350 results about "Phase Code" patented technology

Disclosed is a multiplexing method and apparatus that allows holograms to be spatially multiplexed with partial spatial overlap between neighboring stacks of holograms. Each individual stack can additionally take full advantage of an alternate multiplexing scheme such as angle, wavelength, phase code, peristrophic, or fractal multiplexing, for example. An amount equal to the beam waist of the signal beam writing a hologram separates individual stacks of holograms. Upon reconstruction, a hologram and its neighbors will all be readout simultaneously. An filter is placed at the beam waist of the reconstructed data such that the neighbors that are read out are not transmitted to the camera plane. Alternatively, these unwanted reconstructions can be filtered out with an angular filter at an intermediate plane in the optical system that has a limited angular passband.

The invention discloses a super-resolution fluorescence microscopy method based on tangential polarization, comprising the following steps: carrying out 0-2pi vortex phase coding focus on tangential polarization exciting light, and obtaining an exciting spot below a diffraction limit on a fluorescence sample; adjusting tangential polarization STED laser and the phase coding tangential polarization exciting light to realize confluence and co-axis, focusing on the fluorescence sample to form a circle bread-shaped focusing spot the central point of which coincides with the central point of the exciting spot; adjusting the operating power of the STED laser to cause the area of a luminous point in the exciting spot to reach the super-resolution ratio; and collecting fluorescence emitted from the luminous point and carrying out detection processing to obtain a microimage with the super-resolution ratio. The invention also discloses a device for realizing the super-resolution fluorescence microscopy method based on tangential polarization. In the invention, on the premise of ensuring the super-resolution ratio, the working power of the STED is reduced greatly, thereby lowering bleaching of the sample and avoiding damage for the sample.

A computer implemented method for magnetic resonance imaging is provided. A 3D Fourier Transform acquisition is performed with two phase encode directions, wherein phase code locations are chosen so that a total number of phase encodes is less than a Nyquist rate, and closest distances between phase encode locations takes on a multiplicity of values. Readout signals are received through a multi-channel array of a plurality of receivers. An autocalibrating parallel imaging interpolation is performed and a noise correlation is generated. The noise correlation is used to weight a data consistency term of a compressed sensing iterative reconstruction. An image is created from the autocalibration parallel imaging using the weighted data consistency term. The image is displayed.

Improved apparatus and methods for utilizing holographic waveforms for a variety of purposes including communication, ranging, and detection. In one exemplary embodiment, the holographic waveforms are transmitted over an RF bearer medium to provide, inter alia, highly covert communications, radar systems, and microwave data links. The bearer (i.e., carrier) is optionally frequency-hopped, and various pulse modulation techniques (including variation of the phase-coding clock epoch) applied in order to further increase communications efficiency and covertness. Methods of providing multiple access and high bandwidth data transmission are also disclosed. Improved apparatus utilizing these features; e.g., a wireless miniature covert transceiver/locator, are also disclosed.

A receiver employs a pre-correlation filter to determine the precise timing of, for example, a PRN code on the quadrature channel of a received signal, using an image of the average chip shape that the filter forms for a PRN code on the in-phase channel. The image is expressed as a time series of complex power measurements along the length of a single chip. The averaging process retains the detail of the composite in-phase signal (direct plus multipath signals) while reducing the level of signal noise by an amount proportional to the length of the averaging process. An analysis of the image reveals that there is, in the in-phase channel signal that is averaged, information from the quadrature channel signal. The quadrature channel signal information produces, in the image of the average chip shape of the in-phase channel PRN code, a “wiggle” that corresponds to the timing of the chips of the quadrature channel PRN code. The receiver detects the chip edges of the quadrature PRN code directly from an analysis of the high frequency phase modulations of the complex vector of samples that represents the average chip shape. Using GPS signals, the receiver detects the P-code transitions by synchronizing to the 10.23 MHz phase modulations in the complex vector of samples that represent the averaged chip shape. The receiver uses the detected P-code transitions and, more particularly, the P-code transitions that are closest to the C/A code transitions, to produce P-code phase information that the receiver uses pseudorange calculations to remove biases associated with timing differences between the transmission of the in-phase and quadrature PRN codes.

In a magnetic resonance tomography apparatus employing a FISP pulse sequence, the pulse sequence is repeated with a repetition time T_R with different phase-coding gradient directions and with an alternating operational sign of the flip angle α. The gradient pulse trains are thereby completely balanced. A phase increment ΔΦ=β is generated in addition to the alternating operational sign of the flip angle α between successive excitation pulses, so that the steady state signals for a first and a second spin ensemble optionally have either identical or reversed signal polarities. A first dataset on the basis of identical signal polarities and a second dataset on the basis of reversed signal polarities are obtained by means of the free selection of the mutual signal polarities. A pure image of the first and the second spin ensembles is thus obtained by the addition and/or subtraction of the first and second datasets.

The invention provides a multi-target positioning method of a bistatic multi-input multi-output radar, comprising the following steps of: (1) transmitting mutually orthogonal phase-coded signals by M transmitting array elements, and receiving the phase-coded signals by N receiving array elements, wherein the distances of the M transmitting array elements and the N receiving array elements are all of half wavelengths; (2) carrying out matched filtering on the received phase-coded signals by a matched filter of a receiver of each receiving array element; (3) carrying out multistage Wiener filtering on a matched signal data covariance matrix space, and carrying out forward recursion to obtain a signal subspace; (4) carrying out high-resolution DOA (Direction of Arrival) estimation by using an ESPRIT algorithm, wherein a pairing algorithm is used for carrying out the automatic pairing on two-dimensional parameters; and (5) realizing multi-target positioning according to cross points at two angles so as to obtain the positions of space targets. The multi-target positioning method provided by the invention has the advantages of low computation complexity, high computation speed, high estimation accuracy and can be used for positioning the sea-surface or low-altitude targets during tracking and guidance.

The invention relates to a multi-channel high precision phase control signal generation device which utilizes a programmable read-only memory to generate a customized special circuit in an FPGA (Filed Programmable Gate Array) circuit through a VHDL (Very High Speed Integrated Circuit Hardware Description Language) language programming. The multi-channel high precision phase control signal generation device comprises a phase shift module, a phase coding module, an address coding module and a plurality of multi-channel gates. By taking a high precision active crystal oscillator as an information source, all multi-channel gates works in parallel to receive phase control signals of a host computer and output square wave signals of a multi-channel special phase. The output square wave signals access resonance of a power amplifier to generate sine wave signals with the same frequency and phase with the traditional output signals and the sine wave signals are used for excitation signals of an ultrasonic transducer array element in a phase control type high intensity focusing ultrasonic treatment system; and the frequency of the crystal oscillator is determined by the resonance frequency and the phase control precision requirements of the ultrasonic transducer array element. The invention dramatically increases the channel amount of the phase control signals and enhances the precision of the phase control signals, thereby satisfying the needs of the high intensity focusing ultrasonic treatment system.

A memory management system provides microcode instructions that are divided into multiple tuned phases and stored as separate modules inside a phase code depository. A microcode manager, containing a mode detector, sequence identifier, code loader, drawing data processor and phase executor, interacts with a microcode processor and the phase code depository. The mode detector evaluates a user request for a desired mode. In response to a command from the mode detector, the sequence identifier selects a correct phase sequence that is needed to implement the desired mode. The code loader transfers the phase sequence from the phase code depository to the microcode processor where it is stored in a microcode instruction memory. The memory address for each module within the phase sequence is written to a microcode data memory. The drawing data for the graphics mode is sent from the drawing data processor to the microcode processor, and the phase executor instructs the microcode processor to execute the phase sequence to render the desired mode by processing the drawing data. The resulting data is forwarded to another processor for additional microcode processing, vector processing, rasterization, or the like. The ability to select interchangeable phase modules to implement a desired mode reduces microcode memory requirements and allows easy integration and reuse of previously developed features among different games and other graphics software developers without having to rely on the type of platform.

The invention relates to an integrating method of three-dimensional spatial distribution vortex arrays, and belongs to the field of diffraction optics. A pure-phase code of a two-dimensional uniform-strength vortex optical grating and a pure-phase code of a spiral Dammam wave zone plate are obtained through analytic operation and an optimization algorithm respectively, phase information of the pure-phase codes is overlaid, a lens factor is introduced, discretized phase values are loaded to a spatial light modulator according to the pixel number and the pixel size of the spatial light modulator, and then the corresponding three-dimensional vortex arrays can be obtained. According to the method, the equal-strength and regular-distribution three-dimensional vortex arrays can be obtained, and each vortex beam in the arrays has the specific topological charge number.

The invention discloses a rock heterogeneous quantitative evaluation method based on magnetic resonance imaging. Three-dimensional space orientation of rock can be realized by layer selection pulse, phase coded pulse and frequency coded pulse. An imaging signal can be obtained by applying a spin-echo sequence, and optimization selection of imaging experimental parameters can be carried out through experimental scale. On the basis, a nuclear magnetic imaging signal obtained by experimental measurement is subjected to digital image processing so as to generate a pseudo color graph. By means of the relationship between the porosity and nuclear magnetic imaging signal intensity of a stand sample, the total porosity and porosity and distribution spectrum of a single layer can be obtained. Multi-layer imaging results are compared and a porosity heterogeneous coefficient is defined, so that the longitudinal porosity distribution characteristic and heterogeneity of rock can be obtained. In addition, by applying a first-order spherical variation function model and a grid search method, characteristic parameters of a variation function can be obtained. Heterogeneous coefficients and relative heterogeneous coefficients can be defined to realize longitudinal and horizontal heterogeneous quantitative characterization of rock.

The invention belongs to the radar technology field and the signal processing field, and relates to application of a multiple input multiple output (MIMO) type system, in particular to an MIMO radar sparse imaging algorithm based on a hybrid matching pursuit algorithm. The MIMO radar sparse imaging algorithm comprises the steps that firstly, M emitting array elements emit orthometric phase-coded signals, and N receiving array elements receive the phase-coded signals; secondly, a matched filter of a receiver of each receiving array element conducts matched filtering on the received phase-coded signals; thirdly, fourier transform is conducted on the matched-filtered signals, and a spatial spectral domain echo expression is obtained. Index selection of each time in the HMP algorithm is realized through an OMP algorithm, orthogonality of base signal selection is guaranteed through the operation, and spatial surface elements which are very close to one another can be distinguished when fourier similar characteristics exist in a dictionary matrix; meanwhile, backtracking selection operation in the HMP algorithm is the same as that in an SP algorithm.

Systems and methods for improved thermophotonic imaging are provided in which both amplitude and phase image information is obtained with a high signal to noise ratio and depth-resolved capabilities. Image data obtained from an imaging camera is dynamically averaged and subsequently processed to extract amplitude and/or phase image data. The system may be configured for a wide range of imaging modalities, including single frequency modulation (thermophotonic lock-in imaging), Thermal-Wave Radar imaging or Thermophotonic Radar imaging involving chirp modulation, and Binary Phase Coded Modulation. Such imaging modalities may find application in many diverse areas, including non-destructive testing and biomedical diagnostic imaging including the imaging of teeth and monitoring changes in the tooth over time which are due to pathology such as dental caries or erosion.

The invention discloses a method for realizing far field super-resolution focus, which comprises the following steps: modulating an incident light ray emitted by a laser to a tangential polarized light; carrying out 0-2pi vortex phase coding on the tangential polarized light; and carrying out the far field super-resolution focus on the tangential polarized light which is subject to the 0-2pi vortex phase coding, thus realizing far field focus and horizontal super-resolution and meeting demands of visible light super-resolution focus, especially a scanning confocal microscope. The invention also discloses a relevant device which is applied to the method for realizing the far field super-resolution focus. The invention has simple method and wide application; the horizontal focus effect of the invention is superior to that of the prior art; and the device of the invention has simple system structure, low cost and universality, in particular being suitable for being applied in measuring equipment for precise or ultraprecise microcosmic observation, especially the scanning cofocal microscope.

In a method and MR apparatus for the automatic segmentation of flow images acquired by magnetic resonance tomography for the depiction of tissue or organs traversed with fluid such as blood, at least one phase image of a selected region of the subject is acquired by magnetic resonance tomography, and fluid-traversed regions in the at least one phase image are automatically segmented.

The invention provides a wake-up signal detection method for an underwater acoustic communication MODEM. The method includes the steps that two repeated two-phase code signals generated by a balanced Gold sequence are selected as wake-up signals, sliding correlation treatment between adjacent data block pairs different in length is adopted in a receiving end, a data block start moment corresponding to the maximum correlation value is wake-up signal arrival time, the difference between the length of a data block corresponding to the maximum correlation value and the length of each sent wake-up signal is the Doppler time stretching length, and therefore the wake-up signal arrival time and the Doppler time stretching length are jointly estimated; a current correlation value is obtained in the mode that a product of start data of the currently adjacent data block pairs at last time is subtracted from the sum of a former correlation value and a product of tail data of the currently adjacent data block pairs, the calculation amount is far smaller than that of multiple sliding copy correlation devices, and the method can be conducted in real time under the conditions of dormancy of the underwater acoustic communication MODEM and the low clock frequency of a processor and is high in practicality.

An X-ray detector array includes a scintillator that converts input X-ray radiation to secondary optical radiation output from the scintillator, a first telecentric micro lens array that array receives the secondary optical radiation, a phase coded aperture, where the first telecentric micro lens array directs the secondary optical radiation on the phase coded aperture, a second telecentric micro lens array, where the secondary optical radiation output from the phase coded array is directed to the second telecentric micro lens array, a patterned grating mask, where the second telecentric micro lens array directs the optical beam on the patterned mask, and a photodetector array, where the patterned mask outputs the optical beam in a pattern according to the patterned mask to the photodetector array, where the photodetector array outputs a signal, where a photon fringe pattern is imaged and sampled in the wavelength domain of the radiation from the scintillator.

The invention relates to a poly-phase code radar signal waveform automatic identification method based on continuous wave Doppler (CWD) feature and belongs to the technical field of information countermeasures. According to the poly-phase code radar signal waveform automatic identification method based on CWD feature, a discrete sampling type Choi-Williams conversion is used as a basic tool, a CWD image of poly-phase code pulse compression radar signal is used as a feature extraction object, a Pseudo-Zernike moment of the CWD image, a target number of an image, a time position of a peak power in a CWD and a poly-phase code waveform symmetrical property are taken as features to identify a poly-phase code pulse compression radar waveform, and a neural network which is composed of 10 perceptrons and stops in advance of overall average is set up for automatic waveform identification. The poly-phase code radar signal waveform automatic identification method based on CWD feature has the advantages that the identification precision of the poly-phase code radar signal waveform is improved, the requirement of a signal to noise ratio is further decreased, and a new way can be developed for the design of radar signal identification and sorting by popularized and used in a poly-phase code continuous wave radar signal.

In a method for magnetic resonance imaging, by combined switching of radio-frequency excitation pulses, slice selection gradient pulses, phase-coding gradient pulses and readout gradient pulses, a matrix in the k-space is scanned row-by-row and transformed using a Fourier transformation into a matrix in the spatial domain, with the polarity of the slice selection gradient being inverted during the scanning of the k-matrix, allowing elimination of the ambiguity artifact.