Showing papers on "Sine wave published in 1979"

High‐speed InP optoelectronic switch

Abstract: The successful fabrication and demonstration of an InP optoelectronic switch is reported. The results obtained suggest that this device may be better suited for high‐speed analog signal processing applications than previously reported Si and GaAs switches. In experiments using cw mode‐locked lasers, the switches have exhibited an on‐state impedance of 45 Ω for 40pJ of incident laser energy and an inherent rise time of 30 psec. In addition, the switches have been used to generate a train of 70‐psec‐wide pulses at a 900‐MHz repetition rate, and to sample a 68.9‐MHz sine wave at 275 MS/sec with an accuracy to 0.2 dB (98%) and an on‐off ratio of 40 dB.

A theory for wave-power absorption by two independently oscillating bodies

Abstract: In a recent paper (Evans 1976) a theory was presented for the behaviour of an oscillating two-dimensional cylinder of any shape which was capable of absorbing energy from a given regular sinusoidal wave. In particular an expression was derived for the efficiency of power absorption of the cylinder when oscillating in a single mode in terms of properties of the solution of the so-called radiation problem in which the cylinder is forced to oscillate in the appropriate mode in the absence of the incident wave train. In the present paper this theory is extended to two independent cylinders of arbitrary shape each oscillating in a single mode and capable of absorbing energy in that mode. A general expression for the efficiency is derived which depends on properties of the solution to a new radiation problem, in which one cylinder is forced to oscillate in the presence of the other cylinder, which is held fixed in its equilibrium position. In this case, the efficiency also depends on cross-coupling coefficients related to the force on the fixed cylinder due to the motion of the oscillating cylinder. It is shown that the cylinders can be tuned to absorb all the incident wave energy at a given frequency even for symmetric cylinders, in contrast to the single symmetric cylinder, for which the maximum efficiency has been shown to be 50%. The general solution to the new radiation problem is derived in terms of the solution to the radiation problem for a single cylinder, by assuming that the cylinders are far enough apart for local wave effects to be negligible. The special case of two widely spaced rolling vertical plates is considered in detail and curves showing the variation of efficiency with wavelength are given for a variety of plate spacings and points of rotation.

Tone production method for an electronic musical instrument

Abstract: A method for producing a tone waveform having a desired spectral construction by modulating an input address signal of a selected frequency for a waveform memory. For the modulation of the input address signal, the output of the waveform memory is multiplied by a parameter β of a suitable value and the multiplication product is added to the input address signal. If the input address varies in the manner of, for example, a saw-tooth wave, a desired tone waveform can be produced within a range between a saw-tooth wave and a sinusoidal wave by selecting a suitable value of the parameter β. More specifically, a saw-tooth wave is produced as a tone wave form if a sufficiently large value of β is selected. As β is gradually decreased, the amplitude is decreased from a higher order and the amplitude also disappears from a higher order until the tone waveform becomes a sinusoidal wave when β is zero. The waveform memory having its input address modulated in the above described manner is used not only for directly producing a desired tone waveform but for modulating an input address of another waveform memory. In the latter case, a tone waveform is produced by the other waveform memory.

Power frequency converter

Abstract: A power converter which provides precise waveshape regulation. An input pr waveform (three-phase or single phase power) is rectified and modulated to form a chopped waveform within an envelope defined by the rectified input waveform. The modulation is removed by passing the chopped signal through a low-pass filter. The output of the low-pass filter, which is equal to the instantaneous value of the chopped waveform envelope times the instantaneous value of the duty cycle of the chopped waveform, is converted to a complete sine wave output voltage in a power inverter. The output of the power inverter is sampled and compared with a low-power reference waveform in a differential amplifier. The output of the differential amplifier is phase compensated for the effects of the low-pass filter and applied as an error signal to a pulse-width-modulated oscillator to adjust the duty cycle of the chopped waveform so that the sine wave output voltage follows the reference waveform.

Some alternate vibrator signals

Abstract: The linear swept-frequency sine wave has been the only seismic vibrator drive signal seriously used in almost two decades of operational vibrator activity. However, there are other drive signals and alterations of this commonly accepted signal which offer improved peak-to-side lobe ratios on signal autocorrelations, as well as significant savings in field data acquisition and subsequent data processing times. In fact, one class of input signals allows vibrator signal recordings to have the same time duration as equivalent dynamite signal recordings. Another class provides effective discrimination against periodic interferences such as 60-Hz power-line interference. Fortunately, these characteristics can be combined in the same input signal. The theory which suggests these improvements is outlined, and experimental seismic data which support the theory are shown. Data recorded at identical locations while using one conventional and three alternate input signals of equal bandwidths and energies are compared to show the advantages of the alternate signals.

Composite seismic signal

Abstract: This invention provides for transmission of composite swept sine wave seismic signals wherein auto-correlation side lobes of such signals are reduced. The frequency spectrum of a desired swept sine wave seismic signal is divided into a number of consecutive segments, and the segments are arranged to form a sequence of segments by the order of frequency content. Component swept sine wave seismic signals each covering a segment in the sequence are generated simultaneously from the same location to produce the desired seismic signal. The component swept sine wave seismic signals are generated in a manner so that they alternate as upsweeps and downsweeps for consecutive segments in the sequence of segments. The seismic signal comprising the sum of the component swept sine wave seismic signals will have an auto-correlation function with reduced side lobes. Alternatively, the component swept sine wave seismic signals may be generated successively from the same location in a manner so that they alternate as upsweeps and downsweeps for consecutive segments in the sequence of segments. The reflections are successively recorded and stacked prior to correlation with the sum of the component swept sine wave seismic signals. Used in this manner, the sum of the component swept sine wave seismic signals will also have an auto-correlation function with reduced side lobes.

A system for driving a motor by a pulse width modulation inverter

Abstract: A system for driving an alternate current motor including a pulse width modulation inverter having the two-range driving characteristics, wherein the motor is driven by the pulse width modulation output having a simulated sine wave form at the speed lower than the base speed of the motor and by the pulse width modulation output having a rectangular wave form at the speed higher than the base speed of the motor.

Generation of electric signals having approximately sinusoidal waveforms

Abstract: For the purpose of generating an output signal having a sinusoidal waveform, a digital store stores at different locations binary-coded amplitudes at equally spaced instants of time throughout a complete cycle of a sine wave. Those locations are addressed in turn by means of a pulse counter and the signals supplied by the memory are passed to a digital/analogue converter from which the required output signal is derived. The pulse signal supplied to the counter is obtained from a train of clock pulses by a programmable divider. To effect a frequency change in the output signal (for the purpose of signalling binary data), the divisor of the divider is changed in a sequence of steps so that the overall change in output frequency is less abrupt than would otherwise be the case. The arrangement described is suitable for use in a modem working with the Viewdata system currently adopted by the British Post Office.

Energy economizer for polyphase induction motors

Abstract: A standard three phase induction motor starts with all three of its input connections connected to the three phase power line. Two of these connections are through triacs which remain continously conducting below said motor's particular most energy-efficient speed, which is above about 95% of synchronous speed. This assures full starting torque and undiminished overload handling capability. The triacs, in response to a control signal, may open the circuits over a sufficiently wide portion of the sine wave input voltage to substantially maintain said particular efficient speed under all rated load conditions. To assure smooth operation and maximum energy savings, the two triacs conduct differently at very light motor loads. The DC control voltage which determines the operation of the triacs is generated by a frequency discriminator circuit which receives its information from a load detecting device that is frequency modulated by load/speed related properties inherent to induction motors.

Plasma treatment and device therefor

Abstract: PURPOSE:To have ions reached a substrate with desired and effective energy by applying alternating current such as low-frequency square waves, triangular waves, sine waves to an electrode which control a plasma electric potential CONSTITUTION:For example, capacity type coupling electrodes 10, 11 are provided on and beneath a vacuum container 5 accommodating a semiconductor substrate 6 and a high-frequency oscillator 3 for plasma generation is connected to the electrode 10 Such a plasma treatment device is independently provided with a low- frequency oscillator 12 which generates sufficiently lower frequencies than the frequencies of the high-frequency oscillator 3 and has ions followed sufficiently Treatment such as plasma etching, deposition are performed by applying alternating current such as square waves, triangular waves, sine waves to the electrode 10 and by having ions with desired energy reached the substrate 6 In this way, high accurate treatment will be performed by controlling the energy of the plasma

Interdigital Transducer Models: Their Impact on Filter Synthesis

Abstract: The characterization and comparison of various interdigital transducer (IDT) models used to analyze and design SAW transversal filters are facilitated by partitioning the overall periodic transducer re- sponse into an impulse function, a discrete time sampling function, and m acoustic weighting function in order to describe both wide-band and space harmonic responses. Through this formalism the analog char- acter of an IDT is accounted for by the use of an acoustic function a(f). This perspective is applied to five interdigital transducer models: namely, impulse (equivalent circuit), impulse (sine wave), modified delta function, spectral weighting and space harmonic. The models differ by their a(r) function. The spectral weighting model is de- scribed in detail for its application to apodized and withdrawal weighted transducer design. A new modified delta function model is shown to agree qualitatively with the spectral weighting model for single electrodes, Aperture weighting laws are derived for the models using sampling theory; it is shown that the cla~sicf;~/~ frequency de- pendence holds only for the narrow-band case f = fn and that, in gen- eral, compensation is required for the acoustic weighting function of the model used. Guidelines for evaluating whether or not compensa- tion is needed as well as compensation techniques and alternatives are described.

Apparatus and method for generating waveforms which are particularly suitable for a PWM-driven motor

Abstract: A triangle waveform having substantially linearly sloped, gradually increasing and decreasing edges and having a frequency nf is generated from an n-phase sine wave signal, each phase having a fundamental frequency f. A segment of any of the n-phases of the sine wave is detected when that segment is within a predetermined angular amount from a reference crossing level, such as the zero crossing of the sine wave signal. Successive ones of the detected segments are selected to synthesize the triangle waveform. In the preferred use of this invention, the triangle waveform is compared to a reference signal, such as the sine wave signal from which the triangle waveform is generated, this reference signal having a controllable frequency and amplitude. Pulse transitions are generated at the intersection of the triangle waveform and each of the respective phases of the reference signal. In one embodiment of this invention, the frequency of the triangle waveform is increased by an amplitude-folding technique wherein the triangle waveform (of frequency nf) is folded about a pair of equal but opposite folding levels whenever the triangle waveform reaches either of these levels, so as to produce an amplitude-folded triangle waveform of frequency mf and of peak levels determined by the folding levels.

Velocity matched optical gate

Abstract: The coupling between a pair of coupled wavepaths (11, 12) is modulated by means of a biasing wave travelling in synchronism with the signal in the coupled wavepaths. In particular, by limiting the coupling to a small interval about the zero crossover point of the biasing signal, subpicosecond pulses can be generated by means of a simple sine wave biasing signal. Such a velocity matched gate can be employed as a pulse generator; a modulator; a multiplexer/demultiplexer; and pulse shape analyzer.

Phase detecting circuit

Abstract: Disclosed is a phase detecting circuit having first and second sets of two-phase sine wave signals each set of which has phases different from each other by 90°, an arithmetic operation circuit for detecting a phase difference between the two-phase sine wave signals, and a frequency variable signal generating circuit for producing an output pulse with a frequency varying in accordance with the sum of proportional and integrated values of an output signal from the arithmetic operation circuit. The phases of the sine wave signals are so changed as to minimize the phase difference. The phase detecting circuit is provided with a function generating circuit which counts the output pulses from the frequency variable signal generating circuit and produces the second set of two-phase sine wave signals with phases different from each other by 90° whose phases are changed on the basis of the count data.

Waveform synthesizer with digitally controlled phase adjustment of output

Abstract: A circuit arrangement for producing a composite waveform comprises a multiplexer controlled by a logic network for successively energizing a load with an aperiodic voltage from a switching circuit and one or more sine waves or other periodic voltages continuously produced by respective oscillation generators. The logic network includes a cycle counter stepped by a selected oscillation generator for terminating the transmission of its output voltage ater a preset number of cycles. An analog comparator, continuously receiving a d-c potential from a manually settable voltage source and a sawtooth voltage from each oscillation generator, emits an enabling pulse to the logic network upon detecting a coincidence between the sawtooth voltage of a selected generator and either the manually selected d-c potential or the sawtooth voltage from another selected oscillation generator.

Evaluation of Operational Objective Streamline Methods

Abstract: Objective streamline analysis techniques are separated into predictor-only and predictor-corrector methods, and generalized error formulas are derived for each method. Theoretical analysis errors are obtained from the ellipse, hyperbola and sine wave curve families, curves which taken alone or in combination often describe many meteorological flow patterns. The predictor-only method always under-estimated streamline curvature. The predictor-corrector method overestimated curvature where the stop increment was directed toward increasing curvature and underestimated curvature where the step increment was directed toward decreasing curvature. This led to at least a partial compensation which reduced the cumulative error.

A System Transfer Function for Visual Evoked Potentials

Abstract: The electroencephalogram (EEG) and evoked potentials (EP) have long held the promise of being a way of studying the sensory processing of the brain. If we take the view that the EEG is a continuous output signal, some features of which represent the response to input signals consisting of sensory stimuli, we have an input/output system that seems suitable for application of engineering analysis techniques. Using this approach, Clynes et al. (1964) studied the brain wave responses to step, ramp and sine wave light stimuli. The step stimuli allowed them to obtain the transient response of the “system”, and the sine wave stimuli allowed them to obtain the steady state response. These results, as well as the work of other investigators (Donker, 1975; Montagu, 1967; van der Tweel and Ver- duyn-Lunel, 1965), have demonstrated the nonlinear nature of steady state evoked potentials (SSEP). For stimulation by sine wave modulated light (SML) in the frequency range 5–9 Hz, a persistent second harmonic response is seen even at very low modulation depths. Further evidence of nonlinearity is seen in the poor results in attempting to predict the response to high flash rates based on superposition of responses from low flash rates.

Brass Tone Synthesis by Spectrum Evolution Matching with Nonlinear Functions

Abstract: There has been ample evidence from analytical studies done in recent years that brass harmonic spectra (and probably those of other wind instruments) are somehow related to spectra which can be produced by the nonlinear distortion of a variable amplitude sine wave. It is the purpose of this paper to review this evidence and present some results of attempts to synthesize brass tones using this technique.

A new modulation scheme for multitransmitter simulcast digital mobile radio communication

Abstract: Many mobile radio communication systems require digital siganling simultaneously from multiple transmitters from the viewpoints of efficient frequency utilization and simplified receiver construction. This paper describes a new modulation scheme in order to realize a simulcast digital transmission. In this method modulation signal is made by superimposing a sinusoidal wave on an ordinary rectangular digital wave. When Manchester-coded type signal is used, the frequency of the sinusoidal wave is twice as much as that of the original bit-rate and the relative phase difference between the two waves is different at each base station. In order to clarify the feasibility of this technique, experimental simulation tests are performed on 900-MHz band in two transmitter construction. It is proved that this modulation scheme does not only give the same amount of the improvement effect on the digital signaling on an overlapped area, but also makes the allowable carrier frequency drift several times lager than that of the carrier frequency offset strategy.

Voltage and frequency-controlled AC wave modifier

Abstract: A standard, unmodified AC induction motor has its stator winding energized from a sine wave power source through a signal-responsive wave modifier operative to control the portion of each cycle of the sine wave which is coupled from said source to the stator winding. Load detecting means, comprising a comparatively small AC generator coupled to the rotor of the motor, produces a control signal, varying with variations in the load on the motor, for controlling the wave modifier to increase the field density of the stator winding with increases in load on the motor, and to decrease the field density of the stator winding with decreases in said load.

Calibration source for instruments to measure power and negative sequence current of dynamoelectric machines

Abstract: A calibration signal source for instruments to measure power and negative sequence current of a multi-phase electric power generator. Separate signals are provided to represent load current for each phase of the generator ultimately to be tested, and to represent the instantaneous differences in voltage between each phase and a reference phase. The calibration signals are derived from a single sine wave by providing a plurality of phase shift and voltage difference networks. Means are provided for amplitude control and elimination of harmonic distortion of the single sine wave, and therefore the output calibration signals share these characteristics.

A simple quadrature oscillator for generating triangular waves and square waves

Abstract: A new method for the relatively cheap generation of triangular waves and square waves is described. The present instrument is versatile in generating pairs of waves: two waves for each one of the waveforms. Each one of the waves is 90° out of phase with respect to the other wave of the same form. This quadrature operation is similar to that of common sinewave oscillators, but it is not usually known for the generation of square waves and triangular waves. The new system has been realized successfully and electronically by employing only one integrated circuit.

Optimal Flow Pattern for Mechanical Ventilation of the Lungs. 2. The Effect of a Sine Versus Square Wave Flow Pattern with and without an End-Inspiratory Pause on Patients

Abstract: In four series of patients, the efficiency of ventilation of a sine wave without an end-inspiratory pause was compared to a square wave without a pause, a sine wave with a pause to a square wave with a pause, a sine wave to a sine wave with a pause, and a sine wave with a long pause to one with a short pause. The primary mode of evaluation was through simultaneous airway and arterial argon washout curves. Additional cardiopulmonary measurements were made. Results indicate: (1) a statistically significant improvement in ventilation with a sine wave with a pause; (2) a statistically significant improvement with the longer pause as compared to the short pause.

Stable, inexpensive, low-frequency sine wave generator using digital techniques.

Abstract: Presented is a circuit for the generation of low‐frequency (0.001 Hz to 63 kHz) sine waves possessing stable amplitude and frequency characteristics using digital techniques. The circuit produces a 32‐step approximation to a sine wave at a frequency 1/32nd of the selected digital time‐base frequency. Also presented are a crystal‐controlled time base to drive the generator, and an active filter for removing the high‐order harmonics produced by the generator. Advantages of the digital sine wave generator over analog oscillator techniques are described.

Controller for induction motor

Abstract: PURPOSE:To optimize the preset value of the secondary resistance in the instantaneous reference computing circuit for the primary current through a good speed and magnetic flux control by following thereof to the genuine secondary resistance value of the induction motor CONSTITUTION:When an induction motor 2 is controlled employing a sine wave cyclo converter, the primary voltage and current of a motor 2 is detected and impressed on a secondary resistance R2 correction circuit 34 through 3-phase-2-phase convertion circuits 3 and 32 In the circuit 34, a secondary magnetic flux 2 is detected based on the w-phase signal and the output of a relative value computing circuit 14 and is compared with the result from the computation by a instantaneous reference computing circuit 18-2 whereby the value of the secondary resistance R2 set for the circuit 18-2 is controlled to make the magnetic flux computed equal to that detected This enables change is the set value in the computation circtuit to match changes in the secondary resistance due to temperature change or the like

Rapid method of forming spectra from regularly sampled records by rectangular wave transforms

Abstract: Spectral estimation of signals sampled at equispaced time instants is discussed. Stable periodogram estimates are generally formed from the squares of Fourier coefficients summed over a large number of data blocks. An exact relationship has been shown to exist between Fourier coefficients and ‘rectangular wave’ transforms, which are obtained when the sinusoidal function is replaced by the associated sign function. The coefficients so formed can be unscrambled into Fourier coefficients. A related operation can also be carried out on the powers formed from the accumulated squared-up estimates, but in this case the deconvolution is not exact. Nevertheless, in many practical situations the method provides a very good approximation to the power spectrum. The approach has the advantage that the rectangular wave coefficients can be generated only by additive operations, and these are much faster to implement on a small microprocessor. The technique is applied to digitally simulated data.

Scanning method by ultrasonic wave

Abstract: PURPOSE:To obtain a picture of excellent quality by a device of simple constitution by employing two directional ultrasonic beams as transmitting signals and receiving the reflected waves thereof separately. CONSTITUTION:Oscillating circuits 11a and 11b generate pulse-shaped sine waves for vibrating piezoelectric element arrays 1a and 1b, while deflection signal generating circuits 12a and 12b generate signals for changing directions of sonic wave beam. These signals generated are impressed on the piezoelectric element arrays 1a and 1b of a contactor 1 fitted to a part of a human body, whereby two systems of beams are transmitted. And, the reflected waves from the inside of the body are received by each of the arrays 1a and 1b and each output thereof is sent to a memory part 14 after being subjected to prescribed processing in signal processing circuits 13a and 13b. Then, they are read out in altered sequence of time and supplied to an indicating device 15 as picture signals.

Power Extraction From Ocean Surfaces Waves

Abstract: This paper investigates the use of wave power as a viable energy source. A novel method for using a float to capture the power of waves is proposed, and the responses to a modeled sinusoidal wave form are analyzed. The responses of the system, determined experimentally and analytically, are correlated to illustrate that wave power can provide significant amounts of energy. The method analyzed, when employed on other float devices, increases the energy output of the system.