32results about "Trigometric functions" patented technology

Circuitry for computing a tangent function of an input value includes first look-up table circuitry that stores pre-calculated tangent values of a limited number of sample values, circuitry for inputting bits of the input value of most significance as inputs to the first look-up table circuitry to look up one of the pre-calculated tangent values as a first intermediate tangent value, circuitry for calculating a second intermediate tangent value from one or more ranges of remaining bits of the input value, and circuitry for combining the first intermediate tangent value and the second intermediate tangent value to yield the tangent function of the input value.

The present invention discloses an apparatus and method for implementing an inverse arctangent function using piecewise linear theorem to simplify and used to transform a right-angled coordinate point X and Y to a phase angle theta of an inverse arctangent function. The present invention uses T-line combination to approach an inverse arctangent function between 0 degree to 45 degree, and determines which piecewise linear region the right-angled coordinate point is located at. A coefficient table stored in a memory is used to compute {circumflex over (theta)} which is the approximate value of the phase angle theta. The phase angle {circumflex over (theta)} between 45 degree to 360 degree can be mapped to the approximate phase angle {circumflex over (theta)} between 0 degree to 45 degree using linear combination.

Circuitry for computing a trigonometric function of an input includes circuitry for relating the input to another value to generate an intermediate value, circuitry for selecting one of the input and the intermediate value as a trigonometric input value, circuitry for determining respective initial values of a plurality of trigonometric functions for the trigonometric input value, and circuitry for deriving, based at least in part on a trigonometric identity, a final value of the first trigonometric function from the respective initial values of the plurality of trigonometric functions. The trigonometric function may be any of sine, cosine and tangent and their inverse functions. The trigonometric identities used allow a computation of a trigonometric function to be broken into pieces that either are easier to perform or can be performed more accurately.

The invention discloses a sectional table look-up based arc-tangent function realization method and device. The realization method includes: determining an arc-tangent function lookup table according to the size of inputted data; determining an index value according to a high value of the inputted data, determining an angle compensation value according to a low value of the inputted data, and determining initial angle and compensation slope in the lookup table according to the index value; determining arc-tangent angle according to the initial angle, compensation slope and angle compensation value so as to realize the arc-tangent function. Through the realization method and device, the technical problem about how to realize the arc-tangent function of infinite interval is solved, calculation in the angle solving process of the arc-tangent function is reduced, calculation cost is reduced under the condition that data accuracy is assured, and limited storage space is saved.

A digital sine/cosine wave generator generates discrete values representative of either a sine wave or a cosine wave. The digital sine/cosine wave generator generates sine and/or cosine waves by implementing a difference equation of the form y(n)=b*y(n−2)−y(n−1). One of the initial conditions of the difference equation is selected from a series of values generated by a coefficient generator. The frequency of the sine and/or cosine wave generated by the sine/cosine wave generator is dependent on, and may be selected according to, which of the series of values generated by a coefficient generator is chosen as an initial condition of the difference equation.

A numerical control device wherein a sinusoidal signal generated by a sine wave generation part is input by a control loop excitation part to a control loop of the control object, the input signal input to the control loop and the output signal from the control object are sampled by the data acquisition part periodically, and the sampling data is used by the frequency characteristic calculation part to calculate the frequency characteristic of the control loop to control the control object, wherein the frequency characteristic calculation part uses data obtained by inputting a sinusoidal signal obtained by shifting an initial phase of the sinusoidal signal by a phase shift part provided at a sine wave generation part by exactly a certain amount to the control loop a plurality of times to calculate the frequency characteristic of the control loop to thereby improve the measurement precision regardless of the sampling frequency.

A circuit is provided with a plurality current cells. The current cells each comprise a main current source and an auxiliary current source coupled in parallel. The main current source supplies a main current to a current output of the current cell, and the auxiliary current source supplies an auxiliary current to the current output of the current cell. The main current sources are weighted according to a first predefined waveform, and the auxiliary current sources are weighted according to a second predefined waveform which is different from the first predefined waveform.

The invention discloses a rotary transformer excitation signal generation system and method, and the system comprises a main control module which is used for generating a digital modulation wave which changes according to a sine rule; a low-pass filter which is used for converting the digital modulation wave into a sine wave; a first-stage operation amplification circuit which is used for carrying out the first-stage amplification of the sine wave; a high-pass filter circuit which is used for blocking sine waves; a second-stage operational amplification circuit which is used for carrying out second-stage amplification on the sine waves; and a phase inverting circuit which is used for inverting the sine waves to generate rotary transformer excitation signals. The problems of large weight, large size, high cost and difficulty in integration of the existing rotary transformer excitation signal generation method are solved, and the rotary transformer excitation signal generation method has the advantages of low cost, small size, light weight, easiness in integration and the like.

A frequency characteristic measurement device that measures the frequency characteristic of a measurement target includes: a multi-sine signal generation unit that generates a multi-sine signal; a sweep sinusoidal wave generation unit that generates a plurality of sweep sinusoidal waves; an input signal switching unit that selects any one of the multi-sine signal and the sweep sinusoidal waves so as to input the selected one to the measurement target; a data acquisition unit that acquires, at a predetermined sampling frequency, sampling data of an input signal which is input to the measurement target and sampling data of an output signal which is output from the measurement target; and a characteristic calculation unit that calculates a frequency characteristic including the gain and the phase of the input and output signals in the measurement target from the sampling data of the input and output acquired.

The invention provides a power waveform generator with a four-quadrant feedback loop and a control method thereof, the generator is controlled by a user to respectively output a first control signal and a second control signal through an upper computer and a graphical interface, the first control signal is input into an FPGA + ARM main control board, an instruction is analyzed into a secondary instruction and sent to an auxiliary FPGA, the digital-to-analog converter is controlled to generate a signal after digital-to-analog conversion, and the signal is output to the four-quadrant analog feedback ring to generate an arbitrary waveform signal; the second control signal directly controls the bias adjustment circuit and outputs a proper bias signal to the four-quadrant analog feedback ring; the four-quadrant analog feedback loop superposes the received signals and then outputs voltage and current signals to the digit expansion circuit, further pushes the bootstrap network of the operational amplifier to generate voltage driving waveforms, and further generates power waveforms in any shapes through the push-pull output network.

Method for evaluating temperatures in active heave compensation ropes comprising the following steps: describe the geometry of ropes as composite structures obtained through assemblies of helical components in hierarchical levels: wires, strands and the rope itself; use a mechanical model of the strand that represents the material properties of each wire, under the assumption of linear elastic behavior; use a mechanical model of the rope that represents the combined action of tensile loads and imposed bending curvature; use a thermal model for the evaluation of the rope temperature increase (Ts) with respect to the ambient temperature, the thermal model comprising two main dissipation sources: the friction between strands or rope and a sheave and the friction between wires or between strands and compare rope temperature increase (Ts) obtained by the thermal model with a value of a predetermined temperature threshold.

A function generator for a digital system includes a plurality of sub-function generators. Each sub-function generator has an input that receives a respective input value and has an output that provides a respective output value responsive to the respective input value. A case detector receives a system input value and selectively routes at least a first portion of the system input value to the input of at least one selected sub-function generator. The case detector selects the selected sub-function generator in response to at least a second portion of the system input value. The case detector further suppresses transitions of data on the input of at least one non-selected sub-function generator. The case detector further selects the respective output value provided by the at least one selected sub-function generator and provides the selected respective output value as a function generator output value.

The disclosure relates to improved direct digital frequency synthesizers. A synthesizer in one embodiment is comprised of an accumulator that provides a phase signal and an interpolator having two or more interpolation polynomials. The polynomial that processes the phase signal is selected by comparing the phase signal to a threshold value. A reduced complexity digital circuit is provided for implementing the improved synthesizer.

The invention provides an artificial wave response spectrum fitting calculation method based on multi-phase spectrum iteration, and aims at solving the problems existing in artificial seismic waves ofa traditional frequency domain method fitting envelope design response spectrum, when Fourier amplitude spectrum iteration is carried out, R * 10 groups of random phase spectrums are generated and R* 10 artificial waves are generated in the R-th iteration, and the R * 10 groups of random phase spectrums are calculated. Iteration is carried out by using an error between the average value of the reaction spectrums corresponding to the artificial waves and the designed reaction spectrum, so that the condition that the final fitting result of the random phase spectrum cannot be converged is avoided. In the process of designing the reaction spectrum through frequency domain method fitting, a multi-phase spectrum matrix is mainly used, a single and invariant phase spectrum is not used any more, a complex Fourier phase spectrum is used for each iteration, and the influence of the random phase spectrum of the artificial wave on the convergence precision of a final fitting result is also reduced.