Showing papers on "Sine wave published in 1986"

Speech analysis/Synthesis based on a sinusoidal representation

Abstract: A sinusoidal model for the speech waveform is used to develop a new analysis/synthesis technique that is characterized by the amplitudes, frequencies, and phases of the component sine waves. These parameters are estimated from the short-time Fourier transform using a simple peak-picking algorithm. Rapid changes in the highly resolved spectral components are tracked using the concept of "birth" and "death" of the underlying sine waves. For a given frequency track a cubic function is used to unwrap and interpolate the phase such that the phase track is maximally smooth. This phase function is applied to a sine-wave generator, which is amplitude modulated and added to the other sine waves to give the final speech output. The resulting synthetic waveform preserves the general waveform shape and is essentially perceptually indistinguishable from the original speech. Furthermore, in the presence of noise the perceptual characteristics of the speech as well as the noise are maintained. In addition, it was found that the representation was sufficiently general that high-quality reproduction was obtained for a larger class of inputs including: two overlapping, superposed speech waveforms; music waveforms; speech in musical backgrounds; and certain marine biologic sounds. Finally, the analysis/synthesis system forms the basis for new approaches to the problems of speech transformations including time-scale and pitch-scale modification, and midrate speech coding [8], [9].

DEGDAY: a program for calculating degree-days, and assumptions behind the degree-day approach

Abstract: A BASIC computer program (DEGDAY) for calculating degree-days on microcomputers is presented. The program calculates heating degree-days with the rectangle, triangle, and sine wave methods and calculates cooling degree days with the sine wave method. Assumptions and approximations associated with degree-day calculations are noted. In particular, eight factors affecting degree-days are discussed: 1) substrate availability, 2) enzyme availability, 3) approximations in laboratory estimates of development, 4) approximations in calculating the developmental minimum, 5) approximations in calculating a developmental maximum, 6) approximations in using single values for thresholds, 7) thermoregulation, and 8) limitations of temperature data. The various errors arising from these factors are discussed in relationship to error attributable to differences between actual and estimated degree-days.

A general linear hydroelasticity theory of floating structures moving in a seaway

Abstract: The dynamics of an elastic beam floating on the surface of disturbed water has formed the basis of a fairly comprehensive linear theory of hydroelastic behaviour of ships in waves. The existing theory cannot easily be extended to floating vehicles of more complicated shape (such as semi-submersibles), or to fixed offshore structures. A general method is presented, by which finite elements permit any three-dimensional elastic structure to be admitted in a linear hydroelastic theory. Sinusoidal waves provide the excitation of the structure and the fluid flow is three-dimensional. Some examples are given which illustrate the use of the theory and expose behaviour that has not been encountered hitherto.

Processing of acoustic waveforms

Abstract: A sinusoidal model for acoustic waveforms is applied to develop a new analysis/synthesis technique which characterizes a waveform by the amplitudes, frequencies, and phases of component sine waves. These parameters are estimated from a short-time Fourier transform. Rapid changes in the highly-resolved spectral components are tracked using the concept of "birth" and "death" of the underlying sine waves. The component values are interpolated from one frame to the next to yield a representation that is applied to a sine wave generator. The resulting synthetic waveform preserves the general waveform shape and is perceptually indistinguishable from the original. Furthermore, in the presence of noise the perceptual characteristics of the waveform as well as the noise are maintained. The method and devices disclosed herein are particularly useful in speech coding, time-scale modification, frequency scale modification and pitch modification.

Sine waves enhance cellular transcription.

Abstract: We previously showed that quasirectangular, asymmetrical, pulsed electromagnetic (EM) fields of low frequency can induce increased transcription in Sciara salivary gland cells. A symmetrical sine wave with the same frequency as known biologically effective asymmetric signals was studied in the present investigations. The results demonstrated that signal shape was not a major factor in causing augmented transcription. The pattern of grain density in transcription autoradiograms, as well as the size classes of RNA responsive to EM fields, was the same irrespective of asymmetry or symmetry of the signal. Following short-term exposure of the cells to either type of EM field, S values of new transcripts were consistent with those expected for processed and unprocessed messenger RNA.

Spatial frequency differences can determine figure-ground organization.

Abstract: In three experiments we examined the influence of spatial frequency on perceptual organization. In each experiment a pattern was tested that was ambiguous in terms of figure and ground. In each experiment, the stimuli were 20 variations of the pattern, which were generated by filling the two regions of the pattern with horizontal sine wave gratings differing in spatial frequency. Five spatial frequencies were tested: 0.5, 1, 2, 4, and 8 cycles per degree. The response measure was the percentage of response time one of the regions was seen as the figure. This region was seen as the figure a higher percentage of the time in those stimuli where it contained the relatively higher spatial frequency sine wave grating compared with those stimuli where it contained the relatively lower spatial frequency sine wave grating. Language: en

Electronic sound synthesizer

Abstract: An electronic source synthesizer that employs frequency modulation. Wave-form data of both a fundamental wave and a modulated wave are stored in a RAM as 6-bit digital data. A sine wave signal is produced by modulation wave frequency data and the wave-form data from the RAM. The sine wave signal is multiplied with amplitude data of the modulation wave to obtain the modulation index data (J(t)). The frequency data (w c ) of the fundamental wave and the modulation index data are multiplied. A result of the multiplication provides a read out address of the RAM for storing the wave-form data of the fundamental wave, thereby changing the read out speed of the RAM. The digital data read out from the RAM is converted to an analog sound signal by a D/A converter. Amplitude data (A) of the fundamental wave is pulse-width modulated, and the digital data from the RAM is gated by the modulated pulse. Thus the output of the D/A converter is activated and, forms a sound signal represented by the equation e=A sin J(t) w c t.

Multiaxis robot having improved motion control through variable acceleration/deceleration profiling

Abstract: A digital robot control employs planning and trajectory programs which generate the trajectory plan and trajectory position commands with the use of an acceleration profile and a deceleration profile selected from at least square wave and sine wave profiles.

Long nonlinear waves in a compressible magnetically structured atmosphere

Abstract: The Hohlov-Zabolotskaja equation with an additional boundary condition is shown to describe long nonlinear small-amplitude fast sausage surface waves in a magnetic slab embedded in magnetic environment. It is proved that the obtained boundary problem has no solutions in the form of solitary waves. Approximate solution in the form of nonlinear stationary wave is found with the use of expansion in the power series of small amplitude. Second harmonic generation by a sinusoidal wave is studied. The law of energy conservation is obtained. Results of numerical computations are presented. They show that a sinusoidal disturbance does not overturn. The possibility of transmission of wave energy into corona along a magnetic slab is discussed in connection with these results.

Nonlinear surface acoustic waves on an elastic solid of general anisotropy

Abstract: The effect of elastic nonlinearity on the propagation of Rayleigh waves in an anisotropic elastic solid is considered. A nonlinear integro-differential equation is derived for a quantity which is related to the Fourier transform of the displacement component on the surface. The variation of this quantity along the surface accounts for the slow modulation of the wave through formation and depletion of the different harmonics. Explicit results are given for harmonic generation in an initially sinusoidal wave and for parametric amplification of a weak signal by a pump wave of twice its frequency.

Midlevel carrier modulation and demodulation techniques

Abstract: Several techniques are disclosed for producing modulation of a carrier signal wherein each transition of the modulated carrier signal includes a midrange level and/or two midrange characteristics, the level and/or ratio of the two midrange characteristics representing data carried by that transition. A simplified method over that disclosed in parent application Ser. No. 590,281, filed Mar. 16, 1984 now U.S. Pat. No. 4,613,974 is disclosed herein, and is referred to as a "flipped sine wave" method of producing the modulated carrier signal. Another technique, referred to as a "third harmonic modulation" technique uses the phase relationship between a fundamental and its third harmonic to produce the modulated carrier signal. A technique for storing the modulated carrier on magnetic media and correcting for offset resulting therefrom or from attenuation and advance of the third harmonic relative to the fundamental to permit accurate demodulation is disclosed.

Improving performance of digital sinusoidal oscillators by means of error feedback circuits

Abstract: A few structures for digital sinusoidal oscillators have been proposed, together with the design methods used for such structures. Because of the finite wordlength effects, these structures produce high roundoff errors which change both the amplitude and frequency of the generated sinusoidal signal. This makes it difficult to design an oscillator which generates a sinusoidal waveform with a particular frequency and amplitude. It is shown in this paper that if we add to the direct form digital oscillator a circuit which saves the quantization error and feeds it back for consideration at subsequent iterations, roundoff errors are considerably reduced, and the frequency and amplitude of the generated waveform are very close to those expected by theory. Formulas are derived for the resulting errors and simulation results are given, showing that a significant improvement is obtained by error feedback.

On-line test and diagnostic system for power system stabilizer

Abstract: A method and apparatus for performing a complete functional test of a power system stabilizer connected to the excitation system of an electrical power generator is disclosed. Two tests are performed, one an on-line modulation test, and the second a system response test. In the on-line modulation test, an internal 0.5 hertz sine wave is generated by a microprocessor which is applied as a frequency modulating input to the continuous wave frequency transducer included in the power system stabilizer. Such a signal acts to stimulate intertie mode oscillations and provide a means of determining the gain and phase shift characteristic of the power system stabilizer. In the second test, a voltage step type of signal is generated and applied to the output of the power system stabilizer where it is then coupled to the excitation system of the generator. This has the effect of stimulating local mode oscillations. The generator response to the local mode oscillation is sensed to determine system damping. Both tests are adapted to verify the operational status of the power system stabilizer and the adequacy of its adjustments. Furthermore, a local terminal and a telephone modem are connected to a communication port associated with the microprocessor for enabling the test to be initiated and the results evaluated either locally or remotely.

Nonlinear surface waves on cubic materials

Abstract: The effect of nonlinearity on the propagation of surface Rayleigh waves on an elastic medium of cubic symmetry is examined by applying the results of an earlier analysis for general anisotropic materials. Explicit calculations are given of the parameters relating to the generation of higher harmonics in an initially sinusoidal wave for a series of thirty-five materials for which experimental measurements of the third-order moduli are available.

Multifunctional optical proximity sensor using phase modulation

Abstract: A proximity sensor is defined as the noncontact sensor of end-effector, and is one of the most important sensors for robot control. This paper deals with a new type of proximity sensor which has the capability of measuring spatial information, such as gap distance, inclination angles, and the angular positions of object particles. The measuring principle of the sensor is based on the phase shift of a modulated light signal. For this purpose, six light sources are placed on a cross-shaped pattern that is centered by a photodetector, and the power of light sources are modulated by different phase sine wave signals. The distance and angles can be measured by investigating the received phase information at the predetermined emitting pattern. By experimental measurement, the characteristics of this sensor are obtained and the effectiveness of the sensor is confirmed.

High efficiency MOSFET sine wave generator

Abstract: A high efficiency MOSFET sine wave generator is provided using the class D pulse width modulation principle. A triangle wave at f₀ is compared to a variable amplitude sinusoid at about 1/10 f₀ to provide a pulse width modulated signal for driving a pair of power MOSFETS connected for switching a B+ and a B- power supply. The power switch output is LC filtered and fedback for regulating the amplitude of the modulating sinusoid.

Computer‐controlled apparatus for measuring complex elastic, dielectric, and piezoelectric constants of polymer films

Abstract: Principles and design details are described for a fully automatic system measuring frequency and temperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymer films. A microcomputer is used to control all processes including wave generation, sampling, and calculations. A sinusoidal excitation wave is written onto a RAM, readout by an external clock, and applied to a sample via a D/A converter. The resulting signals related to force, deformation, charge, and voltage are simultaneously sampled using the same clock and are determined as complex quantities through Fourier transformation. Their ratios give corresponding complex response functions. A multifrequency signal consisting of eight sinusoidal waves with frequencies of common ratio 2 is used to obtain frequency spectra over two decades at a time. This system operates over a frequency range from 0.01 to 100 Hz for elastic and piezoelectric measurements and from 0.01 Hz to 10 kHz for dielectric measurements at temperature...

Realization of a New Inverter Circuit for Direct Photovoltaic Energy Feedback into the Public Grid

Abstract: A new regulated utility interactive inverter for direct photovoltaic energy feedback to the mains has been realized. A modulated buck converter converts the photovoltaic dc current to a rectified 50-Hz sine wave current, and the following self-commutated half-bridge generates a 50-Hz sine wave current, which is fed into one phase of the public power grid. This nonclassical inverter needs only three power transistor switches and isolates the grid and the photovoltaic array using a commercial 50-Hz transformer. It acts as a current source, and due to pulsewidth modulation its output is a sine wave current with very low total harmonic distortion of one percent. The overall efficiency of the 1-kW prototype is at least 88 percent between 250 and 1000 W, and the projected efficiency is over 90 percent for 1-20 kW. Furthermore, a circuit which tracks the maximum power available from the photovoltaic generator has been developed. This circuit regulates the input power to its maximum by detecting the phase angle between the voltage and power ripples at the inverter input.

Method and apparatus for providing a visual indication of a relationship between two signals

Abstract: A visual indication of the relationship between first and second electrical signals, such as the left and right channel signals in a stereophonic audio system, is provided through use of a video vectorscope. The first and second signals are used to modulate the amplitude of two sinusoidal waves at a subcarrier frequency and in phase quadrature, so as to synthesize the chrominance portion of a composite video signal. The two modulated sine waves are additively combined, and the resulting signal is applied to the input terminal of the vectorscope.

Resonant Inverters for Photovoltaic Array to Utility Interface

Abstract: A number of high-frequency (hf) link power converter schemes suitable for interconnecting photovoltaic (PV) array to the utility line using resonant inverters are presented. Use of hf resonant inverters result in reduced size, weight and cost. The schemes presented are (i) hf resonant inverter (hfri)-cycloconverter, (ii) hfri-rectifier-pulse width modulated voltage source inverter, (iii) hfri-rectifier-line commutated inverter working with a fixed maximum possible inverting firing angle, and (iv) hfri-rectifier-line connected inverter (with line current modulation). These schemes are compared and based on the comparison, scheme (iii) was selected for initial study and the working principle of this scheme is explained. Although both 1-O and 3-O systems are easy to implement with this scheme, they generate line frequency current harmonics. Also, line pf is less than unity. To overcome these problems, line current is modulated sinusoidally in scheme (iv). In this scheme, hfri is controlled appropriately to obtain a rectified sine wave of 120 Hz in the dc link and the function of line connected inverter is to unfold this waveform (? = 180°) on alternate half cycles to obtain a sinusoidal line current which is in phase with the line voltage. Methods of commutation of line connected inverter are explained. A 3-O system is realized using three identical 1-O systems. Experimental results obtained from a 1-O prototype system for scheme (iv) are presented.

Ultrasonic range finding

Abstract: Range finding equipment is employed in a nuclear reactor to monitor the spacing between structural components (22, 24) of the reactor which are under stress. A manipulator (32) carries a pair of send-receive ultrasonic transducers (30) arranged back to back so as to direct ultrasound signals towards reflectors (26, 28) associated with the structural components to be monitored. The transducers are pulsed with signals derived by gating a few cycles of a sustained reference signal of sine wave form and the resulting echo signals can be used to provide transit time and phase displacement information from which the spacing between the relectors (26, 28) can be derived with a high degree of precision.

Linear VCO with sine wave output

Abstract: A sinusoidal oscillator whose frequency of oscillation bears a linear relation to the controlling voltage VT is presented. The basic configuration involves a four-quadrant analog multiplier to adjust precisely the gain requirement for sustained oscillation with ultra-low-distortion operation. The oscillator results in a linear voltage-to-frequency converter with sine wave output. The circuit makes use of a scaled-resistance element R1/K2 to realize the oscillation frequency f in the form f=Kf0, where the scaling parameter K is a linear function of VT and f0 is the unscaled frequency.

Fiber optic rate sensor

Abstract: In a fiber optic rate sensor employing a Sagnac ring circuit wherein an ocal source launches an optical signal which is divided into two equals signals which are coupled in opposite directions through a multi-turn fiber optic coil to provide two counter-propagating optical signals. The two counter-propagating optical signals are coupled to a photodetector after passing through the multiturn fiber coil. The signals detected at the photodetector have traversed identical optical paths between said source and said photodetector and have undergone a Sagnac phase shift directly related to the rate of rotation of the fiber coil about its axis in inertial space. The two counterpropagating signals are phase modulated by a phase modulator at one end of the fiber optic coil and the output of the photodetector undergoes signal processing in a signal processor to produce a rate output directly related to the rate of rotation of the fiber coil. The improvement being an improved phase modulation and signal processor which comprises a crystal-controlled oscillator providing a sine wave reference signal means for coupling the crystal of the crystal-controlled oscillator to the optical fiber at one end of the coil to produce a non-reciprocal phase modulation of the counter-propagating optical signals, means for multiplying the sine wave reference signal and the output from the photodetector to produce a product output, and means for integrating the product output over a whole number of complete reference cycles to produce the rate output, the sine wave reference signal being coupled to means for integrating to control the integration period of the means for integrating.

Method for coded transmission of color television signals

Abstract: In a method for transmission of color television signals, at least two color information containing signals are coded using code elements comprised of a half period or a full period of a sine wave, the sequence of code elements forming at least one essentially sinusoidal code signal stream. In one embodiment, the code elements form binary code words for conveying different types of information, as hue and saturation of a color picture element. Alternatively, each code element may have an amplitude related to the value of the information to be transmitted, as saturation of a specific primary color. Each code word may comprise a plurality of portions related to different types of information, as different primary colors, audio information and the like. Two code signal streams each forming a sine wave of the same predetermined frequency may be phase displaced by 90 degrees, superimposed and employed in a composite video signal e.g. instead of and at the same frequency as an usual color subcarrier wave.

Shim gap probe

Abstract: A probe for use in determining the thickness of an interface gap between two parts is disclosed. The probe includes a wave spring (13) formed in one end of a thin, flat, elongate piece of resilient steel (11). The wave spring (13) includes three sinusoidal waves having a peak-to-peak separation that is greater than the maximum thickness of the gaps to be measured. Mounted on the wave spring (13), at the bottom of the concave depression (-) formed by each of the sinusoids are strain sensors (43a-d or 61a, b) positioned to sense the radial and circumferential strain applied to the wave spring (13) when the wave spring is positioned in a gap such that the wave spring sinusoids are compressed. Two or four strain sensors may be used to create a half or a full strain gauge bridge at the bottom of each concave depression. In the case of the half strain bridge arrangement, the remaining legs of the bridge are formed by "dummy" resistors located in a controlled environment remote from the wave spring. In a conventional manner, the strain gauge bridges control the magnitude of an electrical signal to provide a strain measurement that is indicative of the compression of the wave spring and, thus, thickness of the gap. Because the wave spring (13) has three sinusoids, information is provided by three strain bridges, allowing two-dimensional taper as well as single dimension thickness information to be produced.

Basic AC Circuits

Abstract: Introduction to Alternating Current AC and the Sine Wave The Oscilloscope and Its Use The Sine Wave and Phase Resistive Circuits Capacitance RC Circuit Analysis Inductance and Transformers RL Circuit Analysis RC and RL Time Constants RLC Circuit Analysis Phasor Algebra Complex RLC Circuit Analysis Resonance

The Taylor internal structure of weak shock waves

Abstract: Description du comportement qualitatif d'ondes non lineaires soumises a des variations geometriques du front d'onde et a un amortissement thermovisqueux lorsqu'elles se propagent sur de grandes distances. Les equations generalisees ou modifiees de Burgers decrivent les ondes

Method and apparatus for generating digital signals representing periodic samples of a sine wave

Abstract: A method and apparatus for generating accurate digital representations of one or more sine waves. A digital signal processor is used to generate the sample digital values, spaced at period T, of a sine wave of frequency F, F<1/2T, using recursive methods. The magnitude of the generated sample values is stabilized and controlled by normalizing the recursively generated samples from time to time, but not necessarily after each recursive calculation. Methods are described for generating values based on the values of two previously generated samples using the recursion formula: y(n)=y(n-1)2 cosω-y(n-2) where ω=2πFT and y(n), y(n-1) and y(n-2) represent three consecutive sample values. The normalizing factor, used for multiplying a recursively generated sample value to stabilize the amplitude, associated with this calculation is ##EQU1## where A is the desired amplitude. Methods are also described for generating two sine waves of the same frequency but displaced in phase, and for generating frequency and phase-shift keyed sine waves. Advantageously, these methods and apparatus minimize the resources required for performing the generation of the sine waves.

Application of Array Processing for Parallel Linear Recursive Kalman Filtering in Underwater Acoustic Exploration

Abstract: In underwater seismic exploration applications using acoustic arrays, the firing pulses suffer from air bubbles due to sudden change in water pressure. In practice, the optimum wave form is obtained after the firing pulse has travelled for about 50 meters in the water column. The wave-form is non-periodic and may be approximated by a damped sinusoidal wave. The wave hits the seabed and propagates through the ocean floor. The exploration task is to obtain information in real time from the reflected signals collected by a number of acoustic receivers. Several recent contributions to the literature on signal processing, computer architecture, and VLSI design show that systolic array processing techniques are extremely useful for designing special purpose devices to solve problems in linear algebra and system analysis. In this paper,we apply Kalman filtering theory and parallel Kalman filters to the exploration problem. Particular emphasis is given to the multi-receiver case as an important application of array processing methodology.