Showing papers on "Sine wave published in 1984"

Visual signal detection. I. Ability to use phase information

Abstract: We present experimental evidence that humans use phase information for detection and discrimination of visual signals (static sine waves) when sufficient a priori information is made available. Under these conditions human performance exceeds that of the best-possible phase-insensitive detector. There is a marked reduction in performance when signal-phase information is not given to the observer.

Magnitude-only reconstruction using a sinusoidal speech modelMagnitude-only reconstruction using a sinusoidal speech model

Abstract: In this paper a sinusoidal model for the speech waveform is used to develop a new synthesis technique that requires specification of only the amplitudes and frequencies of the component sine waves. These parameters are estimated from the short-time spectral magnitude. The resulting synthetic waveform preserves the short-time spectral magnitude during rapid movements of spectral energy such as voiced/unvoiced transitions, and yields speech of very high quality and intelligibility. The approach is sufficiently flexible to also allow for high-quality time-scale modification with the option of time-varying scaling. Finally, results are given for some initial experiments that explore the possibility of magnitude-only waveform coding at 8 kbps.

Inverter for use with solar arrays

Abstract: A controlled switching system for converting the output of several photovoltaic solar arrays into a polyphase alternating electric current. Each array is utilized 100% of the time, and at any particular instant only one array or no array is feeding a particular phase. The specific line to which an array is connected is altered in a cyclic manner by the switching system to synthesize the polyphase current. Energy is not stored in the switching system, but instead is made available as polyphase electric current as soon as it is generated by the photovoltaic arrays. Each phase approximates a sine wave to an extent that is limited by the number of arrays. For the closest approximation, the arrays must be configured to have prescribed voltages and currents. Alternatively, a single array may be partitioned electrically in such a way that the desired voltages and currents are attained.

Geniculate orientation biases seen with moving sine wave gratings: implications for a model of simple cell afferent connectivity.

Abstract: Orientation bias of cat dorsal lateral geniculate (LGN) neurones varied with the spatial frequency of a moving sine wave grating. At low spatial frequencies there was little orientation bias, whereas near the high-frequency limit, the dependence on orientation was marked. It is proposed that, if such cells were to drive the cortical inhibitory interneurones responsible for the orientation sensitivity of striate simple cells, it would explain many distinguishing features of cortical cells besides their orientation sensitivity.

The ventilatory response of the human respiratory system to sine waves of alveolar carbon dioxide and hypoxia.

Abstract: Sine waves of alveolar CO2 at constant high alveolar O2, and sine waves of alveolar hypoxia (1/(PA, O2 -C), C congruent to 32 torr) at constant alveolar CO2 have been administered to three subjects in each case. Sine waves of six different periods were studied, ranging between 900 and 30 s for the CO2 sine waves and 300 and 20 s for the hypoxic sine waves. The sinusoidal variations in ventilation produced by these manoeuvres, expressed as amplitudes and phase shifts, were compared with values predicted from the dynamic responses to alveolar steps of gas tension already to be found in the literature. For the CO2 sine waves, the amplitudes of response agreed well with those predicted at the higher frequencies, but were less than predicted at the lower frequencies. For the hypoxic sine waves, the amplitude of response varied less with frequency than was predicted. For both the CO2 and the hypoxic sine waves, the phase shift of response was less than expected at the higher frequencies. An attempt was made to fit parameters to a simple model, based on the wash-in and wash-out of respiratory gases into and out of a tissue compartment, and used in the literature for describing the responses to step changes. No satisfactory fit was found. It is concluded that the simple model is unsatisfactory by itself for describing the responses to sinusoidal chemical stimulation; features additional to those included in the model are required to explain fully the responses seen. The possibilities for chemoreception at the higher frequencies are discussed in the light of the low phase shifts.

Novel two-phase inverter-fed induction-motor drive

Abstract: A novel two-phase inverter-fed induction-motor drive for essentially constant-speed operation is described, and an example of a 30 W drive is used to demonstrate its performance characteristics and to provide experimental results. The performances of the 30 W motor with two-phase sine wave and inverter supplies are compared, and the speed variation of the inverter drive caused by a supply voltage change is shown to be less than that for a comparable DC motor. A method of predicting the drive performance is presented and is validated by comparisons of theoretical results and test measurements.

The double cnoidal wave of the Korteweg–de Vries equation: An overview

Abstract: Earlier work of the author on the spatially periodic solutions of the Korteweg–de Vries equation is here extended via an in‐depth treatment of a special case. The double cnoidal wave is the simplest generalization of the ordinary cnoidal wave discovered by Korteweg and de Vries in 1895. In the limit of small amplitude, the double cnoidal wave is the sum of two noninteracting linear sine waves. In the oppositie limit of large amplitude, it is the sum of solitary waves of two different heights repeated periodically over all space. Although special, the double cnoidal wave is important because it is but the particular case N=2 of a broad family of solutions known variously as ‘‘N‐polycnoidal waves,’’ ‘‘finite gap,’’ ‘‘finite zone’’ solutions, ‘‘waves on a circle,’’ or ‘‘N‐phase wave trains.’’ It has been shown by others that the set of N‐polycnoidal waves gives the general initial value solution to the Korteweg–de Vries equation. This present work is the core of a three‐part treatment of the double cnoidal wave. This part, the overview, presents graphic examples in all the important parameter regimes, explains how collision phase shifts alter the average speed of the two wave phases from the ‘‘free’’ velocities of the two solitary waves, describes the different branches or modes of the double cnoidal wave (it is possible to have many solitary waves on each spatial period provided they are of only two distinct sizes), and contrasts the results of this work with the very limited numerical calculations of previous authors. The second part describes how the problem of numerically calculating the double cnoidal wave can be reduced down to solving four algebraic equations by perturbation theory. The third part explains how the so‐called ‘‘modular transformation’’ of the Riemann theta functions is important in interpreting N‐polycnoidal waves.

Nonlinear Rayleigh waves: Harmonic generation, parametric amplification, and thermoviscous damping

Abstract: The propagation of surface acoustic waves in a nonlinear isotropic elastic material is investigated. The effects of heat conduction and viscous internal damping, both assumed small, are included. The method of multiple scales is used to investigate the slow modulation of a wave of arbitrary initial profile and a coupled system of integrodifferential equations is obtained for the variation of the different harmonic constituents. Explicit numerical solutions are obtained for the generation of higher harmonics by an initially sinusoidal wave and for the parametric amplification of a weak signal by a pump wave of twice the frequency.

Binaural coherence edge pitch

Abstract: The binaural coherence edge pitch (BICEP) is a dichotic broadband noise pitch effect similar to the binaural edge pitch. The noise is made by summing sine waves with equal amplitudes and random phases. The interaural phase angle is a constant for sine wave components with frequencies below a chosen frequency, and it is a random variable for components with frequencies above that frequency. The chosen frequency is a coherence edge because the signals to the two ears are mutually coherent within any band of frequencies below the edge and they are mutually incoherent in any band above the edge. Sine tone pitch matching experiments show that the BICEP exists for coherence edge frequencies between 300 and 1000 Hz and that it is always matched by a frequency above the edge frequency, by 5%–10%. The effect can be extended to higher edge frequencies, at least 2000 Hz, if the listener is appropriately cued. The results do not depend upon whether the coherent components are presented in phase or completely out of p...

Angular position detector

Abstract: A transducer formed of one or more electrode arrays is positioned in confronting relation and parallel to the plane of rotation of one or more rotating members. A plurality of phase modulated, two-phase, square wave drive signals of the same amplitude and frequency are applied to each electrode. The signals are combined at a central node or electrode to form, as a result of the signal, the superposition of the algebraic sum of all drive signal pairs. Samples of the resultant signal taken at the same frequency and of a duration of less than one-half the duration of the drive signal period provide a multi-step, synchronously detected signal. The detected signal is a multi-step approximation to a sine wave, the phase angle thereof relative to a timing point being proportional to the angular position of the rotating member. The amplitudes and phase shifts of the multi-step detected signal are then reduced to a plurality of vectors, from which two orthogonal vectors are produced which may be mathematically reduced to the amplitude and phase angle of the aforesaid sine wave. The phase angle is transformed or converted into a binary representation of the hand position.

Mixed dual frequency generating system

Abstract: A mixed dual frequency generating system for generating a digital FSK signal or a signal including two mixed frequencies includes a ROM which stores in consecutive addresses sampled data obtained by sampling a sine wave at a sampling frequency. The mixed dual frequency generating system also includes a data extracting circuit for extracting the sampled data from the ROM at the sampling frequency using an extracting step number. An output data fixing circuit changes alternate data extracted from the ROM to data "O", so that a signal having two mixed frequencies can be obtained.

Automatic sampling circuit for ferroelectric hysteresis loops

Abstract: A new type of ferroelectric loop tracer is described which allows continuous compensation for stray capacitances and resistive losses of the sample. The loop tracer works at various frequencies, here 0.1 Hz to 100 Hz, and plots the hysteresis loops at various scales directly onto a chart recorder. A facility exists for sampling any point on the hysteresis loop, thus alloying the loop parameters to be monitored as a function of temperature, frequency, etc. The applied signal, in contrast to the normally used sine wave, is triangular.

Method and apparatus for identifying recorded information segments on a record medium

Abstract: Program segments on a magnetic tape are identified by recording patterns of continuous sine wave signal bursts and blank portions in non-recorded spaces between the program segments, the continuous sine waves all having the same low-frequency relative to the audio frequency band and a selected number of continuous sine waves and a corresponding blank portion of the same length each form one level of a binary signal and a second burst of continuous sine waves and a corresponding blank portion of the same length each form the other level of the binary signal These four elements are arranged to provide an individual address code for each of the program segments on the magnetic tape and are arranged such that they may be read in either direction of tape travel, in order to identify the program segment from either direction, by forming the address code signals as complementary pairs based upon the location of the program segments relative to the ends of the tape

Interpolated value computing device for a waveform generated in an electronic device

Abstract: A device for computing interpolated values of a waveform generated in an electronic device, includes a memory for storing waveform data of a periodic sinusoidal wave, and an address signal generator for generating an address signal. The waveform data consists of sine wave data and cosine wave data. An address signal from the generator or a signal obtained by inverting the address signal (i.e., inverted address signal) is supplied to the memory. Upon receipt of the address signal, the memory reads out the sine wave data or the cosine wave data. Upon receipt of the inverted address signal, it reads out the remaining wave data. The wave data read from the memory is multiplied by a multiplier, which produced an interpolated value. An adder adds this value to the sine or consine wave data read out from the memory when the inverted address signal is supplied to the memory, and computes amplitude value data corresponding to the address signal.

Angle transducer employing polarized light

Abstract: An angle transducer which photo-electrically measures the rotation angle of a shaft by utilizing, a polarizer disc is arranged as follows: the polarizer disc is secured to the shaft to be measured or to the detection shaft of the angle transducer. Two pairs of photo-electric conversion elements are in opposition to light sources across the polarizer disc. The first and second polarizer plates are interposed between the photo-electric conversion elements of each pair. The transmission axes of the first and second polarizer plates differ from each other by 45 degrees. The quantities of light emitted by the light sources or the outputs of the photo-electric conversion elements are modulated by carrier waves of two phases differing 90 degrees from each other. The amplitudes of the outputs correspond to the sine and cosine functions of the double angle of the rotation angle of the shaft to be measured. These outputs form modulated waves of two phases differing 90 degrees from each other. The sum of the modulated waves of two phases, and the difference between the sum and a signal obtained by multiplication of the two phase carrier waves by a predetermined value, are computed by addition and subtraction computers to obtain a phase signal of a sine wave the phase of which is proportional to the rotation angle of the shaft being measured.

Chaotic motion of a weakly nonlinear, modulated oscillator

Abstract: A weakly nonlinear oscillator of natural frequency ω0 and damping ratio δ is driven by an amplitude-modulated force of dimensionless amplitude e, carrier frequency ω, and modulation frequency ω1. Each of (ω - ω0)/ω0, ω1/ω0, and δ is O(e2/3) as e → 0. The response in this resonant neighborhood is a slowly modulated sine wave, the envelope of which is described by three first-order, autonomous, ordinary differential equations. This envelope, which is periodic for δ >> e2/3, is chaotic in certain ranges of (ω - ω0)/ω0 and ω1/ω0 if δ/e2/3 is sufficiently small.

Roughness-Induced Transient Loading at a Sliding Contact During Start-Up

Abstract: The effects of normal contact vibrations, horizontal rider dynamics, and surface texture inputs are combined to examine dynamic loads at a contact during acceleration from rest to a steady state velocity. A constant sliding friction coefficient is assumed. The surface input is either a sine wave or a quasi-random function. The nondimensionalized system equations are solved numerically for a variety of system and input parameter combinations. The most interesting responses occur when the acceleration duration includes a number of periods of at least one of the system resonant frequencies. It would appear that surface-roughness and waviness can cause the normal motions and force fluctuations that occur during the transitions from static to sliding friction.

Angular measurement system

Abstract: A system for measurement of shaft angles wherein a synchro resolver (10) is sequentially pulsed, and alternately, a sine (32) and then a cosine (36) representative voltage output of it are sampled. Two like type, sine or cosine, succeeding outputs (V S1 , V S2 ) are averaged and algebraically related to the opposite type output pulse (V c ) occurring between the averaged pulses to provide a precise indication of the angle of a shaft (18) coupled to the resolver (10) at the instant of the occurrence of the intermediately occurring pulse (V c ).

Distance measurement method making use of electromagnetic wave and system therefor

Abstract: A method an apparatus for measuring the distance to a target wherein FM wave is transmitted to the target and its reflected wave is received. A beat wave is then obtained using the thus-received wave and the FM wave. A sine wave is mixed with the beat wave and a first sideband wave of a plurality of sideband waves of the resultant mixed wave is obtained. Another sine wave is mixed with the sideband wave. Then, a second sideband wave of the thus-obtained mixed wave is separated and detected. In the above manner, phase modulation is applied directly to the above-described beat wave. Information pertaining to distance can then be obtained from the number of peaks of the thus-modulated beat wave. A microwave profile meter suitable for use in the determination of the surface profile of a burden in a blast furnace is also disclosed.

A numerically efficient technique for the simulation of random wave forces on offshore structures

Abstract: A technique is presented for numerical time domain simulation of water particle velocities and acceleration corresponding to a desired wave spectrum. Standard practice is to sum a finite number of sinusoidal components with random phase. The new method uses a simple constant coefficient linear prediction equation to generate time series simulations of water particle kinematics using Gaussian white noise as input. The velocities and accelerations are propagated throughout the offshore structure using a series of numerical convolutions. These methods produce time series whose spectra are smooth continuous functions, not ones approximated by a finite number of sine waves. The new techniques are much more numerically efficient than summins sinusoids, making long simulations feasible.

Pulse width modulator for electronic watthour metering

Abstract: A pulse width modulator for an electronic kilowatt-hour meter includes an integrator having its inputs connected to a square wave clock signal and a sine wave signal proportional to the time derivative of current on the metered circuit. A plurality of series-connected inverters are connected to the output of the integrator to function as a comparator which generates a pulse width modulated signal having a duty cycle proportional to metered current. A negative feedback path including a low pass filter is connected between the output of the last inverter and an input to the integrator to compensate for errors produced by the integrator and inverters, thus permitting the use of low cost inverters fabricated on an integrated circuit.

Torque measurement circuit and method

Abstract: An improved torque measurement circuit and method for an internal combustion engine of the four cylinder, two-cycle type includes synchronous detection circuits and circuits to account for inertia forces due to the mass of the pistons and connecting rods. The synchronous detection circuits multiply a signal directly proportional to torque variations with sine wave and cosine wave signals to produce a synchronous detection signal. A summing circuit is provided to combine the synchronous detection signal with a signal proportional to the square of the angular velocity of the crankshaft of the engine to produce a resultant output signal directly proportional to average torque and independent of speed.

Trouble-shooting circuit of body movement detecting apparatus

Abstract: PURPOSE: To accelevate calculation speed, by trouble shooting by connecting in a single address informations obtained by A/D conversions of a sine wave signals being generated by a body movement detecting apparatus and contrast table of trouble detecting informations. CONSTITUTION: A moving condition of a servo-motor 1 is converted to 2-phase pseudo sine wave signals A, B accompanied by a 90° phase difference by an encoder 2. Outputs A, B of the encoder A, B are converted into digital magnitudes by No.1 and No.2 A/D convertors 3, 4. These signals is led into an address input of a ROM5. A contrast table of trouble detecting informations is stored in the ROM5 and trouble shooting is conducted by contrasting with address in puts. A phase identification apparatus 6 by identifying a direction of the signals A, B and issues pulses for counting to an up-down counter 8. A latch 7 is set when a trouble of the encoder is identified. COPYRIGHT: (C)1986,JPO&Japio

Microprocessor fsk data communications module

Abstract: A microprocessor-based frequency shift keying (FSK) data communications module. The microprocessor selectively modulates and demodulates data directly in terms of a square wave pulse train in which a first frequency is used to convey a binary "1" and a second frequency to convey a binary "0". An input and an output port on the microprocessor are selectively coupled to a transmission line through a transformer, by means of electronic switches. Also included are a bandpass filter for shaping the square waves into sine waves and for filtering noise, and means including a notch filter for generating a carrier detect signal input to the microprocessor, when incoming data is detected on the transmission line. Many of the components in the module are used for both transmitting and receiving data.

Sine wave synthesizer

Abstract: A sine wave synthesizer is employed in an analog signal processing integrated circuit. The circuit includes an integrator driven from a plurality of integration constant capacitors which are sequentially selected by a clocked decoder. Each capacitor is selected by coupling it between the integrator and a switched reference source. The capacitors are selected so that their sequential selection produces a sine wave approximating current in four increments. A first increment of a sine wave is produced according to an ascending selection of integration constant capacitors. Thereafter, the capacitors are selected in reverse in a descending manner to produce a second increment of the sine wave. The switched capacitor phasing circuit is then operated to invert the sine wave signal to produce the third and fourth increments having a negative instead of a positive excursion. The frequency of the sine wave is controlled by the decoder clock input. An output filter stage converts the digitally produced sine wave increments into a smooth sine wave output. This filter is provided with selectable time constants to allow operation at different selected frequencies.