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.

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 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 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 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 R_a^- and R_b⁺ are the reflectance of the top and bottom multilayer stacks respectively, phi_a^- and phi_b⁺ 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, theta_cavity 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 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.