Comments on `SCR-20 Radar Development' and `The SCR-270 in Japan'by Viewager et al

To add to the history of the SCR-270 radar's development (see Viewager et al., vol.3, no.12, p.3-6, 1988 and F. Voltaggio, ibid., vol.3, no.12, p.7-14, 1988) the commenter presents personal recollections regarding the modifications made to several SCR-270 radar sets operating in Hawaii just before the start of World War II     

The untold Pearl Harbor radar story

Ever wonder what happened to the radar set that detected the Japanese aircraft before the raid on Pearl Harbor? This article reveals the fate of that SCR-270 radar set; describes some of the radar development background; and includes typical results of a World War II command, control and communications system that used the SCR-270 as its backbone radar. The SCR-270 was a radio-echo detection and direction finding set for locating aircraft. It operated by transmitting a short-duration pulse of high frequency radio waves, which would be reflected or re-radiated by any metallic or conducting surface within the field of the directive transmitting antenna; therefore, one or more aircraft within the antenna field appeared as a source of reflected radio waves. Rotating the antenna which also served as the receiving antenna, provided a means for determining the azimuth or direction of aircraft. The system measured the time it took a blip or reflected return from the target to appear on a cathode ray tube indicator, to give the distance or range to the detected aircraft. The maximum range of the radar was about 250 miles up to 50,000 feet under all atmospheric conditions including rain, mist, smoke or fog, and during daylight or darkness. The azimuth and range data supplied by the set permitted the plotting of the location of detected aircraft on maps. Major performance characteristics of the radar are provided in the included table     

The SCR-270 in Japan

The deficient state of the radar in use when the war in Korea erupted in 1950 is described. The installation of the SCR-270 radar system is discussed, and its siting is considered. Test and performance results are examined     

Range Instrumentation Radars

The history of range instrumentation radars begins at the end of World War 11, with the SCR-584 radar. Since then, the use of instrumentation radars on ranges all over the globe has expanded greatly to gather metric performance data on aircraft, projectiles, missiles, and satellites. In this paper, key subsystem-level and system-level developments during the past decade are reviewed, including pulse-Doppler, digital range systems, calibration techniques, computer usage, and dualfrequency systems. Recently developed instrumentation radars from domestic and foreign sources are described as are three unique high-power large-aperture systems used for satellite and ballisticmissile measurements. The paper concludes by examining the likely requirements for instrumentation radars of the future.     

Adaptive Radar Detection with Asymptotically Regulated False-Alarm Rate

An adaptive detection procedure is described by which the detection threshold is so adjusted as to provide an asymptotic false-alarm probability PFA that is approximately invariant with changes in radar clutter return amplitude probability density functions (pdf's) in a broad class. The class includes Rayleigh, chi, Weibull, and lognormal pdf's. The receiver noise is also taken into account. The clutter-plus-noise pdf is approximated by a truncated generalized Laguerre series, the coefficients of which are estimated from the radar returns using "cell averaging" techniques. This estimation is assumed to be perfect. The results obtained indicate that the "bias" error, defined as the normalized difference between the design PFA and the asymptotic PFA corresponding to the computed threshold, lies within a fraction of an order of magnitude for 10-3?PFA ? 10-6. For PFA ?10-6 the bias error is more than an order of magnitude. These results are for the case when a single independent radar return is processed at a time. The bias error decreases as the number of postdetection integrations of independent returns increases.     

Multiple-Target Monopulse Radar Processing Techniques

The problem of determining target parameters of a known number of radar targets falling in the same range-Doppler-angle-angle resolution cell is examined for the noise-free case. The required minimum number of radar beams is determined, based upon approximating the beam patterns by a Taylor series expansion, both for the general problem and for factorable beams. Signal processors for target position estimation are developed for the two-target case and equations are presented for the general case.     

Group-Complementary Array Coding for Radar Clutter Rejection

A radar waveform design technique which utilizes Lagrange's method of multipliers to control temporal sidelobes and to reduce Doppler sidelobes is described. This classical method of constrained optimization is applied to the problem of synthesizing a radar wave-form where mismatch loss is the objective function to be minimized. The associated constraints are taken from expressions for the composite temporal sidelobes of the cross-correlation response and the peak correlation response where sets of code words are used to modulate a series of radar pulses. The resulting code sets and receiver reference sets are called group-complementary and produce a trench parallel to or on the range axis of the cross-ambiguity surface.     

气象雷达综合测试系统的设计与实现

以某系列雷达为研究对象,详细介绍了基于PXI总线雷达综合测试系统的硬件组成和软件设计方法,并详细阐述了组建雷达综合测试系统过程中重点、难点的实现方法。实际应用表明：该系统具有通用性强、扩充性好、可靠性高等特点。     

Evaluation of EarthRadar unexploded ordnance testing at Fort A.P.Hill, Virginia

Previously, K. Bakhtar and E. Sagal [ibid. vol. 17, pp. 4-11, 2002] made remarkable claims for the performance of the Bakhtar Associates ground-penetrating radar (GPR) in detecting and classifying buried unexploded ordnance (UXO). In this article, we report the results of the series of blind tests on the EarthRadar carried out during the Fall of 2000 and Spring of 2001, which led to very different conclusions regarding the radar's performance. The contents of this article are excerpted from the final report on the testing, prepared by the Institute for Defense Analyses     

Flight test evaluation of a 35 GHz forward looking altimeter forterrain avoidance

Honeywell has conducted a series of flight tests of a 35 GHz digital microprocessor controlled forward looking radar altimeter. A Bell 206L Jet Ranger helicopter was used to evaluate the capability of the sensor as a detector of various types of terrain collision hazards. The sensor was composed of a covert, spread spectrum radar altimeter processor driving a 35 GHz converter and antenna assembly mounted on a steerable platform. Excellent correlation between predicted performance and observed performance was obtained     

CPLD在雷达测距机中的应用

介绍了CPLD的内部结构及特点 ,重点阐述了CPLD在雷达测距机中的具体应用。     

机翼涂敷吸波材料减缩雷达散射截面的研究

推导出了光滑凸体金属表面涂敷吸波材料时的后向雷达散射截面 ( RCS)公式。对一系列涂敷吸波材料的金属平板进行了 RCS测试和理论计算。为提高计算精度,给出计算 RCS的工程修正方法。在此基础上,对机翼前后缘局部涂敷吸波材料。研究结果表明,机翼前后缘涂敷吸波材料可以有效地控制 RCS     

Computation of the circular error probability integral

The author describes a simplified derivation of the representation of the circular error probability (CEP) integral, which is the integral over a disk centered at the origin of a zero mean two-dimensional Gaussian random variable, as a one-dimensional integral. In addition, two series are presented which can be used to compute efficiently the CEP integral. The domain of applicability of the series and methods for acceleration of the convergence of these series are discussed. The integral occurs in the evaluation of communication and radar signals, and in other statistical applications.<>     

The HAL-3 radar test set

This paper presents the HAL-3 radar test set (called the set in the following) used to measure the technical specifications of the HAL-3 airborne radar and to maintain it based on tested results. Some new techniques are employed in the set, including sinusoidal pulsewidth modulation (SPWM) in the power supply, digital gyro simulator and automatic test module (ATM) with STD industrial control microprocessor series. The specially designed software implements man-machine interaction with menu in Chinese, selects parameters and operation mode, and controls testing procedures. These techniques may be extensively applied to other automatic test instruments     

基于天线安装的菱形翼无人机翼型优化设计

以菱形翼布局高空长航时(HALE)传感器无人机研究为背景,分析了翼型内部安装平面相控阵雷达天线的基本原理。通过推导雷达探测性能的估算方程,建立了在翼型中安装平面相控阵雷达天线的数学模型。采用数值模拟的方法,对典型雷诺数下的RAE2822翼型的气动特性进行了研究并与试验数据进行了对比,验证了使用有限体积法k-ωSST(Shear Stress Transport)湍流模型求解雷诺平均Navier-Stokes方程在这一状态下的可靠性和适用性;同时对不同厚度的NACA 64A系列翼型的流场结构和流动机理进行了分析,在此基础上提出了一种满足平面相控阵雷达天线安装情况下翼型的优化设计思想。优化结果验证了这一设计思想的可行性。     

Homodyned-K fluctuation model

The statistics of the matched filter output are examined for the case of a nonfluctuating target in K-type clutter. The resulting "homodyned-K" backscatter model is a generalization of the classic Rayleigh-Rice model and has applications in radar, sonar, optics, and ultrasonic medical imaging. This paper presents exact and asymptotic equations for the probability density function, survival function, moments, and parameter estimation. The exact equations are expressed as infinite series. Also provided are proof of the series' convergence and guidance for their numerical computation. Examples illustrating the model's application to radar and sonar are presented using electromagnetic and acoustic backscatter data     

频率选择表面机载雷达天线的研究

研究了降低机载雷达天线散射截面的频率选择表面(FSS)极化扭转板。根据Floquet定理利用模式电压概念建立矢量模式,对二维周期阵列的频率选择表面进行理论分析和计算。设计并加工了一种降低机载雷达天线散射载面的频率选择表面极化扭转板结构。计算和实验表明:频率选择表面的极化扭转板在雷达天线工作通带内保持与原极化扭转板的性能不变,而在工作通带外具有降低雷达散射载面的效果。降低雷达散射截面7～10dB。     

空间目标RCS动态测量及特性分析

本文探讨了适用于某型窄带雷达的RCS相对测量法，对部分空间目标进行了RCS测量。利用随机游程检验法对实测的空间目标RCS时间序列进行了随机性检验，得到了与实际情况相符的结果。     

Three R's of radar: recollections, remonstrances, and ruminations

The author describes his experiences in the early days in radar, working on a radar landing system called ground control approach (GCA). He discusses for the disparity between the short time from conception to worldwide deployment of that system and today's 10- to 15-year cycle, as well as GCA's high (100%) availability, and identifies the factors responsible. The author goes on to argue that the radar community has a history of overselling what radar can do. He forecasts future trends and concludes with a few things he has learned over the years