Showing papers on "Phase correlation published in 1971"
TL;DR: The Fourier transform data communication system is described and the effects of linear channel distortion are investigated and a differential phase modulation scheme is presented that obviates any equalization.
Abstract: The Fourier transform data communication system is a realization of frequency-division multiplexing (FDM) in which discrete Fourier transforms are computed as part of the modulation and demodulation processes. In addition to eliminating the bunks of subcarrier oscillators and coherent demodulators usually required in FDM systems, a completely digital implementation can be built around a special-purpose computer performing the fast Fourier transform. In this paper, the system is described and the effects of linear channel distortion are investigated. Signal design criteria and equalization algorithms are derived and explained. A differential phase modulation scheme is presented that obviates any equalization.
2,507 citations
TL;DR: The purpose of this note is to show as clearly as possible the mathematical relationship between the two basic fast methods used for the calculation of discrete Fourier transforms and to generalize one of the methods a little further.
Abstract: The purpose of this note is to show as clearly as possible the mathematical relationship between the two basic fast methods used for the calculation of discrete Fourier transforms and to generalize one of the methods a little further. This method applies to all those linear transformations whose matrices are expressible as direct products.
137 citations
TL;DR: In this paper, the orthogonal nature of the Fourier transform (FT) is maintained by using the trapezoidal rule for the mechanical quadrature of the FT of one, two, and three dimensions.
128 citations
TL;DR: An arbitrary-radix fast Fourier transform algorithm and the design of its implementing signal processing machine are introduced, which yields an implementation with a level of parallelism proportional to the radix r of factorization of the discrete Fouriertransform.
Abstract: An arbitrary-radix fast Fourier transform algorithm and a design of its implementing signal processing machine are introduced. The algorithm yields an implementation with a level of parallelism proportional to the radix r of factorization of the discrete Fourier transform, allows 100 percent utilization of the arithmetic unit, and yields properly ordered Fourier coefficients without the need for pre- or postordering of data.
44 citations
TL;DR: In this article, the Fast Fourier Transform (FFT) was used to calculate time-displaced correlation functions from molecular dynamics data much more rapidly (less expansively) than by using the standard integration technique.
40 citations
23 citations
TL;DR: In this paper, a method for refining and/or extending a set of crystallographic phases by real-space convolution utilizing the fast Fourier transform (FFT) algorithm was proposed.
Abstract: A method is formulated for refining and/or extending a set of crystallographic phases by real-space convolution utilizing the fast Fourier-transform algorithm. The method is applied to extending a set of myoglobin phases and the results show that high-resolution structural information can be obtained from high-resolution intensities and low-resolution phases.
17 citations
Patent•
29 Mar 1971
TL;DR: In this article, a special purpose computing equipment is utilized to perform the Fast Fourier Transform (FFT) algorithm on special purpose computers. And the computing equipment utilizes serial access memory for storing coefficients during interim periods between calculations and by properly alternating between two clock rates for the serial memory, the computer allows the processing of two FFT algorithms simultaneously.
Abstract: Special purpose computing equipment is utilized to perform the Fast Fourier Transform algorithm. The computing equipment utilizes serial access memory for storing coefficients during interim periods between calculations and by properly alternating between two clock rates for the serial memory, the computer allows the processing of two Fast Fourier Transform algorithms simultaneously when the input data for the two algorithms is in different binary order.
14 citations
TL;DR: In this article, a shipborne wave-recording system consisting of a sonic wave gauge, accelerometers, gyroscopes and a computer system is described, where signals from the measuring apparatus are fed directly into a ship-borne digital computer system at a prescribed sampling rate.
Abstract: A shipborne wave-recording system which consists of a sonic wave gauge, accelerometers, gyroscopes and a computer system is described. Signals from the measuring apparatus are fed directly into a shipborne digital computer system at a prescribed sampling rate. The time series of wave heights and the acceleration are transformed into Fourier series using an algorithm of Fast Fourier Transform. Errors contained in the observed wave heights due to ship motion are corrected in the Fourier series by using the Fourier coefficients for the vertical acceleration. Power spectra and waveforms can also be calculated in a short time with this system from Fourier coefficients. Examples of the observational results obtained in the central part of the East China Sea in 1969 are presented.
5 citations
01 Jan 1971
2 citations
TL;DR: A discrete version of the Wiener–Lee transform is presented, so that a digital computer can be employed for the computation.
Abstract: The use of Wiener–Lee transforms to construct one of the frequency characteristics, magnitude or phase of a network function, when the other characteristic is given graphically, is indicated. This application is useful in finding a realisable network function whose magnitude or phase curve is given. A discrete version of the transform is presented, so that a digital computer can be employed for the computation.
TL;DR: In this paper, an optical Fourier synthesis method was applied to the reconstruction of spectra in Fourier spectroscopy, where a Michelson interferometer was used for generating the harmonics.
01 Dec 1971