Sine wave

About: Sine wave is a research topic. Over the lifetime, 12183 publications have been published within this topic receiving 93013 citations. The topic is also known as: sinusoid.

Digital spectra of non-uniformly sampled signals: theories and applications. IV. Measuring clock/aperture jitter of an A/D system

Abstract: Theories and applications of a digital spectrum analysis technique for a class of nonuniformly sampled signals are described. A method based on asynchronous spectral averaging is presented to measure the standard deviation of a clock/aperture jitter of an A/D (analog/digital) system. A sine wave with frequency f/sub 0/ is used as the input test signal to an A/D system. Spectral averaging is performed on many asynchronously acquired data records with length N. The jitter standard deviation is calculated from the measured signal-to-noise (S/N) floor ratio. The expression which relates the S/N to the standard deviation, sigma /sub r/, of the jitter, r, is derived in closed form. Graphs showing good agreement between the theoretical equation and the simulation results are presented. >

Cargo Dimensional and Weight Analyzing System

Abstract: A laser scanner apparatus is disclosed herein for measuring the geometry and physical dimensions of one or more objects in a specified location or platform. The specified location or platform is within a range less than a predetermined maximum object distance. The laser scanner includes a waveform generator that generates a predetermined reference waveform to an analog laser that provides an modulated laser beam responsive to the reference waveform, an optical scanning system which 1) transmits and scans the object with the modulated laser light beam and 2) includes a means for receiving reflected the modulated laser light from the surface of an object on the platform or specified location, an avalanche photo-detector positioned to receive the processed modulated light from the optical processing system, and convert energy in the incident light into an amplitude-modulated range signal, a mixer is provided to down-convert the frequency of the range signal into a lower (LF) frequency. In practice, a first electrical circuit receives the down-converted range signal and converts it into a converted waveform that has a sinusoidal wave falling and rising that correspond to the zero crossings. The reference waveform is also applied to a mixer that down-converts it to the LF frequency. A second electrical circuit receives the down-converted reference waveform and converts it a second converted waveform that has a sinusoidal wave falling and rising that correspond to the zero crossings. A computer receives the first and second converted waveforms and outputs a highly accurate signal indicative of the time delay there between. The time delay is used by the computer system to determine the physical dimension of the particular scanning.

Relationship between the Sine-Wave Response and the Distribution of Energy in the Optical Image of a Line*

Abstract: The method of obtaining the sine-wave response of a lens, both theoretically and experimentally, is described, and it is shown that the line spread-function can be derived from the sine-wave response alone if the spread function is symmetrical. If the spread-function is not symmetrical, it can be computed from the sine-wave response only when the phase function is also known, and an experimental method of obtaining this function is described. The mathematical procedure for the reciprocal inversion of the spread-function and the sine-wave response is confirmed experimentally.

On the filtering properties of evolved gate arrays

Abstract: A small gate array is evolved extrinsically to carry out a low pass filtering task defined over fifteen different frequencies The circuit is evolved by assessing its response to digitised sine waves Two different fitness functions are contrasted One is based on computing the sum of the absolute differences between the actual response and that desired, the other is defined by examining characteristics of the discrete Fourier transform of the output The gate arrays possess some linear properties, which means that they are capable of filtering composite signals which have not been encountered in training This includes signals with noise added and with frequencies which are not in the training set

Elimination of subharmonics in direct look-up table (DLT) sine wave reference generators for low-cost microprocessor-controlled inverters

Abstract: This paper investigates distortion of an inverter reference waveform generated using a direct look-up (DLT) algorithm. The sources of various distortion components are identified and the implications for application to variable speed drives and grid connected inverters are described. Harmonic and subharmonic distortion mechanisms are analyzed, and compared with experimental results. Analytical methods are derived to determine the occurrence of subharmonics, their number, frequencies and maximum amplitudes. A relationship is established identifying a discrete set of synthesizable frequencies which avoid sub-harmonic distortion as a function of look-up table length and a practical method for calculation of the look-up table indices, based on finite length binary representation, is presented. Real time experimental results are presented to verify the analytical derivations.