356results about How to "Improve angle measurement accuracy" patented technology

The invention discloses a vehicle-mounted millimeter-wave radar moving target recognizer. The vehicle-mounted millimeter-wave radar moving target recognizer is characterized in that the recognizer is a frequency synthesizer; a frequency agility continuous signal is modulated into a pulse signal and then is processed into a millimeter-wave signal by up-conversion; after being amplified by a power amplifier, the millimeter-wave signal is transmitted out; an antenna receives a radar echo signal back to a circulator and then the signal is transmitted into a frequency mixer; a high-frequency echo pulse and constant-amplitude high-frequency voltage generated by a high-stability local oscillator are mixed and the signal is reduced to a middle frequency and then is processed by a middle-frequency amplifier; the middle-frequency signal is directly sampled by an A / D (Analogue / Digital) conversion module; after being sampled, echo signals of a whole pulse string are stored into a storage unit; and information of targets, such as quantity, speed and direction, is measured by a signal processing unit and then is transmitted to an alarm executing unit. With the adoption of the structure, the vehicle-mounted millimeter-wave radar moving target recognizer has the advantages that 1 the distance measuring precision and the angle measuring precision of a moving target are improved; and 2 excessive hardware does not need to be added and the production cost is lower.

An on-board multibeam radar apparatus includes a plurality of beam elements that constitute an antenna transmitting a transmission wave and receiving an incoming wave being reflected and arriving from a target in response to the transmission wave, a control unit configured to select a beam element used for transmission and reception out of the plurality of beam elements so as to change a field of view, and a processing unit configured to apply a Fourier transformation to beam element data which are data of a received wave received through the beam element used for transmission and reception selected by the control unit based on the number of elements and the element interval of a desired virtual array antenna so as to create virtual array data, and to perform a predetermined process based on the created virtual array data.

The invention discloses a passive coherent location radar direction finding system based on an Adcock antenna, mainly solving the problem that angles are precisely measured in an environment with strong direct waves and multi-path interferences. The system mainly comprises a signal branch route signal antenna, a receiver A, a signal processor, a constant false alarm rate (CFAR) and track association module and an angle measurement module. The signal antenna applies the Adcock antenna for receiving moving target echo, direct wave and multi-path. The received signal is filtered and amplified by the receiver A, and is transmitted to the signal processor; an analogue intermediate frequency signal is converted into a digital base-band signal via the signal processor, channel adjustment, clutter canceling and range-Doppler two-dimensional correlation are carried out, and the result is transmitted to the CFAR and track association module; the original track is detected by the CFAR and track association module or a target of a new track is formed by the CFAR and track association module, and the angle of the target is measured by the angle measurement module. The invention can realize precisely measurement of angles in an environment with strong direct waves and multi-path interferences.

The invention discloses a collimation measurement system for attitudes and angles among spacecraft devices based on the combination between a robot and a theodolite. The system herein includes a robot, a laser tracker, a laser tracking target (T-MAC), a robot terminal tool, and the like. The system searches a to-be-tested datum cube mirror which is disposed on a spacecraft device by conducting mode identification, and computes the relations of phase position and direction of the datum cube mirror with respect to the theodolite. The laser tracker is intended for calibrating the relative direction relation in a coordinate system of respective spacecraft devices and integrating the measurement results of the theodolite at different measurement positions to the same coordinate system. Based onthe calibration relation and the relative relation, the laser tracker is guided to real-timely track the robot terminal tool and establish the relative relation between the laser track and the robotterminal tool. And eventually, the attitude relation matrix of the spacecraft is computed. According to the invention, the automatic measurement of the attitude relation among different devices is realized, the measurement efficiency can reach one time per half-minute, the measurement precision can be higher than 30'', on-site measurement flexibility is higher, and construction and measurement indifferent places can be much easier.

The invention discloses a CPU (Central Processing Unit) realizing method based on amplitude-comparison direction finding of a multi-frequency point omnibearing passive radar. A CPU and GPU (Graphic Processing Unit) heterogeneous hardware platform is adopted; a processing module with strong parallelism and the processing module with strong logicality are respectively realized on the GPU and the CPU; the platform is simple and high in use ratio; a system is simple in operation and strong in flexibility when being expanded; the coagulation and the angle measurement are carried out in the CPU; specifically, a coagulating-while-comparing amplitude angle measuring method is adopted; trace point coagulation is combined with amplitude-comparison angle measurement, so that the time for recombining the data after coagulation is omitted; the coagulation and angle measurement processes are embedded in multithreading, so that the time is further saved; and a target point containing the angle information is transferred to a terminal display control platform. According to the CPU realizing method provided by the invention, the problems that a target positioning effect of a single-frequency passive radar detecting system is inferior, the multi-frequency precision is high but the calculated quantity is large and the consumed time is long are solved. The CPU realizing method has the advantages of high processing speed, high angle measuring precision, and wide angle measuring scope, and can be applied to the target detection and positioning for the passive radar.

The invention discloses an error compensating method of a photoelectric encoder. An error compensating process of the method is simpler, so as to realize the aim of improving the compensation precision. Equipment provided by the method comprises the photoelectric encoder, a rotating table and a controller. The error compensating method comprises the following special steps of: obtaining y by subtracting z by x, wherein each angle measurement value of the controller is regarded as a value x to be compensated, and each corner value of the rotating table is regarded as a conventional true value z; according to the x and the z, establishing a knowledge base model of the photoelectric encoder by using a least square method, and outputting z'; according to the x and the y, establishing a neural fuzzy model by using a structure of an improved self-adaption neural fuzzy reasoning system, and outputting ynet(k); adding outputs of the established knowledge base model and neural fuzzy model, so as to obtain z'+ynet(k); and respectively inputting each measurement value of the photoelectric encoder to the established knowledge base model and neural fuzzy model so as to compensate, and outputting the compensated values by the controller.

The invention discloses a mechanical scanning meter wave radar based angle measurement method which mainly aims at solving the problem that the angle measurement of a mechanical scanning meter wave radar is low in accuracy by the traditional single pulse method. The mechanical scanning meter wave radar based method comprises step 1, dividing an antenna into two sub-matrixes equally and transmitting pulse signals; step 2, performing coherent accumulation on received echo signals and obtaining data after the accumulation; step 3, performing DET (Discrete Fourier Transformation) calculation on the data after the accumulation; step 4, finding out a point in a doppler channel, reserving M points on the left side and the right side of the point and setting rest points to be 0, wherein the point is corresponding to the doppler frequency; step 5, performing IDFT (Inverse Discrete Fourier Transform) calculation on the data which are set to be 0; step 6, obtaining a sum beam and a difference beam according to obtained two groups of data after the IDFT calculation; step 7, performing the sum and difference beam single pulse angle measurement on the sum beam and the difference beam to obtain an off-axis angle of a target; step 8, adding the off-axis angle to a reference angle to obtain the accurate angle of the target. According to the mechanical scanning meter wave radar based method for improving the single pulse angle measurement, the accuracy of the angle measurement is high, a plurality of targets can be distinguished, and the mechanical scanning meter wave radar based method can be applied to the target accurate positioning and multi-target detection of the mechanical scanning meter wave radar.

The invention discloses a wave beam space domain meter wave radar height measurement method based on compressed sensing and relates to low elevation height measurement under the condition that a signal to noise ratio is low and snapshots are less. A realization process is characterized in that a target signal is extracted from a radar echo and rough measurement of the elevation is performed so that the space domain theta where a target signal elevation is located is obtained; the space domain theta is divided into P parts, wave beam formation is performed in the space domain theta so as to obtain a wave beam transformation matrix B and prewhitening is performed on the wave beam transformation matrix B so as to obtain a whitening wave beam transformation matrix T; receiving data is projected to the whitening wave beam transformation matrix so as to obtain a wave beam domain measurement signal z and an observation matrix phi carries out compression sampling on the z so as to obtain an observation signal y; iterative operation of the whitening wave beam transformation matrix T and the observation signal y is used to obtain a target signal estimation value; a target angle is extracted from the target signal estimation value so as to obtain the target height. By using the method of the invention, sampling points of the target signal and operands are reduced; sidelobes of a signal power spectrum and a space spectrum are effectively reduced; height measurement precision under the low signal to noise ratio is increased; the method can be used in target positioning.

The invention discloses a speed reducer testing equipment which is used for testing the return difference and the elastic constant of a speed reducer to be tested. The speed reducer testing equipment comprises a support platform, and a servo motor, an input rotating wheel, an output rotating wheel, load equipment and an angle sensor which are arranged on the support platform, wherein an output shaft of the servo motor is connected with one of a first side shaft and a second side shaft, which are opposite, of the input rotating wheel so as to drive the input rotating wheel to rotate around a first rotating shaft defined by the first side shaft or the second side shaft; the speed reducer to be tested and the angle sensor are respectively connected with a third side shaft and a fourth side shaft, which are opposite, of the output rotating wheel; the output rotating wheel is meshed with the input rotating wheel to further synchronously rotate around a second rotating shaft which is defined by the third side shaft or the fourth side shaft and parallel to the first rotating shaft; the angle sensor is used for obtaining a torque angle of the speed reducer to be tested. Due to the adoption of the mode, according to the speed reducer testing equipment disclosed by the invention, the angle measurement precision of the speed reducer to be tested is improved.

The invention provides an angle tracking system, which is characterized by comprising a control center, an antenna branch system, a feeder line branch system, an emission branch system, a receiving branch system, a servo branch system and a communication interface branch system. The angle tracking system can search, capture and track unmanned airplanes, precisely position the unmanned airplanes according to orientation information, elevation measurement information and information frame ranging information which are acquired by an angle tracking branch system, emit real-time remote control signals of a flying state of the unmanned airplane and a working state of airborne equipment, and receive real-time remote sensing signals of a flying parameter and detection information of the unmannedairplane and the working state of the airborne equipment; each working row channel is provided with a plurality of frequency points; and the working frequency band is wide, and the anti-interference performance is high.

The invention discloses a direction-of-arrival estimation method based on sparse representation of a spatial smoothing covariance matrix. The method mainly solves the problems that the calculation amount is large, the performance of processing coherent signal sources is poor and consequently errors in passive location estimation are large in the prior art. The method comprises the implementation steps: (1) forming a uniform linear array by antenna receivers, (2) the spatial smoothing covariance matrix output by the array is calculated according to the spatial smoothing technology, (3) vectorizing the spatial smoothing covariance matrix to obtain sparse model vectors, (4) carrying out mesh generation on a spatial domain to construct a perfect base, (5) establishing a constrained optimization equation based on the sparse representation relation between the sparse model vectors and the perfect base, (6) solving the constrained optimization equation according to the convex optimization method to obtain an optimal estimation value, and (7) drawing a magnitude spectrum according to the optimal estimation value to obtain the value of direction of arrival. By means of the method, the calculation speed of passive direction finding is increased, and the performance of estimating the coherent signal sources at a low signal-to-noise ratio is improved. The method can be applied to target reconnaissance and passive localization.

The invention discloses a metrewave radar angle measurement method which mainly solves the problem that in the prior art, signal to noise ratio loss caused by misalignment of Doppler channels is large. The method comprises the steps of (1) carrying out pulse compression on radar echo signals received by an array to obtain pulse pressure echo signals, (2) estimating the target angle, carrying out beam forming on the pulse pressure echo signals through weight vectors constructed through the target angle, (3) carrying out multi-point fast Fourier transform on data after beam forming to obtain precise Doppler frequencies of a target, (4) generating one Doppler weight vector through the obtained precise Doppler frequencies, carrying out weighted filtering on the pulse pressure echo signals through the Doppler weight vector, and (5) carrying out beam-scanning angle measurement using the data after filtering. The metrewave radar angle measurement method has the advantages of being high in angle measurement precision, and stable in performance, and the method can be used for precise target positioning in the technical field of radars.

The invention provides a single-pulse high-precision angle measuring system and method, and belongs to the field of navigation management secondary radars. According to the scheme, base band digital signals are demodulated through synchronized PN codes, original useful signals are restored, and then noise and interference signals are restrained; the amplitude of the restored original useful signals is detected; phase judgment is conducted through the amplitude of a sum channel and the amplitude of a difference channel, and sum amplitude information, difference amplitude information and a phase judgment result are resolved; an OBA value function is acquired according to the resolved sum amplitude information, the resolved difference amplitude information and the resolved phase judgment result for target azimuth calculation. Anti-interference capacity of a novel secondary radar system can be improved, the influence of the multipath effect can be reduced, and the angle measuring accuracy of the novel secondary radar system can be further improved through an improved amplitude single-pulse angle measuring technology adopting an OBA curved surface function method and an accumulated weight processing method.

The invention provides a multi-beam single-pulse angle measuring method based on a beam selection method. The method mainly solves the problem that two-beam single-pulse angle measurement is small in airspace covering range and low in accuracy under the condition of the existing hardware system. The method includes the following detection steps: 1) forming M beams simultaneously in pitching dimensions with each beam 1-degree larger than the last one and dividing the covered airspace into M-1 angle measuring sections; 2) building a discrimination angle curve under the off-line condition according to the ideal antenna receiving signal amplitude difference and ratio; 3) selecting the optimum beam distance and the optimum beam according to each angle measuring section theta i, i+1; 4) determining the affiliated angle measuring section theta i, i+1 according to the target echo strength; 5) determining the optimum angle measuring beam combination in an off-line mode through the step 3) and calculating difference and ratio of radar target echo received by the beam combination. The point that the difference and ratio corresponds to in the discrimination angle curve corresponding to the beam combination is the target angle. The method is small in calculation amount and high in angle measuring accuracy due to the fact that angle measurement is conducted by optimally selecting the optimum beam distance and the optimum beam under the condition of multiple beams.

The invention discloses an angle measurement precision detecting device of an aspect angle monitor for a satellite. A small plane mirror is connected to a mounting base plane position of the aspect angle monitor; the aspect angle monitor for the satellite is arranged on a two-dimension inclined platform and is placed on a two-dimension translation platform; a double-faced simulation swing mirror is arranged on a three-dimension adjusting platform and is placed on a digital display turntable; a first autocollimator and a second autocollimator are placed on a lifting support; the two-dimension translation platform, the digital display turntable and the lifting support are placed on a table top of a detection platform; a central spindle is sleeved in a central hole of the digital display turntable; a standard circular device is placed on a standard block and is close to the central spindle; laser beams emitted by a laser align with a central prism of a five-mirror reflector to form a detection standard optical axis; a dial indicator is fixed on the detection platform; a gauge block is placed above the digital display turntable and between the aspect angle monitor for the satellite and the double-faced simulation swing mirror; one face of the gauge block is close to the mounting base plane of the aspect angle monitor for the satellite; and the other face of the gauge block is close to a first optical surface of the double-faced simulation swing mirror.

The invention discloses a low-elevation-angle direction-of-arrival estimation method based on time reversal. The method comprises the steps of determining an antenna array A which comprises M array elements, transmitting a forward detecting signal by the antenna array A, transmitting the forward detecting signal to the antenna array A after target scattering, obtaining a forward echo time domain signal Yn(t) which is transmitted back after target scattering by an n-th array element in the antenna array A, calculating a time reversal receiving signal yn(t) of the n-th array element in the antenna array and furthermore calculating a covariance matrix RY(omegaq) of the time reversal frequency domain receiving signal at a sampling frequency point omegaq of the n-th array element in the antenna array A; performing bandwidth focusing on the RY(omegaq), successively calculating a focused covariance matrix RY(omega0) of the n-th array element at the bandwidth focusing frequency omega0 and a focused smoothing matrix {RY(omega0)}SS of the n-the array element at the bandwidth focusing frequency omega0, calculating a spatial spectrum function S(theta) of the n-th array element in the antenna array A, and furthermore calculating H maximal values of the spatial spectrum function S(theta) of the n-th array element in the antenna array A, wherein the angle which corresponds with each maximal value is the direction-of-arrival.

The invention relates to direction of arrival estimation for source signals, provides an algorithm for DOA (Direction of Arrival) estimation under a mutual coupling condition of unknown array elements. Under the premise of a sparse reconstruction theory, the algorithm makes full use of all information received by an array, and the angle estimation precision can be improved under strong mutual coupling of the array. The technical scheme adopted by the invention is that the method for sparse DOA estimation under mutual coupling of array elements comprises the steps of 1, calculating a covariance matrix R for a received signal X^(t); 2, performing singular value decomposition on the covariance matrix R; 3, calculating a signal subspace RS for receiving data according to a signal unitary space; 4, building a sparse signal complete dictionary AJ according to parameterization J of a steering vector; 5, building a convex programming function for sparse signal reconstruction according to a norm l1; 6, solving the convex programming function and performing spectrum peak search; and 7, further improving the estimation precision by using a principle of grid refinement. The method is mainly applied to direction of arrival estimation for signals.

The invention discloses a distributed meter wave array radar angle measuring method based on information fusion. The problem that according to an existing technology, angle measuring accuracy in a distributed meter wave array radar is low is mainly solved. The method comprises the steps that (1) according to distributed array antenna structure parameters and radar working parameters, the performance parameters of a distributed array antenna are obtained; (2) a target is detected and tracked, and the number of a distance unit where the target is placed is obtained; (3) data of the distance unit where the target is placed are subjected to beam forming, and a beam forming vector is obtained; (4) a peak value of the beam forming vector is extracted to form a maximum value vector, and an information matrix is formed through the maximum value vector; and (5) an information matrix X is subjected to information fusion according to a fusion criterion, and the angle value of the target is obtained. According to the method, correlation of target information in adjacent multi-frame radar echo data is used, through infusion of the target information in the multi-frame data, influence on target angle measuring of a high-minor-lobe level is lowered, angle measuring accuracy is improved, and the method can be used for target angle measuring.

The invention discloses a direction-of-arrival estimation method based on sparse representation. The method mainly solves the problems that because a similar technology is large in calculation amount and low in angular resolution, the estimation speed of target reconnaissance and passive location is low and estimation errors in target reconnaissance and passive location are large. The method comprises the implementation steps: (1) acquiring output signals of an array and calculating a covariance matrix R of the signals, (2) constructing reconstructed sparse vectors through lower triangular elements of the covariance matrix R, (3) carrying out mesh generation on a spatial domain to construct a perfect base, (4) converting the direction-of-arrival estimation issue into the issue of solving a constrained optimization equation according to the sparse representation relation between the reconstructed sparse vectors and the perfect base, (5) solving the constrained optimization equation according to the convex optimization method to obtain the optimal estimation vectors, (6) drawing a magnitude spectrum according to the one-to-one correspondence of the optimal estimation vectors and spatial domain angles to obtain the direction-of-arrival value. By means of the method, the calculation speed of target reconnaissance and passive location is decreased, and the estimation errors in target reconnaissance and passive location are reduced. The method can be applied to target reconnaissance and passive location.

The invention provides a method for improving the single-pulse angle measuring precision of search radar. The method comprises angle error pre-processing and angle error correction. The angle error pre-processing is to analyze test data of a single-pulse antenna directional diagram of the search radar, and calculate angle error data by adopting data fitting and interpolation methods according to signal difference over sum when parameters are different to form an angle error data table; and the angle error correction is to burn the angle error data table into a memory, then solve difference over sum, search the table according to the difference over sum and relevant parameters to obtain an angle error value and correct the measured target angle error in real time. The method effectively improves the angle measuring precision of the traditional single-pulse angle measuring method, particularly the angle measuring precision when the target deviates from the center of antenna beams greatly. The method is suitable for single-pulse angle measuring mechanism radar, particularly the search radar with low data rate; and the corrected angle error data can be directional or pitched.

The invention discloses an angle position error detecting and compensating device of a round angle position sensor and a compensating method, which are applied to error detection and error compensation of an angle position when a round angle sensor is arranged. The compensating method comprises the following steps that a permanent magnet synchronous motor drives the angle position sensor to be detected to uniformly rotate after an angle position sensor to be detected is installed; angle position data generated by a photoelectric encoder and the angle position sensor to be detected are collected; after the rotation of one mechanical period is finished, an error curve and the maximum error of the angle position sensor to be detected are obtained through computation, and the mechanical installation of the angle position sensor to be detected is provided with evidence; after the optimal installation is finished, the error curve of the angle position sensor to be detected is obtained again, the fitting on the error curve is finished by utilizing a polynomial fitting process, and the compensation to the angle position sensor to be detected can be carried out according to a polynomial obtained through fitting, so that the angle detection error is reduced, and the performance of a system is further improved. According to the compensation method disclosed by the invention, the precision of the mechanical installation of the angle position sensor to be detected is detected, and the angle detection precision is further improved in an error compensation manner.

The invention provides a long distance high resolution laser active imaging device and method based on spatial coding. The device comprises a laser light source, a two-dimensional laser scanning mirror fixed to the light emitting end of the laser light source, a target fixed to a two-dimensional laser scanning lens area, an imaging lens fixed to a target reflection optical path, a photoelectric array detector fixed to the imaging lens imaging optical path, a scanning lens rotation angle measurement device connected to the laser scanning lens, a space decoding and laser distance measurement module connected to the photoelectric array detector through a conductive wire, a computer connected to the space decoding and laser distance measurement module and the scanning lens rotation angle measurement device through conductive wires, and a laser controller connected to the laser light source through a conductive wire. The invention also discloses an image method of the device. In the condition of ensuring high resolution, the detection distance is expanded.

The invention discloses a method for the dimensional-reduction four-channel sun-difference beam angle measurement of a phased array radar. The method includes the following steps that: the phased array radar is determined; sub-array division is performed on N array elements contained by the phased array radar, so that M sub-arrays and the number of array elements contained by each sub-array can be obtained; the sub-array-level sum weight, sub-array-level pitch difference weight, sub-array-level azimuth difference weight, sub-array-level double-difference weight and sub-array element-level weight of the optimized phased array radar are calculated, and the optimal dimension reduction matrix of the phased array radar is calculated; the directivity function of the sum beams of the phased array radar, the directivity function of the azimuth difference beams of the phased array radar, the directivity function of the pitch difference beams of the phased array radar and the directivity function of the double-difference beams of the phased array radar are calculated; and the final pitch directional angle of the target of the phased array radar and the final azimuth directional angle of the target of the phased array radar are estimated.

The invention belongs to the technical field of precision measurement and the field of optical engineering and specifically relates to a combination zeroing laser large working distance auto-collimation device and method. The device consists of a light source, a collimating mirror, a reflecting mirror and a feedback imaging system; according to the method, via adjustment of the reflecting mirror, a reflected light beam is enabled to return to a center of an image plane of the feedback imaging system; an angular deflection measurement device on the reflecting mirror is used for obtaining angular variation of a surface of an object being tested. Because the reflecting mirror is added in a traditional auto-collimation angle measurement system, a problem that measurement cannot be realized when light reflected by the object being tested is deviated from a measurement system can be prevented; an auto-collimation working scope can be expanded while working distance remains the same or working distance is increased while the auto-collimation working scope remains the same; via specific design of the collimating mirror, the feedback imaging system, the reflecting mirror and the like, the combination zeroing laser large working distance auto-collimation device is enabled to be simple in structure and low in manufacture cost; measurement operation can be conducted even in unstable measurement environments, and a technical advantage of rapid measurement can be gained.

The invention relates to a single-axis accelerometer and three-axis magnetic field sensor based attitude measurement system and an attitude measurement method thereof. The system includes: an accelerometer, a three-axis magnetic field sensor, a GNSS module and a data processing module. The accelerometer is a Z axial direction single-axis accelerometer in orthogonal arrangement with a forward shaft and used for measuring gravitational acceleration component so as to obtain the triangle relationship between a ground carrier's roll angle and pitch angle. The data processing module is used for acquiring geomagnetic field model, geomagnetic inclination information and magnetic declination information according to a position information look-up table, and combining the triangle relationship between the ground carrier's roll angle and pitch angle and the three component arrays of a geomagnetic field under a carrier coordinate system to finally work out a course angle, the pitch angle and the roll angle. The new attitude measurement method provided by the invention can realize exact calculation of the carrier attitude angle under a carrier stationary or low speed moving state, can reduce a measurement amount, and avoids introduction of more measurement noise.

This invention discloses a method for calibrating near-field effect of a spherical composite array in a radio frequency simulation system, and relates to the technical field of instrument calibration. The spherical composite array is composed of micro wave and millimeter wave antenna arrays so as to generate electromagnetic wave signals of micro wave and millimeter wave frequency bands. The calibrating method comprises the steps of precisely calculating an electric field distribution near the position of a receiving antenna (normally located at a radiation near field of a transmitting triple antenna) by a full-wave algorithm and a high-frequency algorithm when a given subarray (triple) antenna in the composite array is transmitted in a surrounding environment of same-frequency and different-frequency antenna element; based on phase distribution of an electric field, determining an equivalent phase center of a triple radiation field by a phase gradient algorithm, and calculating a deviation between the equivalent phase center and an equivalent phase center estimated value acquired based on a gravity equation; and calibrating the input power ratio of each unit of the triple according to the deviation value. The method can be used for making a calibrating table, so as to quickly calibrate the near-field effect of the composite array in real time during engineering.

The invention discloses an interference phase assistance-based height measuring method for a delay doppler radar altimeter, wherein the problems that the traditional algorithm is low in resolution andprecision and the angle information of a ground unit is difficult to extract due to the non-coherent superposition of the positive and negative interference phases of a double-antenna system in the prior art can be solved. The method comprises the following steps of establishing a signal model of a delay doppler radar altimeter based on interference phase assistance; processing an echo signal: estimating the noise power and calculating a detection threshold; defining a an interference window; extracting an interference phase angle, namely the included angle between a ground unit relative to the normal line of an antenna array; calculating the height, and estimating the height of an aerial carrier according to the corresponding distances of all distance units in the interference window, and the included angle of the corresponding ground unit relative to the normal line of the antenna array. According to the invention, the angle information of the ground unit can be effectively extracted through three antennas, so that the height measuring precision and the resolution of the radar altimeter are remarkably improved. The method is stable, reliable and low in calculation amount, and can be used for the terrain matching of the interference doppler radar altimeter.

The invention provides a subdivided signal error compensation method of a photoelectric encoder of a tracking control platform. The subdivided signal error compensation method is suitable for the tracking control platform which is formed by a main processor module, a storage module, a display module, a power module, an execution module, a controlled module, an photoelectric encoder measurement module, a communication interface module and a human-computer interaction module. The compensation is performed on the subdivided signal error of the encoder measurement module through the controlled object position of the tracking control platform. The practicability and the field adaptability are high and accordingly an expensive error detection device is not required and a large time delay of complex algorithm does not need to be brought to the platform. Meanwhile, only the shaft system position information needs to be obtained, the tracking control platform, an encoder angle measuring module and a lower layer of software and hardware structure of the platform do not need to be known, and accordingly the portable capability and the operational capability are high, the time and the labor are saved, and a good solution is provided for the encoder subdivided signal error problem which is common in the field of photoelectric tracking control platforms.

The invention discloses a time reversal coherent angle estimation method for a radar low-altitude target, and aims to solve the problem of low angle estimation accuracy of the radar target in a multipath environment. The method comprises the following implementation steps: acquiring radar echo data; performing energy normalization and time reversal on the echo data to obtain a time reversal signal; retransmitting the time reversal signal to obtain time reversal echo data; and further obtaining a covariance matrix, reconstructing a time reversal covariance matrix with the element mean value Toeplitz of the diagonal line of the covariance matrix, performing MUSIC spectrum estimation with the time reversal covariance matrix, and estimating a target angle according to the position of a spectral peak. According to the method, energy normalization and time reversal are performed on the echo data, and the time reversal signal is retransmitted and forms energy accumulation at a target, therebyimproving the signal-to-noise ratio of time reversal echo. Decoherence of the target is realized by the time reversal covariance matrix. Angle estimation of the target is realized by a MUSIC method,so that the estimation method has the advantages of higher angle measurement accuracy, higher probability in successful distinguishing of the target, relatively low cost and wider application range, and is applied to coherent angle estimation of the low-altitude radar target.

The invention relates to the field of nuclear power engineering, aiming to solve the technical prejudices of the prior art that when the standard elevation in the nuclear power engineering is measured, the measuring work load is great, great manpower and material resources are wasted, the measurement precision is low and a triangular elevation measurement method cannot be applied to the nuclear power engineering. The method for measuring the standard elevation in the nuclear power engineering, disclosed by the invention, comprises the steps that: at least one reference standard is selected in a measurement field and a measurement point is set so that a total station located at the measurement point can observe a standard to be detected and the reference standard; the total station is placed on the measurement point and the measurement point is opened to calibrate; a measurement accessory is placed on a target to be detected; the target to be detected is the reference standard and the standard to be detected; measured data is measured and processed to obtain the elevation of the reference standard relative to the standard to be detected; and the measured data is identified. The method for measuring the standard elevation has the advantages of simplicity in operation, less work load, lower cost and high precision, and overcomes the technical prejudice that the short-edge triangular elevation measurement precision is low.