Low-cost technology for multimode radar

A flexible test bed radar architecture is described which includes an integrated RF electronics package that can support multiple radar applications, including surveillance, fire control, target acquisition, and tracking. This type of architecture can significantly reduce the cost, power, size, and weight of electronics on future weapon delivery platforms. The Army Research Laboratory (ARL) is developing technology to support multimode radar requirements. These requirements include the detection and location of moving or stationary low radar cross section targets in heavy ground clutter and the classification and/or recognition of these targets. We address these requirements with commercial-off-the-shelf (COTS) products and the integration of several enabling technologies. The test bed radar includes a direct digital synthesizer (DDS) for frequency-diverse waveform generation, a flexible wideband transceiver for bandwidth extension and frequency translation, and an open architecture signal processor with embedded wideband analog-to-digital converters for real-time acquisition and processing. Efficient signal processing algorithms have been developed to demonstrate multimode radar capability. This paper discusses the various subassemblies, algorithm efficiency, and field experiment results     

Space-borne technology and inversion techniques for radar

This presents recent progress of the state-of-the-art of space-borne radar technology in case of either earth-orbiting or planetary-orbiting satellites and space probes, respectively. In addition to that, recent progress is also discussed concerning specific inversion techniques to evaluate radar measurements; i.e., the art of deriving the relevant physical quantities to be determined such as terrain and depth profiles for planetary surface and/or subsurface structures ((3D)-profiles) from radar data measured depending on signal frequency, aspect angle, polarization, etc., as a function of time.     

Intrusion location capability added to synergistic radar technology

There is a new trend in the outdoor security market that demands more precision in identifying the crossing area of an intruder. Often called intrusion location capability, this capability also presents inherent features such as more accuracy in camera pre-set positioning and temporary disabling of sub-zone and individual sensitivity level per sub-zone. However even though market trend demands them, such features must have minimum impact to overall system cost. How the synergistic radar technology can be modified to offer intruder location capability to a sub-zone area as precise as 10% of the total zone length is presented. For a typical zone length of 100 meters, the zone is sub-divided into up to ten equally spaced sub-zones of 10 meters each, giving an intrusion crossing point resolution of 10 meters. Synergistic radar technology can be applied to buried, surface, wall and roof applications. This intrusion location capability also applies to each of these applications     

Ultra-wideband technology and random signal radar: an ideal combination

Ultra-wideband radar and random signal radar are two types of newly-developed radar systems. This paper introduces the special advantages of the combination of ultra-wideband technology and random signal radar to the international radar community. It shows that these two radar systems have a very close relationship in nature and can gain significant benefits from each other. It can be anticipated that the random signal modulated waveform will open many potential possibilities for the applications of ultra-wideband radar systems to civilian operating environments.     

机载雷达模拟器设计中的DirectDraw和多线程技术

阐述了某型机载雷达模拟器的软件组成,介绍了雷达威力计算时采用的坐标转换方法,详细地论述了在模拟器软件设计中采用的DirectDraw和多线程技术.     

Beam-pointing error compensation method of phased array radar seeker with phantom-bit technology

A phased array radar seeker (PARS) must be able to effectively decouple body motion and accurately extract the line-of-sight (LOS) rate for target missile tracking.In this study,the real time two-channel beam pointing error (BPE) compensation method of PARS for LOS rate extraction is designed.The PARS discrete beam motion principium is analyzed,and the mathematical model of beam scanning control is finished.According to the principle of the antenna element shift phase,both the antenna element shift phase law and the causes of beam-pointing error under phantom-bit conditions are analyzed,and the effect of BPE caused by phantom-bit technology (PBT) on the extraction accuracy of the LOS rate is examined.A compensation method is given,which includes coordinate transforms,beam angle margin compensation,and detector dislocation angle calculation.When the method is used,the beam angle margin in the pitch and yaw directions is calculated to reduce the effect of the missile body disturbance and to improve LOS rate extraction precision by compensating for the detector dislocation angle.The simulation results validate the proposed method.     

Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

Hardware-in-the-loop(HWIL) simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting signal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory(DRFM) system,the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile(HRRP) are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.     

A non-contact lie detector using radar vital signs monitor (RVSM)technology

Traditional lie detector testing requires the subject to be physically attached to a variety of sensors. This is impractical for scenarios such as checkpoints where a large number of individuals are entering at a high rate, necessitating the employment of other methods. Currently, checkpoint officers must make a quick decision to determine if an individual is being deceptive, and if, in turn, they should be searched. The remote detection of deception (RDD) concept uses a non-contact sensor to obtain physiological information that can be used to aid the checkpoint officer's decision. Such a device must be able to sense physiological signals from the body that may indicate deception in an unobtrusive and non-contact manner     

面向全球摆脱危机走访波兰航空工业

波兰的航空产品主要是轻型直升机和轻型通用飞机，其中农用飞机在世界上有较高的声誉，产量也较大，但是近年来波兰的私有化和自由经济政策对波兰的航空工业造成了很大冲击，各个航空工业企业面临着严重的生存危机，迫使波兰的航空工业企业面向全球，积极开发新产品，加大国际合作，扩大产品出口，在激烈的市场竞争中为自己争得一席之地     

波兰空军的现代化计划

在北约东扩之后,波兰空军通过引进新型战斗机、运输机、指挥和侦察系统,积极地进行空军的升级改造,以便更多地承担北约联合防空的任务,并在波兰本土以外为地面部队和海军提供支援。     

Reciprocal radar waveforms

Digitally coded radar waveforms can be used to obtain large time-bandwidth products (pulse compression ratios). It is demonstrated that periodic radar waveforms with zero sidelobes or almost zero sidelobes can be defined. A perfect periodic code is a periodic code whose autocorrelation function has zero sidelobes and whose amplitude is uniform (maximum power efficiency=1). An asymptotically perfect periodic code has the property that as the number of elements in the code goes to infinity the autocorrelation function of the code has zero sidelobes and its power efficiency is one. The authors introduce a class of radar waveforms that are either perfect or asymptotically perfect codes. These are called reciprocal codes because they can be derived through a linear transformation of known codes. The aperiodic performance of the reciprocal code is examined     

Fiber-optic radar calibration

A simple fiber-optic radar calibration target is described. Its operation is based on a wideband fiber, a laser transmitter that is directly modulated by the down-converted radar signal and an optical diode receiver recovering said signal. Further up-conversion having a common local oscillator with the first mixer ensures fidelity of the calibration return. Measured useful bandwidth exceeds 200 MHz and practically any radar RF frequency can be handled when suitable mixers are employed. Amplifiers can be added to the down-converted path as desired to compensate for the fiber loss. Modulation and LO sweep provide easy ways of introducing artificial fluctuations and Doppler frequencies. Particularly pulsed radars are readily tested with the proposed scheme as no restrictions are posed by the radar's TR-switch delays.     

Netted radar sensing

Future radar applications are beginning to stretch monostatic radar systems beyond their fundamental sensitivity and information limits. Networks of smaller radar systems can offer a route to overcome these limitations; for example, networks of radar sensors can counter stealth technology whilst simultaneously providing additional information for improved target classification. More generally, multiple independent sensors can provide an energetically more efficient collector of radar scatter. The relative merits of non-coherent and coherent networks are introduced and the balance between increased performance, complexity, and cost is discussed.     

Generalized radar clutter model

A commonly used density model for radar clutter is chi-square for power, or, equivalently, Rayleigh for amplitude. However, for many modern high resolution radar systems, this density underestimates the tails of the measured clutter density. Log normal and Weibull distributions have proved to be better suited for the clutter in these high resolution radars. Generalizing the chi-square density by replacing it with the noncentral chi-square density and allowing the mean power level (the noncentrality parameter) to vary, we can both suitably shape the clutter density to produce larger tails and model the fluctuation of the average clutter power, commonly referred to as speckle. The resulting form, although appearing cumbersome, readily allows for efficient and accurate computations of the probability of detection in clutter     

Improving intrusion detection radar

The first monostatic microwave intrusion detection sensor with range cutoff was introduced in 1984. This range cutoff circuit as used in the Model 375 and 385 has proven very effective in preventing nuisance alarms beyond a user-defined range. The Intrepid Digital Transceiver introduced in this paper builds upon this proven technology with the addition of a unique digital signal processing routine that measures range to the intruder. Intrepid Digital Transceiver alternately transmits pulses at two discrete frequencies within K-Band. When an intruder enters the detection zone, the Doppler response at each frequency is digitally recorded. The difference between the two frequencies is controlled so that the phase angle between the two Doppler responses can be used to determine the unambiguous range to the target. As a byproduct of the process targets approaching the transceiver can be distinguished from those moving away from the transceiver. Range information is used to enhance the signal processing. The amount of signal integration is increased with range in proportion to the width of the detection pattern so as to optimize the signal to noise ratio (SNR).     

Ground probing radar system

Two types of battery-powered, compact, ground probing radar (GPR) systems have been developed. The systems have CRT displays mounted on antenna units and are used to locate such underground objects as gas pipes, water pipes, and transmission cables. The performance of the systems and results of field tests are reported. The GPR detected 59 of 64 underground gas pipes; a 200-mm-diameter pipe is clearly detected at a depth of 2.3 m     

Novel radar target detection

Herein, a novel method of radar target detection based on 2-dimensional (2-D) fractal dimension is proposed. The proposed approach exploits both range information and azimuth information to estimate fractal dimension. Moreover, the approach can increase the number of data points. The above two merits result in the fractal dimension estimated by this method are more accurate and robust than the previous method. The detection performance is also better than the previous, which only makes use of 1-dimensional (1-D) information to estimate fractal dimension. Theoretical analysis and experimental results show that the proposed method performs well in a strong clutter background. The proposed method is also validated by real-life radar data, and the better result has been achieved.     

Possible ultra-wideband radar terminology

This is a supplement to the terms proposed by Malek G.M. Hussain and James D. Taylor (see ibid., vol.19, no.7, p.39, July 2004).     

SCR-270 radar development

The development of the SCR-270-271 series of radars is traced. These radar had their origin in the work that preceded and eventually culminated in the first US Army radar: Search Light Control Radar SCR-268. The principal technical characteristics of the 270-271 series are summarized and given in tabular form