Timing with Dirty Templates for Low-Resolution Digital UWB Receivers

As a rapid timing synchronization technique for ultra-wideband (UWB) communications, the timing with dirty templates (TDT) technique effectively collects the multipath energy even when the channel is unknown [7]. In this paper, we investigate TDT algorithms for digital UWB receivers with low-resolution analog-to-digital converters (ADC). Different from the original TDT in [7] for analog UWB receivers, our digital TDT synchronizers here can avoid the ultra-wideband analog delay elements which are difficult to implement at the IC level. Our analysis and simulations show that the (non)data-aided digital TDT algorithms remain operational even when the ADC resolution is very low.     

Power-Efficient Clock/Data Distribution Technique for Polyphase Comb Filter in Digital Receivers

A power-efficient clock/data distribution technique for the input registers of the polyphase comb decimation filter is presented. A general form of the proposed technique is developed with respect to the decimation factor. Both proposed and conventional comb filters are implemented using Xilinx Spartan3 low-power field-programmable gate array family. The implementation results show that applying the proposed technique reduces the dynamic power consumption of the second- and third-order polyphase comb filters up to 62.87% and 57.6%, respectively, depending on the decimation factor and the number of quantizer bits. For a particular power consumption, a higher input sampling rate can be utilized by applying the proposed technique. Consequently, the signal-to-noise ratio of a second-order $SigmaDelta$ modulator is increased using second- and third-order modified filters by 21.6 and 20.5 dB, respectively, depending on the decimation factor and the number of quantizer bits.      

Terahertz Heterodyne Array Receivers for Astronomy

Journal of Infrared, Millimeter, and Terahertz Waves - We review the development of multi-pixel heterodyne receivers for astronomical research in the submillimeter and terahertz spectral domains....     

Performance-Scalable Array Architectures for Modular Multiplication

Modular multiplication is a fundamental operation in numerous public-key cryptosystems including the RSA method. Increasing popularity of internet e-commerce and other security applications translate into a demand for a scalable performance hardware design framework. Previous scalable hardware methodologies either were not systolic and thus involved performance-degrading, full-word-length broadcasts or were not scalable beyond linear array size. In this paper, these limitations are overcome with the introduction of three classes of scalable-performance modular multiplication architectures based on systolic arrays. Very high clock rates are feasible, since the cells composing the architectures are of bit-level complexity. Architectural methods based on both binary and high-radix modular multiplication are derived. All techniques are constructed to allow additional flexibility for the impact of interconnect delay within the design environment.     

光控相控阵雷达中的光纤延迟线

着重介绍了利用光纤的延迟特性实现光控相控阵雷达的实时延迟技术.设计了两种延迟阵列,并分别进行了试验验证,试验结果表明这两种延迟阵列各有利弊.综合考虑,方案2优于方案1.     

相控阵雷达数字自适应波束形成技术

本文分析了自适应波束旁瓣起伏机理，从系统要求出发，研究了信号子空间广义旁瓣相消系统（ＧＳＣ）的性能，提出了简化系统结构的级联方法，并分析了Ｂｕｔｌｅｒ网络ＧＳＣ的性能。     

相控阵天线集成技术

低成本、更高频段与可扩展是推动相控阵天线集成技术发展的主要动力。综述了砖 块式与瓦片式两种相控阵天线集成阵列结构,以及多功能芯片与射频晶圆集成技术的发展, 指出开发多功能芯片是当前发展毫米波相控阵天线的重要途径。     

Mini-Annular Phased Array for Limb Hyperthermia

The design concepts of a thin-shell cylindrical or annular phased-array of conformal strip radiators is shown to be suitable for deep heating of phantoms simulating the limbs of the human body. The Mini-Annular Phased Array (MAPA) is presently under clinical investigation for treatment of cancer of the limbs at a limited number of institutions. The effect of frequency and tissue conductivity is shown under simulated conditions for a few sample power-density patterns illustrating the deep focusing of the radiated EM fields. These are compared to a numerical model pattern which can be used to estimate the patterns in varying diameter limbs. The effect of offsetting the limb within the array to steer pattern of heat deposition has also been shown to produce desirable asymmetrical patterns.     

宽带相控阵天线延迟线分析

采用频率无关移相器的相控阵天线的波束指向会随频率发生变化,实时延迟线是提高宽带相控阵天线波束指向精度的重要方法。分析了子阵级采用延迟线,单元级使用移相器的宽带相控阵天线副辫特性,发现当工作频率改变时,由于阵列存在周期相位误差导致天线副瓣电平抬高。针对此问题,提出单元级精细延迟线方案,消除周期相位误差对天线副瓣的影响。仿真结果表明,这种方法在扩展相控阵天线带宽的同时,明显改善了天线的副瓣特性。     

Multiband Low-Noise Receivers for a Very Large Array

The very large array (VLA), presently under construction by the National Radio Astronomy Observatory, is an array of 27 25-m-diam antennas. This paper describes the feed and low-noise, front-end systems used on the antennas. The receiving system allows operation at any one of the four frequency bands: 1.35-1.73 GHz, 4.5-5.0 GHz, 14.4-15.4 GHz, 22-24 GHz. The feed system uses an offset Cassegrain geometry so that the feeds for all four frequency bands can be in position on the antenna simultaneously. The front end comprises a cryogenically cooled parametric amplifier for the 4.5-5.0-GHz range. This paramp is preceded by cooled upconverters or cooled mixers for the other frequency ranges. Measured system performance is presented and some construction details are given.     

Vlsi Array Architectures for Pyramid Vector Quantization

We present parallel algorithms and array architectures for pyramid vector quantization (PVQ) [1] for use in image coding in low-power wireless systems. PVQ presents an alternative to other quantization methods which is especially suitable for symmetric peer-to-peer communications like video-conferencing. But, both the encoding and decoding algorithms have data-dependent iteration bounds and data-dependent dependencies which prevent efficient parallelization of the algorithms for either hardware or software implementations. We perform an algorithmic transformation [2] to convert the data-dependent regular algorithms to equivalent data-independent algorithms. The resulting regular algorithms exhibit modular and regular structures with minimal control overhead; hence, they are well suited for VLSI array implementation in ASIC or FPGA technologies. Based on our parallel algorithms and systematic design methodologies [3], we develop linear array architectures. Both encoder and decoder architectures consist of L identical processors with local interconnections and provide O(L) speed-up over a sequential implementation, where L is the dimension of a vector. The architectures achieve 100% processor utilization and permit power savings through early completion. A combined encoder-decoder architecture is also presented.     

相控阵体制雷达精准自卫干扰技术

面对新一代相控阵体制雷达,采用传统的基于空域、时域、频域大范围“遮盖冶自卫干扰,效率低,干扰效果受限,还带来电磁兼容、电磁暴露等问题。精准干扰是提升对相控阵体制雷达综合对抗效能的有效解决途径。文中对相控阵体制雷达精准自卫干扰技术开展了研究,分析了相控阵体制雷达精准自卫干扰系统设计的主要考虑因素,构建了相控阵体制雷达精准自卫干扰系统的系统架构,在此系统架构上建立了精准自卫干扰数学模型,并通过数字仿真验证了模型的有效性。     

Fast Measurement Technique for Phased Array Calibration

A novel measurement method is proposed in order to measure the active electric fields of the individual antenna elements in a phased array antenna. Fast and accurate measurements can be realized by the proposed method because the electric fields of multiple elements can be obtained simultaneously and no phase measurements are required. Hence, it can be easily applied to the on-board diagnostics and re-calibration in the operating phased array antenna systems. In the first step with this method, the phases of multiple antenna elements are successively shifted with the specified phase intervals while the array power variations are measured. Next, the measured power variation is expanded into a Fourier series and the terms are rearranged to put them into the form of the rotating element electric field vector (REV) method. Finally, the REV solution is used to identify the electric fields of the individual elements. Additionally, a theoretical study is carried out on the accuracy of the proposed measurement method. Simple, closed-form equations have been successfully derived for the measurement errors and the calibration accuracy is theoretically estimated. The proposed measurement method is validated with experimental results and the measurement accuracy is compared with the theoretical prediction.      

大型相控阵外监测系统

讨论了大型相控阵外监测原理,解剖分析了系统性能及系统的构建原则,在给出一误差传递模型基础上,讨论了利用外监测方法修正相控阵通道幅相误差所能达到的精度,文末给出了实例分析结果。     

Efficient VLSI Architectures for Multiuser Channel Estimation in Wireless Base-Station Receivers

This paper presents a reduced-complexity, fixed-point algorithm and efficient real-time VLSI architectures for multiuser channel estimation, one of the core baseband processing operations in wireless base-station receivers for CDMA. Future wireless base-station receivers will need to use sophisticated algorithms to support extremely high data rates and multimedia. Current DSP implementations of these algorithms are unable to meet real-time requirements. However, there exists massive parallelism and bit level arithmetic present in these algorithms than can be revealed and efficiently implemented in a VLSI architecture. We re-design an existing channel estimation algorithm from an implementation perspective for a reduced complexity, fixed-point hardware implementation. Fixed point simulations are presented to evaluate the precision requirements of the algorithm. A dependence graph of the algorithm is presented and area-time trade-offs are developed. An area-constrained architecture achieves low data rates with minimum hardware, which may be used in pico-cell base-stations. A time-constrained solution exploits the entire available parallelism and determines the maximum theoretical data processing rates. An area-time efficient architecture meets real-time requirements with minimum area overhead.     

一种相控阵雷达阵面自动校准方法研究

大型有源相控阵天线的阵面有成百上千甚至数万个收发组件和辐射单元,使得相控阵天线比其他类型的天线要复杂得多而难以维护。首先介绍阵面校准的现状,然后通过外校准的方法对阵面进行校准测试。这种方法实现了阵面自动化校准,提高了阵面校准的效率和精度。测试结果显示,辐射单元间的频带内耦合量稳定在 ? 30 ~ ? 70 dB 之间,设计指标和测试结果一致。     

Transesophageal Phased Array for Imaging the Heart

A 3.5 MHz phased array has been developed for imaging the heart through the esophagus. The ultrasonic probe is fitted on the distal end of an Olympus gastroscope. Transesophageal images of the heart were obtained on ten patients. This paper describes the design and realization of the phased array and presents some clinical results obtained on patients.     

用于相控阵雷达移相单元的激励器的研制

介绍了一种用于相控阵雷达移相单元相位控制的磁通反馈式铁氧体移相器激励器.它对铁氧体磁芯中建立的磁通进行监视.并利用反馈技术获得精密的相位控制。它可以自动补偿激励器、移相器中任何部分的变化。把元件的老化、电源的波动及其他参数变化的影响减至最小。     

线形超声相控换能器阵列的参数优化

线形超声相控阵换能器的参数直接影响着检测系统的性能和制作成本,其声场特性是能否获得并有效利用被检测部位或区域回波信息的决定因素,也是设计换能器阵的主要依据.从建立线形相控阵换能器辐射声场的数学模型出发,研究了不同阵列参数对波束指向性和偏转性的影响,进而给出了相控阵列优化设计中一些重要的规律.     

相控阵天线指向误差分析

首先对相控阵天线的指向误差进行了概述,并对由相位误差引起的随机误差进行了分析。通过比较相控阵天线指向误差的测试结果与分析结果,确定了产生其系统误差和随机误差的主因。对型号批产时的质量控制具有一定指导作用。