Signal

About: Signal is a research topic. Over the lifetime, 674211 publications have been published within this topic receiving 4570168 citations. The topic is also known as: electric signal.

Subspace methods for the blind identification of multichannel FIR filters

Abstract: This paper addresses a problem arising in a context of digital communications. A digital source is transmitted through a continuous channel (the propagation medium), and several measurements are performed at the receiver, either by means of several sensors, or by oversampling the received signal compared to the emission rate. Given only these observations, the baseband equivalents of the corresponding channels have to be recovered. An orthogonality property between "signal" and "noise" subspaces is exploited to build some quadratic form whose minimization yields the desired estimates up to a scale factor. This is in the same spirit as recent works by Tong et al. (see Proc. 25th Asilomar Conf., p.856-860, 1991) but requires fewer computations. Numerical simulations demonstrate the performance of the proposed methods in a channel identification context. >

Electrosurgical generator and system

Abstract: In an electrosurgical generator for generating radio frequency power, the generator includes a radio frequency output stage having two or more output connections, and a power supply coupled to the output stage for supplying power to the output stage. A controller is operable to cause the generator to supply a blended output signal alternating constantly between a first output signal across the output connections in which the radio frequency output voltage developed across the output connections is limited to at least a first predetermined threshold value for cutting or vaporisation of tissue, and a second output signal across the output connections in which the radio frequency output voltage developed across the output connections is limited to a second threshold value for coagulation. There is also provided adjustment means, operable by a user of the electrosurgical generator, for changing between various preset settings for the blended signal, the preset settings each having a predetermined duty cycle of the blended signal that is limited to the first threshold value for cutting or vaporisation, and a predetermined duty cycle of the blended signal that is limited to the second threshold value for coagulation.

Digital Signal Processing : A Computer-Based Approach

Abstract: From the Publisher: "Digital Signal Processing: A Computer-Based Approach" is intended for a two-semester course on digital signal processing for seniors or first-year graduate students. Based on user feedback,a number of new topics have been added to the second edition,while some excess topics from the first edition have been removed. The author has taken great care to organize the chapters more logically by reordering the sections within chapters. More worked-out examples have also been included. The book contains more than 500 problems and 150 MATLAB exercises. New topics in the second edition include: finite-dimensional discrete-time systems,correlation of signals,inverse systems,system identification,matched filter,design of analog and IIR digital highpass,bandpass and bandstop filters,more on FIR filters,spectral analysis of random signals and sparse antenna array design.

Detection of signals in noise

Abstract: Probability. Random Processes. Narrowband Signals. Gaussian Derived Processes. Hypothesis Testing. Detection of Known Signals. Detection of Signals with Random Parameters. Multiple Pulse Detection of Signals. Detection of Signals in Colored Gaussian Noise. Estimation of Signal Parameters. Extensions. References. Bibliography. Index.

Theory of communication. Part 1: The analysis of information

Abstract: Hitherto communication theory was based on two alternative methods of signal analysis. One is the description of the signal as a function of time; the other is Fourier analysis. Both are idealizations, as the first method operates with sharply defined instants of time, the second with infinite wave-trains of rigorously defined frequencies. But our everyday experiences?especially our auditory sensations?insist on a description in terms of both time and frequency. In the present paper this point of view is developed in quantitative language. Signals are represented in two dimensions, with time and frequency as co-ordinates. Such two-dimensional representations can be called ?information diagrams,? as areas in them are proportional to the number of independent data which they can convey. This is a consequence of the fact that the frequency of a signal which is not of infinite duration can be defined only with a certain inaccuracy, which is inversely proportional to the duration, and vice versa. This ?uncertainty relation? suggests a new method of description, intermediate between the two extremes of time analysis and spectral analysis. There are certain ?elementary signals? which occupy the smallest possible area in the information diagram. They are harmonic oscillations modulated by a ?probability pulse.? Each elementary signal can be considered as conveying exactly one datum, or one ?quantum of information.? Any signal can be expanded in terms of these by a process which includes time analysis and Fourier analysis as extreme cases. These new methods of analysis, which involve some of the mathematical apparatus of quantum theory, are illustrated by application to some problems of transmission theory, such as direct generation of single sidebands, signals transmitted in minimum time through limited frequency channels, frequency modulation and time-division multiplex telephony.