64 results about "Z-transform" patented technology

Z-transform calculations may be used to encode (and/or decode) carrier signal independent data (e.g., digital watermarks) to a digital sample stream. Deterministic and non-deterministic components of a digital sample stream signal may be analyzed for the purposes of encoding carrier signal independent data to the digital sample stream. The carrier signal independent data may be encoded in a manner such that it is restricted or concentrated primarily in the non-deterministic signal components of the carrier signal. The signal components can include a discrete series of digital samples and/or a discreet series of carrier frequency sub-bands of the carrier signal. Z-transform calculations may be used to measure a desirability of particular locations and a sample stream in which to encode the carrier signal independent data.

For processing samples of a signal received via a channel represented by an impulse response of W−1 coefficients, the method comprises: determining the W roots of the Z-transform of the channel impulse response; producing an intermediate signal by equalizing the received signal by a zero-forcing method or the like based on an impulse response whose Z-transform is a Z⁻¹ polynomial of degree W-p having as roots those of the W roots which are furthest from the unit circle of the complex plane; and then obtaining estimations of the transmitted signal symbols by applying a Viterbi-type equalization method or the like based on an impulse response whose Z-transform is a Z₋₁ polynomial of degree p having as roots those of the W roots which are nearest to the unit circle.

Systems and methods for transmitting data using various Modulation on Zeros schemes are described. In many embodiments, a communication system is utilized that includes a transmitter having a modulator that modulates a plurality of information bits to encode the bits in the zeros of the z-transform of a discrete-time baseband signal. In addition, the communication system includes a receiver having a decoder configured to decode a plurality of bits of information from the samples of a received signal by: determining a plurality of zeros of a z-transform of a received discrete-time baseband signal based upon samples from a received continuous-time signal, identifying zeros that encode the plurality of information bits, and outputting a plurality of decoded information bits based upon the identified zeros.

The invention discloses a seismic spectrum imaging method based on deconvolution generalized S transform, which comprises the steps that a generalized S transform spectrum is acquired by performing two-dimensional convolution on Wigner distribution of original signals and a Gaussian window, a transform spectrum is acquired by performing generalized S transform on seismic data, and time-frequency distribution of the original signal can be acquired through deconvolution when the generalized S transform spectrum and the Wigner distribution of a window function are known. The seismic spectrum imaging method combines advantages of generalized S transform and Wigner-Ville distribution, generation of a cross term of the Wigner-Ville distribution is effectively suppressed through a generalized S transform window, and the generalized S transform spectrum is enabled to acquire high time-frequency aggregation at the same time; and deconvolution generalized S transform can adaptively adjust an analysis window along with variations of a frequency component, is applicable to time-frequency analysis for unstable seismic data, and can acquire high time-frequency resolution; and the seismic spectrum imaging method is applied to detecting the oil-gas possibility of a reservoir, thereby being conducive to improving the reservoir prediction accuracy.

The invention comprises a method for processing seismic data to generate data related to the location of thin beds in the earth's subsurface. Seismic data windows are defined extending over selected portions of a group of spatially related seismic data traces. Frequency spectra of successively selected windows of the seismic data are generated by applying a transform having poles on the unit z-circle, where z is the z-transform, to the data windows; and the frequency spectra are utilized to generate data related to the location of thin beds in the earth's subsurface.

The invention provides a digital discrete signal hopping sliding discrete Fourier transform method, namely an SDFT (Modulated Hopping DFT, mHDFT) transform method for solving the problem of potential instability and accumulated errors of HDFT transform of an HDFT (hexagon discrete Fourier transform) transform method in practical engineering application. The method utilizes DFT circulating frequency domain shifting characteristics and modified UVT transform for effectively removing twiddle factors in a feedback loop of an HDFT resonator, accurately fixing HDFT poles on a unit circle and obtaining a DFT transform result of a frequency point k at n time, thereby effectively reducing the cumulative errors as well as ensuring the constant stability of the HDFT.

Embodiments of systems and methods for improved measurement of transient thermal responses in electronic systems are described herein. Embodiments of the disclosure use the known thermal transfer function of an electronic system to generate an equivalent resistor-capacitor (RC) network having a dynamic response that is identical to a given power excitation as the actual electronic system would have to that power excitation. Using the analogy between thermal and electrical systems, a Foster RC network is constructed, comprising a plurality of RC stages in which resistors and capacitors are connected in parallel. Subsequently, the analog thermal RC network is converted into an infinite impulse response (IIR) digital filter, whose coefficients can be obtained the Z-transform of the analog thermal RC network. This IIR digital filter establishes the recursive relationship between temperature output at the current time step and measured power input at the previous time step. Using this IIR digital filter, temperature response subject to arbitrary time-dependent power can be calculated in very small amount of time compared with prior art methods.

The invention provides a signal spectrum zooming method based on linear frequency modulation z transform. A symmetrical linear system h(n) is obtained by changing the expression form of a Bluestein equation and carrying out zero filling and periodic extending on the linear system h(n); the method for calculating the Fourier transform of an L point linear system sequence h(n) through a stored L/2+1 point linear system sequence is put forward; the result q(n) of the circular convolution is horizontally moved leftwards by N0 units, the front M values obtained after horizontal movement are multiplied with k (k=0,1,..., M-1), and then the signal partial spectrum with the improved frequency resolution can be obtained. By means of the scheme, the storage data size of the linear system sequence and the Fourier transform of the linear system sequence can be reduced, the storage space is saved, the Fourier transform of an L point linear system can be calculated through the stored L/2+1 point linear system data, the calculated quantity of an FFT is reduced, and the calculating efficiency is improved.

The invention proposes a visual perception correction image compression method based on DCT transform. The method is used for lossy compression of an image, and comprises the following steps: firstly, converting the image into a Ycrcb format via domain space transformation; secondly, decomposing the image into 8x8 image subblocks, and performing DCT transform on each image subblock; thirdly, in a DCT coefficient of each subblock, processing the coefficient through a judgment method and then decomposing the coefficient into a high frequency coefficient and a low frequency coefficient, wherein an error compensation mechanism is adopted for the high efficiency coefficient and visual perception correction transformation is performed on the low frequency coefficient, and then encoding; and finally, the process of reconstructing the image is an inverse operation of the compression process. Through the method of the invention, the image can not only get a higher compression ratio, but also the compression efficiency of the image is not reduced due to the increase of the amount of calculation; and meanwhile, the reconstructed image is analyzed, the image restoration degree is increased, the signal to noise ratio is enhanced, and the image restoration quality is obviously improved, therefore, the visual perception correction image compression method based on the DCT transform provided by the invention has strong practicability.

The invention provides a control circuit and control method for a power converter with adaptive voltage position control. The control method comprises the following steps: acquiring an output voltage difference between an output voltage and an output reference voltage by using a summator; referring to the output voltage difference by using a digital compensator with a Z-transform transfer function so as to generate a pulse width control signal, adjusting least significant bit (LSB) of the denominator coefficient of the Z-transform transfer function to realize the load line controlling function of the power converter; and controlling the pulse width modulation circuit by using the pulse width control signal to generate a pulse width modulation signal for controlling power-on/off of the power of the power converter. Therefore, the control function of a negative load line or a positive load line, and a variable load line controlling function required by a multi-phase converter can be easily realized without complicated operation.

The present invention is related to a method for estimating from an input signal the resonance frequencies of a system modelled as a source and a filter, comprising the steps of—determining the Z-transform of the input signal,—calculating the differential-phase spectrum of the Z-transformed input signal, whereby the Z-transform is evaluated on a circle centered around the origin of the Z-plane,—detecting the peaks on said differential-phase spectrum,—attributing the peaks to either the source or the filter,—estimating the resonance frequencies from the peaks.

The present invention provides a method of down scaling a source data to generate a destination data. By using 2 source points on a discontinued curve as reference, each piece of destination data can be generated. A midpoint of these 2 neighbor pixels is generated with a slope defined at the midpoint points. It is easy to control the sharpness of the interpolation result by adjusting the gain factor of the slope. The final interpolation curve passes the midpoint point of the 2 neighbor source points with a slope S define at the midpoint point but does not pass the 2 original neighbor pixels. Although the curve is not continuous at the source reference points but it is seen as a smooth curve by the human eyes during scaling down. The curve is a linear equation which makes the computing storage and cost very low. The BSSC method is excellent in scaling down even compared to other high order equation interpolation curve. Furthermore, a Z transform is induced to minimize the computing complexity.

The present invention presents the HD video transmission methods in a transform domain. In an aspect of the present invention, at the HD video transmitter the HD video is transformed into the transform domain by a multi-dimensional transform. Through the discrete-time continuous-valued or quasi-continuous-valued modulation, the obtained coefficients in transform domain are preferably carried in parallel in a multiple-access channel in time-domain to the HD video receiver.

A method and apparatus for digitally demodulating a QPSK signal includes resampling a first portion of a digitally sampled data subframe using a plurality of predetermined timing hypotheses. The timing offset is determined from analysis of the resampled data. The digitally sampled data subframes are then resampled based on the timing estimates. The modulation of the resampled data subframe is then removed by squaring the complex I/Q pair twice. A chirp-Z transform is performed on the data from which the modulation has been removed to shift the data into the frequency domain. Use the highest spectral power to determine the frequency offset. A phase offset is determined and the resampled data bursts are derotated and phase-shifted based on the phase offset and the frequency offset.

The invention discloses an LS (Least Square) based phase information calculating method in a complex environment. The method comprises the following steps of simultaneously calculating by adopting short-time chirp-z transform, obtaining signal frequencies, at different moments, of a reference channel through a selected amplitude maximum method and calculating and extracting multiple signal frequencies, exceeding a detection threshold, at the different moments, of the reference channel by adopting a short-time multi-target frequency detection algorithm; and calibrating actual signal frequencies, at the different moments, of the reference channel by adopting a matching discrimination method, which particularly comprises: calculating phase values, corresponding to frequency values of the reference channel at the different moments, of different receiving channels by adopting an LS method. By using the method provided by the invention, the frequency of a useful signal is extracted from a disorderly signal frequency spectrum; a disorderly frequency spectrum brought by random noise and clutter is abandoned; by utilizing the signal frequencies obtained by discriminatory analysis, a mathematic model between an observed signal and a signal initial phase is constructed; and next, the information of the signal initial phase of the corresponding receiving channel is calculated and obtainedby adopting an LS algorithm, so as to be called by other application of target location and the like.

The invention discloses a blind channel estimation method based on OFDM (orthogonal frequency division multiplexing) signal cyclostationary features, and the method is characterized in that on a fixed cycle frequency, z-transform of a delay variable Tau in a period spectrum function of an OFDM received signal is analyzed, and the accurate estimation of channel information is realized by selecting two different correlation values of the z-transform of the delay variable Tau, finally utilizing H(z) containing channel amplitude and minimal phase information and utilizing the existing least square method. Only the frequency spectrum information of one cycle frequency is adopted by the method, the quantity of the cycle frequency is reduced, so that the utilization rate of the frequency resource is effectively improved, the accuracy of the channel estimation is improved, and the performance of the method is obviously better than that of the existing blind channel estimation method through simulation verification; and by analyzing the energy distribution regulation of the self-correlation function of the OFDM received signal, the frequency spectrum information centralizing partial energy is adopted, the rest frequency spectrum information is set as zero, and the quantity of matrixes to be constructed is reduced, so that the calculation complexity is reduced.

A discretization processing method for transforming a transfer function in continuous time systems to a transfer function in discrete time systems is disclosed. To obtain the new transfer function, angular frequency ωa of the original transfer function in continuous time systems is transformed to angular frequency ωc using the bilinear z-transform of the inverse characteristic. In the discretion processing result, the equivalent characteristics of the original transfer function in continuous time systems can be obtained by performing the bilinear z-transform against the new transfer function in continuous time systems having been obtained by the angular frequency transformation of inverse characteristic.

The invention discloses a spatial domain color image blind watermarking method fused with Haar transform by combining the advantages of good concealment of an airspace digital watermarking algorithm and strong robustness of a frequency domain digital watermarking algorithm. According to the method, based on the characteristic that Haar transform has correlation between space-frequency domains, themaximum energy coefficient in a matrix of an image block after Haar transform is directly obtained in a space domain. The embedding and blind extraction of digital watermarks are completed by quantizing the maximum energy coefficient. According to the method, the color image digital watermark can be embedded into the color host image. The method has the advantages of being high in robustness, good in watermark concealment, high in safety, high in execution efficiency and high in embedding amount. The method is suitable for occasions of high-concealment high-capacity color digital image rapidcopyright protection.

The invention discloses a K-L transform-based method for detecting saliency of a small object on the sea. The method comprises: S1, extracting a brightness channel feature graph and two color channel feature graphs in seaborne scene visible image CIELab space; S2, carrying out Fourier transform on all channels obtained by the S1 to obtain amplitude spectra and phase spectra; S3, carrying out K-L conversion on the amplitude spectra, obtained at the S2, of all channels; S4, selecting main components of K-L transform results, obtained at the S3, of the amplitude spectra of the respective channels according to features of a seaborne image data set, and calculating a differential spectrum matrix of all amplitude spectra; S5, combining the differential spectrum matrix, obtained at S4, of all channels with all original amplitude spectra to carry out inverse discrete Fourier transform, thereby obtaining saliency maps of all channels; and S6, calculating a total saliency map by using a dynamic weighting method. According to the invention, small targets are highlighted and a background is suppressed, so that small target detection and tracking on the sea are realized.

The invention discloses a wavelength tag information analysis device and an analysis method. The received sampling signals are subjected to chirp-Z transform (CZT) analysis continuously by J times by a logic processing unit, and the frequency-related information of the continuous J times of each wavelength tag frequency in the sampling signals is counted to resolve wavelength tag information, wherein J is an integer larger than zero. Based on the characteristic of CZT that can select an arbitrary start frequency and frequency resolution (or stop frequency), the device and method provided by the invention can realize spectral zooming during frequency analysis by subjecting the sample signal to Z transform, thereby obtaining higher start frequency resolution, and reducing frequency measurement error caused by picket fence effect.