43 results about "Walsh function" patented technology

An efficient telecommunications receiver system for accurately decoding a received composite signal having a data signal component and a pilot signal component. The receiver system includes a first circuit for receiving the composite signal and extracting a pilot signal and a data signal from received composite signal. A second circuit calculates a log-likelihood ratio as a function of a channel estimate based on the pilot signal. A third circuit scales the log-likelihood ratio by a predetermined log-likelihood ratio scaling factor and provides an accurate log-likelihood value in response thereto. A fourth circuit decodes the received composite signal based on the accurate log-likelihood value and the data signal. In a specific embodiment, the pilot signal and the data signal comprise pilot samples and data samples, respectively. The third circuit includes a carrier signal-to-interference ratio circuit for computing a first signal-to-interference ratio and a second signal-to-interference ratio based partly on the pilot signal. The first signal-to-interference ratio is based on the data samples, and the second signal-to-interference ratio is based on the pilot samples. The first signal-to-noise ratio and the second signal-to-noise ratio provide input to a circuit for computing the predetermined log-likelihood ratio scaling factor that is included in the third circuit. In a more specific embodiment, the first circuit includes a despreader for despreading the received composite signal in accordance with a predetermined spreading function and providing a despread signal in response thereto. The spreading function is a pseudo noise sequence or a Walsh function. The first circuit further includes a decovering circuit that extracts the pilot signal and the data signal from the despread signal. In the illustrative embodiment, the accurate receiver system further includes a circuit for generating a rate and / or power control message and transmitting the rate and / or power control message to an external transceiver in communication with the efficient receiver system.

In one disclosed embodiment, data information is stored in a buffer in a transmitter. The data information is transmitted on a shared channel and control information for recovering the associated data information is transmitted on a dedicated channel. The shared and dedicated channels can be, for example, different portions of the frequency band. The control information can include a spreading factor used to spread the data at the transmitter. For example, the spreading factor can be the length of the Walsh function orthogonal coding used to spread the data. The control information is received over the dedicated channel before the associated data information is received over the shared channel. The control information is then used to recover the associated data information. For example, knowing the spreading factor from the control information, the correct Walsh function can be selected to de-spread, i.e. to Walsh de-cover, the data information.

The invention involves a parallel spread spectrum ('PSS') technique of spreading orthogonal encoded data. In a preferred embodiment, a method and system for communicating data comprises encoding and spreading a data stream using a scheme employing orthogonal Walsh functions, and thereby segmenting the data stream into multiple bit data packets representing one of a number of true or inverted Walsh codes. The data stream is then differentially encoded for either BPSK or QPSK modulation, and spread using a PN-sequence. The parallel spread data stream is modulated for transmission to a receiver. At the receiver, the data stream is recovered by computing a cross correlation between the digitized data stream and a programmed sequence. One of the benefits of the PSS techniques over conventional communication systems is that additional processing gain plus data forward error correction can be simultaneously achieved.

An apparatus and method for transmitting / receiving a PDCCH (Packet Data Control Channel) for efficient packet data transmission in a communication system supporting packet data service. To allow both TDM-transmission and TDM / CDM-transmission of packet data, PDCCHs having different control information are transmitted. A 1PDCCH and a 2PDCCH are selectively transmitted according to the channel environments of users to thereby minimize the transmission power of the 1PDCCH and the 2PDCCH. A PDCCH receiver receives the 1PDCCH and the 2PDCCH using Walsh functions assigned to them, demodulates them, and checks errors in them, thereby obtaining control information about packet data to be received.

In one disclosed embodiment, data information is stored in a buffer in a transmitter. The data information is transmitted on a shared channel and control information for recovering the associated data information is transmitted on a dedicated channel. The shared and dedicated channels can be, for example, different portions of the frequency band. The control information can include a spreading factor used to spread the data at the transmitter. For example, the spreading factor can be the length of the Walsh function orthogonal coding used to spread the data. The control information is received over the dedicated channel before the associated data information is received over the shared channel. The control information is then used to recover the associated data information. For example, knowing the spreading factor from the control information, the correct Walsh function can be selected to de-spread, i.e. to Walsh de-cover, the data information.

The invention discloses a synthesis method of a multifrequency synchronous signal source, comprising the following steps of, determining an amount N of main frequencies in a multifrequency synchronous signal to be synthesized, thereby determining that the signal is subdivided into 2N equal parts within a period T0, wherein N should be an odd number; finding out vectors of first N symmetric odd functions SAL (20, t), SAL (21, t), ......, SAL (2N-1, t) in a Walsh function system within a period, wherein each vector contains 2N elements; summing N vectors to obtain a sum vector g (N, t); carrying out normalization treatment on the sum vector g (N, t) with a sign function sgn () pair, thereby obtaining vectors f (N, t) of multifrequency synchronous signals of +1 and -1 within the period T0; and repeating the f (N, t) with a fundamental frequency period T0 to obtain a periodic multifrequency synchronous signal. The multifrequency synchronous signal source synthesized through the method has various very ideal time domain and frequency domain characteristics and realizes multifrequency synchronous measurement of an impedance spectroscopy.

NMR data are acquired using a phase-alternation of the tipping pulse. Averaged properties are estimated over a window length. The averaged properties are inverted to undo the effects of the averaging. A matrix defined in terms of Walsh functions is used in the inversion.

The invention relates to the technical field of wind profiler radar waveform design, signal processing, waveform generation method and frequency synthesizer circuit. The invention first provides a wind profiler radar phase encoding method and circuit based on Frank codes. The method comprises the steps that the number M of encoding sub-pulses is calculated; a time domain accumulation number Nc is calculated; an encoding cycle number N is selected; the time domain accumulation number Nc and the encoding cycle number N are adjusted to form an encoding matrix FN'*M; and the encoding matrix FN'*M is used to carry out phase encoding of transmitted pulses of an encoding cycle. A wind profiler radar is used for detecting wind direction, wind speed, echo intensity and other meteorological information of an atmospheric wind field. In the prior art, two-phase complementary codes, Walsh function codes or other phase encoding technologies are used to realize width pulse energy and narrow pulse resolution at the same time. The encoding method and circuit, which are provided by the invention, use ordinary pulse or pulse burst waveform, have the advantages of low distance sidelobe and flexible selection of the number of the sub-pulses, can be used to prevent point frequency radio interference, and are suitable for a variety of wind profiler radars.

Disclosed is a method for measuring tilt aberration of Hartmann wavefront sensor subaperture. First-step Walsh function form binary phase modulation and second-step Walsh function form binary phase modulation are respectively conducted to auxiliary optical waves in an auxiliary aperture range through a phase modulator, modulated auxiliary optical waves each time are focused by a micro lens and enter into corresponding single mode fiber lectotype filter, three types of light intensity data emerged in three states of non-modulation, first-step modulation and second-step modulation are received by a single detector at the other end of an optical fiber, a first-step Walsh function coefficient and a second-step Walsh function coefficient of wavelet center front are obtained according to the light intensity data, and tilt aberration coefficients in two directions corresponding to the wavelet center front in the auxiliary subaperture are obtained by utilizing a corresponding proportional relation of the first-step Walsh function and the second-step Walsh function and tilt aberration. The method for measuring the tilt aberration of the Hartmann wavefront sensor subaperture reduces the number of corresponding detecting units of each subaperture sufficiently, greatly reduces detection information content, achieves that in each single subaperture, a single photoelectric detector replaces a photoelectric detector array, accelerates detecting speed and reduces device cost, and meanwhile, detecting precision of wavefront is free from the influence of reduction of the number of the detecting units.

The present invention is directed to a method for canceling the Doppler shift, multi-path propagation, delays, and long time selective fading influences of phase and / or amplitude modulated signals carried by RF sub-carriers, without requiring pilot signals. The number of m=2n, over which individual datum is transmitted in each communication channel, is determined. Pairs of Walsh functions are selected from a Walsh-Hadamard matrix such that each function is not selected more than once. Each signal is partitioned to its I factor and Q factor and coding each I and Q factors of the signals by the pair functions. A corresponding phase and amplitude is allocated for each sub-carrier wherein the amplitude and phase values are determined by the data that is transmitted, the digital modulation scheme or inverse spectral transformation, and signs of both corresponding elements taken from the pair Walsh functions. Data is transmitted over the sub-carriers and received and the corresponding phases and amplitudes of all the received signals are obtained using spectral transformation. The received signals are decoded by changing signs of I and Q factors of the received signals in accordance with corresponding elements from the pair functions, used to decode said signals. The I and Q factors of received signals are summed separately, after changing signs of said I and Q factors of received signals, and each of the summations of I and Q factors is divided by m. The signal is reconstructed using said divided I and Q factors, by calculating its phase.

The invention provides a method of building a coefficient transfer matrix between a Zernike polynomial aberration model and a Walsh function aberration model. According to a linear relation of the Zernike polynomial coefficient and each Walsh function coefficient, coefficient matrix, expanded by Walsh function, of each Zernike polynomial is ensured so as to realize interconversion between a Zernike polynomial aberration model coefficient and a Walsh function aberration model coefficient. If a Walsh function order with a bigger coefficient absolute value is chosen, transfer matrix is reconstructed so as to reduce effectively scale of the coefficient transfer matrix of the coefficient and obtain the Zernike polynomial coefficient information by coefficient information of fewest and optimal Walsh function order. By only detecting one kind of aberration model coefficient, another coefficient corresponding to an aberration model can be ensured by the transfer matrix, wavefront phase distortion can be described by the two kinds of the aberration models respectively in order to achieve the goal of complementing advantages of the two kinds of the aberration models, meanwhile, certain help can be provided for development of a novel wavefront sensor technology.

The invention discloses a quaternion Walsh approximate output method based on angular velocities for an aircraft during extreme flight, which is used for solving the technical problem of poor precision of quaternion outputted by existing inertial equipment when an aircraft is in extreme flight. The technical scheme includes that approximate prescription is realized for a rolling angular velocity p, a pitching angular velocity q and a yawing angular velocity r by the aid of a Walsh function polynomial, a quaternion state transition matrix is directly obtained, and iterative computation precision of specified quaternion is guaranteed. Orders of Walsh approximate expansion for the rolling angular velocity p, the pitching angular velocity q and the yawing angular velocity r are determined according to the requirement of engineering precision, superlinear approximation for a quaternion state equation transition matrix phie[(k+1)T, kT] is realized, iterative computation precision of the specified quaternion is guaranteed, and accordingly output precision of inertial equipment is improved when the aircraft is in extreme flight.

An emit diversity encoded method for common pilot channel of several antennas in WCDMA system features that 2 to the power n-1 radio frames are used as one encode period and Walsh function is used for orthogonal encode of continuous 2 to the power n sign bits as one unit, and distributing it to several antennas.

The invention relates to a pseudorandom sequence generating method. The pseudorandom sequence comprises internal sequences and an external sequence formed by composite connection. The generating method comprises the following steps: detecting the information code value collected or input by a user and setting the external sequence value; determining the adopted internal sequence type according to the external sequence value and the information code value; and finally, connecting the internal sequences in series, wherein the internal sequence is a Walsh function sequence, and the external sequence is an m sequence. In the invention, through the composite connection between the internal sequences and the external sequence, a long-cycle pseudo-code sequence can be used for distance measurement without reducing the information rate; and meanwhile, the resolving difficulty of a receiving end is reduced, and the distance measurement precision is improved.

The invention discloses a geodetic system identification electromagnetic exploration method and a geodetic system identification electromagnetic exploration system based on multipath orthogonal coding. The geodetic system identification electromagnetic exploration method comprises the following steps of: sampling an input signal to obtain a discrete signal; carrying out discrete Walsh transform onN discrete data to obtain coefficients of N Walsh codes; selecting N mutually orthogonal Walsh functions from a Walsh code orthogonal set, and multiplying the Walsh functions by coefficients of the NWalsh codes in a one-to-one correspondence manner to obtain N paths of spread spectrum orthogonal coded signals; combining the N paths of orthogonal coded signals to obtain a total transmitting signal and transmitting the total transmitting signal to a geodetic system; and receiving a total signal transmitted by the geodetic system, performing separation on the total signal by utilizing the N Walsh functions to obtain N paths of receiving signals, and calculating impulse response and noise of the geodetic system by utilizing the N paths of receiving signals. According to the geodetic system identification electromagnetic exploration method and the geodetic system identification electromagnetic exploration system, multipath spread spectrum is carried out on the original input signal, so that the solving precision of the impulse response of the earth system is improved, useful signals and noise are effectively separated, and a basis is provided for acquiring earth medium parameters withhigher accuracy.

In order to overcome the problem in the prior art that a complex flutter model under aerodynamic force and strength change influences can not be effectively expressed, the invention provides an aircraft flutter analysis grid model Walsh modeling method. The method is characterized in that a plurality of grid points are selected in an aircraft engine body shaft system; under aerodynamic force and strength change influences including different flight speeds, atmospheric densities, airflow environments, different temperatures and the like, according to an engine body shaft system decomposition method, a complex flutter grid model is expressed; according to a requirement for establishing the model, the requirements of installing sensors and data and image records are put forward; through an effective flutter flight experiment, data is obtained, and an excitation function is obtained through a measured value of an airflow sensor; a Walsh function is adopted to carry out approximation and equivalent description on a vibration variable; according to a distinguishing method, the solving of three axial vibration equations on an engine body axial system coordinate grid point can be simultaneously determined, and the technical problem in the prior art that the complex flutter model under aerodynamic force and strength change influences can not be effectively expressed is solved.

The invention discloses a private file protection method based on the Walsh code. According to the method, a file to be protected is divided into N file fragments; orthogonal codes generated by a Walsh function and the file fragments are subjected to operation respectively so as to obtain a new file with a disturbed sequence, as a private file; the private file is stored in a disk. If the private file is stolen, the original file can still be cracked out without knowing the orthogonal codes; accordingly, file confidentiality is ensured. If a user needs to restore the original file, the original file can be restored by re-operating with the orthogonal codes to obtain original sequence codes of the original file; accordingly, security of the file can be ensured without subjecting the file to complex encryption algorithms, the orthogonal codes are available for reuse, multiple files can share a single set of orthogonal codes, scrambling the sequence of the orthogonal codes is required only, reusability of codes is greatly improved, and workload is saved.

Method and system for allowing abandoning pilot signals use and for increasing the immunity to Doppler Effect influence in OFDMA based wireless mobile communication systems and as a result, make them more efficient. This is carried out by transmitting N orthogonal I and Q values of symbols, N times on N frequencies, where N is a power of two. In order to be able to select the desired signal from a mixture of N signals, signs of symbol of each signal vary according to one of N-order Walsh functions.

A transmitting device includes: a compressing unit configured to generate and output a compressed digital signal that has been compressed, by converting an input digital signal by use of a Walsh function and extracting a specific frequency component.

A device for multiple row addressing is driven with pulse patterns based on sets of 8 (or more) orthogonal functions which have a less varying frequency content than pulse patterns based on a set of 8 Walsh functions. Mutually orthogonal signals are obtained from at least two types of the orthogonal functions having four elementary units of time. Within the four elementary units of time, one pulse each unit of time has a polarity which is different from the plurality of the other pulses.

In this application, a set of orthogonal functions is introduced whose power spectral densities are all rectangular shape. To find the orthogonal function set, it was considered that their spectrums (Fourier transforms of the functions) are either real-valued or imaginary-valued, which are corresponding to even and odd real-valued time domain signals, respectively. The time domain functions are all considered real-valued because they are actually physical signals. The shape of the power spectral densities of the signals are rectangular thus, the Haar orthogonal function set can be employed in the frequency domain to decompose them to several orthogonal functions. Based on the inverse Fourier transform of the Haar orthogonal functions, the time domain functions with rectangular power spectral densities can be determined. This is equivalent to finding the time-domain functions by taking the inverse Fourier transform of the frequency domain Walsh functions. The obtained functions are sampled and truncated to generate finite-length discrete signals. Truncation destroys the orthogonality of the signals. The Singular Value Decomposition method is used to restore the orthogonality of the truncated discrete signals.

The invention discloses an Euler angle Walsh index approximate output method based on angular velocity, which is used for solving the technical problem of being poor in Euler angle output precision of the current aircraft in the event of carrying out maneuver flight. The technical scheme provided by the invention is as follows: rolling, pitching and off-course angular velocities are expanded according to a Walsh function polynomial by introducing a plurality of parameters; a pitching angle, a rolling angle and an off-course angle are solved in turn; and the expression of an Euler angle is directly subjected to high-order approximation integral, so that solving of the Euler angle is approximated in a super-linear manner. Time update iterative calculation precision of the Euler angle is ensured, so that the accuracy for outputting flight attitudes by inertial equipment is increased.

In order to overcome the problem in the prior art that a complex flutter model under aerodynamic force and strength change influences can not be effectively expressed, the invention provides an aircraft flutter analysis grid model Walsh modeling method. The method is characterized in that a plurality of grid points are selected in an aircraft engine body shaft system; under aerodynamic force and strength change influences including different flight speeds, atmospheric densities, airflow environments, different temperatures and the like, according to an engine body shaft system decomposition method, a complex flutter grid model is expressed; according to a requirement for establishing the model, the requirements of installing sensors and data and image records are put forward; through an effective flutter flight experiment, data is obtained, and an excitation function is obtained through a measured value of an airflow sensor; a Walsh function is adopted to carry out approximation and equivalent description on a vibration variable; according to a distinguishing method, the solving of three axial vibration equations on an engine body axial system coordinate grid point can be simultaneously determined, and the technical problem in the prior art that the complex flutter model under aerodynamic force and strength change influences can not be effectively expressed is solved.

A transmitting device includes: a compressing unit configured to generate and output a compressed digital signal that has been compressed, by converting an input digital signal by use of a Walsh function and extracting a specific frequency component.

In this application, a set of orthogonal functions is introduced whose power spectral densities are all rectangular shape. To find the orthogonal function set, it was considered that their spectrums (Fourier transforms of the functions) are either real-valued or imaginary-valued, which are corresponding to even and odd real-valued time domain signals, respectively. The time domain functions are all considered real-valued because they are actually physical signals. The shape of the power spectral densities of the signals are rectangular thus, the Haar orthogonal function set can be employed in the frequency domain to decompose them to several orthogonal functions. Based on the inverse Fourier transform of the Haar orthogonal functions, the time domain functions with rectangular power spectral densities can be determined. This is equivalent to finding the time-domain functions by taking the inverse Fourier transform of the frequency domain Walsh functions. The obtained functions are sampled and truncated to generate finite-length discrete signals. Truncation destroys the orthogonality of the signals. The Singular Value Decomposition method is used to restore the orthogonality of the truncated discrete signals.

The invention discloses an Euler angle Walsh index approximate output method based on angular velocity, which is used for solving the technical problem of being poor in Euler angle output precision of the current aircraft in the event of carrying out maneuver flight. The technical scheme provided by the invention is as follows: rolling, pitching and off-course angular velocities are expanded according to a Walsh function polynomial by introducing a plurality of parameters; a pitching angle, a rolling angle and an off-course angle are solved in turn; and the expression of an Euler angle is directly subjected to high-order approximation integral, so that solving of the Euler angle is approximated in a super-linear manner. Time update iterative calculation precision of the Euler angle is ensured, so that the accuracy for outputting flight attitudes by inertial equipment is increased.

For combining diversity path signals comprising symbols each modulated in accordance with one of a plurality of orthogonal (e.g. Walsh) functions, a diversity combiner includes, for each path, a demodulator to demodulate each modulated signal symbol in accordance with a selected one of the orthogonal functions, a phase estimator to estimate a phase rotation and amplitude of the diversity path signal from the demodulated signal, and a complex signal multiplier to derotate the phase and weight the amplitude of the diversity path modulated signal in dependence upon the estimated phase rotation and amplitude. The combiner sums real parts of the phase-derotated and weighted modulated signals of the diversity paths, demodulates the combined signal in accordance with all of the orthogonal functions, and selects the maximum demodulated signal for each symbol thereby to determine for the symbol the selected one of the orthogonal functions.

The invention discloses a synthesis method of a multifrequency synchronous signal source, comprising the following steps of, determining an amount N of main frequencies in a multifrequency synchronous signal to be synthesized, thereby determining that the signal is subdivided into 2N equal parts within a period T0, wherein N should be an odd number; finding out vectors of first N symmetric odd functions SAL (20, t), SAL (21, t), ......, SAL (2N-1, t) in a Walsh function system within a period, wherein each vector contains 2N elements; summing N vectors to obtain a sum vector g (N, t); carrying out normalization treatment on the sum vector g (N, t) with a sign function sgn () pair, thereby obtaining vectors f (N, t) of multifrequency synchronous signals of +1 and -1 within the period T0; and repeating the f (N, t) with a fundamental frequency period T0 to obtain a periodic multifrequency synchronous signal. The multifrequency synchronous signal source synthesized through the method hasvarious very ideal time domain and frequency domain characteristics and realizes multifrequency synchronous measurement of an impedance spectroscopy.

The invention discloses a deep learning wavefront restoration method based on a single-frame focal plane light intensity image, and aims to solve the problem that multiple solutions exist when a single far-field light spot inverts a near-field wavefront due to the fact that two groups of wavefronts which mutually rotate by 180 degrees and have a complex conjugate relationship in an adaptive optical system have the same far-field light spot distribution. The wavefront restoration method based on walsh function phase modulation can ensure that far-field light spot distribution corresponds to a unique near-field wavefront, but the calculation speed is still limited by the number of iterations and the single-step iterative calculation time. The deep learning algorithm can self-extract the deepfeature information of the image, so that the mapping relation from the far-field light intensity image to the near-field wavefront can be learned on the basis of phase modulation of the walsh function, the calculation from the far-field image to the near-field wavefront end-to-end is realized, and the iterative calculation process of the traditional wavefront restoration method can be avoided. Based on this, the iterative calculation process of a traditional wavefront restoration method is avoided by using a deep learning algorithm, the calculation efficiency is improved, and rapid wavefrontrestoration of a single-frame focal plane light intensity image is realized.