Showing papers on "Sine wave published in 1976"

A Modified Sine Wave Method for Calculating Degree Days

Abstract: A FORTRAN program is described which uses maximum and minimum temperatures to compute heating and cooling degree days (between and below thresholds, respectively). The temperature cycle is assumed to be a sine wave in which the 1st and 2nd minimum are not necessarily the same. The method is compared With actual planimeter measurements from hygrothermograph charts from Alaska, Arizona, Florida, and Michigan. The data suggest that the bias incurred from the sine wave assumption is somewhat specific to geographical areas. No effect of day length was observed, but in Florida the sine wave method tended to overestimate degree days. A method of correcting for local bias using linear regression is described.

A theory for wave-power absorption by oscillating bodies

Abstract: A theory is given for predicting the absorption of the power in an incident sinusoidal wave train by means of a damped, oscillating, partly or completely submerged body. General expressions for the efficiency of wave absorption when the body oscillates in one or, in some cases, two modes are given. It is shown that 100% efficiency is possible in some cases. Curves describing the variation of efficiency and amplitude of the body with wavenumber for various bodies are presented.

A multiwavelength distance-measuring instrument for geophysical experiments

Abstract: A multiwavelength distance-measuring (MWDM) instrument that utilizes the dispersive nature of the atmosphere has been developed and tested. With this instrument there is no need for the usual meteorological observations and corrections. This MWDM instrument simultaneously measures the optical path length at three wavelengths, two in the optical region of the spectrum and one in the microwave region. The instrument calculates correction terms from the optical path length differences and then computes the corrected base line distance, the first-order effects of temperature, pressure, and water vapor fluctuations along the line thus being eliminated. Field testing demonstrated that the instrument was capable of making consecutive distance determinations with a standard deviation from the mean as small as 4 parts in 108. The long-term stability of the instrument was investigated from June 1974 to November 1974. The results showed a standard deviation of 1.3 parts in 107 when the data were fit to a sine wave of annual periodicity. The amplitude of this sine wave was 3 parts in 107, which was in good agreement with the predicted results of a two-dimensional thermoelastic model.

High speed frequency response measurement

Abstract: A binary pseudo-random sequence generated by a shift register with feedback is used as a noise signal for testing an electrical or mechanical system, and the output is sampled and the power spectra computed by discrete Fast Fourier Transform techniques. The sequence bit interval and sampling interval have a predetermined ratio, and either the noise signal or output test signal is low pass filtered, with the result that closely spaced equal amplitude sine waves are effectively applied to the system under test and their responses separated at the output with no statistical uncertainty.

Speech coding hearing aid system utilizing formant frequency transformation

Abstract: A hearing aid system and method includes apparatus for receiving a spoken speech signal, apparatus coupled to the receiving apparatus for determining at successive intervals in the speech signal the frequency and amplitude of the largest formants, apparatus for determining at successive intervals the fundamental frequency of the speech signal, and apparatus for determining at successive intervals whether or not the speed signal is voiced or unvoiced. Each successively determined formant frequency is divided by a fixed value, greater than 1, and added thereto is another fixed value, to obtain what are called transposed formant frequencies. The fundamental frequency is also divided by a fixed value, greater than 1, to obtain a transposed fundamental frequency. At the successive intervals, sine waves having frequencies corresponding to the transposed formant frequencies and the transposed fundamental frequency are generated, and these sine waves are combined to obtain an output signal which is applied to a transducer for producing an auditory signal. The amplitudes of the sine waves are functions of the amplitudes of corresponding formants. If it is determined that the speech signal is unvoiced, then no sine wave corresponding to the transposed fundamental frequency is produced and the other sine waves are noise modulated. The auditory signal produced by the transducer in effect constitutes a coded signal occupying a frequency range lower than the frequency range of normal speech and yet which is in the residual-hearing range of many hearing-impaired persons.

The differential pair as a triangle-sine wave converter

Abstract: The performance of a differential pair with emitter degeneration as a triangle-sine wave converter is analyzed. Equations describing the circuit operation are derived and solved both analytically and by computer. This allows selection of operating conditions for optimum performance such that total harmonic distortion as low as 0.2 percent has been measured.

Digital eddy current apparatus for sensing and analyzing metallurgical characteristics of an electrically conductive material

Abstract: A digital eddy current apparatus for sensing and analyzing metallurgical characteristics of an electrically conductive material. A square wave is supplied to a resonating circuit which includes a coil used as a sensing element for the conductive material. The resonating circuit produces a sinusoidal wave which is converted into a rectangular pulse which, when the resonating means is at resonance condition if superimposed upon the square wave pulse it would be positioned in the center of one-half of the square wave. The width of the rectangular pulse is a direct function of the amplitude of the sinusoidal wave and phase shift of the sinusoidal waveform is detected by movement of the rectangular pulse from the center position within the square wave. The width and position of the rectangular pulse is a direct function of the metallurgical characteristics of the conductive material.

Method for feeding a welding wire

Abstract: A welding wire feed method and apparatus involves feeding a welding wire in a conduit cable to a workpiece, while maintaining it normally in one plane in the form of a sine curve in the conduit cable.

Apparatus for calculating amplitude values of sinusoidal waves

Abstract: The apparatus comprises a sampling hold circuit for sampling the amplitude of a sinusoidal wave at a predetermined frequency, a data sample extracting circuit for extracting two data samples at two points immediately before and after the peak value of the sinusoidal wave, and an operation circuit responsive to the absolute values of the two data samples for calculating the amplitude value of the sinusoidal wave.

Method and circuit for generation of digitally frequency-shiftable electric signals

Abstract: A first counter operating as a frequency-shiftable frequency divider is caused to reset before its normal count recycle in one setting of a flip-flop to reduce the factor of frequency division in response to a keying signal. A second counter, operating on a digital input derived from the output of the frequency-shiftable divider sequences a logic network to produce a stepped wave output, with steps each of a duration of one or two count intervals sequentially connecting voltage at one of four several non-zero predetermined voltage levels in a predetermined sequence to the output. The stepped wave approximates a succession of half-wave sinusoids of the same polarity in which the bottom step of zero voltage is of zero width so that the last next lowest step of one sinusoid and the first of the next sinusoid join into a single two-period step. This wave is power-amplified and the polarity of alternate half sinusoids is reversed in the middle of the low two-period step, by switching in the output stage under control of the second counter. Strict symmetry of the resulting approximation of a sine wave is obtained with few different resistors defining one quarter of the wave shape. The circuit in the frequency divider that produces frequency changes in response to the keying signal is timed by a logic network to switch over only at alternate transitions of the output sinusoidal wave intervals.

Electronic musical instrument having memories containing waveshapes of different type

Abstract: A plurality of waveshape memories are provided for storing the sampled values of one cycle sinusoidal wave as the fundamental frequency, two cycle sinusoidal wave as the second harmonic, . . . and m cycle sinusoidal wave as the m-th harmonic and, in addition thereto, of harmonic-abundant complex waves such as a triangular wave, a sawtooth wave and a rectangular wave. These waveshape memories are read at the same reading rate. The read out sinusoidal waves and triangular, sawtooth and rectangular waves are controlled in their relative levels in accordance with the tone-color of an intended musical tone wave shape. The sinusoidal waves and the triangular, sawtooth and rectangular waves are thereafter synthesized to produce a desired tone-color wave shape. Since the triangular, sawtooth and rectangular waves contain abundant harmonic components, many kinds of musical tones containing abundant harmonic components can be produced despite a limited number of waveform memories.

Ink injection type writing system using amplitude-modulated electrical signals

Abstract: An ink ejection system of the invention includes an electrical circuit generating sinusoidal wave pulses and a liquid applying unit operable to discharge the liquid in pulsed jets in response to the sinusoidal wave pulses. The circuit comprises means for generating a sinusoidal signal of constant amplitude and frequency higher than the highest instantaneous frequency of a video signal, and means for modulating the amplitude of the sinusoidal signal in accordance with the video signal to generate a signal containing no harmonic components.

Low frequency triangular waveform generator

Abstract: A low frequency triangular waveform generator mixes two high frequency squarewaves having a constant frequency difference to produce a triangular waveform with a fundamental frequency equal to the difference in the fundamental frequencies of the mixed squarewaves. This generator can be adapted to produce squarewaves, sine waves, sawtooth waves, and asymmetrical triangular waves without the use of digital accumulators or ROMs.

A Three Phase Sine Wave Reference Generator For Thyrisitorised Motor Controllers

Abstract: A variable frequency, variable amplitude three-phase low frequency sine wave reference generator is discussed in this paper. The frequency and amplitude are independently capable of being varied by means of two independent dc control voltages. This reference generator is well suited for closed loop control applications such as constant frequency power supplies, constant amplitude power supplies, induction motor control requiring a finite ratio between amplitude and frequency, etc. The reversal of polarity of the dc voltage controlling the frequency reverses the phase sequence. The reference generator has been very satisfactorily used in the control of a three-phase ``subharmonic'' pulse width modulated inverter. The reference generator is also suitable for cycloconverter control.

Digital tone generator

Abstract: A stable generator produces a reference square wave signal having a stable given frequency. Logic circuitry is coupled to the generator to provide a plurality of square wave signals each having a different predetermined frequency, each of the predetermined frequencies having a different predetermined relationship to the given frequency. A switching arrangement is coupled to the logic circuitry to select at least one of the plurality of square wave signals of the logic circuitry. A ring counter, resistor tone mixing circuit and filter are coupled to the logic circuitry to provide as an output signal of the digital tone generator a sine wave tone having a frequency equal to the predetermined frequency divided by a given factor of the selected one of the plurality of square wave signals.

Skipping sine wave pulse plater system

Abstract: A pulse plating system wherein the duty cycle is controlled by skipping pulses in producing the output signal. The circuitry for controlling the skipping of the pulses can either be analog or digital type circuitry.

A New Measure of Television Display Quality Relatable to Observer Performance

Abstract: : This report describes a new, direct measurement method of determining the imaging quality of cathode-ray tube (CRT), line scan displays. This measurement was specifically developed as a more critical and realistic indicator of display quality. The measurement consists of recording the modulation contrast available on the display as a function of spatial frequency. An electronic sine wave generator produces a sine wave intensity pattern of the face of a CRT display. The display luminance distribution is scanned using a telephotometer or microphotometer depending on the size of the display. The modulation contrast of the display is obtained from the photometer scan for several spatial frequencies. The resulting graph showing modulation versus frequency is defined as the Sine Wave Response (SWR) Curve of the display. Since human vision is not linearly related to modulation, it is desirable to transform the modulation axis to another parameter which is linearly related to vision. This can theoretically be accomplished by transforming the modulation contrast to square root of 2 incremented Gray Shades. The resulting Gray Shade Response (GSR) indicates how many gray shades are visible as a function of spatial frequency.

Holographic interferometry using a reference wave with a sinusoidally modulated amplitude

Abstract: A method of holographic interferometry which uses an amplitude-modulated reference wave is proposed for investigating vibration phases. Sinusoidal amplitude modulation of a reference wave yields hologram fringes which are characterized by a function J 2 1 ( α ) cos 2 Δ , where α and Δ are related to vibration amplitudes and phases on object points, respectively. The resultant fringes indicate that vibration amplitude information and phase information are stored separately. The phase information of the vibration is easily obtained as brightness variations of the fringes, independently of the amplitude information.

Analysis and synthesis of an impedance-loaded loop antenna using the singularity expansion method

Abstract: The singularity expansion method (SEM) is used to represent the current on a loaded loop antenna. The shift in the poles of the loop due to impedance loading can be analyzed using contour plots in the complex frequency plane of the Fourier modal impedance transfer functions. The same plot may also be used to determine a loading function which will yield a specified pole pattern leading to frequency or time domain synthesis. A simple example of time-domain synthesis is presented.

The viscous damping of cnoidal waves

Abstract: The viscous damping of cnoidal waves progressing over a smooth horizontal bed is investigated. First approximations are derived for the attenuation of wave height with distance and for the friction coefficient at the bed. Attenuation coefficients are larger than those predicted on the basis of shallow-water sinusoidal wave theory and, unlike the case of sinusoidal waves, they are not independent of wave height. The limiting case of the solitary wave, considered previously by Keulegan (1948), is also discussed.

Envelope Detector Performance for a Partially Coherent-Fading Sine Wave in Noise

Abstract: The performance of a matched filter square-law envelope detector is investigated for a new signal-in-noise model, that of a partially coherent-fading random-phase sine wave in additive zero-mean noise. This model is of interest when analyzing the effects of random amplitude and/or phase channels on narrow-band input signals. The amplitude and the phase of the sine wave are assumed to be independent random processes with known bandwidths. This paper obtains deflection-criteria detection-performance results for the envelope detector as a function of the bandwidths of the amplitude and phase of the signal process, the noise process, the observation time, and the second-moment statistics of the amplitude, phase, and noise processes. The results show quantitatively that the detection performance of the envelope detector is much more sensitive to loss of phase coherence than to loss of amplitude coherence.

A new frequency multiplier made of a magnetic core with multiple holes

Abstract: This paper is a brief description of the operating principle and the circuit configuration of a new frequency multiplier This device uses a magnetic core of unusual shape having multiple holes An AC voltage of a frequency f Hz can easily be converted to a sine wave voltage at an optional multiplied frequency In addition, this device has a number of excellent operating characteristics

Pneumatic sinusoidal loading system

Abstract: Current systems for the application of cyclic loads to soil specimens are reviewed, and a low-cost system which provides a sinusoidal load trace using normal shop compressed air is described. Loading systems employed for cyclic shear testing of soil commonly employ one of two principles. In one type, a double acting piston is coupled to the specimen and the pressure or load is varied by selection through a directional solenoid vave. In those employing the electrohydraulic closed loop, a double acting hydraulic piston is coupled to the specimen. The pneumatic sinusoidal loader developed from commercially available components has 3 elements: a mechanical sine wave signal generator, a volume booster relay, and double-acting piston. The since wave generator consists of an adjustable eccentric, driven by a variable speed motor, connected to a plunger-operated regulator through a crank arm. The volume booster relays and boosts the quantity of air flow required to keep the output pressure matching the signal pressure from the plunger regulator. The main features are outlined of the new piston which has been designed for low inertial mass and low friction. An advantage of this system is the ease of operation. A graph is presented which illustrates the actual recording of a triaxial liquefaction test performed with the system.

Adjustable Voltage and Frequency Polyphase Sine Wave Signal Generator

Abstract: An adjustable-voltage adjustable-frequency polyphase reversible-phase sequence sine wave signal generator is described. This signal generator develops the reference waveforms, in this case sine waves, that are required in the control circuits of certain types of static dc to ac inverters and ac to ac cycloconverters. Digital and linear integrated circuits together with passive components are used to generrate the output signals. The output frequency is adjustable from 0 to 500 hertz; the output voltage is adjustable from 0 to 20 volts peak-to-peak. The phase sequence is reversible on command. The theory of operation together with steady-state and transient performance data are presented.

Underwater acoustic scatter channels with several bounces

Abstract: This paper deals with scattering channels involving signal paths that are reflected several times from the boundary on their way from the transmitter to the receiver. The transmitted signal is a single‐frequency sine wave, and the surfaces from which it is reflected are regarded as being statistically independent. Therefore the autocorrelation function of the received signal has a very simple form consisting mainly of the product of the characteristic functions of the various reflecting surfaces.Subject Classification: [43]30.20; [43]30.40.

Test set for measuring magnetic properties of magnetic amplifier cores by sinusoidal current excitation

Abstract: A test set for measuring magnetic properties of magnetic amplifier cores wherein a repetitive constant current sinusoidal drive signal for producing a magnetic field in the core is repeated at a low duty cycle rate of not more than one full sine wave in one hundred sine waves. The test set includes a test fixture wherein portions of the primary and secondary windings are connected in a cover and table and terminate in mating contacts rigidly extending therefrom, such that when the cover is moved from the table, the windings are separated at their mating contacts so that a test core can be inserted within the windings.

Linearity error measurement in PCM systems - involves transmission of test signal with periodically decreasing then increasing amplitude

Abstract: The linearity error measurement procedure in PCM systems involves a test ac signal which is fed-in and received at the LF side of the system. This test signal has an amplitude corresponding to the amplitude required by the multiplexer and a frequency below the PCM system scanning frequency as in 2339085. The test signal is formed by a sinewave whose frequency lies in the PCM system transmission band. The test signal amplitude is modulated so that it decreases from a maximum to a minimum and then increases again to a maximum giving an X-shaped envelope.

Rate of change in altitude apparatus

Abstract: A rate of change in altitude computer for providing a pilot with information to safely operate an aircraft. A beam of light is communicated through a mask. A gear responsive to altitude rotates the mask. A photocell receives the beam of light as it passes through the mask to produce sinusoidal wave signals. The positive node of the sinusoidal wave signal is modified to activate a transistor which allows a capacitor to be charged for a time period equal to the positive node. During the negative node of the sinusoidal wave signal the capacitor discharges. When the voltage associated with the charging and discharging of the capacitor is averaged, a steady state voltage is produced. The steady state voltage, which is proportional to the rate of rotation of the mask, drives a dial of an indicator to provide an operator with visual information relating to instantaneous rate of changes in altitude.