an alternative estimation procedure, referred to as the combined Capon and approximate maximum likelihood (CAML) method. Via several numerical examples, we show that the proposed CAML method can provide excellent estimation accuracy of both target locations and target amplitudes. In the presence of array steering vector errors, we apply the robust Capon beamformer (RCB) and doubly constrained robust Capon beamformer (DCRCB) approaches to the MIMO radar system to achieve accurate parameter estimation and superior interference and jamming suppression performance.     

Simple Radar Detection Calculation

Barton's [1] procedure is further simplified to require only the use of a single-valued detector loss curve plus ideal detector curves to calculate the performance of envelope detectors with postdetection integration.     

Decision Cells for Positional Radar Identification of Satellites

There is a problem in deciding whether a radar observation of an object in outer space is of a known catalogued satellite or of a newly launched satellite. With some radar systems joint or dumbell radar images of two satellites cause occasional confusion, and appropriate decision theory for this situation is derived. Decision theory for the individual image is given in an appendix.     

雷达检测性能试验等效推算方法

 雷达检测性能是雷达最基本、最重要的性能,雷达检测性能试验是雷达试验的重要内容。由于各种原因,针对雷达的系统级原型试验常常难以开展或者只能极少量地开展,通常只能通过进行大量等效试验来辅助雷达性能的鉴定评估工作。本文针对缺乏原型试验条件下的雷达检测性能评估问题,提出了一种基于试验数据分析的雷达检测性能等效推算方法。首先给出了等效试验与原型试验之间的差异性度量方法,它是等效推算和性能评估的基础;接着对存在原型试验条件下的等效推算方法进行了研究;而后针对通常无法进行原型试验的实际情况,提出了一种基于预测模型和仿真试验相结合的零子样原型试验条件下的等效推算方法;最后通过仿真实例验证了本文方法的合理性和可行性。     

Threshold Control for Automatic Detection in Radar Systems

In automatic detection in radar systems an estimate of background clutter power is used to set the detection threshold. Usually detection cells surrounding the cell under test for the presence of a target are used to estimate the clutter power. In the research reported herein, the target location is taken to be uncertain and thus returns from a target could corrupt this clutter power estimate. It is shown how the threshold should be varied to compensate for the resulting degradation in detection performance. The threshold control procedure is based on a priori information about target location that could be supplied by the radar's tracking system. In addition, a simple procedure for calculating detection and false alarm probabilities for Swerling II target models is presented.     

A Suboptimum Rank Test for Nonparametric Radar Detection

The optimum rank detector structure, in the Neyman-Pearson sense and under Gaussian noise conditions, is approximated by a suboptimum structure that depends on an adjustable parameter. This new rank detector, which operates on radar video signal, includes other well-known detectors as particular cases. The asymptotic relative efficiency (ARE) of the proposed rank detector is computed, with its maximum value the ARE of the locally optimum rank detector (LORD). The detection probability versus signal-to-noise ratio, and the effects of interfering targets are also calculated by Monte-Carlo simulations for different parameter values.     

Radar Identification of Naval Vessels

A scheme is presented for the identification of naval vessels via active multiple-frequency radar interrogation. A major virtue of the described method is the use of a response waveform synthesized using amplitude data only. A prediction correlation using natural resonances associated with substructures on the vessels is applied to synthetically generated matched-filter response waveforms. The identification scheme is tested using measured model data for 8 vessels on a simulated sea surface. A correct identification probability of roughly 77 percent is obtained.     

Radar Detection in Weibull Clutter

Radar detection in Weibull clutter is examined from a statistical detection viewpoint. Weibull clutter parameters are determined and related to measured values of land and sea clutter. Optimum performance in Weibull clutter is determined, and practical receivers that approach this performance are identified. Receiver performance in Rayleigh, log-normal, and Weibull clutter is evaluated and compared.     

A High-Resolution Radar Detection Strategy

A comparison of single range cell detection and integrated contiguous range cell detection for a high range resolution radar is presented. A simulation was used to generate probability of detection curves for the two detection strategies using 10 target models with different target scattering characteristics. The integrated range cell detection strategy was found to be superior in all cases except when the target is composed of a single strong flare point.     

Radar Target Detection and Map-Matching Algorithm Studies

Results of a study of adaptive threshold target detection and map-matching algorithms are presented. Log threshold processing is shown to be preferred over linear threshold processing when the clutter data surrounding the target cell is contaminated by other targets, decoy corner reflectors, or bright clutter cells. Whereas previous studies have resorted to extensive Monte-Carlo simulations of log threshold algorithms, the results were obtained using a novel analytical approach based upon Parseval's theorem.     

Radar Signal Propagation and Detection Through Ice

In this paper we describe the existing and planned radar measurements of the planetary bodies. The dielectric properties of water ice and other potential surface and subsurface materials are discussed, as well as their dependency on temperature and structure. We then evaluate the performance of subsurface sounding radars using these parameters. Finally we describe some laboratory technique to help interpret the radar data, presenting some results obtained using dielectric spectroscopy methods.     

机载单通道雷达实波束扫描的前视探测

针对机载单通道雷达采用合成孔径雷达(SAR)技术、多普勒波束锐化(DBS)技术等途径难以实现载机飞行路线正前方高分辨率成像问题,研究了一种利用方位实波束重叠扫描的新型机载单通道雷达前视探测方法,讨论了提高方位分辨率的可行性和适用条件。该方法根据目标回波强度受到波束扫描增益调制的特点,通过计算修正的Capon空间谱来实现方位超分辨。模拟实验表明,所提方法能够实现机载单通道雷达的前视成像,可以显著提高波束主瓣区域内强弱临近目标的分辨能力。     

Dwelltime Minimization for Radar Target Detection in the Clear

Consider the design of a minimum dwelltime set of coherent, range-unambiguous pulse bursts that will provide a specified target detection performance in a clutter-free ("clear") range interval [Rmin,Rmax]. Practical procedures are presented here for finding these optimal waveform sets versus Rmax/Rmin, subject to a peak transmit power constraint. It is always possible to design a multiple-PRF clear mode that achieves the same effective use of energy as a single-PRF waveform with a 33 percent duty ratio. Slightly higher effective duty ratios can be achieved if the radar is capable of transmitting and processing two interleaved pulse bursts at the same PRF.     

Correspondence - Optimum Radar Signal for Detection in Clutter

It is shown that in order to maximize the detectability of a radar target in clutter whose Doppler is unknown and is uniformly distributed over the Doppler bandwidth a simple CW or narrowband signal is optimal. The optimality criterion is the average deflection coefficient, with the averaging being over target Doppler frequency. Most remarkably the result does not depend on the clutter spectrum but holds for any distribution of clutter energy with frequency.