Showing papers on "Sine wave published in 1975"

Linear and non-linear performance of transducer and pupil in Calliphora retinula cells.

Abstract: 1. Intracellular recordings have been made from the blowfly (Calliphora erythrocephala) retinula cell; apart from the transducer mechanism, these cells also feature a pupil mechanism. 2. At several mean intensity levels, within the apparently linear range of response, frequency characteristics of amplitude and phase and responses to 'delta'-flashes and 'delta'-flash pairs have been obtained. 3. Fourier methods have shown these responses to be mutually compatible, confirming linearity in these circumstances. 4. Non-linear behaviour can be made to appear at the lower frequencies when the modulation depth is increased. 5. Non-linearities can also appear through application of the superposition test: a low frequency sine wave, modulated so as to elicit an apparently linear response, and a high frequence sine wave which does not give rise to non-linearity even at the highest modulation depths can, when superimposed, yield a greater response to the latter when situated at the minima of the former than at its maxima. 6. At frequencies above approximately 1 Hz these superposition non-linearities are attributed to the transducer mechanism gain control. Below this frequency the pupil mechanism takes part considerably in the retinula cell's total observed gain control: its characteristics remain yet to be cleared up. 7. The transducer's linear and non-linear properties fit in closely with those of the Fuortes-Hodgkin model which couples increases in gain and time constants. 8. The Fuortes-Hodgkin model will probably require some quantitative modifications in the originally treated case of Limulus, on account of its pupil. 9. Finally, the merits of Veringa's diffusion model, and the possibility of eventually joining this model with the Fuortes-Hodgkin one are pointed out briefly.

Catv sine wave coding system

Abstract: A means for decoding a generally constant frequency sine wave scrambled television signal uses an automatic gain control circuit in a closed loop. The scrambling, applied at the head end of the television system, applies a greater scrambling level to the audio carrier than it does to the video carrier. The unscrambling signal, the detected audio carrier scrambling signal, is combined with the scrambled signal in an amplifier circuit, the output of which is a basic television signal. There is a residual of the scrambling sine wave remaining in the audio carrier output after unscrambling, but little or no residual scrambling remaining on the video carrier. The residual audio carrier scrambling signal is detected and amplified for application as the unscrambling signal.

A permutation test for periodicities in short, noisy time series

Abstract: We developed a distribution-free, nonparametric statistical test (the permutation-rank test) for verifying the exiscence of significant peaks in power spectral ordinates calculated on noisy, short, time series. In this paper, we demonstrate the application of the test in the case of periodic series generated by the in numero perturbation of the amplitude of a cosine wave of known, single, constant frequency. The test was able to detect the underlying oscillation when it was amplitude-corrupted by noise generated by a standard uniform distribution, with a noise-to-signal ratio of 1 or less.

Method and apparatus for generating high amperage pulses from an A-C power source

Abstract: An a-c source of power is utilized to provide periodic d-c pulses of predrmined amplitude, duration, and frequency by synchronizing the delay sweep of a cathode ray oscilloscope with the sine wave of the a-c voltage input, timing the delay sweep to provide an output signal at the desired frequency and at the particular point on the sine wave which will impart the desired voltage peak thereto, and utilizing each output signal to trigger a first silicon controlled rectifier for initiating a current pulse while simultaneously providing a corresponding signal with a given delay for firing a second silicon controlled rectifier to terminate the current pulse and establish the duration desired thereof.

Synthesizer of multifrequency code signals

Abstract: Synthesizer of multifrequency signals for telephone sets, each multifrequency signal being formed by two concomitant sinusoidal signals of different basic frequencies, said frequencies forming pairs respectively corresponding to the decimal digits and being sub-multiples of a common clock frequency. The sinusoidal signals are pulse trains whose repetition rate varies steppedly in function of time in the following manner. The period of a sine function is divided into p parts and the amplitude of the function taken from the tangent to the negative peaks of the sine curve for p equidistributed values of the argument 2πi/p, i varying from l to p, are approximated by p amplitude values. The periods of the signals having the basic frequences are divided into p time intervals and during these time intervals, a pulse train generator is operated in such a way that its pulse repetition rate be proportional to said amplitude values.

Square wave to sine wave converter

Abstract: A square wave to sine wave converter of the type which utilizes an integrr, an amplifier and a sine wave shaper in the signal processing operation has an automatic gain control circuit which responds to signal variations both at the output of the integrator and the output of the amplifier to insure a constant amplitude triangular wave at the input of the sine wave shaper as the frequency of the square wave changes.

Evaluating analog-to-digital converters

Abstract: Dynamic performance of an A/D converter cannot be assessed by conventional tests since they employ slowly varying inputs. In this paper, a digital computer procedure is developed to determine the presence and extent of errors due to time jitter, nonlinearity, gain, quantization, and locked bits. The procedure is based on discrete power-spectrum analysis of recorded outputs of the A/D converter using a weighted or nonweighted sine wave input. In the latter case, a discrete weighting of the recorded output must be performed before power-spectrum analysis. Outside of the narrow band containing the signal spectrum, the power spectrum corresponds to the errors in the A/D converter.Error models are suggested and implemented in a simulation program which is executed to show the power spectra for various combinations of errors. On this basis an A/D converter evaluation procedure is proposed and illustrated by an example.

Precision test frequency generator

Abstract: A precision test frequency generator capable of selectively providing a sinusoidal output wave within a frequency range simulating the output of a flowmeter yielding a sinusoidal signal whose frequency is proportional to flow rate, the signal having a noise component superimposed thereon. The generator is constituted by a stable high-frequency standard coupled to a selectable output counter providing intermediate-frequency pulses whose repetition rate is a sub-multiple of the high-frequency standard and a predetermined multiple of the desired output frequency of the generator. The pulses are converted into a triangular wave whose frequency corresponds to the desired output frequency, the triangular wave having a staircase formation whose number of steps is determined by the multiple. The triangular wave is converted into a sinusoidal wave of the same frequency with a staircase modulation component simulating the flowmeter output signal.

Dual tone multiple frequency generator

Abstract: A dual-tone multiple frequency signal generator is provided for use with telecommunications systems, data transfer systems and other applications. The tone encoding system utilizes MOS/LSI integrated circuitry on a single chip powered directly by telephone line voltages. An electronic keyboard circuit provides synchronized pulses to decode single-pole, single-throw keyboard switches by row and column. A crystal-controlled oscillator generates a reference frequency which is divided according to the row and column of an activated keyboard switch to obtain two pulse signals having frequencies representative of the activated switch. The outputs of the divider circuitry are fed to programmed logic array which generates two digitally coded signals each representing a sinusoidal waveform. A digital-to-analog ladder network converts the digitally coded signals to continuous sine waves, and an operational amplifier combines the sinusoidal waveforms to provide a dual-tone output. The integrated circuitry also utilizes electronic switches for the common functions of tone transmission, including applying power to the oscillator, disconnecting the audio transmitter and attenuating the input to the receiver. Complementary-symmetry, metal-oxide semi-conductor elements implement the circuitry design with bi-polar transistors on the same chip performing some of the common function switching.

Methods and apparatus for speed-control of induction motors

Abstract: A method of energizing a single-, three-, or poly-phase A.C. motor for continuously-variable speed control from a fixed-frequency supply of corresponding phase. Each phase is modulated by a continuously-variable modulation wave of sub-supply frequency to provide two continuously-variable sideband frequencies, either of which can be used to supply the motor. The modulation wave is sampled in each cycle of the A.C. supply and a full-wave rectified resultant modulation wave compared with a cosine wave of supply frequency. Each phase is gated by solid-state switch means for current flow from amplitude equality to next-following cosine zero. Optionally, secondary modulation, by a square wave of supply frequency, is used.

A sine wave generator using a frequency-dependent negative conductance

Abstract: A realization of a variable frequency RC oscillator, using the concept of frequency-dependent negative conductance, is proposed, The frequency variation is obtained by controlling a single resistance in the network.

A silicon diode array scan converter for high-speed transient recording

Abstract: A double-ended scan converter tube has recently been developed which uses a silicon diode array for the storage target. The purpose of the device is to capture high-speed single transients or low-repetition-rate signals and to retain the information until it can be read out at speeds slow enough for handling by conventional processing and display circuits. Improvements in wide-bandwidth deflection and the resolution of both writing and reading guns, combined with a charge gain of 2000 in the target, enables data to be stored at unprecedented rates. Information writing speeds of 2 × 1012tracewidths/s are possible with the device, sufficient for displaying a full-screen 2-GHz Sine wave. To reliably digitize the readout for signal processing, a signal-to-noise ratio of about 20:1 is required which the device, will provide at speeds up to 5 × 1011tracewidths/s. Resolution at a 50-percent modulation level is 400 TV lines per horizontal scan (15.7 cycles/mm at the target).

Digital FSK time rate of change modulator

Abstract: A digital FSK time rate change modulator is responsive to a digital input signal and generates either a first or a second output frequency. The FSK modulator switches from one output frequency to the other in small increments over a predetermined time interval. The FSK modulator includes means for generating a first and a second timing signal and input means for receiving the digital input signal. An up-down counter having an up-count input and a down-count input counts up and down between a first and a second state. First gating means is coupled to the output of the up-down counter and to the input means and passes the second timing signal to the up-count input when a high level digital input signal is present on the input means and the up-down counter is not in the second state. Second gating means is coupled to the output of the up-down counter and to the input means and passes the second timing signal to the down-count input when a low level digital signal is present on the input means and the up-down counter is not in the first state. Variable counter means divides the first timing signal by predetermined number in response to the count on the up-down counter and generates a digital output signal. Sine wave generator means is coupled to the variable counter means and generates a digitally approximated sine wave having the same frequency as the digital output signal from the variable counter means.

Separation-Like Similarity Solutions on Two-Dimensional Moving Walls

Abstract: it may be recognized that the closer a plate deflection comes to a sine wave, the smaller the edge effect error and thus the greater the accuracy achieved. This is borne out by the results of Table 1 where it may be seen that the larger discrepancies occur for the compressive forces, where the plate deflection tends to deviate from a sine wave, than for tensile forces, where the plate tends to behave more and more like a membrane, the exact shape for which is a pure sine wave. Figure 1, which shows the variation in frequency with in-plane load for the isotropic plate (computed using the edge effect method and the series solution), further illustrates this trend. For completeness, Table 2 shows the buckling loads obtained using the edge effect method for the various cases of orthotropy and, in the case of the isotropic plate, shows the accurate value presented by Taylor. The accuracy of the method for buckling problems is somewhat poorer than that for natural frequency calculations for plates subject to zero or tensile in-plane forces. But, since the method is believed to always yield a lower bound for single plates (which is not necessarily the case for plate systems), the results still have utility. ASME, Journal of Applied Mechanics, Vol. 38, No. 3, Sept. 1971 pp. 699-700. 5 Taylor, G. I., "The Buckling Load for a Rectangular Plate with Four Clamped Edges," Zeitschrift fur Angewandte Mathematik und Mechanik, Vol. 13, 1933, p. 147.

Method and apparatus for generating digital dual frequency signals

Abstract: A dual tone multiple frequency digital tone generator for a PCM/TDM electronic telephone system. A digital representation of a dual tone signal is generated from a multi-bit command character by determining the phase angle of two frequencies specified by the command character relative to an independent time reference signal, converting paired phase angles to amplitude signals representative of the amplitude of a sine wave having each calculated phase angle, and summing the amplitude representations to generate a value corresponding to the digital representation of the frequency pair at that particular instant. Individual phase angles are calculated by generating a multi-bit digital character corresponding to the phase angle of a sinusoidal reference signal of the particular frequency. This character is preferably generated by multiplying a multi-bit digital character having n-bits representing the fractional part of the number of seconds elapsed from some reference time by a multi-bit digital character having m bits representing the frequency of the sinusoidal signal, m and n both integers. The resulting m + n bit product consisting of an m-bit integral part and an n-bit fractional part is examined and the p most significant bits to the right of the decimal point are selected, p being an integer. The value of n determines the accuracy of the product relative to the absolute value of the phase angle, while the value of p determines the resolution of the phase angle representation. Both n and p are preselected in accordance with the required accuracy of the frequency representation.

Line deflection circuit arrangement

Abstract: A circuit is a combination of a switched mode power supply and a TV deflection circuit. It features a pair of switches and a pair of inductors that are tuned to selected frequencies so that when the switches are off, the inductor voltages have a half sine wave shape.

Frequency shift keyed toned generator

Abstract: A frequency shift keyed (FSK) generator producing an output frequency which is determined by gating through a selected one of a plurality of crystal controlled oscillators. The oscillator output is divided by a digital frequency divider to the operating tone frequency. The square wave output of the divider is filtered to a sinewave by an active tracking bandpass filter which is instantaneously switched to the operating frequency simultaneously with the selection of the appropriate crystal controlled oscillator.

Certain Statistical Distributions Involving Special Functions and their Applications

Abstract: The objective of the paper is to show that a certain generalized Bessel distribution is a useful theoretical tool because, through mixing procedures, specialization of parameter values and integral representation considerations, it unifies the theory of a broad class of special distributions; and that it is a useful tool because it has applications in radio communication. The random sine wave problem and distributions for fluctuating radar targets are studied in terms of this distribution with particular emphasis on amplitude, phase and component distributions. The marginal pdf and characteristic function corresponding to Bennett’s (Rice’s) distribution of a random sine wave plus stationary Gaussian noise are obtained when the sine wave amplitude is assigned a generalized Bessel prior distribution. The Bennett problem is also reduced to a randomly phased sine wave without noise and the corresponding marginal pdf and characteristic function are obtained from the noise corrupted case. Non-uniform phase distributions are also treated in terms of generalized distributions and the corresponding amplitude and component pdfs are provided. The distribution of a useful quadrat if form in which the random variates are the squares of a generalized component corrupted by Gaussian noise is also provided. The quadratic form distribution is then used as a basic model for fluctuating radar cross section (RCS) and includes the Swerling RCS models and the Nakagami amplitude distributions as special cases. The authors also provide the corresponding pulse-train probability distributions for two pulse integration schemes using either scan-to-scan or pulse-to-pulse amplitude independence. Many of the pdfs and characteristic functions provided in the paper are expressed in terms of both closed form expressions and mixture representations.

Method of processing a signal, and corresponding devices

Abstract: In the synchronous detection signals of frequency Fo immersed in a noise, an auxiliary signal is produced having a period 1/2 Fo and in the form of a rectified symmetrical wave, by rectifying a symmetrical wave of period 1/Fo. The signal to be filtered is multiplied by the auxiliary signal and synchronous filtering or synchronous detection on the frequency Fo is performed on the signal obtained after the above-mentioned multiplication. Preferably the auxiliary signal is produced in the form of a rectified sinusoidal wave and a square wave reference signal from which the above-mentioned symmetrical wave is derived, having the period 1/Fo, is also used to control the synchronous detection or the synchronous filtering.

Logic elements for reactor period meter

Abstract: Logic elements are provided for a reactor period meter trip circuit. For one element, first and second inputs are applied to first and second chopper comparators, respectively. The output of each comparator is O if the input applied to it is greater than or equal to a trip level associated with each input and each output is a square wave of frequency f if the input applied to it is less than the associated trip level. The outputs of the comparators are algebraically summed and applied to a bandpass filter tuned to f. For another element, the output of each comparator is applied to a bandpass filter which is tuned to f to give a sine wave of frequency f. The outputs of the filters are multiplied by an analog multiplier whose output is 0 if either input is 0 and a sine wave of frequency 2f if both inputs are a frequency f.

Generator for producing sinewave - adds square waves of identical frequency and amplitude but progressively displaced in phase

Abstract: The sineware generator produces its sinewave output by adding several square wave sings which are of identical frequency but which are displaced progressively in phase. A shift register with feedback is coupled to a clock generator and has the same number of stages as there are square waves that need to be produced. The clock generator frequency is an integral multiple of the frequency of the required sinusoidal output signal. The outputs of each stage of the shift register are connected over resistors to a common point where they are added together to give the sinewave or more precisely, an approximated sinewave.

Computerized lighting system

Abstract: An apparatus for converting d.c. current to a.c. current has a multivibrator receiving a direct current operating potential. A differentiator has an amplifier connected to the multivibrator. It produces substantially square wave form output currents. A wave shaper filter is operably connected to the differentiator to shape the wave form into that of a sine wave and a cosine wave respectively. An amplifier is operably connected to the wave shaper filter. The apparatus has a transformer operably connected to the amplifier and to a load. In a preferred specific embodiment the load is a fluorescent lamp, or the like.

Digital-to-synchro converter

Abstract: A digital-to-synchro converter accepts digital distance data comprising either a binary coded decimal (BCD) signal or a train of pulses of any desired format. The converter comprises a digital-to-synchro converter whose output represents the distance data that controls a signal generator synchronized to a sinusoidal reference voltage. The signal generator output are pulses representing sample and hold control signals which are applied to a sample and hold circuit. The sine wave is sampled by the sample and hold circuit, and the output is a DC voltage that is proportional to the sine of the desirable synchro rotation angle. This voltage is applied to an analog multiplier for generating the controlling signals which are then amplified before being routed to provide distance measurements at the synchro receiver.

Products of random sine waves

Abstract: The probability density of the product of n independent sine waves of random phases is determined.

Calculating the exact probability distribution of the pulse of a sine wave in narrow-band normal noise by means of infinite series (Corresp.)

Abstract: The exact solution is provided for the probability distribution (PD) function of the modulo 2\pi phase of a sine wave in narrow-band normal noise by means of several infinite series. Closed-form exact results are reported at \pi/4 and 3\pi/4 .

Image Formation Under Partially Coherent Illumination

Abstract: —The generalised theory of image formation as developed by Hopkins depends essentially on the validity of the concept of ‘effective source’. The purpose of this paper is to examine this question of validity in relation to the size of the primary source. The state of coherence at the objects plane has been investigated. It has been found that, under certain condition, the coherence on the object plane is no longer spatially stationary. Also, the effect of the size of the primary source on the image of sine wave objects has also been considered.