Radar in the Soviet Union and Russia: a brief historical outline

This paper outlines the historical development of radar in the Soviet Union and Russia. Emphasis was given to only two classes of radars: surveillance radars for air defense (AD) systems; and radars for surface-to-air missile (SAM) systems.     

History of monopulse radar in the USSR

Monopulse radars have played an important role in air and missile defense systems since the development of the monopulse technique in the late 1940s. This paper outlines the application of monopulse radars in Russian defense systems, starting with the Moscow ABM system and continuing in instrumentation and air defense radars now widely deployed in Russia and elsewhere     

Ukraine institute of radio astronomy high-resolution radars

A review is given of recent activities undertaken in the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine for the development of high-resolution radars. The radars developed include 95- and 36-GHz cloud radars and an airborne, Ku-band SAR radar system. They are capable to perform real-time, high-resolution measurements. The set-up of these instruments, the novel technical solutions, and the signal processing technique introduced are discussed. The results obtained with such instruments during measurement campaigns are presented as well.     

VHF (metric band) radars from Nizhny Novgorod ResearchRadiotechnical Institute

This paper gives an overview of VHF (metric band) radars developed and manufactured in Nizhny Novgorod Research Radiotechnical Institute ¹ during 50 years of its existence. The salient features, technical performances, advantages and problems of those radars are discussed     

Mapping lightning channels in a thunderstorm by radar

The state of Georgia has experienced a number of tornados that occur without warning, and, in several cases have caused fatalities. Researchers at the Severe Storms Research Center (SSRC) of the Georgia Tech Research Institute (GTRI), Georgia Institute of Technology are attempting to detect tornado formation within severe thunderstorms occurring in the vicinity of Atlanta, Georgia, using non-radar sensors that may provide early tornado warning and provide cueing to existing National Weather Service (NWS) radars. The goal of these studies is to increase the warning time of tornado formation within the parent thunderstorm. GTRI researchers use real-time S-band Doppler weather radar data from three National Weather Service WSR-88D NEXRAD radars to complement the development of the non-radar tornado sensors. Three NWS Doppler radars provide severe weather surveillance coverage of the north Georgia area to determine if a thunderstorm contains the Doppler signature that indicates tornado formation. The radar data, displayed on a work station developed and optimized for tornado detection by the National Severe Storms Laboratory (NSSL), serves as ground truth data for the non-radar sensor development. GTRI can display cloud to ground (CG) lightning strikes, a capability provided by overlaying data from a national monitoring network onto the radar reflectivity map. GTRI also uses a local lightning direction finder (DF) system that supplies azimuth and range to the lightning strike. This paper discusses the early lightning channel research and the passive parasitic radar system being operated by the SSRC.     

Medium PRF Performance Analysis

A discussion of various types of x-band airborne radars is presented together with their systematic development through the years to the present time. Starting with simple, low pulse-repetition frequency (PRF) radars for measuring radar-target range, airborne radar development proceeded with more sophisticated high PRF Doppler radars where radar-target range and range rate were measured simultaneously. The use of Doppler (frequency) in signal processing allowed the separation of moving from nonmoving targets (ground), enabling the detection of moving targets in the presence of ground clutter. More recent developments in waveform generation and selection has resulted in the development of medium PRF radars, whereby a greater degree of tactical flexibility in target detection is achieved by combining the desirable features of both low and high PRF radars. Part of the available literature gives an overview, together with a specific example of the design and performance of an airborne medium PRF radar. Here, however, the systematic evolution of these radars is emphasized and the necessary theoretical background is developed for their performance calculations. Modern day airborne radars may be equipped with all three modes of operation, low, medium, and high PRF, allowing the operator to utilize the mode best suited for the tactical encounter. Low PRF and high PRF radars have been described elsewhere and are given here primarily for the sake of completeness and for the necessary background for developing medium PRF radar equations. They are also needed for developing the reasons why medium PRF radars came into being.     

国外机载海面监视雷达发展现状与趋势

首先对目前西方国家装备的较先进的机载海面监视雷达进行了介绍,总结了它们的技术特点。现役机载海面监视雷达具有多功能和多工作模式的特点,除增强了对高海况下的小目标检测能力外,还新增了气象探测、SAR/ISAR和HRRP等先进功能。最后指出了机载海面监视雷达未来发展趋势。     

Angle Estimation in Amplitude Comparison Monopulse Systems

The problem of estimation of angle of arrival in amplitude comparison monopulse (ACM) radars in the presence of internally generated thermal noise is considered. A pulse-type radar is assumed and angular noise is postulated to be absent. In the treatment of the problem, explicit inclusion of various simple models for the pulse returns is made to draw a relationship between the a priori statistics of the echo signals and the ability to estimate the angle of arrival in ACM radars. A maximum likelihood analysis is made to determine the form of the estimates of angle of arrival for the various cases and the accuracy of these estimates is evaluated as a function of the signal-to-noise ratio per hit and of the number of hits. Although most of the estimates considered have already received attention, many of the results are believed to be new.     

New Developments in Radar and Radio Sensors for Aircraft Navigation

Recent developments in airborne Doppler and ground mapping navigation radars and ground and satellite based radio systems are described. Simultaneous lobing and slope tracking techniques can remove the well-known Doppler sea bias error in fast and slowly moving vehicles. Doppler velocity information can be extracted from coherent forward-looking mapping radars, and high position fixing accuracy can be achieved by synthetic aperture radars. In radio navigation systems, such as Loran, Omega, and satellite systems, direct-ranging and differential techniques greatly reduce the geometric dilution and propagation effects which have plagued conventional radio navigation systems. The advantages gained by mixing of the data from these and other navigation sensors in a digital multisensor system are discussed and approaches for processing these data are suggested.     

Airborne GMTI radar position bias estimation using static-rotatortargets of opportunity

In target tracking systems: using GMTI (ground moving target indicator) radars on airborne platforms, the locations of these platforms are available from GPS-based estimates. However, these estimated locations are subject to errors that are, typically, stationary autocorrelated random processes, i.e., slowly varying biases. In situations where there are no known-location targets to estimate these biases, the next best recourse is to use targets of opportunity at fixed but unknown locations. Such targets can be, e.g., static rotators (ground-based radars with rotating antenna), which yield detections in moving target indicator (MTI) radars. It is shown that these biases can be estimated in such a scenario, i.e., they meet the complete observability condition. Following this, the achievable accuracy for a generic scenario is evaluated. It is shown that accurate georegistration can be obtained even with a small number of measurements     

Multipath Tracking Errors in Elevation-Scanning and Monopulse Radars

The tracking performance of elevation- scanning and monopulse radars in the presence of multipath propagation are compared. The key difference between these two generic types of radars is the way they respond to moving targets. There are no significant differences between their responses to pure specular multipath, nor to diffuse multipath for targets on radial courses. However, they are found to respond quite differently to the diffuse com ponent for low-altitude crossing targets. For these conditions the tracking errors for elevation-scanning radars may be several times those for monopulse radars.     

Reacting to new air defence threats: a netcentric approach to the Hungarian air defence system augmented by VHF radars

Different types of distributed radar systems and data fusion centers are increasingly used by surface-based air defense systems. Besides the well-established airborne threats, new platforms for air surveillance and attacking devices have appeared and recognized air picture (RAP) production needs to be revised and modified following the events of September 11, 2001. From a military operational and logistic support point of view, it is well-known that not only the long range radars currently in operation, but also the recently procured radars, degrade in performance rapidly and their maintenance costs are high. Using the possibilities offered by emerging technical developments, the problem is to upgrade sensors and existing infrastructure in a way that exploits the information gathered optimally. It is the opinion of this author that one of the most promising approaches to emphasis net-centricity is the use of radar-triangle netcentric structures augmented by netted VHF radars to solve these tasks in a cost-effective manner. This work introduces an analysis of a solution that fully integrates newly required capabilities into the current long range radar net and infrastructure, keeping research and development (R&D) and maintenance at a low cost.     

基于随机文法的多功能雷达识别方法

 针对多功能雷达采用复杂体制而造成的辐射源不能正确识别问题,提出了一种基于随机文法(SG)的辐射源识别算法。该算法基于多功能雷达的句法模型,将威胁数据库中的多功能雷达文法分为随机正则文法(SRG)和随机上下文无关文法(SCFG)两种情况,并分别构造随机有限自动机(SFA)和随机下推自动机(SPDA)对测量辐射源进行识别。仿真实验表明,该方法不仅能识别出多功能雷达辐射源的型号及模式,而且能识别出雷达辐射源的功能状态,并进而推断出雷达辐射源的威胁等级。     

Passive localization of frequency-agile radars from angle andfrequency measurements

It is well known that the position of a stationary radar can be estimated by a single moving observer from angle and/or frequency measurements taken passively at different points in its trajectory. Depending on the measurement set different localization methods result: the bearing method (BM), the frequency method (FM), and the combined method (CM). Previous studies analyze the three methods on the basis of constant emitter frequencies. However, radars with constant emitter frequencies are not realistic. Frequency drift and frequency hopping have to be taken into account. Therefore, to include radars the emitter model has been extended by drift and frequency hopping in this study, and the estimation methods have been reanalyzed. The effects of the model extensions become transparent in a parametric Cramer-Rao (CR) analysis. The results obtained in this way are confirmed by Monte Carlo simulations taking maximum likelihood (ML) as estimation procedure     

Probability of Pulse Coincidence in a Multiple Radar Environment

Elementary probability theory is used to develop three formulas for the probability of two or more pulses being coincident at an observer's aircraft position in a multiple radar environment. The first formula is for nonscanning tracking type radars with different pulsewidths (PWs) and pulse repetition frequencies (PRFs), the second is for generically identical nonscanning radars with similar PWs and PRFs, and the third is for scanning type radars such as air search radars with similar PWs and PRFs. The probability of coincidence is related to the mean-time-between-coincidences (MTBC) and to the average coincidence rate. Two sample problems are given.     

俄罗斯的航空可焊钛合金

介绍了俄罗斯航空工艺研究院最新推出的航空可焊钛合金的牌号及性能简况     

Polish radar technology

Polish radar research and development since 1953 is reviewed, covering the development and production of surveillance radars, height finders, tracking radars, air traffic control (ATC) radars and systems, and marine and Doppler radars. Some current work, including an L-band ATC radar for enroute control, a weather channel for primary surveillance radar, signal detection in non-Gaussian clutter, adaptive MTI filters and postdetection filtering, and a basic approach to radar polarimetry, is examined.<>     

2D雷达组网中目标高度估计误差的Cramér-Rao限

 在由2坐标雷达组成的雷达网中,推导了目标高度估计误差的CRLB(Cram&;#225;r-Rao限),并通过不同条件下的数值计算得到了一些结论。结果表明,目标高度估计误差的CRLB既与雷达的测角误差有关,也与目标和2个雷达站形成的夹角有关系,雷达配置在不同的高度上有利于目标高度估计的收敛性。这些结论对于2坐标雷达组网以及雷达网中的传感器管理具有指导意义。     

Patch diameter limitation due to high chirp rates in focused SARimages

Polar-format processed synthetic aperture radar (SAR) images have a limited focused patch diameter that results from unmitigated phase errors. Very high chirp rates, encountered with fine-resolution short-pulse radars, exasperate the problem via a residual video phase error term. This letter modifies the traditional maximum patch diameter expression to include effects of very high chirp rates