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43results about How to "Solving Phase Blur Problems" patented technology

Microwave device impedance measurement calibration method

InactiveCN103675457AOvercome Difficult Machining ProblemsReduce the numberResistance/reactance/impedenceUltra-widebandMicrowave
The invention introduces a microwave device impedance measurement calibration method. The method comprises the following steps: (1), calculating time-delay transmission line transmission parameters through real-time measured data of straight-through calibration member scattering parameters and time-delay calibration member scattering parameters; (2), embedding a newly added virtual transmission line in an original time-delay calibration member, and calculating the transmission parameters of a virtual time-delay calibration member; (3), according to a conventional TRL calibration method, extracting calibration coefficients of a measuring clamp, and performing matrix inversion and multiplication operation to obtain a microwave device de-embedding transmission parameters; and (4), performing impedance normalization transformation on the microwave device de-embedding transmission parameters to obtain normalized microwave device normalization scattering parameters relative to system measurement reference impedance. The method makes up the measurement errors caused by inconsistence of transmission line characteristic impedance and the system measurement reference impedance, and realizes microwave device impedance measurement with an ultra wide band and high precision. At the same time, the improved microwave device impedance measurement calibration method can substantially reduce design processing requirements of a calibration device, thereby having high versatility.
Owner:NAT UNIV OF DEFENSE TECH

Method and device for fluorescence interference microscopic measurement based on stimulated radiation

The invention belongs to the technical field of surface topography measurement, and discloses a method and a device for fluorescence interference microscopic measurement based on stimulated radiation. The method includes: firstly, coating surfaces of a measured piece and a reference mirror; secondly, subjecting the measured piece and the reference mirror to stimulation of monochrome detection laser; and finally, resolving interference fringes on a detection surface. The device a laser device, a converging objective lens, a first pinhole, a collimation and beam expanding objective lens, a beam splitting prism, a reference focusing objective lens, the reference mirror, a displacement driver, a detection focusing objective lens, the measured piece, an imaging converging objective lens, a narrow-band filter, a second pinhole and a detector, wherein the converging objective lens, the first pinhole, the collimation and beam expanding objective lens, the beam splitting prism, the reference focusing objective lens, the reference mirror and the displacement driver are disposed on a direct light path of the laser device along a light transmitting direction, the detection focusing objective lens and the measured piece are disposed on a reflected light path of the beam splitting prism, and the imaging converging objective lens, the narrow-band filter, the second pinhole and the detector are disposed on a transmission light path of the beam splitting prism. By the design that surfaces of the measured piece and the reference mirror are coated by the aid of a vacuum evaporation coating method, measurement light is guaranteed to be capable of returning to a detection system after being reflected by a measured surface, high-NA(numerical aperture) and high-slope surface detection is achieved, and the device is applicable to ultra-precise measurement of three-dimensional topographies of high-NA and high-slope spherical surfaces, aspheric surfaces and free-form surfaces.
Owner:HARBIN INST OF TECH

Method for measuring TEC value of ionized layer by utilizing SAR satellite

ActiveCN103792535ATaking into account the estimation accuracyDistance Phase Effect CancellationElectrical measurementsRadio wave reradiation/reflectionImaging qualityIonosphere
The invention discloses a method for measuring a TEC value of an ionized layer by utilizing an SAR satellite. After satellite-borne SAR transmission pulse signals penetrate through the ionized layer, the phase of the satellite-borne SAR transmission pulse signals contains complete TEC information of the ionized layer on the propagation path. By means of the method, multiple sub-bands are selected from the SAR signals with a certain band width, so that a freedom degree needed by phase ambiguity resolution is provided. Through the optimized design of parameters of the sub-bands and other technical means, the influence on phase position ambiguity resolution processing from an electromagnetic wave propagation distance phase is eliminated while the estimation accuracy of the TEC value is considered. Finally, a phase ambiguity resolution equation is built, and high-accuracy estimation of the TEC value of the ionized layer is achieved. The estimated TEC value of the ionized layer is utilized to supplement a satellite-borne SAR echo phase, and the satellite-borne SAR imaging quality and interferometry accuracy can be effectively improved.
Owner:XIAN INSTITUE OF SPACE RADIO TECH

Carrier synchronization method and device for deep space communication

The invention discloses a carrier synchronization method and device for deep space communication. The carrier synchronization method is characterized in that, a process of only emitting carriers exists in each time of building a communication link, and information in the stage is used for capturing carrier signals; the signals are put into an orthogonal demodulation loop, after matched filtering I and Q branches are respectively subjected to table look-up mapping so as to prevent phase deviation having phase ambiguity; in a synchronous tracking stage, the invention provides a simple and convenient phase demodulation tracking loop design method which utilizes judgment of polarity, and thereby circuit design is simplified; phase deviation information output by the phase demodulation loop is put into a loop filter, and phase changes of local carriers are timely adjusted according to deviation result of the loop filter. The carrier synchronization method and device for deep space communication can solve the problem that common carrier synchronization technologies have phase ambiguity, and is simplified in design of the phase demodulation loop, thus being easy to achieve from the aspect of hardware.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Laser white light compound interference measuring device and method

The invention discloses a laser white light compound interference measuring device and method. Monochromatic light phase shift interference can be combined with white light scanning interference to improve the measurement performances of the system. The measurement device comprises a white LED light source, a collimating lens, a filter, an optical microscopic interference module and an image acquisition device. The measurement method comprises the steps of: performing white light scanning interferometry of a measured sample; performing monochromatic light phase shift interferometry, wherein itis only needed to put the filter at front of a beam splitter mirror, and other portions are the same as the white light scanning interference; and combining a white light scanning interferometry andthe monochromatic light phase shift interferometry to solve the phase fuzzy problem in the monochromatic light phase shift interference. Compared to the white light canning interference, a compound interferometry result is higher in precision. Besides, the system provided by the invention employs an Michelson interference structure, the transverse measurement range is far larger than the measurement range of a commerce white light interference Mirau structure, and therefore, the laser white light compound interference measuring device and method has bigger advantage for large-size part surfacedetection.
Owner:XI AN JIAOTONG UNIV

Radar object positioning method based on machine learning

The invention proposes a radar object positioning method based on machine learning. According to one embodiment of the invention, the method comprises the steps: carrying out the range-direction pulse compression of a target echo signal received by an along-track two-channel SAR (synthetic aperture radar), obtaining an interference phase matrix, sequentially inputting the interference phase vectors corresponding to all distance units in the interference phase matrix into a neural network, and obtaining a result of judgment whether each distance unit has a moving object or not and the orientation position x0 of the moving object. According to the embodiment of the invention, the method avoids problems of complex orientation pulse compression, radial speed estimation and faced phase fuzziness of a conventional ATI (along-track interference) method, thereby solving a problem that the positioning precision of the moving object is decreased because of error accumulation in the above process. The method is higher in positioning precision of the moving object, is lower in time consumption, and can meet the demands of high instantaneity and high positioning precision.
Owner:CHINA ACADEMY OF SPACE TECHNOLOGY

Stimulated radiation based Mirau fluorescence interference microscopic measurement device

The invention belongs to the technical field of surface topography measurement and relates to a stimulated radiation based Mirau fluorescence interference microscopic measurement device. The measurement device comprises a laser device, a converging objective lens, a first pinhole, a collimation and beam expanding objective lens, a beam splitter, a focusing objective lens, a displacement driver, a reference mirror, a beam splitting prism, a measured piece, an imaging converging objective lens, a narrow-band filter, a second pinhole and a detector, wherein the converging objective lens, the first pinhole, the collimation and beam expanding objective lens and the beam splitter are disposed on a direct light path of the laser device along a light transmitting direction, the focusing objective lens, the displacement driver, the reference mirror, the beam splitting prism and the measured piece are disposed on a reflected light path of the beam splitter, and the imaging converging objective lens, the narrow-band filter, the second pinhole and the detector are disposed on a transmission light path of the beam splitter. Surfaces of the measured piece and the reference mirror are coated by the aid of a vacuum evaporation coating method. By the design that surface properties of the measured piece are changed through coating, measurement light is guaranteed to be capable of returning to a detection system after being reflected by a measured surface, high-NA(numerical aperture) and high-slope surface detection is achieved, and the measurement device is applicable to ultra-precise measurement of three-dimensional topographies of high-NA and high-slope spherical surfaces, aspheric surfaces and free-form surfaces.
Owner:HARBIN INST OF TECH

Radar angle and distance estimation method based on tensor high-order singular value decomposition

The invention provides a radar angle and distance estimation method based on tensor high-order singular value decomposition, and the method comprises the following steps: constructing an MIMO radar receiving array comprising k subarrays, obtaining the receiving data of a target echo through the MIMO radar receiving array, and constructing a third-order tensor signal model; decomposing the three-order tensor signal model by adopting a high-order singular value to obtain tensor-based signal subspaces; extracting a receiving matrix of the signal subspace to realize MIMO radar target DOA parameter estimation; and extracting a signal subspace and an emission matrix corresponding to each subarray, eliminating the phase ambiguity problem caused by the coupling of the target DOD parameter and the distance, achieving the automatic pairing of the target DOD and the distance with the DOA parameter, and finally achieving the estimation of the target DOD parameter and the distance parameter of the MIMO radar.
Owner:HAINAN UNIVERSITY

Wi-Fi indoor multi-user positioning method based on principle of phased array

The invention discloses a single-equipment Wi-Fi indoor multi-user positioning method based on principle of a phased array. The method mainly includes two parts of angle measurement and distance measurement; in an indoor environment, an antenna array is deployed, and then angle measurement is carried out with the idea of the phased array; and by means of scanning from coarse granularity to fine granularity, scanning time is reduced; by means of an equi-signal method, the precision of angle measurement is increased. By means of the steps, angles of all the targets can be acquired; and finally distance measurement to the targets is carried out via a multiple-frequency method, and the angle information and distance information are combined to complete the multi-user positioning.
Owner:XI AN JIAOTONG UNIV

Positioning system and positioning method based on soft position information of single base station

The invention provides a positioning system and method based on single base station soft position information, and the system comprises a positioning base station which is used for receiving positioning data transmitted by a user terminal, and generating a positioning result based on the positioning data; the user terminal is used for sending positioning data to the positioning base station and receiving a positioning result; the positioning base station comprises an antenna array, a clock synchronization module, a measurement module, a soft position information extraction module, a communication module and a positioning module, and the user terminal comprises a wireless measurement module, a communication module and an inertial measurement unit. The soft position information extraction module is used for extracting soft position information from the measurement information related to the position of the user; and the positioning module is used for estimating the user position according to the soft position information and inertial data of the user terminal. According to the positioning system and the positioning method provided by the invention, the problem of phase ambiguity caused by the fact that the array antenna spacing is greater than the half-wavelength in single base station positioning can be effectively solved, so that the positioning precision can be remarkably improved by increasing the antenna array aperture.
Owner:罗维智联(北京)科技有限公司

Signal direction-of-arrival estimation method and device based on sparse symmetric array

The invention discloses a signal direction-of-arrival estimation method and device based on a sparse symmetric array, and the method comprises the following steps: S1, constructing the sparse symmetric array which consists of a plurality of uniform sub-arrays with unequal array element intervals; S2, calculating and constructing a fourth-order cumulant vector with a uniformly changed phase difference through the fourth-order cumulants of the received data of the different sub-array elements, and constructing a toeplitz matrix equivalent to the uniform linear array covariance matrix through thefourth-order cumulant vector; and S3, estimating azimuth angles of all the information sources by utilizing a sparse reconstruction method based on the constructed toeplitz matrix. Through the method, the problems of array aperture loss and too low information source angle estimation precision of an existing uniform linear array can be solved.
Owner:广州通导信息技术服务有限公司

Radio frequency direction finding method and system

The invention provides a radio frequency direction finding method. The method comprises the following steps of, for an N-element uniform circular array antenna, obtaining a voltage phase difference between each path of antenna and a first path of antenna through a phase discriminator; recording each phase difference as an initial phase difference when an incoming wave enters the circular array antenna at an elevation angle of 0 degree; constructing a complex number corresponding to each antenna according to the voltage phase difference and the initial phase difference; calculating a theoretical phase difference between each antenna and the first antenna according to the elevation angle and the azimuth angle; introducing a vector X and a direction vector G, calculating the difference between the iteration times k+1 and a two-dimensional incident angle of the iteration times k by combining the elevation angle and the azimuth angle of the two-dimensional incident angle of the iteration times k+1 calculated by the constructed complex number, comparing at a threshold value, and entering an output elevation angle and an azimuth angle when the difference is smaller than the threshold value; otherwise, adding 1 to the value of k, and calculating the theoretical phase difference again. The method is advantaged in that complex operation is adopted, a phase ambiguity problem is avoided, direction finding precision is improved, and an iterative algorithm is adopted so that operations such as logic judgment are avoided.
Owner:SOUTHWEST CHINA RES INST OF ELECTRONICS EQUIP

Tamed spread spectrum communication system based on fast Fourier transformation

The invention discloses a tamed spread spectrum communication system based on fast Fourier transformation. The tamed spread spectrum communication system comprises a training sequence module, a code phase mapping module, a framing transmitting module, a capturing module, a tracking module, a data interception module, a fast inverse Fourier transformation module, a point multiplication module, a fast Fourier transformation module, a data pseudo code transformation result extraction module and a data demodulation module. By adoption of the tamed spread spectrum communication system, the code length of a spread spectrum code is not limited by the number of correlators, and anti-interference capacity and confidentiality are improved.
Owner:BEIJING INST OF CONTROL ENG

Surface acoustic wave positioning system and method fusing intensity and phase information

The invention discloses a surface acoustic wave positioning system and method fusing intensity and phase information. The surface acoustic wave label is of a double-frequency double-channel structure,and the center distance from the reflecting gratings of the two propagation channels to the interdigital transducer is inversely proportional to the center frequency of the interdigital transducer. The reader is connected with three reader antennas through a one-to-three switch, and the three reader antennas are respectively located at three fixed positions. Before system positioning, a positioning area is divided into a plurality of sub-areas without a phase ambiguity problem, fingerprint points are arranged in geometric centroids of the sub-areas to establish a fingerprint library, the characteristic value of each fingerprint point comprises 12 characteristic values including echo signal intensity and phase, and then the sub-area where a positioning target is located is determined by adopting a fingerprint positioning algorithm. And finally, the unambiguous phase difference of the echo signal is taken as distance measurement information, and thus obtaining a two-dimensional coordinate of the positioning target through a trilateral positioning algorithm. The invention has the characteristics of high positioning precision and low system cost, and not only solves the problem of phase ambiguity, but also eliminates the temperature influence.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

An ultra-short baseline five-element receiving array and its underwater acoustic positioning method

The invention relates to an ultra-short basic line five-element receiving array and a water sound locating method thereof. According to the ultra-short basic line five-element receiving array and the water sound locating method thereof, five receiving elements are arranged on the bottom surface in a barrel-shaped array watertight shell and are evenly distributed with the center of the bottom surface as the circle center in the circumferential direction. By selecting all combinations of any three receiving elements in the array, a target orientation value is obtained through the three elements in each combination, the obtained target orientation values of all the combinations are averaged to obtain an average value serving as an initial orientation value of a measured target, and the initial orientation value meets set calculation accuracy and serves as a final orientation value of the measured target. By means of the ultra-short basic line five-element receiving array, redundant equal-precision measurement base lines are obtained through the minimum number of the elements, target locating is re-inspected and resolved by means of the geometrical relationship among the five redundant equal-precision measurement base lines, so that the problem of phase ambiguity is resolved, effectiveness of redundant data judging is guaranteed, and effectiveness and reliability of target orientation calculation are enhanced.
Owner:HARBIN ENG UNIV

A Method for Estimating Incoherent Direction of Arrival under Phase Error

The invention discloses a method for estimating an incoherent direction of arrival under phase error. Determine the form of the DOA estimation signal under the phase error; calculate the covariance matrix of the array observation data, and obtain an asymptotically noise-free and phase-error-free vector model through eigenvalue decomposition, modulo, vectorization and square processing in turn; The asymptotic vector model is approximated and equivalently summed by the linear model based on the characteristics of the high-power reference source, and is based on l under the cosine overcomplete base dictionary. 2 ‑l 1 The norm-minimizing sparse reconstruction method obtains DOA estimates. The present invention is insensitive to phase error, has high estimation accuracy and low computational complexity, and can complete effective estimation of the direction of arrival of multiple target sources without two-dimensional spectral peak search and multiple reference signal sources.
Owner:YANSHAN UNIV

A direction finding method and system based on a radio frequency analog receiving system

ActiveCN111693936BAvoid the problem of unbalanced input signal amplitudeSolving Phase Blur ProblemsRadio wave finder detailsPhase detectorElevation angle
The invention provides a direction finding method based on a radio frequency analog receiving system. For an N-element uniform circular array antenna, the phase difference between each antenna and adjacent antennas is obtained through a phase detector, and recorded as the phase of the phase detector. difference; when the incoming wave is incident on the circular array antenna with the elevation angle of 0°, the phase difference of each phase detector is recorded as the initial phase difference; the complex number corresponding to each phase detector is constructed; according to the elevation angle and azimuth angle, k is the number of iterations , calculate the theoretical phase difference of each phase detector; introduce the vector X and the direction vector G, and combine the constructed complex numbers to calculate the elevation angle and azimuth angle of the two-dimensional incident angle with the iteration number k+1; the calculation iteration number is k+1 and the iteration The difference between the two-dimensional incident angles of order k is compared with the threshold value, and if it is less than the threshold value, it enters the output elevation and azimuth angles; otherwise, the value of k is increased by 1, and the theoretical phase difference is calculated. The advantage of the method lies in that it avoids the problems of operations such as logical judgment, phase ambiguity, and unbalanced amplitude of the input signal of the phase detector, and improves the direction finding accuracy.
Owner:SOUTHWEST CHINA RES INST OF ELECTRONICS EQUIP

Tamed spread spectrum communication system based on fast Fourier transformation

The invention discloses a tamed spread spectrum communication system based on fast Fourier transformation. The tamed spread spectrum communication system comprises a training sequence module, a code phase mapping module, a framing transmitting module, a capturing module, a tracking module, a data interception module, a fast inverse Fourier transformation module, a point multiplication module, a fast Fourier transformation module, a data pseudo code transformation result extraction module and a data demodulation module. By adoption of the tamed spread spectrum communication system, the code length of a spread spectrum code is not limited by the number of correlators, and anti-interference capacity and confidentiality are improved.
Owner:BEIJING INST OF CONTROL ENG

Method and system for improving detection accuracy of delay line surface acoustic wave (Surface Acoustic Wave) sensor

The invention discloses a method and a system for improving the detection accuracy of a delay line surface acoustic wave (Surface Acoustic Wave) sensor and relates to a detection method and a detection system of the SAW sensor. The method for improving the detection accuracy of the delay line SAW sensor comprises the following steps of: 1, firstly searching a corresponding relation that delay time and a phase are changed with a measured temperature; 2, then establishing a corresponding relation between the measured temperature and a delay time difference as well as a phase difference; 3, and finally obtaining a corresponding relation between the phase difference and the measured temperature. In the invention, the demodulation of delay time measurement and the demodulation of phase measurement are combined; the advantage of accurate demodulation of the phase is essentially utilized; the demodulation process has small calculated amount; the method and the system are convenient to implement in an FPGA (Field Programmable Gate Array); the demodulation accuracy is improved; the problem of phase ambiguity in the phase demodulation process of the delay line SAW sensor is solved; and by utilizing the method, the effects that the temperature detection accuracy can reach 0.05 DEG C and the temperature detection range is at least in the range of 0 DEG C to 50 DEG C are realized, so the problem of phase ambiguity really can be solved by combining the delay time measurement and the phase measurement to carry out demodulation.
Owner:CHONGQING UNIV

A method of radar target location based on machine learning

The invention proposes a radar object positioning method based on machine learning. According to one embodiment of the invention, the method comprises the steps: carrying out the range-direction pulse compression of a target echo signal received by an along-track two-channel SAR (synthetic aperture radar), obtaining an interference phase matrix, sequentially inputting the interference phase vectors corresponding to all distance units in the interference phase matrix into a neural network, and obtaining a result of judgment whether each distance unit has a moving object or not and the orientation position x0 of the moving object. According to the embodiment of the invention, the method avoids problems of complex orientation pulse compression, radial speed estimation and faced phase fuzziness of a conventional ATI (along-track interference) method, thereby solving a problem that the positioning precision of the moving object is decreased because of error accumulation in the above process. The method is higher in positioning precision of the moving object, is lower in time consumption, and can meet the demands of high instantaneity and high positioning precision.
Owner:CHINA ACADEMY OF SPACE TECHNOLOGY

Single-device WiFi indoor height detection method based on phased array principle

The invention discloses a single-device WiFi indoor human body height detection method based on a phased array principle. The single-device WiFi indoor human body height detection method mainly comprises an angle measurement part and a distance measurement part. According to the technical scheme, in the indoor environment, an antenna array is deployed, angle measurement is conducted by means of the idea of a phased array, scanning time is shortened by means of scanning from coarse granularity to fine granularity, angle measurement precision is improved by means of an equal signal method, and the angles of different parts of the body can be obtained through the steps; and then distance measurement is performed on different body parts by using a multi-frequency method, and angle information and distance information are combined to obtain a body trunk heat map, so that the purpose of height detection is achieved.
Owner:XI AN JIAOTONG UNIV

A Method of Measuring Ionospheric Tec Value Using SAR Satellite

ActiveCN103792535BTaking into account the estimation accuracyDistance Phase Effect CancellationElectrical measurementsRadio wave reradiation/reflectionImaging qualityIonosphere
The invention discloses a method for measuring a TEC value of an ionized layer by utilizing an SAR satellite. After satellite-borne SAR transmission pulse signals penetrate through the ionized layer, the phase of the satellite-borne SAR transmission pulse signals contains complete TEC information of the ionized layer on the propagation path. By means of the method, multiple sub-bands are selected from the SAR signals with a certain band width, so that a freedom degree needed by phase ambiguity resolution is provided. Through the optimized design of parameters of the sub-bands and other technical means, the influence on phase position ambiguity resolution processing from an electromagnetic wave propagation distance phase is eliminated while the estimation accuracy of the TEC value is considered. Finally, a phase ambiguity resolution equation is built, and high-accuracy estimation of the TEC value of the ionized layer is achieved. The estimated TEC value of the ionized layer is utilized to supplement a satellite-borne SAR echo phase, and the satellite-borne SAR imaging quality and interferometry accuracy can be effectively improved.
Owner:XIAN INSTITUE OF SPACE RADIO TECH

A High Linearity Phase Demodulation Realization Method for Coherent Phase Tracking of fmcw Radar

A high-linear phase demodulation implementation method for coherent phase tracking of FMCW radar, by converting the beat frequency signal s of the receiving end b Each M point in (p) is taken as a row to obtain the detection matrix I N×M , for the detection matrix I N×M Perform FFT on each row to get the frequency domain matrix RP N×M , take the column m where the target is located in the matrix 0 The data RP(n, m 0 ), realize the reconstruction of CW radar signal, and obtain the quadrature CW radar intermediate frequency signal: eq_I(n)=real(RP(n, m 0 )), eq_Q(n)=imag(RP(n, m 0 )), where: real and imag represent the real part and the imaginary part, respectively, and then demodulate with the EDACM algorithm to obtain the motion trajectory of the detection target. The invention solves the phase ambiguity problem faced in the coherent phase target tracking process of the FMCW radar by reconstructing the single-frequency continuous wave (CW) radar signal and demodulating the EDACM algorithm on the received radar information signal.
Owner:上海希卡立科技有限公司

Michelson Fluorescence Interferometric Micrometer Measuring Device Based on Stimulated Emission

The invention belongs to the technical field of surface topography measurement and relates to a stimulated radiation based Michelson fluorescence interference microscopic measurement device. The measurement device comprises a laser device, a converging objective lens, a first pinhole, a collimation and beam expanding objective lens, a first beam splitting prism, a focusing objective lens, a displacement driver, a reference mirror, a second beam splitting prism, a measured piece, an imaging converging objective lens, a narrow-band filter, a second pinhole and a detector, wherein the converging objective lens, the first pinhole, the collimation and beam expanding objective lens and the first beam splitting prism are disposed on a direct light path of the laser device along a light transmitting direction, the focusing objective lens, the displacement driver, the reference mirror, the second beam splitting prism and the measured piece are disposed on a reflected light path of the first beam splitting prism, and the imaging converging objective lens, the narrow-band filter, the second pinhole and the detector are disposed on a transmission light path of the first beam splitting prism. Surfaces of the measured piece and the reference mirror are coated by the aid of a vacuum evaporation coating method. By the design that surface properties of the measured piece are changed through coating, measurement light is guaranteed to be capable of returning to a detection system after being reflected by a measured surface, high-NA(numerical aperture) and high-slope surface detection is achieved, and the measurement device is applicable to ultra-precise measurement of three-dimensional topographies of high-NA and high-slope spherical surfaces, aspheric surfaces and free-form surfaces.
Owner:HARBIN INST OF TECH

Time frequency synchronization unit and method for OFDM system receiver

The invention provides a time frequency synchronization unit and method for an OFDM system receiver. The time frequency synchronization unit comprises a frame synchronization controller, a frequency offset compensating controller and a synchronization estimation effective counter. When the count value of the synchronization estimation effective counter is 0, the frame synchronization controller confirms that frame synchronization is carried out for a received signal. When the count value of the synchronization estimation effective counter is 1, the frame synchronization controller confirms that the frame synchronization is not carried out for a next frame received signal, and the frequency offset compensating controller confirms that the frequency compensation is carried out for the next frame received signal based on a fractional frequency offset which is estimated aiming at the current frame received signal. When the count value of the synchronization estimation effective counter is2, the triggering time is synchronous, and the frequency offset compensating controller confirms that the frequency compensation is carried out for the next frame received signal based on a fractionalmultiple frequency offset and an integral multiple frequency offset, which are estimated aiming at the current frame received signal, so that the frequency synchronization is realized.
Owner:FUJITSU LTD

A direction finding method and system based on digital interference system

ActiveCN111693934BSolving Phase Blur ProblemsAvoid operations such as logical judgmentsDirection findersElevation angleAngle of incidence
The invention provides a direction finding method based on a digital interference system, comprising: for an N-element uniform circular array antenna, converting a space electromagnetic wave into a digital voltage signal, and processing the voltage signal to obtain the voltage phase of each antenna; When the incident circular array antenna is 0°, the phase of each antenna is recorded as the test phase; the complex number corresponding to each antenna is constructed according to the voltage phase and the test phase; the theoretical phase of each antenna is calculated according to the initial phase of the elevation angle and azimuth; the introduction vector X and the direction vector G, combined with the constructed complex number to calculate the elevation angle and azimuth angle of the two-dimensional incident angle with the iteration number k+1. Compare, enter the output elevation angle and azimuth angle less than the threshold value; otherwise, add 1 to the value of k, and calculate the phase difference again. The advantage of the method lies in the use of complex number operations, which avoids the problem of phase ambiguity and operations such as logical judgment, and improves the direction finding accuracy.
Owner:SOUTHWEST CHINA RES INST OF ELECTRONICS EQUIP

Fluorescence interference microscopic measurement method and device based on stimulated radiation

The invention belongs to the technical field of surface topography measurement, and discloses a method and a device for fluorescence interference microscopic measurement based on stimulated radiation. The method includes: firstly, coating surfaces of a measured piece and a reference mirror; secondly, subjecting the measured piece and the reference mirror to stimulation of monochrome detection laser; and finally, resolving interference fringes on a detection surface. The device a laser device, a converging objective lens, a first pinhole, a collimation and beam expanding objective lens, a beam splitting prism, a reference focusing objective lens, the reference mirror, a displacement driver, a detection focusing objective lens, the measured piece, an imaging converging objective lens, a narrow-band filter, a second pinhole and a detector, wherein the converging objective lens, the first pinhole, the collimation and beam expanding objective lens, the beam splitting prism, the reference focusing objective lens, the reference mirror and the displacement driver are disposed on a direct light path of the laser device along a light transmitting direction, the detection focusing objective lens and the measured piece are disposed on a reflected light path of the beam splitting prism, and the imaging converging objective lens, the narrow-band filter, the second pinhole and the detector are disposed on a transmission light path of the beam splitting prism. By the design that surfaces of the measured piece and the reference mirror are coated by the aid of a vacuum evaporation coating method, measurement light is guaranteed to be capable of returning to a detection system after being reflected by a measured surface, high-NA(numerical aperture) and high-slope surface detection is achieved, and the device is applicable to ultra-precise measurement of three-dimensional topographies of high-NA and high-slope spherical surfaces, aspheric surfaces and free-form surfaces.
Owner:HARBIN INST OF TECH

A laser white light composite interferometric measurement system and method

The invention discloses a laser white light compound interference measuring device and method. Monochromatic light phase shift interference can be combined with white light scanning interference to improve the measurement performances of the system. The measurement device comprises a white LED light source, a collimating lens, a filter, an optical microscopic interference module and an image acquisition device. The measurement method comprises the steps of: performing white light scanning interferometry of a measured sample; performing monochromatic light phase shift interferometry, wherein itis only needed to put the filter at front of a beam splitter mirror, and other portions are the same as the white light scanning interference; and combining a white light scanning interferometry andthe monochromatic light phase shift interferometry to solve the phase fuzzy problem in the monochromatic light phase shift interference. Compared to the white light canning interference, a compound interferometry result is higher in precision. Besides, the system provided by the invention employs an Michelson interference structure, the transverse measurement range is far larger than the measurement range of a commerce white light interference Mirau structure, and therefore, the laser white light compound interference measuring device and method has bigger advantage for large-size part surfacedetection.
Owner:XI AN JIAOTONG UNIV
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