Optical Fiber Delay-Line Signal Processing (Correction)

Due to a clerical error, the above paper by K. P. Jackson, S. A. Newton, B. Maslehi, M. Tur, C. C. Cutler, J. W. Goodman and H. J. Shaw appeared in the March 1985 issue (pp. 193-210) without being identified as an Invited Paper.     

声表面波信号处理器件的进展与应用

综述了近１０年声表面波抽头延迟线、延迟线等声表面波信号处理器的新发展及在系统中的应用。     

Transferred Electron Logic Devices for Gigabit-Rate Signal Processing

A new approach for designing transferred electron logic devices (TELD's) is presented and experimental results described. Electrolytic thinning of GaAs wafers has been used to maintain uniform nd product across the wafers and minimize variations in the device characteristics. TELD's have been fabricated and their performance studied. The devices are evaluated as threshold Iogic elements. The parameters studied are 1) switching characteristics, 2) shortest pulses that can be processed, and 3) device delay and dissipation. Experimentally, pulses as small as 80 ps wide have been processed through transferred electron logic gates (TELG's) with device delays of the order of 50 ps and delay-dissipation product of 5-10 pJ, which make them suitable for gigabit-rate signal processing.     

磁共振射频信号对医疗器械影响的数值和实验研究

广泛研究了在MRI系统中的医疗器械射频致热问题。采用全波电磁仿真和热仿真工具,研究了器械长度与器械尖端周围的最大温升的相关性。测试结果显示,“最坏情况”的温升测量结果与仿真数据一致。该工作提出了一种高效、准确的方法,用来评估多种不同尺寸的医疗器械在磁共振环境下的射频致热情况。     

Implicit and Explicit Model-Based Signal Processing for the Analysis of Short-Term Cardiovascular Interactions

The paper stresses the importance of model-based signal processing in the analysis of the cardiovascular regulation mechanisms. It is remarked that even traditional signal processing implicitly assumes a model and interprets data according to it. Therefore, traditional signal processing is here referred to as implicit model-based signal processing in contrast with explicit model-based signal processing directly stemming from modeling considerations. The paper points out the advantages that can be achieved by rendering explicit the underlying model structure when it is implicit and by jointly applying implicit and explicit model-based signal processing approaches when dealing with complex, interacting,closed-loop biomedical systems. These advantages are rendered practical over several examples derived from the study of the short-term cardiovascular regulation performed by the autonomic nervous system.     

有机聚合物光波导延迟线研制的新进展

由于孔径效应和孔径渡越时间的限制,传统的相控阵雷达难以在大扫描角下实现大瞬时带宽,有机聚合物光波导延迟线可解决这一问题。先介绍了有机聚合物光波导延迟线的原理和优点,接着综述了三种延迟线：利用聚酰亚胺制成的4位有机聚合物光波导延迟线,多层结构的有机聚合物光波导延迟线,开关选择的超长有机聚合物光波导延迟线。     

Approximate Signal Processing

It is increasingly important to structure signal processing algorithms and systems to allow for trading off between the accuracy of results and the utilization of resources in their implementation. In any particular context, there are typically a variety of heuristic approaches to managing these tradeoffs. One of the objectives of this paper is to suggest that there is the potential for developing a more formal approach, including utilizing current research in Computer Science on Approximate Processing and one of its central concepts, Incremental Refinement. Toward this end, we first summarize a number of ideas and approaches to approximate processing as currently being formulated in the computer science community. We then present four examples of signal processing algorithms/systems that are structured with these goals in mind. These examples may be viewed as partial inroads toward the ultimate objective of developing, within the context of signal processing design and implementation, a more general and rigorous framework for utilizing and expanding upon approximate processing concepts and methodologies.     

Parametric Devices and Masers: An Annotated Bibliography

This bibliography is restricted to books and periodical articles published prior to October, 1959. No attempt has been made to include the voluminous material to be found in technical reports, patents or similar sources.     

Low Distortion Multicasting of an Analog Signal by Self-Seeded Parametric Mixer

We present a linear multicast of an analog signal in a two-pump self-seeded parametric device. The linearity of the parametric multicasting is assessed by two-tone measurements of the third-order intermodulation products and radio-frequency spectral analysis. Experimental results show the linear behavior of a four-photon mixer over a wide range of input signal power.      

Dynamic Eigenstates of Parametric Interactions in Randomly Birefringent Fibers

In fiber-based parametric devices employing nondegenerate four-wave mixing, there exist dynamic eigenstates for the signal and idler, for which there is no change of polarization as the waves propagate. For the case of parametric amplifiers with two pumps of arbitrary polarization, the eigenstates are the sum of the Stokes vectors of the pumps. For nonlinear Bragg scattering, the eigenstate polarizations are determined by the sum of two Stokes vectors of one pump plus one of the other pump. Separated coupled-wave solutions for the evolution of the signal and idler are obtained for each eigenstate.      

Signal Processing in Cognitive Radio

Cognitive radio allows for usage of licensed frequency bands by unlicensed users. However, these unlicensed (cognitive) users need to monitor the spectrum continuously to avoid possible interference with the licensed (primary) users. Apart from this, cognitive radio is expected to learn from its surroundings and perform functions that best serve its users. Such an adaptive technology naturally presents unique signal-processing challenges. In this paper, we describe the fundamental signal-processing aspects involved in developing a fully functional cognitive radio network, including spectrum sensing and spectrum sculpting.      

视频处理中的重采样

针对数字视频领域信号重建的问题,分析了各种常见的算法,对算法的性能和复杂度进行了分析,根据硬件实现的要求,选取了一种较合适的算法,并给出了硬件实现的结果。     

Linear Signal Processing by Acoustic Surface-Wave Transversal Filters

The impulse response of acoustic surface-wave (ASW) filters is determined by the configuration of an array of planar transducers tapping the acoustic signal propagated in the piezoelectric substrate. The transducer configuration is derived here by applying the generaI procedure used for the synthesis of linear transversal filters, which consists in time sampling the required impulse response and arranging the spacing and weights of the taps according to the time intervals and amplitudes of the impulse-response samples. The design of the tapping structure that synthesizes the impulse response of ASW transversal filters is based on a nonuniform sampling procedure, previously developed by the authors, that meets the particular requirements of ASW device operation. The features of this design procedure are presented, and several geometries of tapping transducers corresponding to impulse responses of different characteristics are discussed. The application of the procedure to the design of typical ASW filters is illustrated by the results of experimental models.     

机载PD雷达信号处理分析软件仿真

根据某雷达信号处理硬件系统的主要处理方式,分析了机载PD雷达信号处理的算法及其主要过程,提出了软件构造模型及其接口方式。文中介绍了基于上述分析编程的机载PD雷达信号处理系统的仿真模型工具包,分析了工具包使用的软件仿真的算法及编程实现方法。该工具包包含了从雷达回波AD采样数据直到产生目标原始点迹的主要过程模块,可以得到各处理节点的中间信号,较好地实现了对硬件系统的仿真分析,具有灵活、真实和实用的特点。     

Parametric GLRT for Multichannel Adaptive Signal Detection

This paper considers the problem of detecting a multichannel signal in the presence of spatially and temporally colored disturbance. A parametric generalized likelihood ratio test (GLRT) is developed by modeling the disturbance as a multichannel autoregressive (AR) process. Maximum likelihood (ML) parameter estimation underlying the parametric GLRT is examined. It is shown that the ML estimator for the alternative hypothesis is nonlinear and there exists no closed-form expression. To address this issue, an asymptotic ML (AML) estimator is presented, which yields asymptotically optimum parameter estimates at reduced complexity. The performance of the parametric GLRT is studied by considering challenging cases with limited or no training signals for parameter estimation. Such cases (especially when training is unavailable) are of great interest in detecting signals in heterogeneous, fast changing, or dense-target environments, but generally cannot be handled by most existing multichannel detectors which rely more heavily on training at an adequate level. Compared with the recently introduced parametric adaptive matched filter (PAMF) and parametric Rao detectors, the parametric GLRT achieves higher data efficiency, offering improved detection performance in general.     

语音信号处理技术

语音信号处理用以实现人一人、人一机器和机器一人的通信，是现代通信领域的重要环节。本文详细介绍了其三个分支，即语音编码、语音合成、语音识别和理解的研究和应用现状及其发展。