Showing papers on "Sine wave published in 1987"

Interleaved digitizer array with calibrated sample timing

Abstract: A digitizer system includes M digitizers, each producing a separate waveform data sequence representing a succession of instantaneous magnitudes of an input signal at sample times determined by a periodic clock signal. Transmission of the clock signal to each digitizer is delayed by a corresponding adjustable delay time so as to control the relative sample timing of the digitizers. To adjust sample timing, a sine wave signal is applied as the input signal to each digitizer such that the M digitizers produce M separate waveform data sequences in response to said input signal and the M data sequences are interleaved and windowed to form a single waveform data sequence. A first sequence of complex numbers representing a discrete Fourier transform of the single waveform data sequence is generated and then a second sequence of M complex numbers is formed from elements corresponding to relative magnitude peaks of the first sequence. A third sequence of M complex numbers is generated representing an inverse discrete Fourier transform of the second sequence and the phase angle of each number of the third sequence is computed and divided by the input signal frequency to produce a set of M numbers, each representing a timing error for a corresponding one of the M digitizers. The time delay corresponding to each digitizer is then adjusted by the amount of the timing error.

Uninterruptible power supply

Abstract: An uninterruptible power supply device uses a transformer with a first primary winding and secondary winding tightly coupled to one another to transmit AC input electrical power to a voltage sensitive load. A series regulator switches taps in the first primary to keep the load output voltage within certain limits during minor variations in the AC input voltage. A standby inverter supplies standby power to the load after a loss or large variation in the AC input voltage by driving PWM pulses into a secondary primary winding of the transformer. The transformer loosely couples the second primary winding to the secondary winding to aid in synthesizing the output sinusoidal wave from the PWM pulses. The regulator opens all of the taps to prevent the inverter from supplying power to the AC input. A voltage monitor continuously senses the AC waveform of an AC sample signal produced from the output load voltage in the normal mode and from the AC input voltage in the standby mode to determine forward and reverse transfers between modes. A clipped AC sample signal detector inhibits transfer in high peak current conditions, and a digital phase-locked loop circuit operating at a fraction of the AC input frequency synchronizes the phase of a precision sine wave signal with the phase of the AC input voltage.

Multirate sinusoidal transform coding at rates from 2.4 kbps to 8 kbps

Abstract: It has been shown [1] that an analysis/synthesis system based on a sinusoidal representation leads to synthetic speech that is essentially indistinguishable from the original. By exploiting the peak-to-peak correlation of the sine-wave amplitudes [2], a harmonic model for the sine-wave frequencies, and a predictive model for the sine-wave phases [3], it has also been shown that the sine-wave parameters can be coded at 8 kbps. In this paper a new technique is described for coding the sine-wave amplitudes based on the idea of a pitch-adaptive channel vocoder. Using this amplitude-coding strategy and operating at a total bit rate of 4.8 kbps, it was possible to code and transmit enough phase information so that very intelligible, natural sounding speech could be synthesized. This 4.8 kbps system has been implemented in real-time and has achieved a Diagnostic Rhyme Test (DRT) score of 95. At 2.4 kbps no explicit phase information could be coded, but by phase-locking all of the sine waves to the fundamental, by adding a pitch-adaptive quadratic phase, and by adding a voicing dependent random phase to each sine wave, natural sounding synthetic speech could be obtained. This new system is currently being implemented in real-time so that intelligibility tests can be performed.

Comparative evaluation of computer methods for calculating the best-fit sinusoid to the digital record of a high-purity sine wave

Abstract: A comparative evaluation of programs used in the “equivalent bit” test is described. Four methods of determining the best-fit sine wave were tested using computer generated data contaminated to varying degrees with white noise. These data were supplemented with actual records of sine waves obtained using fast digitizers with 6- to 12-bit resolution and record lengths of between 512 to 16 000 words. The programs were evaluated for relative accuracy, absolute accuracy, and efficiency, both in terms of how often each method converged and also of how much computer time each method took to converge.

Magnetic rotary sensor for detecting absolute position of rotating body

Abstract: A magnetic rotary sensor has a rotary drum carrying thereon magnetically recorded codes representative of discrete positions obtained by dividing one rotation of the drum into a predetermined number of positions. Further, an interval between the adjacent discrete positions identified by the codes is interpolated by interpolation signals generated on the basis of a sine wave signal and a cosine wave signal, which are so produced by magnetic signals additionally recorded on the drum that the periods thereof correspond to the interval. Accordingly, a magnetic rotary sensor can be realized, which is capable of identifying the rotational positions of a rotating body with high resolution without increasing the rotary drum in size.

Buckling of Rectangular Orthotropic Plates Under Biaxial Loading

Abstract: Simply supported edge conditions are considered, for which the buckling modes consist of integer numbers of half sine waves in the two perpendicular directions. This note con siders the usual design case of specified load ratios. The lowest buckling mode in biaxial compression is shown to have a single half wave in an effectively short direction, or in both directions if the plate is effectively nearly square. The tension/compression case has a single half wave in the tension direction. The number of multiple half waves can be ap proximately determined to minimize numerical search computations.

Speech analysis-synthesis system using sinusoidal waves

Abstract: From a speech signal, spectrum information as a plurality of line spectrum data, pitch position data and amplitude data are extracted. Each of the sinusoidal wave signals of different frequencies is allotted to the predetermined line spectrum data. The frequency of the sinusoidal wave signal is changed with the pitch position being the boundary. The plurality of sinusoidal wave signals are added and the added result is modulated by the amplitude data to transmit the modulated signal as the transmission data. The line spectrum data, the pitch position data and amplitude data are extracted from the modulated signal. The replica of the speech is produced on the basis of these extracted data.

Control unit for non-circulating current type cycloconverter

Abstract: The invention relates to a control unit to control a continuous cycloconverter of the non-circulating current type which performs frequency conversion of an AC power source using a semiconductor element a to perform commutation by the AC power source and variable speed operation of an AC motor. Sine/cosine waves as secondary magnetic flux directional signals are obtained by a sine/cosine wave generator based on the slip phase and the rotor phase of the motor; deviation between torque current set value supplied from a speed controller and torque current feedback value is outputted as torque voltage adjusted value by a torque current control element, and deviation between exciting current set value supplied from a magnetic flux controller and exciting current feedback value is outputted as exciting voltage adjusted value by an exciting current control element; the torque and exciting voltage adjusted values are converted into alternating voltage set values using the sine/cosine waves as parameters, and the torque current set value and the exciting current set value are converted into alternating current set values also using the sine/cosine waves as parameters; the alternating voltage set value and the alternating current set value converted are outputted to a control circuit to alternately operate switching of the semiconductor elements of positive and negative groups which constitute the cycloconverter, and the amplitude error and the phase error produced between the alternating current set value supplied to the cycloconverter and the alternating drive current actually supplied to the motor can be reduced significantly.

Circuit techniques for use in a digital phase-angle generator

Abstract: A proven basic technique for the digital generation of two sine waves having a known and adjustable phase difference has been used to produce a commercial phase-angle standard. While the final performance for this instrument meets or exceeds those previously reported for a unit built by the National Bureau of Standards, a number of different circuit techniques have been used to achieve greater phase resolution, circuit simplifications, easier mechanisms for detecting possible circuit problems, and significant cost reductions.

Image representation by zero and sine-wave crossings

Abstract: Signal representation by its points of crossing of a reference signal is considered with emphasis on applications to images. Some results that are elaborated for the representation of one-dimensional signals by their sine-wave crossings are extended and applied to images. The issue of the stability of the reconstruction algorithms is examined through derivation of bounds on the mean-square error caused by inaccuracies in the determination of crossing locations and by the effect of out-of-band energy. These bounds highlight the dependence of the reconstruction error on major parameters of the underlying signal and the reference sine Wave. Computational results on images reconstructed from their sine-wave crossings support the theoretical results and indicate that the bounds are tight. The representation of signals by their crossings of a reference signal is further examined in the context of a general framework of unique representation wherein the signal is modeled as a sample path of an ergodic band-limited random process. The idea of a scheme for signal representation that is almost stable in a probabilistic sense is introduced and discussed.

PWM waveform generator

Abstract: A PWM waveform generator generates the digitized waveform which may control an inverter so that the inverter output is pulse width modulated and generates a sine wave after filtering. A frequency controlling means includes a cycle clock cycling an address counter which addresses step data in a ROM, and the ROM data is fed to a PWM counter. This PWM counter has a clock input to reset a flip-flop and the output passes through a polarity switch to obtain the digitized waveform. This frequency controlling means is modified by an amplitude controlling means wherein the PWM counter is clocked at a variable frequency rate to control the width of the pulses directly proportional to the desired effective amplitude of the output waveform. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.

New Servo Method With Eccentricity Correction Circuit

Abstract: To shorten the access time of optical disk equipment, a small optical head and an eccentricity correction circuit are required. This paper describes both a small optical head with a combined prism and a roof-shaped prism and an eccentricity correction method with synchronized sine wave. Two newly developed prisms make it possible to form the optical head by using only six optical parts. Eccentricity correction is performed by moving the actuator according to the synchronized sinusoidal correction signal. The amplitude and phase of the correction signal are matched to those of the track movement by a microcomputer. This eccentricity correction can reduce a 200 µm eccentricity to 10 µm , improve tracking ability, and shorten the random access time.

Optical interference angular velocity meter

Abstract: PURPOSE:To obtain an angular velocity by providing a means which performs feedback control over a frequency shift or phase modulating so that a detection output is zero, a means which extracts a specific frequency component from a beat signal of processed light and unprocessed light, and a means which detects the phase with a signal from an alternating signal source. CONSTITUTION:Coherent light L1 from a light source 11 is separated by the 2nd directional coupler 13 into opposite-directional light L2 and L3, which are inputted to an optical waveguide 14 and made to interfere with each other, obtaining L4. Then, L5 is extracted by the 1st directional coupler 12 and converted 15 photoelectrically to open a gate with the saw-tooth wave signal of the 2nd an oscillator 21; and a phase difference output obtained by performing synchronous detection 17 at the frequency of the 1st oscillator 19 is integrated 23 and fed back to an oscillator 21, which is controlled by a comparator 24. Part of the light L2 and light L3 before and after phase modulation and serrodyne are extracted by a directional coupler 29 and made to interfere with each other and they are converted 26 photoelectrically and amplified 31, and then only the primary higher harmonic component is extracted by a BPF 32. A sine wave of frequency fm from the oscillator 19 is shifted 35 in phase and mixed 33, and the mixture output is counted 37 after being passed through an LPF 36. Consequently, the angular velocity is detected accurately with the constitution.

Elementary deterministic theories of frequency and amplitude stability in feedback oscillators

Abstract: First, the linear theory of frequency stability when applied to nearly sinusoidal feedback oscillators is critically reviewed. In this respect, a definition of the so-called linear oscillator is clarified. Then, the describing-function method and the Chua and Tang approach are applied to obtain new expressions for the oscillation-frequency and oscillation-amplitude stability of feedback oscillators considered as nonlinear networks.

Top and bottom pincushion distortions correcting circuits to be used for picture tube having aspherical face plate

Abstract: A top and bottom pincushion distortions correcting circuit suitable for a television receiver using a picture tube having the face plate of aspherical surface. This distortion correcting circuit comprises an adder circuit which adds a parabolic signal of horizontal cycle and a sine wave signal of horizontal cycle with adequate mixture rate and a waveform shaper which converts a saw wave signal of vertical cycle to an S-shaped wave signal. A combining signal obtained from the adder circuit is modulated by the S-shaped wave signal in the balanced modulator. The top and bottom pincushion distortions of raster are corrected by the modulated combining signal. The combining signal corrects pincushion distortions of the top and bottom scanning lines of raster and the S-shaped wave signal is used for correcting the pincushion distortion of internal raster.

Mixed-phase deconvolution of speech based on a sine-wave model

Abstract: This paper describes a new method of deconvolving the vocal cord excitation and vocal tract system response. The technique relies on a sine-wave representation of the speech waveform and forms the basis of an analysis-synthesis method which yields synthetic speech essentially indistinguishable from the original. Unlike an earlier sinusoidal analysis-synthesis technique that used a minimum-phase system estimate, the approach in this paper generates a "mixed-phase" system estimate and thus an improved decomposition of excitation and system components. Since a mixed-phase system estimate is removed from the speech waveform, the resulting excitation residual is less dispersed than the previous sinusoidal-based excitation estimate or the more commonly used linear prediction residual. A method of time-varying linear filtering is given as an alternative to sinusoidal reconstruction, similar to conventional time-domain synthesis used in certain vocoders, but without the requirement of pitch and voicing decisions. Finally, speech modification with a mixed-phase system estimate is shown to be capable of more closely preserving waveform shape in time-scale and pitch transformations than the earlier approach.

Harmonic inductor for generation of an energy conserving power wave

Abstract: An energy convertor for generating a power output waveform that contains a fundamental sine wave and a controlled amount of the third harmonic wave to eliminate the sinusoidal peaks and to provide a desired flat top at reduced amplitude. The synchronized generation of the third harmonic is achieved in combination with a new inductor that enhances the harmonic in the magnetic path around the inductor.

Apparatus for measuring differential impedances

Abstract: An apparatus for measuring differential impedances which incorporates a CMOS timer in place of the sine wave generator in a typical AC bridge configuration. A toroidal signal transformer having its primary and secondary windings tightly twisted together and wound around the core lessens temperature drift characteristics. The differential bipolar current signal provided by the secondary winding is passed through an AC to DC converter which is switched by a field effect transistor, thereby eliminating the need for prior art inverter comparator circuits. Finally, by use of a bandpass filter after the signal transformer and by insertion of a capacitor before the AC to DC converter, the need for the active filter stage used in the prior art is eliminated.

On the Measurement of Shock Waves

Abstract: The classic theoretical formulations of finite-amplitude distortion invariably depict continuous sinusoidal waves which develop into sawtooth or N-shaped waves. In practice, where ultrasonic wave- forms at high intensities are measured by a PVDF hydrophone con- nected to an oscilloscope, waveforms are observed with gross asym- metries between positive and negative pressure amplitudes, high- amplitude spikes, notches, ringing, and other peculiarities. In princi- ple, additional nonlinearities in the driving stages or the receiving sys- tem may influence the observed waveform. However, it is not necessary to invoke nonlinearities in the transmit or receive systems to explain the time-domain appearance of many waveforms. Instead, linear mechanisms exist which affect the waveshape. The first is a relative phase shift betwen the fundamental and second (and higher) harmonics which occurs in a diffraction-limited focused field. This alters the time- domain appearance but not the spectral content of the observed signal. The second class of linear mechanisms involves hydrophone cable and impedance mismatch effects which alter both time- and frequency-do- main characteristics of the actual pressure waveform incident on the hydrophone. These effects and others are illustrated. The results form the basis for some recommendations on experimental procedures in nonlinear wave propagation.

Sine-wave synthesis using walsh functions

Abstract: An investigation of the synthesis of sine waves from a truncated series of Walsh waves of ascending sequency is described. Computer simulation of the model is carried out in establishing potential circuit performance. A prototype circuit has been built and tested to add validity to the theoretical results.

Detecting device of torque

Abstract: PURPOSE: To detect a torque from the time of stop to the time of high speed, by obtaining sine wave outputs from magnetoresistance effect elements disposed opposite to magnetic rotary encoders which are provided on the drive side and the load side of a rotating shaft, and by detecting an angular difference between these outputs. CONSTITUTION: Drums 2 and 2' having N and S poles 3 and 3' recorded thereon are provided on a rotating shaft 1 at a prescribed gap between them, and sensors 4 and 4' consisting of magnetoresistance effect (MR) elements R 1 and R 2 are disposed opposite to these drums at a small gap therefrom. The MR elements R 1 and R 2 are disposed in separation by λ/2 from each other when an interval between the N and S poles is λ. The resistances of the elements R 1 and R 2 are varied due to changes in intensities of the N and S poles. The shaft 1 is distorted when a torque is applied thereto, and causes a phase difference proportional to the torque between outputs due to variations in the resistances of the sensors 4 and 4'. By taking out only a fundamental wave by offsetting a third harmonic component by means of bridge connection, on the occasion, the torque is detected as a phase difference between outputs of sine waves. By this method, the torque is detected highly precisely from the time of stop to the time of high speed. COPYRIGHT: (C)1989,JPO&Japio

Segmentation of range images using sine wave coding and Fourier transformation.

Abstract: A laser scanner is used to produce a digital range image which is sine wave coded and Fourier transformed to obtain an efficient segmentation of planar and cylindrical surfaces. Extension to complex shape is also discussed.

Feeding system using polyphase multiple pwm inverter

Abstract: PURPOSE:To control higher harmonics by inserting a reactor having a plurality of windings between a polyphase multiple PWM inverter and a load so that there exists a given phase relation between carrier signals of PWM signals. CONSTITUTION:A three-phase double inverter 2 composed of two sets of three- phase inverters supplies a three-phase double winding motor 4 with electricity via a three phase-composed coupling reactor 3. Said motor is provided with two sets of windings of three-phase windings 11-23 with O1-O2 as neutral points, and respective windings are connected with two sets of three-phase arms 113-233 of said inverter via the windings 111-232 of three-phase cores 31-33 of the coupling reactor 3. In order to use the function of absorption and elimination of harmonic voltage by the coupling reactor 3 effectively, it is necessary that a given phase relation exists between a signal wave and a carrier wave. This means that a phase difference between signal waves of output voltage fundamental harmonics is set to pi/6 and phase differences between carrier waves with all phase are made equal to each other at the point of time when a sine wave signal increases from zero.

Endurance of electrical insulation under non-sinusoidal voltage stress

Abstract: This paper will discuss the manner in which the number of partial discharges per cycle in a single insulation void depends on the applied voltage for any periodic waveshape, including sinusoidal, in which only one positive and one negative peak per cycle occur, and will then describe the effect of intermediate peaks during the cycle. Finally, a general procedure will be suggested for estimating conservatively the relative endurances of insulation subjected to an arbitrary periodic voltage wave, compared to a sine wave of the same peak-to-peak magnitude. We assume that the insulation is electrically loss-free.