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.

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.

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.

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 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.

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 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.

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.

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.

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.