Showing papers on "Sine wave published in 2003"

Optimum design of magnet shape in permanent-magnet synchronous motors

Abstract: In order to improve the efficiency of the permanent-magnet synchronous motor, which is closely related to its magnet shape, we have designed magnets in various shapes. A parallel top sine wave design has proved to be an optimum plan. This design adds three time components of induced phase voltage, which enables the amplitude of induced line voltage to increase about 14.9%. The design's simplified approximate arc configuration has important engineering applications.

Noise Radar for range/Doppler processing and digital beamforming using low-bit ADC

Abstract: Pulse compression radar is used in a great number of radar applications. Excellent range resolution and high resistance to electronic countermeasures (ECM) can be achieved by long wideband modulated pulses, which spread out the transmitted energy in frequency and time. By using random noise as the waveform, the range ambiguity can be suppressed as well. In this paper, noise radar for Doppler/range indication and digital beamforming is described. Main factors influencing the resolution and sidelobe level in range and Doppler are surveyed. In particular, the possible use of binary or low-bit analog-to-digital converters (ADCs) in noise radar is analyzed, which highly improves the signal-processing rate and reduces the costs. The very significant improvement of sidelobe suppression, when an extra noise signal is added before ADC, is explained theoretically and confirmed by simulation results. Mostly, the random signal is transmitted directly from a noise generating high-frequency source. A sine wave, which is phase or frequency modulated by random noise, is an alternative, giving lower range sidelobes, and higher transmitted mean power when peak-limited transmitters are applied. The dynamic requirements and the bandwidth of the modulating signal can be reduced as well.

Novel approach to the design of direct digital frequency synthesizers based on linear interpolation

Abstract: This paper presents a novel approach to the design of direct digital frequency synthesizers (DDFSs) with phase-to-sinusoid amplitude conversion blocks based on linear interpolation. For such DDFSs, the first quadrant of the sine function is approximated with a number of linear segments. Simple control circuitry reconstructs a full sine wave by symmetry. DDFS architectures using linear interpolation are first discussed, and an analysis of their spectral properties is given. From this analysis, an upper bound is provided for the spurious free dynamic range (SFDR) that can be attained for a given number of linear segments. A detailed and systematic procedure for the selection of linear segment coefficients achieving a desired SFDR is then proposed. A generalized multiplierless linear interpolation DDFS architecture is described, and specific designs achieving 84 and 96 dBc of SFDR are discussed and compared with previous work. It is shown that the complexity of synthesizers based on the new approach, in terms of the number of transistors and silicon area, is significantly less than that of previously presented DDFS designs of similar performance.

Techniques of Wind Vector Estimation from Data Measured with a Scanning Coherent

Abstract: The results of a theoretical study of the feasibility of wind velocity vector estimation from data, measured with a scanning coherent Doppler lidar, are presented. The estimation techniques considered are (a) the direct sine wave fitting (DSWF) and the filtered sine wave fitting (FSWF), where at first the radial wind velocities are estimated and then the wind vector is estimated from the dependence of the radial velocity versus the azimuth angle of the scanning; and (b) the maximum of the function of accumulated spectra (MFAS) and the maximum likelihood for the wind vector estimation (WV ML), where the wind vector is estimated directly from data measured by a scanning lidar without intermediate estimation of the radial wind velocities. It has been shown that due to strong averaging of noise fluctuations in accumulated spectra, the WV ML and MFAS techniques allow one to estimate the wind vector with acceptable accuracy at an essentially lower signalto-noise ratio (SNR) than the methods of the sine wave fitting, where noise can be the source of many spurious estimates of the radial wind velocity. The ability to find optimal criterion (in the case of MFAS) for acceptance or rejection of the wind vector estimate has been analyzed. The amount of measured data needed for spectral accumulation in order to realize optimal performance has been calculated.

Techniques of Wind Vector Estimation from Data Measured with a Scanning Coherent Doppler Lidar

Abstract: The results of a theoretical study of the feasibility of wind velocity vector estimation from data, measured with a scanning coherent Doppler lidar, are presented. The estimation techniques considered are (a) the direct sine wave fitting (DSWF) and the filtered sine wave fitting (FSWF), where at first the radial wind velocities are estimated and then the wind vector is estimated from the dependence of the radial velocity versus the azimuth angle of the scanning; and (b) the maximum of the function of accumulated spectra (MFAS) and the maximum likelihood for the wind vector estimation (WV ML), where the wind vector is estimated directly from data measured by a scanning lidar without intermediate estimation of the radial wind velocities. It has been shown that due to strong averaging of noise fluctuations in accumulated spectra, the WV ML and MFAS techniques allow one to estimate the wind vector with acceptable accuracy at an essentially lower signal-to-noise ratio (SNR) than the methods of the sin...

Study of critical behavior in concrete during curing by application of dynamic linear and nonlinear means.

Abstract: The monitoring of both linear and nonlinear elastic properties of a high performance concrete during curing is presented by application of compressional and shear waves. To follow the linear elastic behavior, both compressional and shear waves are used in wide band pulse echo mode. Through the value of the complex reflection coefficient between the cell material (Lucite) and the concrete within the cell, the elastic moduli are calculated. Simultaneously, the transmission of a continuous compressional sine wave at progressively increasing drive levels permits us to calculate the nonlinear properties by extracting the harmonics amplitudes of the signal. Information regarding the chemical evolution of the concrete based upon the reaction of hydration of cement is obtained by monitoring the temperature inside the sample. These different types of measurements are linked together to interpret the critical behavior.

Modulation method for a multiple drive system based on a two-stage direct power conversion topology with reduced input current ripple

Abstract: A new proposed two-stage multidrive direct power conversion (DPC) topology suited for multidrive application is proposed, having an input port for a three-phase power supply and several output ports to connect three-phase loads, which are independently controlled and allow for sine wave in - sine wave out operation. This is a cost effective topology compared to a standard matrix converter because the multiple three-phase loads share the cost of the controlled rectification stage. A new method to reduce the high frequency ripple from the input current is proposed based on interleaving the switching patterns of the inversion stages, which have to form two groups, allowing for size reduction of the input current filter. This is validated by experiments on a realistic laboratory prototype, while its limitations are determined by simulations.

Active type vibration noise controller

Abstract: PROBLEM TO BE SOLVED: To provide an active type vibration noise controller in which computational quantity required to obtain reference signals is reduced and which provides sufficient vibration noise control effect. SOLUTION: In the active type vibration noise controller, the filter coefficients of an adaptive notch filter 14 are successively updated so that error signals outputted by a microphone 18 are minimized based on the error signals and first reference signals, wherein the first reference signals are obtained by subtracting signals that are obtained by multiplying a sine correction value C1 based on the sine value of phase characteristics by reference sine wave signals of vibration noise frequencies from signals that are obtained by multiplying a cosine correction value C0 based on the cosine value of the phase characteristics in signal transmission characteristics from a loudspeaker 17 generating canceling vibration noise to the microphone 18 by reference cosine wave signals of vibration noise frequencies. Moreover, filter coefficients of an adaptive notch filter 15 are successively updated so that error signals are minimized based on the error signals and second reference signals, wherein the second reference signals are obtained by adding signals that are obtained by multiplying the reference sine wave signals by the cosine correction value C1 to signals that are obtained by multiplying the reference cosine wave signals by the sine correction value C0. COPYRIGHT: (C)2005,JPO&NCIPI

Pwm inverter device

Abstract: When switching from a sinusoidal wave voltage output to a 6-stp voltage output, it is difficult to obtain a smooth mode switching and a complicated switching processing is required. This problem is solved by a PWM inverter device having PWM pulse output means (2) for comparing a phase voltage instruction with a triangular carrier wave and outputting a PWM pulse signal, the device further including voltage instruction processing means (1) operating in such a manner that among phase voltage instructions, a phase having the maximum absolute value is selected and if this phase voltage instruction is greater than the maximum value of the carrier wave, the phase voltage instruction subtracted by the maximum value of the carrier wave is subtracted from each phase voltage instruction and if this phase voltage instruction is smaller than the minimum value of the carrier wave, the phase voltage instruction subtracted by the minimum value of the carrier wave is subtracted from each phase voltage instruction, so that the value obtained by the subtraction is used as each phase output voltage instruction, and in the other cases, the phase voltage instruction is used directly as the phase output voltage instruction for output to the PWM pulse output means (2).

Motor control apparatus and motor control method

Abstract: When a switch between sine wave voltage drive and rectangular wave voltage drive is effected based upon the motor rotation speed and a motor torque command value, an AC voltage forming an intermediate wave is generated by combining the sine wave and the rectangular wave and is applied to the motor.

Synchronous motor driving device, control method for synchronous motor driving device, refrigerator-freezer, and air conditioner

Abstract: PROBLEM TO BE SOLVED: To provide a synchronous motor driving device wherein rectangular wave excitation in which any excitation width between 120° and 180° inclusive is selectable and sine wave excitation can be accomplished by one piece of circuitry, and the excitation wave form can be changed in a very short time according to driving conditions (high-efficiency driving conditions, low-noise driving conditions) required for a synchronous motor to be driven. SOLUTION: The synchronous motor driving device is used to drive a synchronous motor through an inverter device. The driving device comprises: an output voltage vector computing means that determines the output voltage vector outputted by the inverter device according to a command value of rotational speed; a rectangular wave exciting means that outputs voltage in rectangular waveform with any excitation width between 120° and 180° inclusive according to the output voltage vector; a sine wave exciting means that outputs voltage by sine waveform excitation according to the output voltage vector; and an excitation waveform selecting means that selects an excitation method and an excitation width according to conditions required in driving the synchronous motor. COPYRIGHT: (C)2005,JPO&NCIPI

Elimination of subharmonics in direct look-up table (DLT) sine wave reference generators for low-cost microprocessor-controlled inverters

Abstract: This paper investigates distortion of an inverter reference waveform generated using a direct look-up (DLT) algorithm. The sources of various distortion components are identified and the implications for application to variable speed drives and grid connected inverters are described. Harmonic and subharmonic distortion mechanisms are analyzed, and compared with experimental results. Analytical methods are derived to determine the occurrence of subharmonics, their number, frequencies and maximum amplitudes. A relationship is established identifying a discrete set of synthesizable frequencies which avoid sub-harmonic distortion as a function of look-up table length and a practical method for calculation of the look-up table indices, based on finite length binary representation, is presented. Real time experimental results are presented to verify the analytical derivations.

Self oscillation circuits

Abstract: An object of the present invention is to provide a small size output transformer capable of producing sine wave oscillation at stability and high efficiency. A drive circuit including a switching circuit is connected to DC power source input units 12 a , 12 b , and an output transformer 10 is connected to the drive circuit. At the drive circuit, the switching circuit is turned on and off on the basis of a feedback signal of the primary side resonance voltage induced in the input side primary winding of the output transformer. The energizing direction of the DC power source to the output transformer is converted in clockwise and counter-clockwise direction by the on and off of the switching circuit, and the power source is applied as the AC signal to the input side primary winding of the output transformer. The phase detecting means detects the phase of the resonance waveform at the primary side of the output transformer 10 and outputs the phase signal. The control circuit connected to the drive circuit converts the signal of the phase detecting means to two phase signals of mutually reversal phases and outputs the drive signal for the on-off control of the switching circuit of the drive circuit.

An Effective Search Method for Gravitational Ringing of Black Holes

Abstract: We develop a search method for gravitational ringing of black holes. The gravitational ringing is due to complex frequency modes called the quasinormal modes that are excited when a black hole geometry is perturbed. The detection of it will be a direct confirmation of the existence of a black hole. Assuming that the ringdown waves are dominated by the least-damped (fundamental) mode with the least imaginary part, we consider matched filtering and develop an optimal method to search for the ringdown waves that have damped sinusoidal wave forms. When we use the matched filtering method, a data analysis with a lot of templates is required. Here we have to ensure a proper match between the filter as a template and the real wave. It is necessary to keep the detection efficiency as high as possible under limited computational costs. First, we consider the white noise case for which the matched filtering can be studied analytically. We construct an efficient method for tiling the template space. Then, using a fitting curve of the TAMA300 DT7 noise spectrum, we numerically consider the case of colored noise. We find our tiling method developed for the white noise case is still valid even if the noise is colored.

Effective resolution of analog to digital converters

Abstract: ADCs have always been bottlenecks in electronic systems. Currently, ADCs are often integrated on a semiconductor substrate with other mixed-signal circuits. This creates a need for clever strategies for error measurement and correction. This paper describes an analytical method which allows implementation of the necessary test on-cell. The main requirement is to produce a high-quality sine wave on the board. The parameters of this effective resolution measurement procedure can be easily (in real time) accumulated by typical digital circuitry.

Positioning control device for two-stage actuator

Abstract: In a positioning control device for a two-stage actuator having a coarse-movement actuator and a fine-movement actuator, a notch filter having a cutoff frequency fn is provided to a coarse-movement control loop, and the fine-movement actuator is driven by a sine wave of the frequency fn. At the frequency fn, a head position signal becomes identical with an output signal of the fine-movement actuator, by which the gain of the fine-movement actuator can be estimated by an adaptive identification unit with high accuracy based on the control input to the fine-movement actuator and the head position signal.

Audio decoding apparatus and method for band expansion with aliasing suppression

Abstract: A wideband, high quality audio signal is decoded with few calculations at a low bitrate. Unwanted spectrum components accompanying sinusoidal signal injection by a synthesis subband filter built with real-value operations are suppressed by inserting a suppression signal to subbands adjacent to the subband to which the sine wave is injected. This makes it possible to inject a desired sinusoid with few calculations.

Signal processing using non-linear regression with a sinusoidal model

Abstract: A method for processing signals, such as a tomography signal, in the time domain provides both high spatial resolution and high frequency resolution but at low cost. The method uses non-linear regression with a sinusoidal model to fit a sine wave to a portion of the signal that is less than a full cycle of a wave of the signal.

Tactile sensing method and system

Abstract: A system for detecting tactile information includes strain-gauge touch sensors and a controller. Based on the sum output from each of tough-sensor sensor units, an analyzer in the controller calculates touch force Fi(t) at each measurement point. An automatic gain control adjusts the voltage amplitude Ai(t) of a sine wave of frequency fi applied to the sensor units at each measurement point to bring the voltage amplitude measured at each measurement point in line with a target voltage. The adjusted voltage Ai(t) is applied to the bandpass filter with a composite sine wave y(t) which includes sine waves of each frequency corresponding to the adjusted voltage amplitude Ai(t). This makes it possible to reduce the number of lines between the controller and touch sensors that includes numerous measurement points, and enables the gain of the touch sensors constituted by strain gauges to be controlled within an appropriate range.

Improving sine-fitting algorithms for amplitude and phase measurements

Abstract: In this paper, improved sine-fitting algorithms for the measurement of amplitude and phase difference between two records of digitized sine waves with the same frequency are presented. These algorithms can be used for example in impedance measurements or to accurately measure the input and the output of a linear system to be characterized in the frequency domain both in amplitude and in phase.

Device and method for evaluating optical distortion of transparent plate body

Abstract: A device and method for evaluating the optical distortion of light passing through a transparent plate body. To image a grid pattern (2) through a glass plate (3) by means of imaging means (4), 4n±α CCD pixels are provided for n grids (pairs of bright and dark portions) and α Moire fringes are formed. According to the gray data on the captured image, the sine wave of phase A and that of phase B shifted from phase A by 90° are combined. The phase angle of each pixel on the Lissajous figure is calculated from the sine waves of phase A and phase B. The refractive power is calculated from the phase angular velocity which is the difference between the phase angles of the pixels.

Direct digital frequency synthesizer for cellular wireless communication systems based on fast frequency-hopped spread spectrum technology

Abstract: Direct digital frequency synthesizer (DDFS) are used for generating an oscillator signal ( ( t )) with an approximately sinusoidal waveshape and can advantageously be applied to wireless RF transceivers in a cellular communication system based on a fast frequency-hopped spread spectrum (FHSS) technology. The invention particularly refers to a method for reducing spurious harmonics, voltage and/or current glitches in the frequency synthesizer's noise power density spectrum ( ( kf )) caused by phase truncation, amplitude and time quantization errors introducing jitter into the waveform of the output signal ( ( t )). Thereby, discrete P -bit phase difference values (Δϕ s ( nT )) serving as frequency control words (FCWs) are repeatedly accumulated to generate P'-bit samples of a digital sawtooth signal ( ϕ s ( nT )) with a predefined time period ( N · T ), which are then submitted to a phase-to-sine-amplitude conversion of the obtained discrete phase input values ( ϕ s ( nT )) into a set of discrete sine amplitude sample values ( s ( nT )). After that, these sine amplitude sample values ( s ( nT )) are converted into an approximation of a quantized analog sine wave ( a 1 '( t )). According to one embodiment of the underlying invention, spurious harmonics (DSCs) are spread over the entire signal spectrum by adding a P "-bit number word representation of a random number ( r ( nT )) to the obtained sine amplitude sample values ( s ( nT )). Thus, the periodical structure of glitches, phase truncation and quantization errors ( ( nT )) of the approximated sine wave ( ( t )) is destroyed and its spurious discrete noise power density spectrum ( ( kf )) caused by said error signal ( ( nT )) is transformed into a broadband continuous noise power density spectrum ( ( f )). Finally, the additive noise is compensated by subtracting a digital-to-analog converted representation of said random number ( r ( nT )) from the quantized analog sine wave approximation ( a 1 '( t )) at the analog output port of the direct digital frequency synthesizing unit (DDFS).

A novel time-domain method of analysis of pulsed sine wave signals

Abstract: Sine wave packs are used in the nondestructive evaluation of materials, most commonly in the form of ultrasonic waves. An example of such methods is the use of electromagnetic acoustic transducers (EMATs) in the evaluation of metallic structures. Reflected EMAT signals are often highly polluted by noise. Elimination of noise and extraction of peak amplitude are important signal processing tasks associated with the analysis of EMAT signals. This paper presents a method of noise elimination and information extraction for pulsed sinusoids. The functionality of the proposed method is exemplified through noise reduction and peak detection of EMAT signals. The proposed method offers a simple and robust technique of signal analysis which is suitable for real-time industrial applications since it requires a relatively low level of computational resources.

Device for expanding and reproducing audio frequency band

Abstract: PROBLEM TO BE SOLVED: To reproduce a harmonics tone string near an original sound in the frequency band expanding processing of a sound signal. SOLUTION: A high-pass filter 3 takes out components of the harmonics tone string from an input sound signal and a frequency shifting part 4 performs frequency shifting of the components of the harmonics tone string. A cross correlation operation part 5 and a sinusoidal wave table 6 recursively perform cross correlation operation between the input sound signal and the output of the frequency shifting part 4 while changing an amount of the frequency shifting and decides an amount of the frequency shifting with which the result of the operation shows the maximum correlation. A frequency shifting part 7 shifts the frequency of the input sound signal by the decided amount of the frequency shifting and a high-pass filter 8 takes out components equal to or higher than a second specific frequency from the output of the frequency shifting part 7. An adder 12 adds the input sound signal and the output of the high-pass filter 8 whose level is adjusted in a level adjusting part 9. COPYRIGHT: (C)2005,JPO&NCIPI

Driving method and driver of dc brushless motor

Abstract: PROBLEM TO BE SOLVED: To provide a driving method and a driver of a DC brushless motor in which a conventional r.p.m. of the DC brushless motor is attained during high speed operation while keeping a high motor efficiency at low speeds by winding the stator winding greatly thereby lowering the torque (r.p.m.). SOLUTION: A rectangular wave having a conduction angle of 120-150° or an equivalent waveform is outputted at low speeds, a rectangular wave or a sine wave having a conduction angle of 130-180° or an equivalent waveform is outputted with a specified frequency at high speeds and only the specified frequency is varied while sustaining a constant duty. High efficiency low noise operation is realized at low speeds and a peak current for the effective current can be suppressed because a high speed can be ensured stably and the current waveform approaches a sine wave. COPYRIGHT: (C)2005,JPO&NCIPI

Audio decoding apparatus and audio decoding method

Abstract: A wideband, high quality audio signal is decoded with few calculations at a low bitrate. Unwanted spectrum components accompanying sinusoidal signal injection by a synthesis subband filter built with real-value operations are suppressed by inserting a suppression signal to subbands adjacent to the subband to which the sine wave is injected. This makes it possible to inject a desired sinusoid with few calculations.

ADC testing using interpolated fast Fourier transform (IFFT) technique

Abstract: An ideal transfer characteristic of an analogue-to-digital converter (ADC) is simulated and an arbitrary nonlinearity error is introduced. A full-scale sine wave is also simulated and applied to ADC input. The interpolated fast Fourier transform (IFFT) technique is used to determine accurately fundamental and other harmonics in the output spectrum of the ADC. The signal-to-noise ratio and the effective number of bits (ENOB) are computed on the basis of FFT and IFFT for different resolutions of ADC and test conditions. The effects of rectangular and Hanning time window functions on the determination of frequency components are reported. The proposed method of dynamic testing of the ADC is useful for users as well as manufacturers.