155 results about "Phase factor" patented technology

An OFDM system embeds sequence information in the transmitted signal that reduces peak average power ratio (PAP) with minimal impact on the overall system efficiency. A marker is embedded onto the transmitted information that is used to identify the combining (inversion) sequence at the receiver. In one embodiment, selected tones in a cluster are rotated when the corresponding phase factor rotates the cluster.

There is provided a PTS (Partial Transmit Sequence) OFDM (Orthogonal Frequency Division Multiplexing) scheme for reduction of a PAPR (Peak-to-Average Power Ratio). In an OFDM transmitting apparatus for peak power reduction according to the present invention, an rotational sub-block partitioner partitions an input data block of length N into M, the number of sub-block, and distributes the partitioned data of each data block in M sub-blocks one by one rotationally. M IFFTs (Inverse Fast Fourier Transformers) perform N / M-point IFFT on N / M data assigned to each of the M sub-blocks and M coefficient multipliers multiply the N / M data output from each IFFT by a predetermined coefficient to give orthogonality to the frequency components of the N / M output data. A phase factor optimizer optimizes M phase factors to minimize a PAPR using the N / M output values of each coefficient multiplier. M multipliers multiply the optimized M phase factors by the outputs of the coefficient multipliers. A transmitter sums the outputs of the M multipliers on a symbol-to-symbol basis in the same positions and transmits the sum.

The invention provides an optimization design method of a low-orbit communication and navigation enhancement mixed constellation. The method comprises the following steps: determining a satellite orbit type; determining a satellite orbit height; determining a minimum observation elevation angle; selecting constellation configuration; determining an orbit inclination angle; determining a satellite quantity; determining an orbit surface quantity and a phase factor; selecting initial ascending node right ascension in an optimized mode; analyzing coverage performance of the low-orbit communication and navigation enhancement mixed constellation; and after traversing ends, comparing all mixed constellation parameters satisfying design requirements, and selecting an optimal solution. The method has the following advantages: through combination of factors needing to be considered for design of a communication and navigation enhancement constellation at each phase, the designed low-orbit communication and navigation enhancement mixed constellation can satisfy user demands, is excellent in constellation performance, is small in satellite quantity and quite good in compatible mutual operation capability between constellations.

The invention puts forward an IQ unbalance correcting technology based on a digital pre-distortion system and belongs to the field of wireless communication. After quadrature modulation, signals enter the digital pre-distortion system by two paths, channel estimation is firstly conducted to obtain corresponding estimation parameters and data initialization is carried out; then based on input in-phase signals and orthogonal signals, direct current offset factors of the in-phase signals and the orthogonal signals are calculated and direct current compensation is conducted; based on the input in-phase signals and orthogonal signals, gain unbalance factors and phase unbalance factors of the in-phase signals and the orthogonal signals are calculated; according to a mirror image correction model, corresponding factors are substituted to carry out the mirror image correction; finally, the compensated gain factors and the phase factors are updated and the IQ unbalance correcting process is completed. By means of the digital pre-distortion correcting method against the IQ unbalance distortion, system hardware complexity and the cost can be reduced, and meanwhile error estimation precision and compensation precisions are improved.

The invention discloses a dispersion compensation method for a broadband light source. A polarization-preserving fiber polarization coupling testing system based on a Michelson interferometer is formed by the broadband light source, and the Michelson interferometer compensates the optical path difference between an excitation mode and a coupling mode in the polarization-preserving fiber, and a detector acquires an interference signal; specifically, the method comprises the following steps of: intercepting the initial data acquired by the detector through a window function, and taking out the interference data Imain between the excitation modes and the interference data Icoupling between the excitation mode and the coupling mode; respectively executing Hilbert transformation and Gaussian fitting on the Imain and the Icoupling, obtaining envelopes (I)main and (I)coupling of the interference signal, getting a birefringence dispersion coefficient Delta D according to a ratio Eta of the width of the (I)main to the width of the (I)coupling at a 1 / e part, obtaining a phase factor needed for the dispersion compensation, and then multiplying the phase factor by a nonlinear frequency spectrum function with dispersion information to eliminate nonlinear phase items causing the widening of the interference signal envelopes; and finally, obtaining the dispersion compensated interference signal Icomp by executing Fourier inversion on the obtained linear frequency spectrum function.

The invention discloses a method and device for mapping demodulation reference signals (DMRS). The method comprises the following steps: generating DMRS sequences, multiplying the DMRS sequences by different phase factors respectively to generate DMRS sequences corresponding to each layer, carrying out orthogonal code cover (OCC) treatment on the DMRS and mapping the DMRS on physical resource blocks (PRB). The method and the device have the following beneficial effects: the problems of mutual offset and mutual reinforcement of the DMRS are avoided in the precoding process by multiplying the same DMRS by different phase factors respectively and mapping the DMRS on different layers, thus improving the precision of channel estimation.

The embodiment of the invention discloses a method and a device for indicating and determining a precoding vector, which relate to the precoding technology and are helpful for realizing the followingbeneficial effects: on the basis of guaranteeing the precoding vector to reach certain accuracy, rationally setting overhead of indication information of a feedback indication superposition factor, and thereby improving system overall performance gain. The method may comprise the following steps: generating the indication information, and sending the indication information, wherein the indicationinformation is used for indicating a plurality of component vectors of an ideal precoding vector and the superposition factor of each component vector, wherein the superposition factor of the component vector comprises at least one of the following types: a broadband amplitude factor, a narrowband amplitude factor and a narrowband phase factor; and except for a normalized benchmark component vector, at least two component vectors of the plurality of component vectors have different quantization bit numbers of the superposition factors of the same type.

An Orthogonal Frequency Division Multiplexing (OFDM) communication system that multiplexes data with a plurality of orthogonal sub-carrier frequencies, which includes a transmitter for converting a serial data stream into parallel data, and segmenting the parallel data into a plurality of blocks having a plurality of data blocks; inserting reference data having information representing a phase value and a position into which the reference symbol is inserted, into each of the segmented blocks; Inverse Fast Fourier Transform (IFFT)-transforming the respective blocks into time-based signals where sub-carrier frequencies are separately assigned to the data blocks; and determining phase factors of the IFFT-transformed time-based signals to reduce a Peak-to-Average Power Ratio (PAPR) where non-linear distortion occurs due to coincidence of phases of the data blocks IFFT-transformed with the sub-carrier frequencies, and phase-rotating the IFFT-transformed signals according to the determined phase factors before transmission.

The present invention provides a method and system for reducing the peak to average power ratio (PAP) of a signal with low computational complexity. According to one embodiment, the present invention is applied to reduce the PAP of an OFDM signal. According to an alternative embodiment, the present invention, is applied to reduce the PAP of a CDMA signal. Rather than seeking the optimum solution, which involves significant computational complexity, the present invention provides for a number of sub-optimal techniques for reducing the PAP of an OFDM signal but with much lower computational complexity. In particular, according to one embodiment utilizing the PTS approach, an iterative technique is used to assign phase factors to each of a set of partial transmit sequences from a set of possible phase factors. Experimental results using the iterative technique showed only a slight degradation (1 dB) from the optimal approach using the same number of subblocks and subcarriers. In an alternative embodiment, which avoids feedback required by the iterative approach, a sequence of phase factors are generated randomly and assigned to each of a set of partial transmit sequences. This procedure is repeated for a pre-determined number of trials and the random sequence generating the lowest PAP is selected. In a third embodiment, a set of phase factors is generated using a structured sequence such as a Walsh sequence.

The invention discloses a multi-angle forward scattering transmittance meter, which comprises a transmitting terminal, a receiving terminal and a control system, wherein the transmitting terminal comprises a modulation circuit and a light source transmitting unit; the receiving terminal comprises photoelectric conversion units and a signal processing circuit; the light source transmitting unit emits a light pulse with a fixed frequency; the emitted light is received by three photoelectric conversion units arranged in a forward scattering direction, and converted into an electric signal after being scattered by atmosphere under the action of the modulation circuit; a weak tested signal is detected through the signal processing circuit and the tested signal is collected through an A / D (alternating / direct) chip, and corresponding meteorological visibility can be calculated by an ARM (Advanced RISC (Reduced Instruction-Set Computer) Machines) embedded control system. According to the invention, different scattering phase factors correspond to different scattering phase functions so that the visibility precision is improved; a scattering signal is received by three scattering angles with 20, 35 and 50 degrees; the fault of a photoelectric detector is judged by comparison of three visibility values and the reliability of a visibility meter is improved.

The invention discloses a holographic calculation method for suppressing laser speckle effect. The method includes the steps of 10, setting a positon of a spatial light modulator into a holographic plane (u, v) and a positon of an object to be reconstructed, into an objective plane (x, y), and determining a distance z from the objective plane (x, y) to the holographic plane (u, v); 20, establishing a function of light propagation between the holographic plane (u, v) and the objective plane (x, y), and calculating a complex amplitude hologram; 30, correcting the complex amplitude hologram obtained in the step 20 to obtain complex amplitude h'(u, v)=A'(u, v)*exp[i Phi<0>(u, v)] of upper light field of the updated holographic plane; 40, extracting a phase factor to obtain an all-phase hologram p(u, v)=exp[i Phi<0>(u, v)], and encoding and calculating p(u, v) to obtain a hologram displayable. The method has the advantages that the speckle effect caused by high coherence of laser is effectively alleviated, and reconstruction quality of the hologram is greatly improved.

The present invention provides a method and system for reducing the peak to average power ratio (PAP) of a signal with low computational complexity. According to one embodiment, the present invention is applied to reduce the PAP of an OFDM signal. According to an alternative embodiment, the present invention is applied to reduce the PAP of a CDMA signal. Rather than seeking the optimum solution, which involves significant computational complexity, the present invention provides for a number of sub-optimal techniques for reducing the PAP of an OFDM signal but with much lower computational complexity. In particular, according to one embodiment utilizing the PTS approach, an iterative technique is used to assign phase factors to each of a set of partial transmit sequences from a set of possible phase factors. Experimental results using the iterative technique showed only a slight degradation (1 dB) from the optimal approach using the same number of subblocks and subcarriers. In an alternative embodiment, which avoids feedback required by the iterative approach, a sequence of phase factors are generated randomly and assigned to each of a set of partial transmit sequences. This procedure is repeated for a predetermined number of trials and the random sequence generating the lowest PAP is selected. In a third embodiment, a set of phase factors is generated using a structured sequence such as a Walsh sequence.

The present invention discloses a multicarrier data transmission method. A candidate phase factor sequence with small cross correlation is chosen from the unit circle of a coordinate space in advance. The method comprises that, A. the data waiting for transmitting in the transmitting end are processed by using all candidate phase factor sequences, the PAPR values of processing results are computed and compared, the candidate phase factor sequence corresponding to the PAPR minimum value is determined for the phase factor sequence selected; B. the processing result corresponding to the PAPR minimum value is considered as the main information, and the master information and the group numbers of the phase factor sequence selected are transmitted to the receiving end together; C. the receiving end determines the phase factor sequence selected according to the group numbers received, and makes the main information received be restored to the data waiting for transmitting.

The invention discloses a method for reducing an FBMC-OQAM system peak-to-average power ratio based on peak tracking feedback. The method comprises the following steps: 1) pre-grouping sub-carriers for carrying FBMC symbols, successively executing inverse Fourier transform and multi-phase filter modulation to real part and virtual part partitioning signals, to obtain a time domain sending signal; 2) circularly detecting the position point located by the maximum peak of the time domain signal, and executing the phase rotation to the data at the corresponding position point of the partitioning signal; 3) finding out a group of the optimal phase factor combination to multiply by the data at the selected position point, and enabling the sum to be minimum, namely reducing the peak at the position; and 4) using the data with the optimized phase to replace the original signal to generate new time domain signal. The method is capable of reducing the peak-to-average power ratio through a peak tracking feedback algorithm, enabling a power amplifier at the sending terminal to be positioned in the linear state, and improving the communication quality without the transmission signal distortion. Compared with the traditional method, the method has the lower computation complexity and the better effect of reducing the peak-to-average power ratio.

Disclosed is a method of obtaining data describing an object structure. The method comprising the steps of: (a) illuminating the object structure with illuminating radiation; (b) modulating the phase of the illuminating radiation after scattering by the object structure, the modulation comprising applying a first phase factor dependent upon at least one controllable parameter and an aberration function having a form of a subadditive function of a vector norm; (c) capturing a plurality of intensity patterns, wherein each intensity pattern corresponds to a unique value of the at least one controllable parameter; and (d) reconstructing the data describing the object structure based on the plurality of intensity patterns. Also disclosed are corresponding inspection and lithographic apparatuses, a method of manufacturing devices and a computer program.

This invention relates to a method to reduce the peak-to-average and orthogonal frequency division multisystem with low peak-to-average, the core of the invention is: before anti-Fourier IFFT transform, the transmitter completely removes or retains part of the initial phase of modulated transmit sequence, and add the transfer function; the receiver removes the transfer function obtained after fast Fourier FFT transform in the frequency domain sequences, carry through the initial phase processing to the frequency domain sequences removed the transfer function, then resume to this transmit sequence. The invention only does N times complex multiplication when adding the transfer function, so it can reduce the implementation complexity of the transmitter and receiver under the premise to effectively reduce peak-to-average. In addition, through the use of this method of keeping part initial phase of transmit sequence by multiply initial phase of transmit sequence with phase factor, the source do not need to send any redundant information like side band information, therefore further lower the implementation complexity of transmitter and receiver.

The invention relates to a varying phase correction method of seismic data of seismic graph with high resolution. The invention comprises that the seismic data is collected and pretreated; the phase factor is constructed; the model gather is determined; for a single shot spot and detection spot trace gathers, the phase correction factors of the shot spot and detection spot trace gathers is determined through a computation algorithm of phase correction factor; the phase correction factors of all the shot spots and detection spot trace gathers is determined; the phase correction for each seismic data gather is conducted according to the phase correction factors of shot spot gathers and detection spot trace gathers, so that the corrected seismic profiles are obtained. The invention can correctly estimate the wavelet phase variation which is caused by the structure variation of shallow surface on the seismic record; the phase correction is conducted on the basis; the phase variation caused by surface variation is eliminated, so that the aim of improving the resolution of seismic record is attained.

A resource distribution method for a physical uplink shared channel is characterized by comprising the steps of enabling the physical uplink shared channel (PUSCH) of multi-subband user equipment (UE) to occupy symbols 4-8 of a subframe 2, a subframe 3 and a subframe 4; configuring PUSCH demodulation reference signals in the subframes by combining phase factors, and transmitting the PUSCH demodulation reference signals and data through the subframes. The invention further discloses a resource distribution device for the physical uplink shared channel. A high PAPR (peak to average power ratio) is avoided, and accordingly performance of a whole system is improved.

The invention relates to a method and a system for generating a double-exponential Bessel Gaussian beam, which is designed for realizing superposition of multiple Bessel Gaussian beams with differenttransverse wave vectors and specific amplitude. A linearly-polarized Gaussian beam firstly passes through a vortex phase plate, a phase factor is introduced to the linearly-polarized Gaussian beam, and a Gaussian vortex beam is generated; the Gaussian vortex beam then passes through an amplitude spatial light modulator which is loaded with at least two circular amplitude holograms, through regulating the transmittance of the circular amplitude hologram, the amplitude of the Gaussian vortex beam (the double-exponential Bessel Gaussian beam) is further regulated, and a double-exponential BesselGaussian beam angular spectrum function is generated; and finally, Fourier transform is carried out to generate the double-exponential Bessel Gaussian beam. The double-exponential Bessel Gaussian beamsuperposition flexibility is higher, and the operation of generating the double-exponential Bessel Gaussian beam is simple.

The invention discloses an SLM (Selected Mapping) method of an SFBC (Space Frequency Block Coding) MIMO-OFDM (Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing) system based on an F matrix, solving the problems of high peak-to-average power ratio and high computation complexity of SFBCMIMO-OFDM signals in the MIMO-OFDM system. An algorithm for lowering the peak-to-average ratio and the calculation complexity of the system is provided by researching the orthogonality of SFBC coding-based signals on antennas in an MIMO system. According to the SLM method of the SFBC MIMO-OFDM system based on the F matrix, the SFBC signals are processed by utilizing the F matrix of a given phase sequence; an obtained optimal phase factor is subjected to quadrature encoding and acts on the SFBC signal of each antenna; in such a way, the to-be-sent signal on each antenna can be prevented from being subjected to IFFT (Inverse Fast Fourier Transform) for multiple times; and therefore, the calculation complexity of the system is lowered. Meanwhile, by the adoption of the F matrix, the MIMO-OFDM system obtains a good peak-to-average ratio performance.

The invention discloses a phase factor preferred pair method for reducing PAPR (Peak To Average Power Ratio) of an OFDM (Orthogonal Frequency Division Multiplexing) signal. The method comprises the steps as follows: obtaining an optimal phase factor sequence in a way of iteratively optimizing a phase factor matrix, namely randomly generating the Q*V phase factor matrix in which Q is P2, P is the number of user settings and V is the number of phase factors, dividing the phase factor matrix into two sub-matrixes, carrying out dot product on phase factor sub-vectors in the sub-matrixes and a data frequency domain signal matrix respectively to obtain phase rotation results, sorting the PAPRs of the phase rotation results from small to big, selecting sub-vectors corresponding to the front P PAPRs, obtaining two groups of the sub-vectors from the two sub-matrixes, and carrying out addition operation on the sub-vectors in the first group and the second group to reconstruct the Q*V phase factor matrix. The phase factor matrix can be optimized by multi-time iteration, and the phase factor vector used for enabling the PAPR of the transmission signal to be minimal is selected as the optimal phase factor sequence from the optimized phase factor matrix. By adopting the method, a better phase factor can be more quickly and effectively obtained to reduce the PAPR of an OFDM system.

The invention discloses an adjacent harmonic and inter-harmonic separation and measurement method under an IEC (international electrotechnical commission) framework. The method includes the following steps: firstly, performing discrete sampling on a power grid signal; secondly, performing ten-cycle Hanning window addition DFT / FFT (discrete Fourier transform / fast Fourier transform) spectral transformation on a sampling value according to IEC standards so as to obtain a spectrum; thirdly, multiplying the spectrum by rotary phase factors to obtain a new spectrum; fourthly, solving a vector sum of neighboring spectral lines of the new spectrum so as to offset sidelobe interference of rest components on the new spectrum, and solving corresponding frequency, a frequency deviation value and amplitude phase via a spectral line phase cancellation interpolation method; fifthly, rejecting spectrum leakage values of a fundamental component and the rest components at spectral line attention positions on a frequency domain; sixthly, solving a harmonic spectrum value to obtain parameters of h subharmonics, and solving parameters of inter-harmonics adjacent to the h subharmonics. By the method, the problem that the parameters of the two adjacent harmonics and inter-harmonics cannot be measured accurately during limited data asynchronous sampling is solved.

The invention discloses a harmonic wave measurement method based on spectral energy interpolation. According to ten cyclic wave detection environments meeting the IEC standard, concrete parameters of a certain component are detected out accurately, and an IEC method only can roughly detect out the amplitude of signals within the certain frequency band; from the point of view of spectral energy in a signal frequency domain for the first time, transformation and interpolation of an energy spectrum are carried out by multiplying the frequency spectrum by a rotation phase factor, influence of overlaid leakage of sidelobes of the frequency spectrum is eliminated by mutual offset of energy of interference components, and the detection precision of the frequency, the amplitude and the phase position is improved; when the components in signals are likely submerged in noise signals, main signals are highlighted through transformation of the spectrum energy, and therefore usable signals are extracted from the noise signals effectively. The method is based on a DFT / FFT algorithm recommended by the IEC standard, the principle is simple, the effect and stability are good, and the method has certain engineering application value and good application prospects.

The invention relates to a dielectric loss on-line accurate measurement method based on phase factor transformation and interpolation. The method includes following steps of: 1) performing digital sampling on voltages and currents at both ends of electric power capacitive devices, and obtaining discrete sampling values of the voltages and the currents; 2) performing discrete Fourier transform in which a Hanning window is added on the discrete sampling values of the voltages and the currents, and performing phase factor transform on frequency spectra of the voltages and the currents and obtaining new frequency spectra of the voltages and the current; 3) performing three-spectral line superposition and interpolation on fundamental components of the new frequency spectra of the voltages and the currents, and obtaining fundamental phase values of the voltages and the currents; and 4) performing conversion on the obtained fundamental phase values of the voltages and the current, and calculating a dielectric loss angle delta and a dielectric value tan delta. Compared with the prior art, the dielectric loss on-line accurate measurement method based on the phase factor transformation and interpolation is simple and accurate.

The invention discloses a method for using a polar region ice exploring radar to extract a polar region ice layer position. Two-dimensional Fourier transformation is performed on a radar echo signal propagating in a multilayered medium, and a two-dimensional frequency spectrum of the radar echo signal propagating in the multilayered medium is obtained; the two-dimensional frequency spectrum is multiplied by a reference phase factor, and a radar echo signal influenced by range migration is obtained; metric inverse Fourier transformation is used to perform range migration correction on the radar echo signal influenced by the range migration to converted to a range-Doppler domain, and radar echo signal with influence of a range migration factor linear term being eliminated is obtained; a secondary and tertiary range frequency compensation function and a reference function of azimuth direction compression are used to process the radar echo signal with influence of the range migration factor linear term being eliminated, and a fully compensated radar echo signal is obtained; and later azimuth direction Fourier inverse transformation is performed, a focused image is obtained, and by performing range coordinate contraction on the focused image, the position of a layer target detected by the polar region ice exploring radar is obtained.

An organic light emitting device consists of a layered structure including a top multilayer stack, a bottom multilayer stack, a cavity layer between the top multilayer stack and the bottom multilayer stack, and an organic light emitting region within the cavity layer. The layered structure is constructed such that the product of phase factors xi1 and xi2 is. greater than 80% at the center of at least one emitting wavelength region and for a normal viewing angle, wherein where Ra- and Rb+ are the reflectance of the top and bottom multilayer stacks respectively, phia- and phib+ are the phase changes on reflection for the top and bottom multilayer stacks respectively, alpha1 beta1 are respectively the real and imaginary parts of the phase thickness of the cavity layer, alpha2 and beta2 are respectively the real and imaginary parts of the phase thickness of the light-emitting region at the operating wavelength of the device, x is the mean distance of light emitting region from the bottom multilayer stack, n and k are the refractive index and absorption coefficient of the cavity layer, thetacavity is the emitting angle inside the cavity layer, and d is the physical thickness of said cavity layer. This condition improves the light output efficiency of the device.

The invention provides a design method of a free-adjustable central symmetric vortex beam mask. The complex transmittance function t of the central symmetric vortex beam mask is obtained by combininga central symmetric spiral phase factor, a cone lens transmittance function and a blazed grating; and the complex transmittance function t is loaded into a spatial light modulator by a computer so asto obtain the free-adjustable central symmetric vortex beam mask. The designed mask can generate the central symmetric vortex beam with adjustable optical lobe size and optical ring radius in the farfield of the mask; The size of optical lobes on the left and right sides of the ring is controlled by the phase reconstruction factor (PRF), and the radius of the optical ring is controlled by the cone angle of a cone lens, and the method has quite important application prospect in the field of particle manipulation.

The invention discloses a low-complexity peak-to-average ratio restraining method for an optical communication DCO-OFDM (direct current-biased optical-orthogonal frequency division multiplexing) system. The low-complexity peak-to-average ratio restraining method comprises the following steps of firstly, performing precoding DFT (discrete Fourier transform) on inputted digital modulation signs so as to reduce correlation between the signs; secondly, performing subblock division and conjugate symmetry on a precoded data sequence; and finally, selecting a suboptimal phase twiddle factor for each subblock so as to reduce a peak-to-average ratio. Because IFFT (inverse fast Fourier transform) and suboptimal iterative loop phase factor selection are carried out sequentially, the implementing complexity of the system can be reduced while the peak-to-average ratio is restrained.

A method and system for designing and implementing a finite impulse response (FIR) filter to create a plurality of output signals, each output signal having the same frequency but at a different phase shift from the other output(s), is described. Values are determined for the resistors, or other elements having impedance values, in a FIR filter having a plurality of outputs, such that each output has the same frequency response but a different phase than the other output(s). This is accomplished by the inclusion of a phase factor in the time domain calculation of the resistor values that does not change the response in the frequency domain. The phase shift is constant and independent of the frequency of the output signal.