Showing papers on "Sine wave published in 1971"

The output properties of Volterra systems (nonlinear systems with memory) driven by harmonic and Gaussian inputs

Abstract: Troublesome distortions often occur in communication systems. For a wide class of systems such distortions can be computed with the help of Volterra series. Results, both old and new, which will aid the reader in applying Volterra-series-type analyses to systems driven by sine waves or Gaussian noise are presented. The n-fold Fourier transform G n of the nth Volterra kernel plays an important role in the analysis. Methods of computing G n from the system equations are described and several special systems are considered. When the G n are known, items of interest regarding the output can be obtained by substituting the G n in general formulas derived from the Volterra series representation. These items include expressions for the output harmonics, when the input is the sum of two or three sine waves, and the power spectrum and various moments, when the input is Gaussian. Special attention is paid to the case in which the Volterra series consists of only the linear and quadratic terms.

Comparison of theory and experiment in peristaltic transport

Abstract: Various theoretical aspects of peristaltic motion have attracted considerable attention in the recent literature. There also exists a difference of opinion concerning the definition of peristaltic reflux. Thus far, there has been no completely satisfactory experimental verification of any of the theoretical analyses. The present article describes some details of an experimental work which was carried out to verify the theoretical analysis of peristaltic transport in a two-dimensional channel with one fixed wall and one flexible wall on which a travelling sine wave is imposed. An approximate correction for finite width was introduced. Comparison of the theoretical and experimental results shows a good agreement and gives verification to the theoretical analysis. In the light of the experimental results, a discussion of the different definitions of peristaltic reflux is presented.

Linearized dispersion relation and green's function for discrete-charge-transfer devices with incomplete transfer

Abstract: A small-signal (linearized) theory of discrete-charge-transfer-device performance is presented for the case of incomplete charge transfer. Specifically, the dispersion relation is derived which relates the charge-transfer efficiencies presently characterizing these discrete (in space and time) devices to the usual measures of device or transmission-line performance based on the attenuation, dispersion, phase velocity, etc., of sine waves. In a more general sense this emphasizes the applicability of conventional signal theory to these new devices. The impulse solution or Green's function is then shourn to be the equivalent of a bivariate distribution in probability theory. More generally the utility of (deterministically interpreted) probability theory is emphasized by showing the equivalence of a general small-signal theory to a random-walk process.

Noise Reduction by Applying Modulation Principles

Abstract: This paper presents techniques for determining nonperiodic spacing of events for the purpose of reshaping noise‐frequency spectra. The object of the application is to provide reduced noise levels and the redistribution of the frequencies at which there is noise energy so as to generate fewer perceptible sounds. Three analytical techniques for predicting the noise spectrum resulting from nonuniform spacing are presented. Emphasis is focused on a semigraphical design technique using Bessel functions, which has proven to be of great value in the actual selection of modulated event spacing. Fourier analysis of an impulse approximation and a sinusoidal wave approximation are two other alternative techniques presented. The techniques outlined are applied to the problem of reshaping the noise spectrum of a 22‐blade fan in a 5‐hp induction motor. A comparison of predicted results provides an evaluation of the alternative approaches.

System for digitally controlling a vibration testing environment or apparatus

Abstract: A system for controlling a vibration testing environment or apparatus such as a shaker table with a random signal in order to subject a specimen on the table to vibrations having a predetermined power spectral density is disclosed. The movement of the specimen is sensed and converted into a digital signal representative of the power spectral density of the movement. This digital signal is compared with the predetermined or desired spectral density and the results of the comparison are utilized with a digitally generated random phase angle to produce a random digital signal. This random digital signal is converted to a time-domain, analog driving signal for driving the apparatus. The same system may be used for high intensity sound testing and sine wave testing.

Differential doppler detection for rf intruder alarm systems

Abstract: An intruder detection system in which an RF transmitter is connected through a length of transmission line to a transmit/receive antenna, both transmitter and antenna are matched to the line. Diode detectors are connected in opposite directions to the line at points spaced a quarter wave length apart. The diodes connect through low-pass filters to the balanced inputs of an AC coupled amplifier which extracts the doppler sine wave from the oppositely traveling transmitted and received waves on the line. The doppler sine wave is squared and the pulses are integrated to trigger an alarm. A band pass filter is so positioned in the line to reduce false alarms by defining a specific radio frequency bandwidth and also allows the detectors to be used to time the transmitter oscillator.

Encoding and decoding system for catv

Abstract: A video signal encoding system is provided by amplitude modulating a video carrier modulated with video, with a sinusoidal waveform whereby the amlitude levels of the sync portion of the video waveform as well as the video portion of the video waveform are altered. Decoding may be achieved by remodulating the encoded video waveform with a decoding sine wave in antiphase with the encoding sine wave and thereafter modulating the result, to eliminate residual error, with a cosine function wave applied in phase opposition to the error component of the resultant, which has twice the frequency of the basic encoding sine wave, but preferably the sequence of the decoding remodulations is reversed.

Device for the audible reproduction of a cardiogram with speech-like sounds

Abstract: A device for the audible reproduction of electrophysiological signals, which includes a serially connected sine wave generator and pulse shaper in which these signals are reproduced in the form of speech-like sound signals, and a pair of band pass filters of which one is frequency tunable to vary the monotonic signals from the pulse shaper in response to deviations in the electrophysiological signals so that the deviations are reproduced as speech-like deviations in these sound signals.

D c voltage multipliers and polarity converters

Abstract: Circuits to perform voltage multiplication and polarity conversion function using diodes and capacitors, driven by a voltage sensing and/or an amplifier stage, for rectified nonfiltered sine wave voltage as input. Circuits to perform voltage multiplication and polarity conversion function using diodes and capacitors driven by an astable multivibrator for battery or rectified, filtered a-c voltage as input voltage.

Digital sweep generator for generating analog signals

Abstract: A digital sweep generator for digitally generating an analog since wave signal of constant or varying (sweep) frequency, includes means for generating a rate-of-change clock, a slope clock and a sine function, via digital circuits. The rate-ofchange clock determines the rate-of-change in the frequency of a sinewave across a desired range of frequencies for a given time interval. The slope clock occurs at the exact increments selected to produce a given sinewave frequency as determined by the rateof-change clock. That is, if a sweep sinewave signal is desired, the rate-of-change clock is introduced to modify accordingly the means for generating the slope clock. The slope clock is then introduced to the means for generating a sine function to digitally produce the sinewave signal as the function of the input slope clock rate. Each slope clock represents a point on the slope of the generated sinewave, corresponding to equal increments of 360* of a sinewave. Two outputs are provided; a digital word corresponding to the sinewave, and the analog sinewave signal delivered therefrom via a digital-to-analog converter.

Fsk digital transmitter

Abstract: A digital transmitter used in data sets for digitally constructing sine waves to transmit mark and space information signals over a communication channel. A medium frequency oscillator supplies the basic timing for selecting consecutive segments of a sine wave and an amplitude selector generates signals representing the amplitudes of each segment to be supplied to a digital to analogue converter. Through several steps of frequency division, the phase angle error at the frequency shifts, due to mark and space transistion, is reduced to an extremely small angle. The apparatus shown is applicable to the several frequency ranges of data sets.

Methods of measuring the modulation transfer function of photographic emulsions

Abstract: The different methods of measuring the modulation transfer function of photographic emulsions are discussed in four sections; (i) sine wave methods, (ii) Fourier transformation of the line spread function, (iii) coherent light processing methods, and (iv) calculation from scattering measurements. Particular attention is paid to the effects of the non-linearities of the photographic process, and to the effects of film grain noise on the measured transfer function. A brief discussion of the related microdensitometry is also included.

Weak quadratic interactions of two-dimensional waves

Abstract: This paper reports on weak quadratic interactions which can occur with two-dimensional waves on shallow water layers and in the capillary-gravity range on deep water layers. It supplies experimental support of theoretical predictions for resonant interactions, but, perhaps of more significance, it explores in detail interactions which occur under conditions near resonance.Waves of approximately sinusoidal form are introduced on the surface of water in a long rectangular tank. For deep water a rapid distortion in the sinusoidal wave and sometimes additional crests are observed because of energy exchange among the first, second and third harmonics at frequencies where both surface tension and gravity are important (7·5–13 c/s). An even greater exchange of energy can be observed on shallow water layers at low frequencies. For example, a wave train with seven secondary crests can be observed when the wave maker is operated at 3·04 c/s in a water layer of 0·65 cm.Measured amplitudes and phase angles of the Fourier components of the wave train are described by a system of equations using only quadratic interactions among participating harmonics. The exchange of energy among Fourier components under certain conditions is explained in terms of the rate of change of relative phase angles of the different harmonics.

Status of OTF in 1970

Abstract: The concept of the assessment of image quality by means of the optical transfer function (OTF) is traced from the early use of sine wave test charts through to the development of the high precision...

Remote control systems

Abstract: A mechanically actuated, radio frequency transmitter capable of providing radio frequency transmissions, without the need of stored electrical energy or external electrical energy, for utilization in remote control systems, consisting of an AC generator comprising a mechanically actuated rotor which is caused to rotate in close proximity to a stator assembly by rack and pinion means thereby resulting in induced electrical energy in the form of a sine wave; a tone generator; radio frequency oscillator means; and a single antenna for transmitting at least one signal generated by the radio frequency oscillator means. A receiver system eliminates the necessity for conventional oscillator by combining signals received from the transmitter, producing an intermediate frequency signal and demodulating the resulting signal by tone amplifier and filter means.

Change of current or voltage acutated protecting relay

Abstract: A control device responsive to a change in magnitude and/or phase of an alternating potential sine wave signal in which a first quantity derived by integrating the signal is compared with a second quantity derived by differentiating the signal.

Sinusoidal waveform generator

Abstract: There is disclosed an arrangement for generating sinusoidal waves of low harmonic content and relatively high output level wherein selected square waves of related amplitude and frequency derived from a digital frequency synthesizer are utilized to trigger conventional driving circuits. The outputs of these driving circuits are combined and the complex signal obtained therefrom fed to an integrator which provides the desired signal wave form.

Fail-safe code keying transmitter

Abstract: This disclosure relates to a fail-safe code keying transmitter wherein a modulating signal is reshaped to remove the harmonic producing portions therefrom prior to the modulation of a carrier wave. The code keying transmitter includes an electronic switching circuit and a series resonant L-C circuit for transforming the leading edge of the square-wave input signal into one half cycle of a cosine wave and for transforming the trailing edge of the square wave input signal into another half cycle of a cosine wave and employs a modulating circuit for varying the carrier wave in accordance with the transformed cosine wave.

Zero-crossing jitter detection method and circuit

Abstract: An electronic circuit and method for providing a d.c. voltage proportional to the randomness of the zero-crossings of an input sine wave signal includes a hard limiter for converting the sine wave to a square wave of the same frequency, a narrow band filter tuned to twice the frequency of the input sine wave signal for removing all the spectral energy except that centered at the second harmonic and a circuit for converting any energy at the output of the filter to a d.c. component which represents the randomness of the zero-crossings (zero-crossing jitter).

Digitally controlled sine wave generator

Abstract: Shown is a sine wave generator provide a highly stable output frequency which may be selected by an input signal from a digital computer. A crystal controlled oscillator provides its output to a digital counter, the output of which is compared with a register loaded by the computer. Each time the count equals the loaded value a flipflop is triggered and the counter reset causing the flipflop to provide a square wave output of a predetermined frequency. The square wave is then filtered by a digitally controlled filter to provide a final output which is a sine wave of the desired frequency.

Frequency to direct current converter

Abstract: A frequency to direct current converter is provided in which an input signal, which may be a sinusoidal wave or a pulse train, is applied to a first bistable logic circuit to determine its state The logic circuit is utilized to provide an input indicative of an input signal to a second bistable logic circuit to which timing pulses are applied from an external clock source The timing pulses initiate a change in the states of the bistable logic circuits so that a direct current pulse of uniform width is produced for each input wave applied to the first bistable circuit The direct current pulses may be averaged or utilized to control a chopper circuit to produce a direct current output indicative of the frequency of the input signal

Wide-band doubler and sine wave quadrature generator

Abstract: A wide-band signal quadrature and second harmonic generator comprising a voltage-controlled phase shifter which provides an output representing a phase-shifted sine input signal. The input signal and the phase shifter's output are multiplied by a multiplier whose output, after integration, is used to control the illumination levels of photoresistors in the phase shifter so that the output of the phase shifter is the cosine of the sine input signal. The multiplier's output when phase lock is achieved is the second harmonic of the sine input signal. The photoresistors in the phase shifter have large dynamic ranges of resistance changes to enable the generator to operate over a wide band of input signal frequencies.

Programmable multi mode phase sensitive voltmeter

Abstract: Phase sensitive measurements of the fundamental component of a test signal having a complex waveform is performed in two distinct modes of operation using an unshifted and shifted sine wave reference signal. In each mode, the component is examined with respect to either the in-phase or quadrature phase of the reference signal. In measuring the total value of the fundamental component of the test signal with respect to the in-phase shifted reference signal, the reference signal is shifted, in a variable phase shifter having two wideband multipliers, in such a manner that the in phase component of the reference signal is maximized and the quadrature component of the reference signal is minimized. The test signal is multiplied by the in-phase shifted reference signal. The resulting signal is a measure of the total value of only the fundamental component of the test signal.

Modulator-demodulator apparatus for communication of digital data over voise grade telephone lines

Abstract: A data modem (modulator-demodulator) apparatus for transmitting and receiving digital data over voice grade telephone lines having a multivibrator, a two station counter providing frequencies fo and f 1 with 2/1 ratios, composite signal generator responsive to the f o and f 1 signals to provide a pulse train comprising an integral number of cycles of fo and f 1, wherein one cycle of f1 is provided for each binary one in the incoming digital data signal and two cycles of fo are provided for each binary zero in the incoming digital data signal, filter means for transforming the pulse train into an approximation of a sine wave for coupling over a voice grade telephone line, means for receiving the sine wave containing information, a limiting amplifier and digital comparator for converting the sine wave back into a digital signal, a two stage counter providing an output zero for each pair of pulses in the digital signal, an integrator-comparator providing an output one level for each single cycle of f1, and means for combining outputs from the integrator-comparator and the two stage counter to provide the reconstructed digital data signal.

A New Fast Computing RMS-to-DC Conversion

Abstract: A new approach to ac-to-dc conversion is presented, with applicability both to phase-sensitive rectification and to whole-signal determination. In the former case, it provides insensitivity to effects of signal distortion up to any desired harmonic number, with elimination of effects up to the tenth harmonic a practical possibility. In the whole-signal situation with reasonable amounts of distortion, applying the method reduces effects of harmonics up to the tenth as well. In the whole-signal implementation, the computation yields an excellent approach to true rms, for sinusoidal waves with reasonable amounts of harmonic contamination, and for a wide range of other signals as well, including square and triangular waves. Most significantly, performance capabilities of the new converters include speed and dynamic range as well as accuracy. A converter for 400 Hz and higher settles in 110 ms; for 60 Hz and higher, in 400 ms???both much faster than rms converters using thennal devices. Dynamic range exceeds 60 dB.

Digital variable quadrature sine wave voltage controlled oscillator

Abstract: A pulse voltage controlled oscillator running at four times the desired frequency f triggers a two stage shift register which has an inverted feedback loop. The outputs of both stages are similar square waves of frequency f, and they are set at a 90* phase difference of each other. Since a square wave of frequency f possesses only harmonics of odd orders, a low pass filter which rejects 3f can admit a square wave frequency varying between f and 3f. A pair of identical filters coupled to the outputs of respective shift register stages provide output signals of corresponding frequency which are 90* out of phase. For a frequency range extending between 3f and 9f, another pair of filters are required, etc. Additional shift registers may be added to the two stage shift register to provide output signals with a phase shift equal to the corresponding fraction of 360*.

A time-of-flight study of waves guided by a plasma column

Abstract: Describes an experiment designed to measure the group velocity of waves guided by a plasma column. Using very short high frequency sine wave burst signals, we were able to perform a time-of-flight experiment. The dependence of the group velocity on ( omega pe(r)) was directly obtained.

Push-pull amplifying devices with class d transistorized amplifiers

Abstract: In a push-pull amplifying device comprising two transistorized class D amplifiers, the input signal of each of these amplifiers is formed by the superposition of two in-phase waves, one of which is a sine wave and the other a rectangular one, the sine wave signal providing most of the input current required to ensure saturation during the conductive periods and in particular in the centre part of these periods.