Showing papers on "Sine wave published in 1998"

Controller for pulse width modulation circuit using AC sine wave from DC input signal

Abstract: A pulse width modulation (PWM) controller suitable for use with a variety of open loop topology power supply circuits including ring generator circuits. The controller and the circuit realized therefrom utilizes an open loop topology to achieve the desired output voltage waveform. The PWM controller is suitable for realizing a plurality of different open loop converter topologies such as such as buck, boost, forward and push-pull topologies. The PWM controller is adapted to provide the required signals to control the various possible open loop converter topologies. The controller functions to generate a PWM signal that is used to generate a half wave sine wave signal. The controller includes the necessary functionality to control the duty cycle of the generated PWM signal so as to produce a full wave sine wave at the output of the output bridge circuit.

Output filters for PWM drives with induction motors

Abstract: When an induction motor is energized from a pulse width modulated (PWM) inverter, through long connecting cables, its insulation system can be severely stressed. The high dv/dt voltage pulses at the output of the inverter cause traveling waves in the connecting cable between the inverter and the motor. When the traveling wave reaches the motor, a large impedance mismatch is present which leads to a reflected voltage wave that, when added to the incoming incident wave, can reach two times the inverter output voltage. The resulting overvoltage at the motor terminals stresses the insulation system and can lead to reduced motor life. Various output filter arrangements can be used to condition the inverter output voltage before it is applied to the cable. The advantage of adding output filtering is that the dielectric stress on the motor insulation and the inverter cable charging current can both be reduced. The major disadvantages of adding filtering is that they represent extra cost, they require extra mounting space, and they introduce extra losses in the system. The most commonly used types of inverter output filters are: simple output line inductors; output limit filter; sine wave output filter; and motor termination filter. These filters are discussed.

Pulse-driven Josephson digital/analog converter [voltage standard]

Abstract: The authors have designed and demonstrated a pulse-driven Josephson digital/analog converter. When used as a programmable voltage standard, this device can synthesize metrologically accurate ac waveforms as well as stable dc voltages. We show through simulations that Josephson quantization produces a nearly ideal quantization noise spectrum when a junction is driven with a typical waveform produced by a digital code generator. This technique has been demonstrated in preliminary experiments with arrays of 1000 junctions clocked at frequencies up to 6 Gb/s, where sine waves of a few millivolts in amplitude were synthesized at frequencies up to 1 MHz.

PWN controller use with open loop flyback type DC to AC converter

Abstract: A controller and ring generator circuit realized therefrom utilizing an open loop flyback topology to achieve a desired output voltage waveform. A characteristic feature of the controller is that it provides the required signals to control a ring generator circuit having an open loop fly back topology. The controller functions to generate a PWM signal that is used to switch the primary of a transformer on and off. The controller includes the necessary functionality to control the duty cycle of the generated PWM signal so as to produce a sine wave output on the secondary of the transformer. The controller also includes overcurrent protection circuitry that tracks the load current by sensing the current through the primary winding. In addition, the circuit permits negative current in the secondary by use of a synchronous rectifier circuit coupled to an additional secondary transformer winding. An output bridge circuit creates a full sine wave from the generated half wave output.

Transfer function analysis of the constant voltage anemometer

Abstract: The transfer function for the constant voltage anemometer (CVA) circuit has been derived in terms of circuit and hot-wire parameters and the expressions for the natural frequency and damping ratio have been obtained. Bandwidth in each case was determined from the plot of the normalized transfer function. The theoretical bandwidth behavior calculated from the transfer function plots for the prototype agrees with independent tests of the prototype using laser radiation heating of the hot wire in an air jet. The near constant value of the bandwidth of the CVA with the variation in the hot-wire overheat and its Reynolds number that were observed with the laser tests have been substantiated with the theoretical values from the transfer function. Bandwidth testing with sine wave injection, in situ time constant measurement for proper compensation setting, method to optimize the design to have nearly a constant bandwidth even with different compensation time constants and the operational advantages of CVA are also discussed.

Continuous frequency dynamic range audio compressor

Abstract: An improved multiband audio compressor (10) is well behaved for both wide band and narrow band signals, and shows no undesirable artifacts at filter crossover frequencies The compressor includes a heavily overlapped filter bank (16), which is the heart of the present invention The filter bank filters the input signal (56) into a number of heavily overlapping frequency bands (58) Sufficient overlapping of the frequency bands reduces the ripple in the frequency response, given a slowly swept sine wave input signal, to below about 2 dB, 1 dB, or even 05 dB or less with increasing amount of overlap in the bands Each band is fed into a power estimator (18), which integrates the power of the band and generates a power signal (60) Each power signal is passed to a dynamic range compression gain calculation block (20), which calculates a gain (62) based upon the power signal Each band is multiplied by its respective gain in order to generate scaled bands (64) The scaled bands are then summed to generate an output signal (68)

Method and apparatus to measure non-coherent signals

Abstract: A method of measuring non-coherent electrical signals using either windowed or non-windowed digital signal processing. The method includes the steps of providing a digitized version of the non-coherent electrical signal; generating a matrix A of correlations between sine and cosine components of known correlation frequencies and sine and cosine components of signal frequencies; generating an inverse matrix A −1 of the correlation matrix; generating a second matrix B of correlations between sine and cosine components of the correlation frequencies and the digitized non-coherent electrical signal; and generation of a third matrix C which represents the measured amplitudes of the sine and cosine components of the non-coherent electrical signal.

Noise-Induced Tuning Curve Changes in Mechanoreceptors

Abstract: Fibers from the tibial nerve of rat were isolated and spike activity recorded using monopolar hook electrodes. The receptive field (RF) of each recorded unit on the glabrous skin of the foot was mechanically stimulated with waveforms comprised of various frequency sine waves in addition to increasing levels of white noise. Single-unit responses were recorded for both rapidly adapting (RA) and slowly adapting (SA) units. Signal-to-noise ratio (SNR) of the output was quantified by the correlation coefficient (C1) between the input sine wave and the nerve responses. The addition of noise enhanced signal transmission in both RA and SA fibers. With increasing noise, the initially inverted "V"-shaped, zero-noise tuning curves for RA fibers broadened and eventually inverted. There was a large expansion of the frequencies that the RA receptor responded to with increasing noise input. On the other hand, the typical shape of the SA fiber tuning curves remained invariant, at all noise levels tested. C1 values continued to increase with larger noise input for higher frequencies, but did not do so at the lowest frequencies. For both RA and SA fibers the responses with added noise tended to be rate modulated at the low-frequency end, and followed nonlinear stochastic resonance (SR) properties at the higher frequencies. The changes in the tuning properties due to noise found here, as well as preliminary psychophysics data, imply that external noise is relevant for sensing small periodic signals in the environment. All current models of sensory perception assume that the tuning properties of receptors determined in the absence of noise are preserved during everyday tasks. Our results indicate that this is not true in a noisy environment.

Obtaining order in a world of chaos [signal processing]

Abstract: Measurements of a physical or biological system result in a time series, s(t)=s(t/sub 0/+n/spl tau//sub s/)=s(n) sampled at intervals of /spl tau//sub s/ and initiated at t/sub 0/. When a signal can be represented as a superposition of sine waves with different amplitudes, its characteristics can be adequately described by Fourier coefficients of amplitude and phase. In these circumstances, linear and Fourier based methods for extracting information from the signal are appropriate and powerful. However, the signal may be generated by a nonlinear system. The waveform can be irregular and continuous and broadband in the frequency domain. The signal is noise-like, but is deterministic and may be chaotic. More information than the Fourier coefficients is required to describe the signal. This article describes methods for distinguishing chaotic signals from noise, and how to utilize the properties of a chaotic signal for classification, prediction, and control.

Using sine wave histograms to estimate analog-to-digital converter dynamic error functions

Abstract: This paper describes a new method for developing analog-to-digital converter (ADC) error function models using modified sinewave histogram methods. The error models may be used to digitally compensate for nonlinearities introduced by the converter. The histogram modification involves sorting of converter output samples based upon an estimated associated input derivative signal. This error model is based upon a previously unpublished result which shows that sinewave histograms yield distinctly different expected errors for each state based upon input signal slope associated with each output sample. This result thus provides a dynamic dependence for expected errors measured by means of histogram methods. Sorted sinewave histograms are used to estimate slope dependent expected errors at each ADC output state (code). The method provides improved error representation by providing error basis functions for every output code. Simulated results prove that this method removes all slope dependent errors for complex ADC architectures while experimental results for an 8-bit 200 MSPS ADC yielded more than 10 dB improvement in spurious-free-dynamic-range (SFDR) over the full Nyquist band. The new method is thus shown to possess wideband dynamic error character.

Forecasting Tourist Arrivals: Nonlinear Sine Wave or ARIMA?

Abstract: This article builds a model for data series that have both seasonal and nonseasonal ARIMA patterns. In this type of model, the seasonal and nonseasonal elements are multiplied by each other. The model is then used to fit the tourist arrival data. Specifically, this approach is applied to Singapore tourist arrival data, and the fitted model is then used to forecast the tourist arrivals. It is shown that the proposed model generates forecasts with lower error magnitudes than a sine wave nonlinear time-series model. Policy implications are also addressed.

Apparatus for controlling a discharge lamp in a backlighted display

Abstract: The described DC to AC inverter efficiently controls the amount of electrical power used to drive a cold cathode fluorescent lamp (CCFL). The output is a fairly pure sine wave which is proportional to an input control voltage. The output waveform purity is ensured by driving a symmetrical rectangular waveform into a second-order, low pass filter at the resonant frequency of the filter for all conditions of line voltage and delivered power. Operating stress on the step-up transformer is minimized by placing the load (lamp) directly across the secondary side of the transformer. When configured to regulate delivered power, the secondary side may be fully floated which practically eliminates a thermometer effect on the operation of the lamp. All of the active elements, including the power switches, may be integrated into a monolithic silicon circuit.

Motor control device and method therefor

Abstract: PROBLEM TO BE SOLVED: To reduce the fluctuations of a torque, when performing switching between sinusoidal wave control and rectangular wave control. SOLUTION: The phase and amplitude of a sinusoidal wave a1, that is the voltage waveform of current PWM sinusoidal wave control, are obtained. Also, the phase of a rectangular wave c1 for generating a torque that is equivalent to a current motor torque is obtained. The rectangular wave c1 may be regarded as a sinusoidal wave with a calculated phase and a limitless amplitude. Therefore, the phase and amplitude are simultaneously and continuously changed from a sinusoidal wave a1 into a rectangular wave c1. A PWM processing is performed to a sinusoidal wave signal with the phase and amplitude that are changing to generate the control signal of an inverter, thus obtaining a voltage waveform b1 with the middle phase and amplitude between moments before and after switching. A motor torque corresponding to the voltage waveform b1 is equal to or close to the motor torques before and after the switching. COPYRIGHT: (C)1999,JPO

System and method for automatically detecting a set of fundamental frequencies simultaneously present in an audio signal

Abstract: A system and method for automatically detecting and identifying a plurality of frequencies simultaneously present in an audio signal, as well as the duration, amplitude, and phase of those frequencies, then filtering out harmonic components to determine which frequencies are fundamentals. The system includes a computer readable medium of instruction code that decomposes the signal into its component sine waves by computing and comparing correlations between the input signal and sine waves at various phase and amplitude combinations. The system also employs several optimization and error correction routines.

Controlling device for conversion of DC power to sine wave AC power

Abstract: A controlling device for conversion of DC power to sine wave AC power, including a boosting circuit, a sine wave generating circuit, a PWM wave generating circuit, a drive module, an MOSFET output circuit, a filter circuit, a protection circuit and a feedback circuit. The MOSFET output circuit outputs PWM wave by all-bridge type, whereby the safety in operation of the circuit is ensured and sine wave AC current is output.

Analytic behavior of the LMS adaptive line enhancer for sinusoids corrupted by multiplicative and additive noise

Abstract: The least mean squares adaptive line enhancer (LMS ALE) has been widely used for the enhancement of coherent sinusoids in additive wideband noise. This paper studies the behavior of the LMS ALE when applied to the enhancement of sinusoids that have been corrupted by both colored multiplicative and white additive noise. The multiplicative noise decorrelates the sinusoid, spreads its power spectrum, and acts as an additional corrupting noise. Closed-form expressions are derived for the optimum (Wiener filter) ALE output SNR as a function of the residual coherent sine wave power, the noncoherent sine wave power spectrum, and the background additive white noise. When the coherent to noncoherent sine wave power ratio is sufficiently small, it is shown that a nonlinear (e.g., square law) transformation of the ALE input results in a larger optimum ALE output SNR.

Sine output DDSs. A survey of the state of the art

Abstract: This paper presents a survey of the latest techniques and hardware advances in sine output direct digital synthesizers (DDSs). First, a brief description of the theory of sine output DDSs is presented. A sine output DDS has the advantage of being able to synthesize high spectral purity sine wave signals over a wide range of frequencies utilizing compact digital integrated circuits containing an accumulator, a sine look-up table, and a digital-to-analog converter (DAC). (The DDS is completed with an output filter.) The DDS can produce an output frequency from zero to a maximum frequency that is on the order of 1/3 of the clock frequency of the digital components. The principal advances in DDSs have been in increasing the maximum frequency (clock speed) and in increasing the spectral purity (spur reduction). Second, sine output DDS designs are examined that fall into two broad categories: designs for high speed and spectrally clean performance and designs for applications that require special features. Results are presented showing how the spectral purity of the DDS is related to the complexity and performance parameters of the digital components. Recent advances in architectural techniques are described that are designed to optimize spectral performance while minimizing architectural complexity. Finally, a survey of the latest DDSs and components developed by several manufacturers are described presenting key performance parameters such as clock speed, spectral purity, frequency resolution, DC power consumption, and special features. A plot of reported spurious performance on DDSs (or DACs for DDSs) is presented revealing a performance barrier that designers are striving to break. The advances necessary to break this barrier will be discussed.

Evaluation system for analog-digital or digital-analog converter

Abstract: There is provided an evaluation system for an A-D converter or a D-A converter capable of evaluating factors of a compounded fault and measuring an effective number of bits with a high accuracy and with a reduced volume of computation, independently of a testing frequency. A sine wave signal is applied to an A-D converter under test. Maximal or minimal values of a cosine wave component and a sine wave component in the converted output are aligned. A square root of a sum of squares of samples is formed to determine an instantaneous amplitude. The amplitude of the sine wave signal is interleaved into the series of instantaneous amplitudes. A difference series for the interleaved instantaneous amplitude series is formed by digital moving differentiator means. Alternatively, a Wavelet transform is applied to the interleaved instantaneous amplitude series, and a maximum amplitude therein is detected by a peak finder, and the detected value is delivered as representing an estimated effective number of bits.

Square Wave Analysis

Abstract: About two hundred years ago, the French mathematician J. B. J. Fourier asserted that any function with period 2ir can be expressed as a trigonometric series. This great idea has had an important influence upon many sciences including mathematics and physics. In electronics, Fourier analysis has been playing an important role, and a signal is often considered as a superposition of many sine and cosine waves with different frequencies. However, with the development of switching circuits and pulse technique, it becomes very easy to generate and process square waves. For example, it’s quite convenient to obtain a system of square waves with different frequencies from a common high-frequency pulse by means of counters, whereas it’s complicated to do the same thing with sine and cosine functions. Again, multipliers and summers for square waves are very simple.

Sound and light emitting fish lure and method of attracting fish

Abstract: A fishing lure emits continuous sine wave generated sounds to emulate the sounds produced by fish themselves. A waterproof casing contains electronic circuitry that includes a precision oscillator integrated circuit for generating a continuous sine wave sound that is swept about a predetermined center frequency of approximately 3.0 kHz and that extends between a low frequency of approximately 1.8 kHz and a high frequency of approximately 4.2 kHz. The output of the precision oscillator is coupled to a miniature piezoelectric speaker for audibly reproducing the generated sine wave sound. An LED flasher integrated circuit coupled to the precision oscillator integrated circuit serves to control a light emitting diode to flash at a predetermined rate or be constantly lit to thereby act as an additional fish attractor in combination with the emitted continuous sine wave sound.

System for signal path characterization with a reference signal using stepped-frequency increments

Abstract: A system that utilizes a reference signal for testing signal paths for complex frequency response (linear distortion), and non-linear distortion. This reference signal, which is also known as a ghost canceling reference signal or a training waveform, has excellent properties for channel characterization. The reference signal is a waveform that operates for a major time interval that is subdivided into multiple minor time intervals. During each minor time interval, a sine wave oscillates at a constant angular velocity or frequency. The sine wave frequency may take uniform steps between the minor time intervals, or it may skip a group of frequencies. The phase of the waveform may optionally be continuous between the end of one minor time interval and the start of the next minor time interval. This waveform is generated by loading the time sample values from a digital memory into a digital to analog converter (D-A), or by rapidly reprogramming a numerically-controlled oscillator. The reference signal can also be analyzed for the presence of non-linear distortion. Broadband RF channels, such as cable television channels, or baseband channels, such as telephone channels may be characterized using this waveform.

Uninterruptible power supply with AC sine wave output and energy recycle function

Abstract: An uninterruptible power supply with sine wave AC output and energy recycle function is disclosed. The uninterruptible power supply makes use of a DC/DC converter to boost and convert the DC voltage of a battery set to a full-wave rectified shaped DC voltage. A microcontroller is provided to generate a full-wave rectified shaped DC reference signal to force the DC/DC converter to follow the reference signal for adjusting its output to a full-wave rectified shaped DC voltage. The full-wave rectified shaped DC voltage is converted by an inverter to a sine wave AC voltage for providing uninterruptible power. An energy recycle charger is further provided to recycle redundant energy to the battery set.

A new phase model for sinusoidal transform coding of speech

Abstract: A phase modeling algorithm for sinusoidal analysis-synthesis of speech is presented, where short-time sinusoidal phases are approximated using a combination of linear prediction, spectral sampling, delay compensation, and phase correction techniques. The algorithm is different to phase compensation methods proposed for source-system LPC in that it has been tailored to sinusoidal representation of speech. Performance analysis on a large speech data base reveals an improvement in temporal and spectral signal matching, as well as in the subjective quality of reconstructed speech. The method can be applied to enhance phase matching in low bit rate sinusoidal coders, where underlying sine wave amplitudes are extracted from an all-pole model. Preliminary subjective results are presented for a 2.4 kb/s sinusoidal coder.

Converting apparatus of voice signal by modulation of frequencies and amplitudes of sinusoidal wave components

Abstract: A voice converter synthesizes an output voice signal from an input voice signal and a reference voice signal. In the voice converter, an analyzer device analyzes a plurality of sinusoidal wave components contained in the input voice signal to derive a parameter set of an original frequency and an original amplitude representing each sinusoidal wave component. A source device provides reference information characteristic of the reference voice signal. A modulator device modulates the parameter set of each sinusoidal wave component according to the reference information. A regenerator device operates according to each of the parameter sets as modulated to regenerate each of the sinusoidal wave components so that at least one of the frequency and the amplitude of each sinusoidal wave component as regenerated varies from original one, and mixes the regenerated sinusoidal wave components altogether to synthesize the output voice signal.

Method and apparatus to measure jitter.

Abstract: A system and method for measuring jitter. One class of embodiments is particularly useful for testing the aperture jitter of a high speed Analog to Digital (A/D) converter. Aperture jitter in a Sample and Hold circuit (S/H) or in an A/D converter introduces noise into the sampled signal, which is more extreme in areas of the input waveform that have a steep positive or negative slope. The preferred embodiment allows an easy and inexpensive way to measure aperture jitter in S/H and A/D circuits. The technique can also be adapted for measuring edge jitter in digital clock signals or in analog sine wave signals.

Active vibration noise suppressing device

Abstract: PROBLEM TO BE SOLVED: To enable suppressing vibration noise independently of variation of a vibration noise source SOLUTION: This device 4 is constituted so that a cosine wave signal and a sine wave signal synchronizing with a frequency of an engine pulse are generated from a cosine wave generator 6 and a sine wave generator 7, the generated sine wave signal is multiplied by the generated cosine signal and an adaptive notch filter coefficient W0 by a coefficient multiplier 9 in an adaptive notch filter 8 for suppressing a vibration noise, the generated sine wave signal is multiplied by an adaptive notch filer coefficient W1 by a coefficient multiplier 10, an output in which output of the coefficient multipliers 9 and 10 are added by an adder 11 is outputted to a secondary vibration noise generator 3, a secondary vibration noise is generated, and a vibration noise is canceled In this case, update quantity of an adaptive notch filter coefficient is changed based on a step size parameter varied based on amplitude of an output of the adaptive notch filter 8 directly before updating an adaptive notch filter coefficient, and thus, a vibration noise based on an engine pulse is suppressed

ADC nonlinearities and harmonic distortion in FFT test

Abstract: This paper deals with the analysis of harmonic distortion in uniform and nonuniform analog-to-digital converters (ADC), when the test signal is a pure sine wave. Mathematical relationships between harmonic distortion, input signal parameters and ADC nonlinearity errors are derived Finally, numerical simulations of A/D processes validate the analytical results.