Showing papers on "Sine wave published in 1983"

Day-Degree Methods for Pest Management

Abstract: Recommendations are made for reporting day-degree methods which may have practical applications. Standardized thresholds (40, 50, and 60°F, or 5, 10, and 15°C) should be used. Day-degrees may be either sine wave approximations or exact units determined by instrumentation. Methods are proposed for converting current day-degree models to standardized thresholds and, ultimately, to actual day-degrees.

Electrical load drive and control system

Abstract: A circuit for varying the power supplied from a D.C. power supply to a moderate to high powered load such as a motor is disclosed. Trapezoidal voltage and current waveforms are used approaching the maximum load power delivery available from sine wave drives and the minimum dissipation in the driver circuitry available with square wave drives, while at the same time minimizing the generation of undesirable electromagnetic interference (EMI).

Method of fitting hearing prosthesis to a patient having impaired hearing

Abstract: Disclosed is a process of fitting a hearing prosthesis to a deaf or severely hearing impaired patient. The prosthesis is connected to the patient, and a signal is then applied to the prosthesis across an audioband. The frequency response of the prosthesis is adjusted so that the patient detects a desired response to the signal. In one application the prosthesis may include a sound processor driving a transmitter, a transcutaneous receiver, and an implanted electrode. A constant amplitude signal is applied to the sound processor, and the frequency response of the sound processor is adjusted so that the patient detects a generally uniform response to the signal. Other signals can be applied, such as bursts of a sine wave or other periodic wave, and band-filtered noise can be employed with the band center frequency being swept either step-wise or continuously. The transmitter and receiver are first adjusted for normal operating coupling and then a constant amplitude continuous sinusoidal signal, for example, is applied. In a multiple channel system, the signal is applied sequentially to each channel. For each channel, the signal is varied in discrete frequency steps across an audio band, and the frequency response of the transmitter is adjusted so that the patient detects a generally uniform response. The dynamic range is identified at each such frequency step between a threshold level and a discomfort level to establish desired aided thresholds and discomfort levels.

Model reference adaptive control of system having purely deterministic disturbances

Abstract: This note presents results relating to the adaptive control of linear time invariant systems having purely deterministic disturbances such as sine waves, biases, etc. Two key points are made. First, it is shown that the usual ARMA model used in adaptive control can also include a description of purely deterministic disturbances. Second, it is shown that the existing convergence theory for adaptive control schemes can be extended in a very straightforward way to the case where disturbances are present.

Kinetics of Oxidation of Potato Chips under Constant Temperature and Sine Wave Temperature Conditions

Abstract: Lipid oxidation in potato chips at 30, 37 and 45°C followed zero order kinetics as measured by peroxide value (PV). An Arrhenius plot of log k versus (T°K)-−1 snowed slight underprediction at low temperatures. Data from constant conditions were used to predict the extent of this free radical reaction under a sine wave temperature fluctuation (25/45°C with a 24 hr period). Predictions of effective rate constant, temperature and extent were found to agree to within 3.5% of the actual results up to a PV of 7 where bimolecular oxidation occurred. The sine wave condition entered the bimolecular oxidation sooner than was observed under steady data for the same effective temperature.

Comparison between constant-current and constant-temperature hot-wire anemometers in high-speed flows

Abstract: A comparison is made between the performance of constant‐current (C.C.A.) and constant‐temperature (C.T.A.) anemometers in measuring various characteristics of turbulence in supersonic flows. The two systems are comparable, with regard to the bandwidth and to the signal‐to‐noise ratio, provided that the overheat is not too low in the case of the C.T.A. system, and that suitable corrections be applied to the C.C.A. system. Besides, the two types of apparatus are similar in that their use is very time consuming, a separate adjustment being required for each point of measurement in the flow and each overheat, especially adjustment of the C.T.A. bandwidth, using a sine wave technique, and adjustment of the thermal lag compensating circuit of the C.C.A. system. They differ in that rigorous corrections, dealing for example with electrical noise and insufficiency of the bandpass, are more easily determined in situ and applied with the last system, while the former is better adapted to rapid measurements in blow‐down facilities, or when only high overheats are required. As for the level of the electronic noise, it seems to be equivalent in the two systems. Besides, when turbulent intensities and spectral densities are measured in a continuously running tunnel, the results are more reliable if they are obtained with the C.C.A. system, except for measurements of transverse fluxes of heat or momentum performed using an inclined hot wire. Hence the two types of apparatus appear to be complementary.

A digitally programmable switched-capacitor universal active filter/oscillator

Abstract: A universal second-order switched-capacitor filter section has been fabricated on an NMOS chip. The device can perform all five basic filter types as well as a sine wave oscillator without external components, while requiring only an external clock. The filter type is determined by selecting one or more of three input pins. The filter response is determined by ten external programming pins which may be either digitally controlled or hard wired.

Modulation Methods Related to Sine-Wave Crossings

Abstract: A bounded band-limited signal may be represented by its sine-wave crossings, i.e., by a set of points on the time axis at which it crosses a reference sinusoid. If, at these points, pulses of a standard shape are generated, we obtain a position modulated pulse train. This pulse train is analyzed in detail. Two other modulation methods related to sine-wave crossings are also discussed, namely, edge position modulation of a square wave and bipolar pulse duration modulation. In all cases, the modulated waves may be expressed as sums of an infinite number of sinusuidal carriers amplitude modulated by Chebyshev polynomials of modulating signals.

Phase synchronization and control circuit

Abstract: A circuit for generating control signals used in detecting a power failure in an uninterruptible power supply in which the A.C. signals of the power supply are examined to output a first signal representing the zero crossing of the A.C. signals. This first signal is used to reset an oscillator whose output clock signals are synchronized with the frequency of the A.C. signals by a phase lock loop circuit. The clock output of the phase lock loop circuit operates a counter whose output count is used to address a programmable read-only memory which outputs binary bits to a digital-to-analog converter which in turn outputs a full wave rectified sine wave operating at the system frequency which is used as a reference to detect the occurrence of a power failure in the main source of A.C. power signals. A second control signal is generated indicating a power failure condition which is used in switching an inverter into the power supply for supplying A.C. signals to a load.

Antennas for Nonsinusoidal Waves: Part: III-Arrays

Abstract: In the previous two papers, we discussed the Hertzian electric dipole and the large-current radiator, used either as radiators or sensors Several radiators or sensors can be combined into an array In the case of sinusoidal waves, such an array would yield more power and a directional pattern of the power called the antenna power pattern For nonsinusoidal waves, one obtains additional patterns In the particular case of a time variation of the electric and magnetic field strengths equal to that of a rectangular pulse, one obtains an antenna slope pattern caused by the change of the time variation of the field strengths as functions of azimuth and elevation angles This change is often called a distortion, but in reality it provides us with additional information for the angular resolution Sinusoidal waves cannot provide this information due to their lack of a bandwidth This paper investigates both the regular sensor array using the sum of all sensor outputs, and the monopulse array that uses the difference between the sums of the sensor outputs of the right and the left halves of the array Radiator and sensor arrays for nonsinusoidal waves have been built at least since 1975, but the circuits required for the utilization of the slope patterns are still at the frontier of our technology for pulse durations in the order of 1 to 01 ns, which are primarily of interest

Method and apparatus for generating digital signals representing periodic samples of a sine wave

Abstract: A method of generating the digital representation of a sine wave. A digital signal processor is used to generate the sample digital values, spaced at period T, of a sine wave of frequency F, using the value of the previous sample, e, the corresponding value of cosine, f, and two constants, c=sin2πFT and d=cos2πFT. The next value of sine, S=ed+cf; the value of the corresponding cosine, C=df-ce. The magnitude of c and d are rounded up so that c 2 +d 2 ≧1. Any calculated values of S or C which exceed unity in magnitude are limited to a magnitude of unity. This limiting operation accomplishes the normalization operation necessary to avoid exponential build-up due to accumulated round-off errors, and does so more efficiently than was previously possible. Sine waves with a 50 dB signal to noise ratio have been generated using this method.

Propagation of finite‐amplitude ultrasonic waves in air—I. Spherically diverging waves in the free field

Abstract: An investigation of the free‐field propagation in air of sinusoidal spherical waves of finite amplitude is described. It includes experiments made at 20.4 kHz and a theoretical interpretation using weak shock theory. The acoustic source used was a new high‐power and highly directional ultrasonic transducer which is able to generate a nearly pure sinusoidal wave at sound pressure levels over 160 dB. The experiments were done in an anechoic chamber, using a cw mode. They consisted essentially of measuring the amplitude of the fundamental component of the wave and its first three harmonics for different source levels and at various distances along the axis of the source. In addition, oscillograms and directivity patterns were recorded. In general, the experimental data confirm the predictions of the theoretical model.

Variable-speed constant-frequency alternator

Abstract: A variable-speed constant-frequency alternator compensating for changes in speed of the prime mover by electromagnetically rotating the rotor's magnetic poles around the rotor. If the prime mover has a rotational speed above or below that required to produce the desired output frequency, the magnetic poles rotate about the rotor in a forward or reverse direction, respectively. To connect the alternator to an external a.c. source, the alternator's controls match its output to the precise amplitude frequency, and phase of the external source. The rotor, for each magnetic pole pair, includes three windings. Three-phase power in these windings, produces the magnetic pole pair and rotates it relative to the rotor. Each winding couples to a flopper circuit having k sets of resistances. The resistances, taken in turn, have an inverse proportionality to the magnitude of the desired sine wave for the three-phase current in the rotor's windings. Coupling these resistances, one at a time, to a constant voltage source creates the equivalent sine wave current for the rotor's windings. A transducer produces the same number of pulses per revolution of the rotor as the number of resistances in the flopper circuit. Insufficient or excessive rotor speed results in the counting of too few or too many pulses. The controller then induces a shifting of the flopper circuit to rotate the magnetic poles on the rotor to maintain the output frequency constant.

Kinetics of Protein Quality Loss in Enriched Pasta Stored in a Sine Wave Temperature Condition

Abstract: The rate of loss of protein quality in enriched pasta was studied at constant temperature (30, 37 and 45°C) and under a continuous sine wave temperature fluctuation (25/45°C with a 24-hr period). Both loss of lysine by the fluoro-dinitro benzene (FDNB) method and a bioassay (Tetrahymena thermophila growth) for protein quality were employed. Significant loss of protein quality occurs in about 1 yr at temperatures above 30°C. The bioassay method showed that nutrient losses other than lysine could be occurring. Data from the constant temperature studies were used to predict the losses that occurred for the sine wave condition using the Hicks-Schwimmer model as modified with an Arrhenius approach. The prediction model gave about 15% error in comparison to actual losses. In addition, the rate of loss for the sine wave (25/45°C) was greater as predicted than the rate of loss at a constant mean temperature of 35°C.

Error correcting circuit of resolver

Abstract: PURPOSE:To correct electrically a position detecting error generated mechanically, by detecting a phase difference of sine-wave applied to a stator coil of resolver and output wave of rotor coil, and correcting a discrete value corresponding to the phase difference with a corrected value of memory. CONSTITUTION:Zero cross circuits detecting circuits 20, 21 are installed in a position detecting circuit 2 and these circuits 20, 21 convert output wave sin(omega0t+ theta+theta') of rotor coil, and sine wave sinomega0t applied to a stator coil into rectangular waves T1, T2 by the zero-voltage slicing. Leading pulses T5, T4 of the rectangular waves T1, T2 by leading detecting circuits 23, 24 are applied to FF24 and a gate signal T5 corresponding to the phase difference is applied. A counter 26 counts clockpulses CLK during the period of output of the signal T5. In ROM30, measured errors of each phase difference of resolver have already been stored and the discrete value of a counter 26 is added with the corrected value of ROM30 by an adding circuit 31 and it is outputted as phase difference theta. Thus, the position detecting error generated mechanically can be corrected electrically.

Technique for secure communications on FM radio channels

Abstract: This present invention relates to a system for providing secure communications without bandwidth expansion using an encryption method called masking whereby a masking signal is generated at the transmitter using a secret key which includes a predetermined threshold signal-to-noise ratio level that when added to a frequency modulated (FM) signal produces an unintelligible signal. Any type of masking signal as, for example, a sine wave, an FM signal, or bandlimited Gaussian noise, may be used. At the receiver, the corresponding masking signal used by the transmitter is regenerated and subtracted from the FM signal before demodulation. Because of the FM threshold effect, perfect removal of the masking signal is not required. It is only necessary to subtract enough of the masking signal such that the resulting signal-to-noise ratio (SNR) is above the required threshold for reliable demodulation of the original signal.

Resolution system for interferometer

Abstract: Analog-to-digital conversion and a computer produce finer resolution for interferometer distance measurement. The system applies to a laser interferometer producing two detected signals with voltages 19 and 20 that vary to form two sine waves in quadrature as interference fringes occur. A pair of analog-to-digital converters 21 and 22 converts each of these signals into digital values subdividing each sine wave fringe cycle into a plurality of increments. An up/down counter 25 supplied with a significant digit from each of the converters counts fringes corresponding to changes in path lengths. A computer 30 arranged with access to the fringe count and the digital increments determines a distance measurement based on the fringe count and a fine resolution of the distance measurement based on final values of the signals at any subdivided fringe cycle increments after changes in the path lengths.

High frequency inverter

Abstract: A pulse width modulated D. C. to A. C. inverter circuit includes a first set of MOSFETS operated at a line frequency for transmitting high frequency clock pulses to a second set of MOSFETS for outputting a D. C. signal derived from a D. C. source. The inverter is part of an uninterruptable power supply and is operated upon the failure of the line A. C. to supply A. C. signals to a load. The high frequency clock signals are modulated on the A. C. output of the inverter. Two separate and distinct power switching channels are provided with each channel supplying one half of the sine wave outputted by the inverter.

Stable sine wave generator

Abstract: A sine wave generator which utilizes a PROM for storing a predetermined bit pattern which is converted to a corresponding pulse waveform generated in response to a very accurate and stable clock pulse. The pulse waveform is shifted to a very exacting voltage level and is filtered by a band-pass filter to derive the desired fundamental frequency sine wave. The amplitude and frequency stable sine wave may be utilized in linear variable differential transformer (LVDT) apparatus for measuring the position of a controlled object such as a turbine valve. The arrangement may also be utilized for generating additional sine waves bearing some predetermined phase relationship with respect to one another for other control or signal processing applications.

Electroconvulsive therapy and the seizure threshold.

Abstract: The use of a pulsatile square wave stimulus for a large series of electroconvulsive treatments under conditions of routine clinical practice is compared to the equivalent experience with a sine wave stimulus. The literature indicates that both waveforms are equally effective convulsants. However, in this series, the induction of a convulsion was found to be much more difficult with the pulsatile square wave such that the rate of failure to convulse was four times that compared to sine wave stimulation. A number of variables that may affect the seizure threshold during ECT were examined. It is concluded that the benefit obtained by reducing the electrical energy transmitted to the patient with the pulsatile stimulus offsets the difficulty encountered in reaching the seizure threshold.

Instrument for measuring electrical resistance or reactance

Abstract: An instrument for measuring electrical resistance or reactance comprises a sine wave generator which generates an a.c. signal and reference signals for a phase sensitive detector. The a.c. signal is applied to a decade attenuator which adjusts its amplitude in dependence on a range switching. The signal is passed to a bridge section, wherein it is applied to a component to measure the value thereof. A voltage output, indicative of the value, is fed to a gain block, wherein its amplitude is re-adjusted in dependence on an input from the range switching. The voltage output is operated on by a phase sensitive detector and passes to a digital display. In the reactance mode, set by a function switching, the a.c. signal is phase shifted before being applied to the component, so that the voltage output is in phase with the reference signals.

Thin film vertical recording head

Abstract: PURPOSE:To attain recording to a two-layer film medium of high saturation magnetization with a low level of magnetomotive force, by providing an AC bias magnetic field generating means which produces an AC bias magnetic field of a frequency high enough to give no effect to a recording signal. CONSTITUTION:A winding 11 is wound around an auxiliary magnetic pole 10 made of a ferromagnetic matter such as ferrite, etc., and a current of a sine wave and a rectangular wave of a frequency several times as high as the maximum frequency of the signal to be recorded is applied to the winding 11 from an AC bias generating source 12. Thus a magnetic field obtained by superposing an AC bias magnetic field onto a recording magnetic field produced by the recording current flowed to a spiral thin film coil 2 is applied to a medium. Thus a Co-Cr vertically magnetized film 8 is magnetized up to its saturated level, and the same recording magnetic field as that obtained by a constitution of a single unit of the coil 2 can be obtained even with a small level of current flowed to the coil 2. Furthermore the effect of the AC bias frequency on a reproduction signal is avoided.

A switched-capacitor realization of a spectral line enhancer

Abstract: An adaptive system is described that tracks the peak of the spectral density function of the input signal. The system has been designed so that it can be easily realized in a single MOS integrated circuit using switched-capacitor (SC) techniques. Many characteristics, such as the transient response and the tracking of sine waves corrupted by noise, of a prototype (built from discrete components) are described.

Dc power source device

Abstract: PURPOSE:To reduce the distortion of an input current, by inputting the outputs of three high frequency converter circuits to rectifying and smoothing circuits, and synthesizing the outputs of the rectifying and smoothing circuits in series. CONSTITUTION:The high frequency converter circuits 1, 2, and 3 are pushpull self-excited inverters, into which AC sine wave voltages whose phases are different by 2/3pi are inputted, respectively. When the AC voltage is inputted into the high frequency converter circuit 1 and the rectifying and smoothing circuit 4 through a full wave rectifier DB1, transistors Q1 and Q2 are turned ON and OFF alternately, and a high frequency voltage Vout is generated in an output winding n3 of an oscillating transformer T1. The high frequency component is smoothed in the rectifying and smoothing circuit 4 and converted into a full wave rectified voltage of low frequency again. Said operation is performed in the other two circuits in the similar way. The outputs V01, V02, and V03 are synthesized in series, and the final output voltage VDC is obtained.

Circuit for reducing intermodulation distortion in a frequency-modulated signal

Abstract: An intermodulation distortion reducing circuit for a frequency-modulated signal comprises a sinusoidal wave shaping circuit supplied with an input frequency-modulated signal including an intermodulation distortion component, for shaping the waveform of the input frequency-modulated signal into a waveform closely approximating a sinusoidal wave, and a mean DC level detecting circuit supplied with an output signal of the sinusoidal wave shaping circuit, for detecting a mean DC level of the output signal of the sinusoidal wave shaping circuit and producing a detection output. The sinusoidal wave shaping circuit is supplied with the detection output of the mean DC level detecting circuit and a waveform shaping quantity thereof is varied to obtain the waveform closely approximating the sinusoidal waveform. The sinusoidal wave shaping circuit produces a frequency-modulated signal having a waveform closely approximating a sinusoidal waveform, with its intermodulation distortion component reduced.

Configuration measuring method utilizing moire fringes

Abstract: PURPOSE:To make the measurement highly accurate, by moving a projecting grating, and detecting the variation in the amount of light at a point to be measured as the phase of the Moire fringes by using a specified expression. CONSTITUTION:The mesh shaped projecting grating 4 is moved in the surface direction at a constant speed, and light is irradiated from a light source 6 through a condenser lens 5. The transmitted light is projected on a body to be checked 1 through a projecting lens 2. The reflected light is focused on a secondary image pickup element 10 through a focusing lens 3 and a relay lens 9. Its output signal is supplied to an operating circuit 11. A triangular wave is taken out of each position of the mesh and approximated by a sine wave S. A phase standard sine wave S0 is generated through an input and output device 12. The difference phi between S and S0 is computed by using the specified expression. Said computation is executed for every address in the mesh, and the configuration of the object is determined. Therefore, the measurement of the configuration is performed highly accurately.

New algorithm for spectrum estimation and an associated VLSI design

Abstract: By treating the reflection coefficients as independent variables, a new recursive algorithm is introduced which results in a lower prediction error and stable filters. Its performance is evaluated using sine waves in noise and pulse Doppler radar data, and is found to be substantially better than those of Burg's algorithm, Makhoul's covariance-lattice method and Marple's least-squares algorithm. Thus, although a lower error is not always desirable, the above procedure leads to better spectra for the type of data used. The spectrum of the new algorithm is the same as that of Fougere's algorithm whenever the latter reaches a solution, but its speed is substantially higher and it avoids `oscillations?, which made the previous computational requirements excessive. The higher speed is mainly achieved by using the covariance instead of the data in the iterations, and the `oscillations? are avoided by introducing a relaxation procedure. A regular structure of VLSI implementation is also introduced.

Acoustic wave propagation in randomly distributed spherical particles

Abstract: An experimental study has been conducted on the propagation of ultrasound at 1 and 5 MHz in a random medium consisting of a suspension of polystyrene spheres (mean diameter 0.589 mm, standard deviation 0.666 mm) in a solution of water and sugar. A burst of sine waves with repetition frequency of 200 Hz and pulse width of 15–20 μs was transmitted to the random medium. The experimental results for the attenuation and pulse broadening for the transmission and backscattering plus attenuation as a function of the receiving angle for transmission at different frequencies and particle concentrations are presented in this paper. Comparisons are given with some theoretical calculations.