Showing papers on "Sine wave published in 1970"

The fluid mechanics of the ureter from a lubrication theory point of view

Abstract: The function of a healthy ureter is analyzed in terms of a fluid-mechanical model. To the extent that the Reynolds number is of the order of one, the fundamental equations are shown to reduce to those of the theory of lubrication. It is found that from the point of view of the pressure variation with time (the urometrogram) the important part of the peristaltic wave is the constricting part. For this reason this part of the wave is represented with an algebraic expression of the form h ∼ x n making it possible to find closed form solutions. Using Fourier analysis in defining the complete wave shape of the ureter it was also possible to obtain numerical solutions. For both cases it is shown that there is good agreement between the theoretical and experimental pressure distributions, this not being the case for sinusoidal wave shapes. An approximate equation for the flux is developed and a universal relation is presented connecting the maximum pressure, flux and kinematic behaviour of the ureter.

Digital sine wave generator

Abstract: An accurate source of constant frequency pulses drives an adjustable modulus digital divider, which divides the input pulse repetition rate by exact integers. The pulse repetition rate of the output of the divider is made directly proportional to the desired frequency of a sine wave that is to be generated. The output of the divider continuously clocks a four-bit binary updown counter from the all-zero condition to the all-one condition and then back down cyclically. This up-down counter programs a digital sine wave decoder in which logic circuits convert the binary pattern from the output of the up-down counter into a binary pattern that is a stepwise approximation to a sine wave. A conventional digital-to-analog converter converts the binary pattern from the sine wave decoder into a corresponding analog signal, which is filtered to remove undesirable frequency components. The result is a reasonably pure sine wave whose frequency is accurately controlled by the pulse repetition rate from the variable modulus divider.

Digital signal generator synthesizer

Abstract: Illustrative embodiments of the present invention shown and described include digital logic systems for generating signal waveforms of desired types. A relatively few digital logic modules are connected to generate a variety of desired waveshapes in a linear manner. Apparatus for generating rectangular waves, saw-tooth waves, sine waves, and sine waves having amplitude, pulse, frequency and phase modulation applied to them are disclosed.

Fitting Sine Curves to 24 h Urinary Data

Abstract: IN studies of biological rhythms it is often desirable to obtain an objective estimate of the phase and amplitude of a suspected rhythm from observation recorded over a single cycle, such as a single period of 24 h. The usual technique is to attempt to fit the observations to a sine curve. Most techniques of fitting a sine curve are applicable only to a series of points and, for conventional methods, the points must be uniformly spaced in time. Many biological data, especially of renal excretion but also of respiratory or heat exchange, represent the average value of the variables since the previous sampling. The sampling intervals are often irregular and are correctly represented graphically by a histogram, though in published work they are often presented as points at the midpoint of the collection period. This does not cause much distortion if the time intervals are short and equal, but a gross distortion of the actual behaviour is introduced when, for example, there are long collection periods of urine as in a night's sleep.

Digital hearing aid gain analyzer

Abstract: A digital display hearing aid gain analyzer is provided for measuring the gain of hearing aids over a predetermined frequency range. A sine wave oscillator generates a predetermined sine wave frequency in an anechoic chamber. The hearing aid to be tested is then connected in the chamber to a microphone pickup housed in a 2 cubic centimeter coupler and picks up and amplifies the sine wave signal in the chamber which is then converted from a linear sine wave signal to a logarithmic signal to a digital type signal indicative of the gain of the hearing aid which is then displayed on Nixie tubes.

Statistics of Combined Sine Waves

Abstract: The first‐order probability density of sums of sine waves having random phases and amplitudes is approximated using a method developed by H. E. Daniels [Ann. Math. Stat. 25, No. 4, 631–650 (Dec. 1954)]. Three cases are discussed: (1) random phase and equal amplitude, (2) random phase and sine‐distributed amplitudes, and (3) random phase and rectangularly distributed amplitudes. Detailed results are presented for the first two cases. It is shown that extremal statistics may be quite poorly estimated by an assumption of normality.

High density communications system

Abstract: Binary data is encoded in sinusoidal form. Two complementry sine waves at the binary data frequency are generated; one is positively biased, the other is negatively biased. The binary data selectively gates each sine wave. At the receiver, a zero dc level sine wave is recovered and clock pulses are derived from the peaks of the recovered wave. One binary level is produced when a clock pulse coincides with a positive peak of the incoming sinusoid; the other binary level is produced when a clock pulse coincides with a negative peak of the incoming sinusoid.

A sine wave oscillator

Abstract: A closed-loop oscillatory system, comprising an RC differentiator, a new type of an RC network and two transactors in cascade is described. For certain system conditions the circuit produces a sine wave oscillation whoso frequency is varied over a wide range from a very low to a high value. The main feature of the system is that the generation of a very low frequency oscillation is possible without incorporating a large value of the RC product. The frequency relation is derived and the results are presented in graphs.

Electronic integrator system

Abstract: A solid-state integrator that receives tow information signals, namely, a weight signal and a speed signal, integrates these signals and provides an output signal proportional to the product thereof that is indicative of total weight of material that has passed a scale. The weight signal comes from the scale and is a negative DC voltage having an amplitude proportional to the weight per unit length of conveyor belt. The speed signal comes from a belt rider measuring wheel operated pulse generator and consists of 100 uniform width pulses per foot of belt travel. An amplifier at the integrator input amplifies the weight signal and has an input bias adjusting potentiometer for zero calibration and an attenuation adjusting potentiometer at its output for span calibration. Span refers to the correct total weight of a run of several belt circuits with a test weight. Zero refers to zero total weight of a run of several belt circuits empty. For integration purposes, the speed pulses are shaped, get in step with the clock, and are stretched to desired width by a clock controlled preset pulse width generator. This pulse, called ''''fill'''' pulse, whose width is precisely controlled by the clock, operates an analog gate via a gate driver, allowing DC voltage representing weight on a scale to enter the integrator and charge the integrating capacitor therein. The integrator is bidirectional and will accumulate both positive and negative charges and will provide a DC voltage having a polarity and amplitude proportional to the algebraic sum thereof. The integrator receives two control signals, namely, a fill pulse described previously and ''''dipout'''' pulses, the latter being essential in an integration process -- without them the integrator would saturate. Dipout pulses can be in step with the clock pulse, or in step with the inverted clock pulse, depending on demand. The dipout pulses operate the other analog gate via a gate driver which allows the positive or negative half-cycles of the sine wave voltage to discharge the integrator capacitor. Dipout is started by a voltage level detector so that the integrator does not exceed its capacity in continuous running. The uniform dipout quantities are counted in a forward-backward operable weight totalizer to provide a running indication of the total weight of material that has passed over the scale and for other control and indication purposes. This method of integration -- where the sine wave drives the transducer, generates clock and inverted clock pulses, controls the pulse width of the fill pulse and the pulse width of the dipout pulse, and the same sine wave is used for dipping out the integrator -- all this provides ''''bridging action,'''' that is, automatic self-compensation in response to frequency or amplitude variation in the sine wave voltage so that no error will be introduced in the output.

Digital frequency change control system

Abstract: A fast-operating frequency-shift-controlled system for transmitting information in which a simulated sine wave is generated digitally and in which the frequency of the generated wave is shifted without discontinuities and thereby transmits data at an increased speed.

Generator for short duration high frequency pulse signals

Abstract: Very narrow pulses of high-frequency sine wave electromagnetic energy are formed by use of a gated or pulse modulated continuous-wave source feeding a transmission line network having a time-limited impulse response and adjusted to provide a series resonance with the leakage capacity of the source gating or modulating switch for the purpose of assuring that a maximum of the available energy is employed to form the output and that the output level is nulled before and after the generation of the high-frequency pulse

Dc to ac inverter for producing a sine-wave output by pulse width modulation

Abstract: A DC to AC bridge inverter circuit produces a sine wave output of low-harmonic content. One transistor of each pair of transistors in opposite arms of the inverter bridge is switched into conduction at the desired output frequency; i.e., 400 times per sec. for a 400 Hz. output. The remaining complementary transistor of each pair is switched on and off n times per alternation to produce n constant amplitude, variable width output pulses during each alternation. The duration of the conduction time of the complementary transistor is controlled so that the area of each pulse is equal to the area of the corresponding sinusoidal segment where each sinusoidal segment represents an angle phi , in electrical degrees equal to: phi = 180 DEG / n. These variable width output pulses are applied to a filter to produce a sinusoidal output having low-harmonic content. A clock-driven logic system controls the complementary transistor of each transistor pair turning it on n times per alternation and turning it off at different times during each interval to produce the desired sinusoidal pulse width modulation. The turnoff pulses are generated by a clock-driven divider and associated AND gates. Each of the AND gates is energized in response to a predetermined count from the divider to produce a turnoff pulse during each of the n intervals at a point in time during each interval such that the pulse width is proportional to the sine of the angle.

Tachometer and method for obtaining a signal indicative of alternator shaft speed

Abstract: An improved tachometer which includes an alternator connected to a shaft whose speed is to be measured and which generates an alternating voltage. Electrical circuits perform a non-linear operation on the generated alternating voltage and produce a unidirectional output proportional to the speed of the shaft by order-independent iterative pairwise binary operations. One embodiment of electrical apparatus for performing such operations is a sine wave generator followed by square law operations on the generated voltages followed by an operational summer. Another embodiment includes a square wave generator followed by bridge rectification of the square waves to produce a unidirectional signal followed by a star or tree of diodes to produce an auctioneering circuit which passes the largest rectified voltage. Another embodiment of this invention is a tachometer in which a velocity signal is derived from computations based on the alternator terminal potentials and currents.

Signal frequency synthesizer

Abstract: A plurality of binary related anti-coincident pulse trains which are precisely related in frequency and phase to a reference frequency are generated in a binary rate multiplier. The rate multiplier includes gating and control circuitry whereby predetermined combinations of these pulse trains are selectively summed together to provide various output frequencies. The output of the binary rate multiplier, which comprises square wave signals having a predetermined frequency relative to the reference signal frequency, are divided to minimize the effects of irregularities in the frequency of the multiplier output and to provide square waves having substantially uniform periods. These square waves are then appropriately gated and filtered to produce quadrature related sine waves.

Effect of Non-uniform Aperture Illumination on the Rectangular Wave Response of a Diffraction Limited Imaging System with a Slit Aperture

Abstract: A study has been made of the effect of an amplitude filter on the intensity distribution and contrast of the Fraunhofer diffraction images of a general periodic bar pattern when the image forming system is diffraction limited and employs a narrow rectangular aperture. The amplitude distribution over the exit pupil (pupil function) has been taken of the form: T(s) = as2 + (1 - a/2), where a is a constant of the value 2⩾a⩾-2. The value of bar width which gives a wave response nearly similar to that of sine wave has been pointed out. Incoherent illumination of the object has been assumed throughout.

Digital to analog converter

Abstract: A digital-to-analog converter converts a digital pulse train into a sine analog voltage and a cosine analog voltage whose frequency is proportional to the pulse repetition rate. A binary digital counter receiving the pulses counts up and down between zero and a preselected upper limit count in response to up and to down input signals respectively. A first analog signal generator generates one voltage step of one quadrant of a staircase sine voltage wave for each discrete count stored in the counter, and a second analog signal generator derives one voltage step of one quadrant of a staircase cosine voltage wave for each discrete count stored in the counter. Up/down circuit means operable after the counter has counted backwards to zero count applies the up signal to the counter and is also operable after the counter has proceeded forward to the upper limit count to apply the down signal to the counter. Means operable each time the counter counts backward to zero reverse the polarity of the voltage steps of the staircase sine wave to form the positive and negative half cycles of the sine w ave, and means operable each time the counter proceeds to the upper limit count reverse the polarity of the voltage steps of the staircase cosine wave to form the positive and negative half cycles of the cosine wave.

Sine wave static inverter

Abstract: A sine wave static inverter produces a sine waveform from the output of a step wave generator by removing the higher harmonics from a step waveform. A first embodiment short circuits the higher harmonic signals across the secondary winding of a transformer thus permitting only the first harmonic sine wave to reach the output. A second embodiment applies only higher harmonic signals from a generated step waveform 180* out of phase with a second generated step waveform so that only the first harmonic of the second step waveform appears at the output.

Effect of an apodizing screen on the rectangular and triangular wave response of a circular aperture with incoherent incident light

Abstract: A theoretical study has been made of the effect of an apodizing screen in front of a circular aperture on the images of periodic objects with rectangular and triangular transmission profile. Irradiance distribution and contrast in the far field diffraction images have been calculated assuming the incident illumination to be completely incoherent. Object functions which give wave response similar to sine wave response (OTF) have been identified.

Biasing Circuitry for Tunnel Junctions

Abstract: A method of generating bias has been developed which greatly facilitates studying the voltage‐current characteristics of tunnel junctions. A triangle wave to sweep the bias, a dc level for offset, and a small amplitude sine wave used for taking derivatives are all summed in a dc amplifier. The junction is biased by the attenuated output of this amplifier with either a high or low impedance load line. The two transistor circuits which largely comprise this bias supply are compact and battery powered, minimizing grounding problems.

Phase shift detector

Abstract: An apparatus for measuring the phase of an input signal utilizing cross-correlation techniques. In a first channel, the input signal is digitally compared with a reference pulse train having a pulse density distribution which approximates a sign wave and is then integrated. In a second channel, the input signal is digitally compared with a pulse train signal whose pulse density distribution approximates a cosine wave and is then integrated. The first and second channel integrators are cross coupled to form a harmonic oscillator. A digital counter provides a measure of the time elapsed before the oscillator signal reaches a zero phase. This measurement is proportional to the phase of the original input signal.

Binaural Fusion: Its Limits as Defined by Signal Duration and Signal Onset

Abstract: The results of two experiments on the interaural frequency limits for binaural fusion indicate that (1) the limits for binaural fusion decrease as a direct function of signal duration for both low‐ and high‐frequency sine waves, and (2) signal onset is a significant factor in the determination of the spectral limits for binaural fusion only for high‐frequency sine waves and low‐frequency sine waves of short duration. In general, these results are consistent with a model of binaural interaction in which fusion is determined by a tonotopically organized mechanism, fusion being the product of binaural activity in a channel of limited bandwidth.

Active balanced modulator circuit

Abstract: An active balance modulator circuit wherein the active switching elements of the modulator circuit are switched suddenly or in jumps as if controlled by a square wave carrier signal but utilizing a sine wave carrier input signal. Each of the respective switching elements of the balanced modulator circuit is coupled with a further respective switching element to form a pair of differential amplifiers. The carrier wave input signal is utilized to directly control only the further one of the switching elements of each differential amplifier. Further embodiments wherein the further switching elements are simultaneously utilized as the active elements of a second balanced modulator circuit and as the active elements in the diagonal arms of a ring-type balanced modulator circuit are also disclosed.

Pulsed x-ray control system with improved film darkening

Abstract: A circuit for use with a grid pulse X-ray tube which is operated at its maximum rated kv. and ma. The circuit provides more film darkening than would otherwise be possible when the X-ray tube is operated under such a maximum load. The circuit includes a filter which converts the output of the high-tension transformer from a sine wave to substantially a square wave which is then fed to the input of the X-ray tube. The pulsing of the grid is controlled by other circuits in such a way that the X-ray tube conducts symmetrically about the midpoint of the sine wave. Such precise timing of the grid pulse to initiate conductivity of the X-ray tube aids the filter in its function of providing a square wave to the X-ray tube input.

A New Technique for the Performance Analysis of a Polarizing Microscope with Crossed Nicols

Abstract: Modulation of a general periodic object of a triangular wave profile has been investigated in the case of a polarizing microscope with crossed nicols. Expressions for the irradiance distribution have been derived. The system has been assumed to be operating in incoherent illumination. Results in the form of curves have been given for the irradiance distribution and triangular wave response of the optical system. The limiting case when the triangular wave object reduces to an object of infinitely thin lines has also been discussed. A close similarity has been shown between the triangular wave response for a particular object function and the sinewave response of the system.

Diffraction images of a general periodic rectangular wave object in a polarizing microscope with crossed polarizers.

Abstract: Diffraction images of a general periodic rectangular wave object formed by a polarizing microscope with crossed polarizers have been investigated. Expressions for the intensity distribution in the images have been obtained. Results have been presented for the intensity distribution and contrast in the diffraction images of the system. A close similarity has been shown between the rectangular wave response corresponding to a particular bar width and the sine wave response.

A computer simulation of unbiased sine-wave recording

Abstract: A computer simulation is described which uses the approximation that the output voltage derives from longitudinal tape magnetization acquired solely from the longitudinal head field. Using a simple noninteracting M_{r}-H model, the remanent state of 200 points per half-wavelength of tape is calculated by following each point's field history as it passes the record head. We discuss the amplitude and phase angle of the magnetization sinusoids obtained by harmonic analysis. At short wavelengths (wavelength less than coating thickness) we find, for regular γ-Fe 2 O 3 tape, that although the peak output is limited by record head field gradient effects, the over-recording phenomenon is attributable to the field shape. The process of "optimizing" the record current is thus shown to be explicable in terms of the record head field geometry. These conclusions hold equally for "partial penetration" recording of high density digital waveforms.

Propagation of Low‐Frequency Electrostatic Waves in a Magnetic Field

Abstract: The properties of low‐frequency electrostatic waves propagating at various angles to a magnetic field in a plasma are studied. Numerical calculations are used to determine the phase velocities, group velocities, damping decrements, and propagation directions for frequencies between zero and twice the ion cyclotron frequency. A model is presented which simulates experimental time‐of‐flight studies of finite wave packets generated by sine wave bursts.

Power and surface-state loss analysis of charge-coupled devices

Abstract: In order to determine the operating limits of charge-coupled devices, a model that approximates the charge-coupled device with a traveling sine wave potential has been analyzed for operating power and losses attributable to surface states. The model has been applied to a 16-bit, four phase, CCD shift register with an active area of 0.0015 mm2per bit, and it gives the following predictions: Surface state losses with a 10-MHz clock will amount to approximately 1.1%/bit (at N_{ss} = 10^{11} /cm2eV) when an input signal level of 10-12coulomb is used in an n-channel device. Higher or lower signals, or a p-channel structure will lead to higher losses. Under the same conditions, the real driving power can be no less than 7 µwatts/active bit, and reactive driving power, expressed as reactive volt-amperes, is 26 µwatts/empty bit and 230 µwatts for a charged bit. The applicability of these results to the realizable device will be shown.

Deflection of uniformly loaded circular plates upon equispaced point supports

Abstract: A simple formula is derived for predicting the flexure of uniformly loaded point-supported circular plates. The classical solution of Michell for a clamped plate under a single point load is extended for any number of point loads regularly spaced around a circle concentric with the plate edge. The resulting series for the edge moments and shears are summed and are shown to be very similar to a simple sine wave. Replacing the exact expressions by single sine waves enables the clamped edges to be set free by a simple superposition of solutions. The point reactions are equilibrated by a uniform load and the resulting deflection surface for a free uniformly loaded point-supported plate is obtained immediately. Deflection curves for the particular case of a plate supported at three points are given in the form of contours of equal deflection. This particular case is compared with some experimental results which were obtained by optical methods.For three supports, maximum deviation from the flat is leas...

Sinusoidal oscillations in active RC filters

Abstract: A feedback system consisting of an amplifier and an activo RC filter hag been described. It is observed that for certain variations in the filter configurations and for both positive and negative gains of tho amplifier sine wave oscillation is generated in the system for specific system conditions. The frequency of oscillation can be varied over a wide range by the variation of the gain of the amplifier. Expressions for the frequencies of oscillations in the oscillatory modes have been given and the conditions of oscillations have been derived. The analysis has been experimentally supported.