Showing papers on "Sine wave published in 1995"

An improved sine-wave fitting procedure for characterizing data acquisition channels

Abstract: This paper presents a new sine-wave fitting procedure for characterizing data acquisition channels and analog-to-digital converters. It overcomes most of the problems encountered with the classical three- or four-parameter sine-wave fitting procedure described in IEEE Standard 1057. The stochastic properties of the new procedure are thoroughly analyzed. Its performance is illustrated by simulations and measurements with a high-frequency sampling scope.

A high performance sine wave inverter controller with capacitor current feedback and "back-EMF" decoupling

Abstract: This paper presents a state space approach to the problem of controlling a single phase PWM inverter with an LC output filter. These types of inverter are often used in uninterruptable power supplies (UPS) where a sine wave output voltage is to be maintained. Output voltage control is structured around an inner filter capacitor current loop where capacitor current is sensed via a single, small current transformer. This avoids the expense of multiple, active current sensors found in alternative designs. Performance of the capacitor current loop is enhanced with active decoupling of both the DC bus and the equivalent "back-EMF" of the output voltage. The output dynamic stiffness of the system is analyzed and plotted. Experimental results yield less than 0.5% total harmonic distortion (THD) at full load (8 kW), with transient response times of less than 200 /spl mu/s. >

A high resolution multibit sigma-delta modulator with individual level averaging

Abstract: A second-order sigma-delta modulator with a 3-b internal quantizer employing the individual level averaging technique has been designed and implemented in a 1.2 /spl mu/m CMOS technology. Testing results show no observable harmonic distortion components above the noise floor. Peak S/(N+D) ratio of 91 dB and dynamic range of 96 dB have been achieved at a clock rate of 2.56 MHz for a 20 kHz baseband. No tone is observed in the baseband as the amplitude of a 10 kHz input sine wave is reduced from -0.5 dB to -107 dB below the voltage reference. The active area of the prototype chip is 3.1 mm/sup 2/ and it dissipates 67.5 mW of power from a 5 V supply. >

Air conditioning device

Abstract: An air conditioning device is arranged such that an output voltage from a commercial power source is converted into a direct current by a rectifying circuit and a smoothing condenser, and thereafter, it is further converted into an AC voltage having a variable frequency by an inverter under the control of a microcomputer, thereby supplying it to a power compressor. Between the rectifying circuit and the smoothing condenser, provided is an active filter for shaping an input current to be an approximate sine wave almost in phase with an input voltage by switching a power transistor. The switching control section and the microcomputer for controlling the switching are activated independently by separately provided power sources. The switching control section supplies a high level signal when the active filter is a normal condition, while supplies a low level signal when the active filter is abnormal. A circuit which generates a low level signal when the power supply to the switching control section is shut off is provided. This enables the microcomputer to determine the occurrence of abnormality in the active filter or the switching control section even when the power supply is shut off.

Phase-locked vocoder

Abstract: The phase vocoder is widely used to provide high-fidelity time stretching or contraction of audio signals such as speech or monophonic musical passages. Two problems bedevil the reconstructive phase of this technique. First, the frequency estimate is usually multi-valued and one does not know how to choose which of the possible frequencies given by the analysis to use in resynthesis. Second, a sinusoidal component in the incoming sound always excites several channels of the analysis; the reconstructed sine waves can interfere with each other, giving rise to a reverberant sound. An improved formulation of the phase vocoder is proposed for which the first difficulty does not arise; and a means of phase-locking adjacent channels of the resynthesis is proposed which alleviates the second one.

Semiconductor power losses in AC inverters

Abstract: The AC induction motor is the workhorse of modern industry. Worldwide about 50 million motors are installed every year which are greater than 1/2 hp. Three-phase induction motors are very simple and inexpensive to build. An AC motor may be used for variable speed applications with the addition of an AC inverter. An accurate model of semiconductor power losses is necessary to design a reliable invertor system using a minimum amount of silicon. Equations for the average and RMS transistor and diode currents are derived based on a quantitative analysis of the current waveforms. Conduction losses in the semiconductor devices are then approximated using a piecewise linear approximation of the device's on-voltage characteristics. Measurements of switching energy versus current are used to obtain a curve of losses versus current. Integration of these losses over a full sine wave period is used to obtain a closed form expression for switching losses as a function of sine wave current. Total losses, conduction losses and switching losses are compared to thermal measurements. The model is further tested by comparing predicted and actual losses at different PWM frequencies.

Two algorithms for adaptive retrieval of slowly time-varying multiple cisoids in noise

Abstract: Two algorithms for tracking parameters of slowly varying multiple complex sine waves (cisoids) in noise (the multiple frequency tracker and the adaptive notch filter) are described. For high signal-to-noise ratio (SNR), the properties of the algorithms (i.e., stability, noise rejection, and tracking speed) are studied analytically using a linear filter approximation technique. The tradeoff between noise rejection and tracking error for both algorithms is shown to be similar. Different choices of the design variables are discussed, namely (i) minimal mean-square estimation error for random walk modeled frequency variations and (ii) minimal stationary estimation variance subject to a given tracking delay. >

Subscriber line impedance measurement device and method

Abstract: A device and method for line impendance measurement using a multi-frequency test signal (figure 1b, 1c) waveform in a signal injection technique featuring analysis of acquired line test response data. A multi-frequency test signal waveform (figure 1b, 1c) is injected into the subscriber line (figure 3), to obtain by data acquisition the line response in terms of voltage measurements, which are processed via a digital filter (14) to analyze a specific sine wave frequency. Using a multi-level rectangular wave signal as the test signal and analyzing at the dominant frequency derived from the rectangular signal, or other harmonics, it is possible to derive the line characteristics, including amplitude attenuation and phase shift, which constitute line impedance.

Radar sensor/processor for intelligent vehicle highway systems

Abstract: A radar sensor/processor for intelligent vehicle highway systems. The radar sensor/processor provides the range, speed, identity of, and selective communications with, vehicles equipped with a transponder in a first cooperative interrogator/transponder mode, and provides information on the range and speed of vehicles without a, or with an inoperative, transponder in a second noncooperative mode. The interrogator includes a first direct digital synthesizer, with an associated first input binary tune register, for producing a sine wave output, a multiplier for multiplying the sine wave output to produce an X-band signal, and a bi-phase single sideband modulator which modulates the X-band signal with data to be transmitted. The interrogator receiver receives a returned transponder reply signal, and includes a balanced mixer for downconverting the reply signal. A down-converted carrier signal is extracted, and is an input to a control loop which includes a second direct digital synthesizer, its associated second input binary tune register, a phase detector, and an A/D converter. The control loop rapidly adjusts the count in the second binary tune register to bring the output frequency of the second direct digital synthesizer into exact correspondence with the down-converted carrier signal. A subtraction of the respective counts in the input binary tune registers for the first and second direct digital synthesizers is a measure of the vehicle speed.

Large amplitude sinusoidal voltammetry

Abstract: A large amplitude sine wave is applied as the excitation potential to a amperometric measurement to produce a current output that is a phase shifted sine wave containing faradaic information at many frequencies. A current obtained from a conventional potentiostat coupled to the electrode is coupled to a lock-in amplifier that monitors the signal at one frequency at a specified phase angle. Since most of the background remains at the fundamental frequency, a higher harmonic of the fundamental frequency of the sinusoidal sweep frequency is monitored. By locking in on the higher harmonic components, the faradaic signal is therefore distinguished from the background signal. The background is diminished thereby allowing signal recognition at low analyte concentrations and increasing the signal-to-noise ratio.

The effects of accumulated timing jitter on some sine wave measurements

Abstract: This paper investigates the effects of accumulated timing jitter on the signal-to-noise ratio (SNR) and on the phase angle measurement of real sine waves. These measurements are done via the Fast Fourier Transform (FFT) method. Accumulated timing jitter occurs when the sine wave is sampled by an unstable clock where the clock periods are randomly changing. Also, accumulated jitter is a problem in ramp-type bases that were often used in sampling oscilloscopes. Expressions for an estimate of the signal-to-noise ratio [SNR/sub (est.)/] and phase variance in terms of the jitter distribution parameters and the number of FFT points (N) are derived. The derived expressions are verified through computer simulations. Finally, a comparison between independent and accumulated jitter is presented. >

Optical encoder having a combination of a uniform grating and a non-uniform grating

Abstract: A main scale 11 and an index scale 12 are arranged in parallel with each other so as to be relatively movable. A light source 10 for irradiating collimated light on the main scale 11 is provided above the main scale 11. A light detecting devices 13a and 13b for detecting the amount of light which pass trough the index scale 12 are provided below the index scale 12. The main scale 11 has an uniform grating which consist of transmitting portions 14 and non-transmitting portions 15 which are formed with a uniform width and alternately arranged by uniform pitch P. The index scale 12 has non-uniform grating portions 12a and 12b whose phase are mutually shifted 90 degrees. Transmitting portions 16 and non-transmitting portions 17 of the non-uniform grating portions are arranged at the same pitch as the main scale 11. Each width of the non-transmitting portions 17 is equal to each width of sliced portions of a sine waveform sliced by 10 slice levels, the sine waveform is represented bottom-to-bottom and whose wavelength is equal to one pitch of the uniform grating. The non-uniform gratings 12a and 12b substantially work as the sine wave gratings, so that an output signal excluding the harmonic components distortion can be obtained.

Speech encoding method, speech decoding method and speech encoding/decoding method

Abstract: A speech encoding/decoding method calculates a short-term prediction error of an input speech signal that is divided on a time axis into blocks, represents the short-term prediction residue by a synthesized sine wave and a noise and encodes a frequency spectrum of each of the synthesized sine wave and the noise to encode the speech signal. The speech encoding/decoding method decodes the speech signal on a block basis and finds a short-term prediction residue waveform by sine wave synthesis and noise synthesis of the encoded speech signal. The speech encoding/decoding method then synthesizes the time-axis waveform signal based on the short-term prediction residue waveform of the encoded speech signal.

Absolute position detection apparatus and error compensation methods therefor

Abstract: An absolute position detection apparatus which comprises sine and cosine wave generators for generating one or more sets of sine and cosine waves within a cycle, analog-to-digital converters for converting the incoming sine and cosine waves generated by the sine and cosine wave generators into digital values. An arithmetic unit is used for calculating a compensation for errors including offset, amplitude and phase errors on the basis of the digital values from the analog-to-digital converters. In the apparatus, the arithmetic unit operates on a phase angle from phase angles found by the arithmetic performed prior to or during said error compensations and the digital values from the analog-to-digital converters, whereby a low-priced, highly reliable absolute position detection apparatus can be achieved without the addition of compensation circuits to the hardware.

A critical note on histogram testing of data acquisition channels

Abstract: Histogram testing is used to measure the transfer characteristic of a digitizer in order to quantify and to analyze its nonlinear behavior. In this paper it is shown that this method is very insensitive to the out-of-phase components of the digitizers' response to a sine wave excitation. This can lead to an underestimate of the nonlinear behavior of the digitizer. >

High frequency sinusoidal generation using delta-sigma modulation techniques

Abstract: An analog sine wave generator based on a digital resonator and a bandpass delta-sigma (/spl Delta//spl Sigma/) modulator is presented Except for a 1-bit D/A, this design is entirely digital allowing precise control over the amplitude and frequency of oscillation Furthermore, it is area efficient as it does not require a ROM or a multiplier Unlike previous designs, this circuit is capable of operating at any ratio of the clock frequency We envision that this device will be used in communications circuits or as a test stimulus for mixed-signal ICs

Continuous and discontinuous sine wave synthesis of speech signals from harmonic data of different pitch periods

Abstract: A method for decoding encoded speech signals uses sine wave synthesis based on harmonics of the original speech signal. The harmonics are obtained by transforming the original speech signal from a time domain to a frequency domain, and the harmonics are arranged as sequential frames with the harmonics of a given frame having a pitch period that may or may not be the same as the pitch period of another frame. According to the decoding method, data arrays respectively containing amplitude data and phase data of the harmonics are zero-padded to provide the arrays with a pre-set number of elements. Inverse orthogonal tarnsformation of the data arrays produces time domain information used to generate a time domain waveform signal for restoring the encoded speech signals. The different pitch periods of the frames are normalized to each other either by smooth (continuous) or acute (discontinuous) interpolation depending on the degree of change in the pitch period between the frames.

Frequency-based BIST for analog circuit testing

Abstract: In this paper we propose a configuration for a VLSI analog sine wave generator with an appropriate frequency BIST. The generator is used for testing circuits that require sinusoidal input signals with a variable frequency as an input stimulus. The detectors indicate any deviation of the frequency input signal from the nominal value /spl plusmn//spl epsiv/. A sine wave generator and two different BISTs are proposed: the defection and translation (DandT) T-BIST approach and the frequency-counter BIST approach. Some experimental results are also presented.

Method and device for synchronization of transmitter and receiver in a digital system

Abstract: In an OFDM system, pre-FFT synchronisation is performed on the received signal before conversion from the time domain to the frequency domain, i.e. before the signal is subject to FFT processing. Data is transmitted in frames. A plurality of frames may be transmitted as a super-frame. Each super-frame commences with at least one synchronisation frame and is followed by a defined number of information carrying frames. One, or more, synchronisation frames contains a chirp signal. A chirp signal is a sine wave signal having a frequency which changes linearly with time. Two adjacent synchronisation frames may each contain a chirp signal. The chirp signals in adjacent frames have their frequencies changing in opposite senses, i.e. one chirp signal has a frequency which increases with time, the up-chirp, while the other chirp signal has a frequency which decreases with time, the down-chirp. A bit pattern is stored in the receiver which corresponds to the decoded chirp signal, i.e. the chirp signal after it has been digitally processed by the receiver. The received signal is compared, after digital processing, with the stored bit pattern.

High efficiency supply for electroluminescent panels

Abstract: Apparatus for operating electroluminescent panels. An electroluminescent panel is driven by a voltage source feeding a modified bridge driven by a pulse width modulated signal. By using a pulse frequency above the range of human hearing and a modulating signal that is a sine wave of the proper frequency for operating the panel, a sine wave is generated across the panel without requiring bulky low frequency magnetic components.

Bandwidth Enhanced Sinusoidal Modeling in Lemur

Abstract: We present a system for sound modeling and synthesis that preserves the elegance and malleability of a sinusoidal model, while accommodating sounds with noisy (non-sinusoidal) components. We use an enhanced McAulay-Quatieri (MQ) style analysis that extracts bandwidth information in addition to the sinusoidal parameters for each partial. To produce noisy components, we synthesize with sine wave oscillators that have been modified to allow the introduction of variable bandwidth. The enhanced MQ analysis and the bandwidth-ehanced oscillators are implemented in Lemur, a widely distributed MacintoshTM program (free at the demonstration), which will be used to demonstrate the technique.

Scannerless range imaging with a square wave

Abstract: Scannerless range imaging (SRI) is a unique approach to three dimensional imaging without scanners. SRI does, however, allow a more powerful light source to be used as compared to conventional Laser Radar (LADAR) systems due to the speed of operation associated with this staring system. As a result, a more efficient method of operation was investigated. As originally conceived, SRI transmits a continuous intensity modulated sinusoidal signal; however, a square wave driver is more energy efficient than a sinusoidal driver. In order to take advantage of this efficiency, a square wave operational methodology was investigated. As a result, four image frames are required for the extraction of range using a square wave to unambiguously resolve all time delays within one time period compared to a minimum of three frames for the sinusoidal wave.

Ultrasonic wave diffusing and oscillating device for beauty treatment

Abstract: PROBLEM TO BE SOLVED: To avoid concentration of ultrasonic waves at a center, generation of radio noises, and the danger of an electric shock by superimposing on the fundamental high-frequency current of an oscillator a high-frequency current having a lower frequency than the former for modulation. SOLUTION: High frequencies of about 100kHz or more are produced from components 21 to 23. These frequencies are tuned to the resonance frequency of an oscillator 7 and an oscillating plate 8. A rectangular or sin wave of about 20 to 100kHz is imparted to a waveform input line 25, am plified, and modulated by a modulation signal circuit 4. When one 26 of the secondary windings of the component 21 is grounded and a casing wire 3 is grounded, a pole of the oscillator 7 and the metallic oscillating plate 8 are also grounded. This constitution, even with the use of ultrasonic waves of high frequencies, allows the ultrasonic waves that concentrate at the center to be diffused to ensure absolute safety while enhancing cosmetic effects. COPYRIGHT: (C)1997,JPO

Encoder unit for providing to a servo motor control unit position data which is adjusted to account for processing delays

Abstract: In an encoder unit for interpolating analog signals such as sine waves and triangular waves to obtain higher resolution or absolute values through A/D conversion and arithmetic processing, a delay time of data which is caused by A/D conversion and arithmetic processing time is eliminated to prevent deterioration of control performance. A storage unit for holding detected angular data and an output compensation unit for compensating the delay time are provided and a position change occurring during the delay time is predicted by the output compensation unit from angular data obtained from current and previous sampling cycles, and the delay time is compensated by adding the predicted position change to the current sampling data. Deterioration of the control performance can be prevented and inexpensive low-speed A/D converter and arithmetic processor can be used, and, therefore, required costs can be reduced.

Control of PWM voltage inverters in the pulse dropping region

Abstract: The overmodulation of pulse width modulated (PWM) inverters causes a nonlinearity in the feedforward channel. The type of modulator, sine wave, space vector or third harmonic, establishes the characteristics of the transition region's nonlinearity. The characteristics for a number of modulation strategies are introduced. Test results from commercially available volts per hertz (V/F) drives reveal their inability to provide rated voltage even at rated input conditions. The adverse effects of the overmodulation region on current regulated AC inverters are demonstrated by experimental results. A compensated modulation technique (CMT), adaptable to continuous and discontinuous modulators, provides the exact inverse of the nonlinearity; thus it produces a smooth transition to six-step operation without inducing a voltage transient. Experimental results presented in the paper demonstrate the CMT's smooth transition to six-step and the improved performance of the CMT-PWM. Finally, a comparison of the CMT with the other known overmodulation strategy shows the CMT provides a simple technique with essentially identical harmonic characteristics. >

New apparatus for thermal diffusivity measurements of refractory solid materials by the periodic stationary method

Abstract: An apparatus for the thermal diffusivity measurement of refractory solids at high temperatures (800–1800 K) by the periodic stationary method is presented. A cylindrical geometry for the sample has been chosen. The radial heat flow through the measurement cell is sine modulated and induces a thermal sine wave over the lateral side of the sample. The thermal diffusivity is determined from the measurement of the phase change and the amplitude ratio between two points of the sample. Thus, the thermal diffusivity can be obtained in two manners. The difference between these results is a criterium for the validity of the measurement. Experimental results on a sample of a cordierite based sintered material (Cecorite 130P) are presented. They show good agreement with the results of the CODATA Task Group on Thermophysical Properties.