45 results about "Echo doppler" patented technology

The vehicle classification method includes: the time-domain radar signal of single-frequency continuous wave radar is used as input to conduct time-frequency analysis to obtain a radar echo Doppler frequency spectrum chart changing along time; by Hafford counterchange the Doppler chart is mapped into a scattered central position parameter image; through characteristic picking-up, Karhunen-Loeve(K-L) screening and compressing, a characteristic sample is obtained, which is classified using Fisher rule to obtain the vehicle-type classification. For multi-type condition, multiple two-type classifiers are used to conduct respectively pairwise classification, according to the result of the classifiers said above the classification result is obtained by voting. Advantage: simple and reliable structure and low cost, conducting classification synchronously with detecting and speed-measuring of vehicles.

The invention provides a sonar moving target imaging method based on target echo Doppler characteristics, which comprises the following steps of: performing band-pass filtering on echo data of each basic element in a receiving basic array; performing band-pass filtering on each frequency point signal to acquire band-pass data of each frequency point; performing quadrature demodulation on the datasubjected to band-pass filtering of each frequency point to acquire an analytic signal form of a real signal; performing Chebyshev weighting and focusing operation on the echo data subjected to quadrature demodulation of each frequency point; acquiring image data of each frequency point in a polar coordinate system by fast Fourier transform (FFT) beam forming; and performing interpolation mergingon the image data subjected to FFT beam forming of each frequency point, and converting an image in the polar coordinate system into an image which accords with the visual habit of people in a rectangular coordinate system by sector conversion. By the FFT beam forming, the method can be implemented by an FFT algorithm in digital signal processing, and the requirement of system real-time imaging is met.

The invention provides a coherent simulation method for a radar echo Doppler frequency based on real-time frequency measurement. The specific process comprises the steps that step one, a simulator performs envelop extraction on transmitting signal pulses of a radar, and the simulator performs clock counting N3 by using a local clock in N2 radar transmitting pulse periods; step two, a corrected Doppler frequency simulation variable f'd is calculated, wherein f'd=fd*(N1N2 / N3)*(1 / [alpha]), fd represents the Doppler frequency corresponding to a simulated target, alpha represents a nominal frequency ratio of working clocks of the radar and the simulator, and N1N2 / N3 is a frequency correction coefficient; and step three, coherent simulation for the radar echo Doppler frequency is realized by using the Doppler frequency simulation variable f'd. Coherent simulation for the radar echo Doppler frequency can be realized quickly according to the method.

The invention discloses a target positioning method for correcting an angle measurement error based on echo Doppler information, and the method comprises the steps: constructing a target positioning system for correcting an angle measurement error based on echo Doppler information, wherein the constructed system comprises a data obtaining module and a target positioning module; obtaining the target Doppler frequency and inertial navigation measurement information through the data obtaining module, and resolving the target position through the target positioning module. The method can achieve the accurate resolving of the target position on the basis of a target angle measurement error comprising an error through the echo Doppler information and inertial navigation measurement information,and provides guidance for the precise striking of a missile.

The invention provides a method for forming a wave field through high-frequency ground wave radar. The method is used for extracting the effective wave height from high-frequency ground wave radar echoes, and the wave field is obtained through the wave height inverse algorithm. The wave height extracting algorithm is acquired according to the specific value of a first-order peak to a second-order peak in the radar echo Doppler spectrum, the obtained effective wave height can be used for estimating the azimuth angle through a multiple signal classification (MUSIC) algorithm, and thus azimuth information of the wave height is obtained. When the extracted effective wave height includes azimuth angle information and distance information at the same time, wave height distribution of the radar within the range of a detected sea area can be obtained, and accordingly the wave field is formed. An initial wave field is subjected to subsequent treatment including replacement, interpolation and smoothness, and then the final wave field can be obtained. The wave field forming algorithm is not only applied to a narrow beam radar system but also applied to a compact-array wide beam radar system.

The invention discloses a method for inversion of a surge wave height by a high frequency ground wave radar. The method comprises the following steps: selecting a high frequency ground wave radar echoDoppler spectrum for inversion and performing independent calculation on each radar echo Doppler spectrum to determine a noise level at a given time and place; with a high-energy Bragg single peak asa reference, carrying out de-ocean-current processing on the radar echo Doppler spectrum; screening out a spectrum capable of carrying out follow-up spectrum shape analysis; identifying a surge spectrum peak in the spectrum; determining an actual measured position of the spectrum peak; carrying out quality checking on the actual measured position of the spectrum peak; carrying out calculation toobtain a surge angle; and calculating the surge wave height. According to the invention, with the high-frequency ground wave radar for observing the surge, a novel way is provided for providing surgeobservation data and the observation precision of the sea surface wave is improved by assisting the way effectively. The method has the important practical and scientific values.

The present invention relates to a method for detection of a sea level wave height through adoption of an S-waveband Doppler radar. The method comprises: the step 1, employing an S-waveband Doppler radar to obtain a sea echo Doppler spectrum, extracting the center frequency of the obtained N-frame Doppler spectrum, obtaining a center frequency sequence, and obtaining a measured radial speed sequence according to the Doppler effect; the step 2, removing an average value for the vertical speed measured by the radar, and performing discrete Fourier transformation and Modulo square to obtain a speed spectrum; the step 3, according to the linear wave theory, obtaining the conversion relation of the speed spectrum and a sea wave spectrum, and obtaining the sea wave spectrum; the step 5, according to the mathematic relation between the efficient wave height and the sea wave spectrum, employing the spectral moment method to obtain the wave height; and the step 5, employing the zero-moment singular value removal method to allow the abnormal efficient wave height to recover normality. The method for detection of sea level wave height through adoption of the S-waveband Doppler radar provides a new detection means for obtaining the sea level wave height through adoption of a microwave Doppler radar, has high detection precision and wave field spatial resolution, and is simple and clear in results.

The invention provides a multiple-input multiple-output synthetic aperture ladar (SAL) signal processing method, which can effectively solve the conflict between an azimuth high resolution and a range direction wide swath, and realize high resolution wide swath SAL imaging. The method comprises the steps of: N array elements respectively receiving target echo signals, each array element performing residual video phase compensation processing and form simplification processing on the target echo signals; each array element performing Fourier transform of azimuth on the target echo signals after form simplification processing; performing solving ambiguity processing on observation vectors formed by target echo Doppler signals mixed by the N array elements; and arranging elements of target echo Doppler signal vectors without fuzziness according to fuzzy component numerical magnitudes, and employing a Doppler frequency spectrum to splice complete target echo Doppler signals without fuzziness, thereby obtaining an SAL image.

The invention provides a rotor laser doppler and micro-doppler composite signal emulator, which belongs to the dynamo-electric signal processing and laser radar technology field. A special acousto-optic modulator bipass optical path is utilized to successfully create a rotor laser doppler and micro-doppler composite signal, for instance, a laser radar echo signal of a helicopter, so military targets that have rotors and move at a high speed is simulated. Furthermore, through integration of superheterodyne detection optical paths, the created signal is detected successfully. The military targets that have rotors and move at a high speed, such as a helicopter, can be identified accurately so that enemies and friends are distinguished and accidental injuries at a battle field are avoided. Although current researchers provide a theoretical formula of the laser radar echo doppler and micro-doppler frequency shift signal, such a laser echo signal is not created in a laboratory. The rotor laser doppler and micro-doppler composite signal emulator is capable of effectively creating such laser echo signals, and the signals can be integrated with detection optical paths, so successful detection is realized.

The invention provides a high-frequency ground wave radar wave field forming method based on a ratio of a first-order peak to a second-order peak. The method comprises the following steps: dividing afirst-order peak area from an echo Doppler spectrum; figuring a power ratio of the first-order peak to the corresponding second-order peak of each distance, and a first-order peak arrival angle; establishing a reference power ratio-wave height model through wave height data of a reference buoy in combination with the power ratio of the position of the reference buoy; correcting the reference powerratio-wave height model of each distance according to an attenuation model to obtain a corrected power ratio-wave height model; substituting the power ratio of each distance into the corrected powerratio-wave height model to obtain the wave height of each distance; and performing interpolation and smoothing on the wave height of each distance to obtain a final wave field. The high-frequency ground wave radar wave field forming method provided by the invention has the advantages of good spatial resolution and high measurement precision; the result of the wave field is more stable.

The invention discloses a method and a device for estimating sea surface wind speed based on line spectrum intensity in radar echoes. The method comprises the steps of establishing an experiential model in which intensities of a first-order peak and a secondary harmonic peak are changed along air speed, firstly estimating model parameters by fitting by taking air speed data measured in real time by virtue of a site buoy and air speed estimated on a radar close range unit by virtue of a conventional second-order spectrum method as standards, then estimating air speed by virtue of the intensities of the first-order peak and the secondary harmonic peak in an echo Doppler spectrum, weighting and combining the estimating model parameters with the air speed, so as to obtain a final air speed estimation value. According to the method and the device, the problem of high-frequency ground wave radar that an existing air speed estimation method based on an echo second-order spectrum is not accurate enough is solved; the intensities of a first-order Bragg peak and the secondary harmonic peak in the echo Doppler spectrum are related with the air speed value, so that the air speed can be directly extracted from line spectrums including the first-order peak, the secondary harmonic peak and the like, and the estimation precision of the sea surface wind speed by the high-frequency ground wave radar is substantially improved.

The invention relates to a laser coherence detection device for ceramic surface defect. According to the device, a single-frequency laser outputs the laser by an optical fiber coupler, a loop device, and a receiving and transmitting telescope to detect the ceramic product surface; the detection echo passes through the loop device, a polarizing beam splitter and the optical fiber coupler, and is subjected to frequency mixing coherence with the intrinsic light on the surface of a detector; the coherent signal is amplified and sampled by filtering, and the structure size of the ceramic product surface defect is calculated by extracting the superposition modulation signal amplitude of the continuous echo Doppler frequency shift signals.

The invention discloses an ocean surface wind field measurement method based on a shipborne high frequency ground wave radar and relates to an ocean surface wind field measurement method. The problemsthat a traditional ocean surface wind field measurement tool is difficult to deploy and maintain, a large area cannot be measured and the observation efficiency is low are solved, and the problem that the detection ocean area and measurement performance of a shore-based high frequency surface wave radar are limited is solved. The method comprises the steps of (1) selecting first-order ocean surface echo Doppler broadening spectrum corresponding to a distance gate, (2) determining a Doppler frequency corresponding to an incident azimuth of ocean unit echo of a detected azimuth, (3) establishing a corresponding relation between a wind direction and an expansion factor, (4) extracting an unambiguous wind direction and a corresponding expansion factor, (5) establishing a corresponding relation between a wind speed and an expansion factor, (5) repeating steps (2), (3), (4) and (5) and orderly obtaining wind fields corresponding to different detection azimuths in the distance gate, and (7)repeating steps (1), (2), (3), (4), (5) and (6) for N times and obtaining an ocean surface wind field of a whole ocean area within a radar detection range. The method is used in the field of wind field measurement of the ocean surface.

The invention discloses a low-repetition-frequency precise speed measurement method based on multiple carrier frequencies. The method comprises the steps: constructing a low-repetition-frequency precise speed measurement system based on multiple carrier frequencies, wherein the constructed system comprises a fuzzy Doppler frequency acquisition module, a signal processing module and a target radialvelocity resolving module; obtaining the fuzzy Doppler frequency of each carrier frequency through the fuzzy Doppler frequency acquisition module; carrying out the differential processing of the fuzzy Doppler frequencies through the signal processing module, and resolving the radial speed of a target through the target radial velocity resolving module. The method can achieve the resolving of theradial speed of a radar pointing to the target under the condition that echo Doppler frequency in a low-repetition-frequency system is fuzzy severely through the Doppler frequency difference of multiple carrier frequencies and the linear relation of linear speed between the radar and the target, and is high in speed measurement precision.

Aiming at the problem that the fractional-order Fourier transform algorithm in the impulse noise environment is invalid, the invention is designed to suppress the interference of impulse noises basedon the nonlinear transform-Sigmoid transform. The invention provides a novel method for jointly estimating the Doppler frequency shift spreading factor and the time delay of an LFM impulse radar basedon the energy gathering characteristic of the fractional-order Fourier transform. According to the invention, the method comprises the steps of firstly, combining the Sigmoid transform algorithm withthe fractional-order Fourier transform algorithm and providing a Sigmoid-based fractional-order Fourier transform (Sigmoid-FRFT) algorithm; secondly, realizing the joint estimation of the Doppler frequency shift spreading factor and the time delay based on the peak point searching of the Sigmoid-FRFT. The above method does not need any priori knowledge of noises, and has strong tolerance to low signal-to-noise-ratio noises. Experimental results show that the method is relatively high in parameter estimation precision and low in computational complexity under impulse noises.

The invention discloses a method for inverting an undirected sea wave spectrum by using multi-frequency high-frequency radar ocean echoes. The method comprises the following steps of: dividing a fan-shaped to-be-measured ocean unit; extracting a relatively strong side first-order peak of a fan-shaped to-be-measured ocean unit echo Doppler spectrum of a single-frequency high-frequency radar; separating out a corresponding outer second-order spectrum region, and calculating the ratio of the region to the stronger side first-order peak energy; linearizing the outer second-order spectrum region, and obtaining an undirected sea wave spectrum coefficient matrix of the single-frequency radar sea echo; and repeating the steps for different radar transmitting frequencies to obtain an undirected sea wave spectrum coefficient matrix of the multi-frequency radar ocean echo, solving the pseudo-inverse of the undirected sea wave spectrum coefficient matrix through singular value decomposition, and inverting the undirected sea wave spectrum. The method has the advantages that the method can adapt to complex and changeable marine environments with large sea condition changes, the requirement for accurately inverting the undirected wave spectrum under various sea conditions is met, and the problems that the accuracy of inverting the undirected wave spectrum by a traditional single-frequency high-frequency radar is not high, and the performance is limited by the sea conditions are solved.

The invention provides a quadrature-modulation-based echo Doppler frequency simulation device. A local oscillator signal and a ground line are connected to a power divider through two paths; the powerdivider carries out outputting based on two paths; the two paths are connected to a mixer A and a mixer B respectively and then are connected to an input terminal of a combiner; and the mixer A and the mixer B are connected to two paths of orthogonal signals IF1 and IF2. According to the invention, on the basis of combination of the quadrature modulation phase method and the mixing technology, modulation of the echo Doppler frequency is realized; and different echo Doppler frequencies can be simulated by changing the frequency of the quadrature modulation signal. Therefore, the quadrature-modulation-based echo Doppler frequency simulation device has advantages of high suppression, high frequency accuracy, high frequency stability, low power consumption, and good economy.

The invention discloses a short-pulse non-coherent radar intermediate-frequency echo construction method. According to the method, waveform translation and additional phase compensation are carried out on point target echoes of each pulse radiation by using a stop-jump hypothesis model; waveform translation is divided into integer sampling interval translation and residual sampling interval compensation; the additional phase compensation is used for compensating an echo Doppler effect caused by target motion; the clutter construction comprises the following steps: generating a sample target sequence with specific speed distribution by utilizing a Monte Carlo method according to a set clutter speed distribution spectrum, generating a target echo by utilizing a point target echo generation method, and finally, adjusting weight coefficients of the target echo and the clutter according to a set signal-to-clutter ratio, and adding the weight coefficients to form an overall echo. The echo waveform formed by the invention can be played on a waveform generator or any waveform generator, and can be used as signal input of a radar intermediate-frequency receiver to form a closed loop of technology research and development.

The invention provides a radar actual measurement echo data processing method, electronic equipment and a storage medium. The method comprises the steps: obtaining radar actual measurement data, and generating a radar echo Doppler spectrum based on Fourier transform; estimating the average clutter-noise ratio of each distance unit of the radar echo Doppler spectrum, and obtaining a boundary based on the average clutter-noise ratio of each distance unit so as to divide the radar detection area into a short-range area, a medium-range area and a long-range area; and carrying out signal-to-noise ratio calculation in the short-range area, carrying out signal-to-noise ratio calculation in the medium-range area, and carrying out signal-to-noise ratio calculation in the long-range area. According to the invention, the radar echo area is divided, and the signal-to-clutter ratio, the signal-to-clutter-noise ratio and the signal-to-noise ratio of the short-range area, the medium-range area and the long-range area are calculated according to the dominant situation of different energies in the divided area, so that the situation that the signal-to-clutter ratio is inaccurately estimated due to the influence of the energies in different distance areas is avoided, and a foundation is laid for improving the accuracy of a radar detection performance evaluation result.

The invention is a device, system, and method for monitoring function of heart valves. The invention includes a disposable patch having simple transducers and simple processing for monitoring heart valve performance via echo Doppler and processing the data to determine blood flow velocities and / or blood flow gradients.

The invention discloses a target positioning method for correcting angle measurement errors based on echo Doppler information. The method first constructs a target positioning system for correcting angle measurement errors based on echo Doppler information. The constructed system includes: a data acquisition module and The target positioning module obtains the target Doppler frequency and inertial navigation measurement information through the data acquisition module, and the target positioning module calculates the target position. The method of the invention can accurately calculate the target position by relying on the echo Doppler information and the inertial measurement information on the basis of the error-containing target angle measurement results, and provides guidance for precise strikes of missiles.

The invention discloses a high-resolution squint SAR echo Doppler spectrum recovery method and system. The method comprises the following steps: acquiring original echo data, and carrying out range-direction fast Fourier transform on the original echo data to obtain range-direction FFT data; performing range pulse compression on the range FFT data to obtain pulse compression data; performing Doppler frequency shift elimination on the pulse compression data to obtain Doppler frequency shift elimination data; carrying out azimuth deramp processing on the Doppler frequency shift elimination data to obtain deramp processing data; performing azimuth linear frequency modulation Z transformation on the deramp processing data to obtain CZT data; carrying out the Doppler modulation recovery on the CZT data to obtain an aliasing-free two-dimensional frequency spectrum, and then obtaining a high-resolution SAR image through a frequency domain imaging algorithm. According to the method, interpolation operation is avoided, the operation is simplified, the imaging quality is ensured, and the method is more universal.

The invention provides a coherent simulation method for a radar echo Doppler frequency based on real-time frequency measurement. The specific process comprises the steps that step one, a simulator performs envelop extraction on transmitting signal pulses of a radar, and the simulator performs clock counting N3 by using a local clock in N2 radar transmitting pulse periods; step two, a corrected Doppler frequency simulation variable f'd is calculated, wherein f'd=fd*(N1N2 / N3)*(1 / [alpha]), fd represents the Doppler frequency corresponding to a simulated target, alpha represents a nominal frequency ratio of working clocks of the radar and the simulator, and N1N2 / N3 is a frequency correction coefficient; and step three, coherent simulation for the radar echo Doppler frequency is realized by using the Doppler frequency simulation variable f'd. Coherent simulation for the radar echo Doppler frequency can be realized quickly according to the method.

The invention provides a method for inverting a wave height by using small-aperture high-frequency radar ocean echoes. The method comprises the following steps: acquiring a wide-beam echo Doppler spectrum of a distance ring to be measured; extracting the first-order spectrum of the wide beam with the maximum amplitude and the second-order spectrum of the outer side of the wide beam near the first-order spectrum, and calculating the energy ratio of the two; calculating the wave vector amplitude under the condition of ocean current, and further obtaining an inversion coefficient vector in combination with radar system parameters; an inversion coefficient vector corresponding to each Doppler angular frequency is obtained through repeated calculation, all the inversion coefficient vectors are combined to obtain an inversion coefficient matrix, the pseudo-inverse of the inversion coefficient matrix is solved through singular value decomposition, and an undirected sea wave spectrum is obtained through inversion; and the undirected sea wave spectrum is integrated to obtain the effective wave height. The method has the advantages that the method is not sensitive to ocean current influence, the undirected wave spectrum can be accurately inverted from the wide-beam echo Doppler spectrum, the accuracy of wave height parameter estimation is improved, and the method is suitable for a high-frequency radar with a small aperture, is convenient to use and has development and application prospects.

The invention discloses a ship attitude motion component removal method based on spatial displacement. The method comprises the following steps of: establishing an expression of comprehensive Dopplerfrequency shift measured by a shipborne coherent radar; calculating six-degree-of-freedom ship motion amplitude response factors on the basis of sea wave frequency component distribution characteristics according to the style data of a ship body under the condition that the ship body is excited by waves of a unit wave height; based on a sea wave frequency spectrum measured by the radar at the lastmoment, obtaining the fluctuation rule of a ship by constructing a wave surface equation of a regular sea surface, and then obtaining the sea surface wave height displacement of the position of the ship body; performing six-degree-of-freedom coordinate conversion under an earth coordinate system and a ship coordinate system; calculating the spatial displacement of a radar antenna in a time periodaccording to the space coordinate difference between a previous moment and a next moment; finally solving the additional Doppler frequency shift caused by the attitude motion component of the ship body, and removing the component from the radar echo Doppler frequency shift. The method can effectively improve the extraction effect of the radial velocity of real water quality points of sea waves, and improves the precision of coherent wave-measuring radar sea wave parameter inversion.

The invention discloses a method and a device for estimating sea surface wind speed based on line spectrum intensity in radar echoes. The method comprises the steps of establishing an experiential model in which intensities of a first-order peak and a secondary harmonic peak are changed along air speed, firstly estimating model parameters by fitting by taking air speed data measured in real time by virtue of a site buoy and air speed estimated on a radar close range unit by virtue of a conventional second-order spectrum method as standards, then estimating air speed by virtue of the intensities of the first-order peak and the secondary harmonic peak in an echo Doppler spectrum, weighting and combining the estimating model parameters with the air speed, so as to obtain a final air speed estimation value. According to the method and the device, the problem of high-frequency ground wave radar that an existing air speed estimation method based on an echo second-order spectrum is not accurate enough is solved; the intensities of a first-order Bragg peak and the secondary harmonic peak in the echo Doppler spectrum are related with the air speed value, so that the air speed can be directly extracted from line spectrums including the first-order peak, the secondary harmonic peak and the like, and the estimation precision of the sea surface wind speed by the high-frequency ground wave radar is substantially improved.

The invention discloses a nonstandard format vertical sounding ionogram data processing method. A background noise value is used as the amplitude value of an invalid echo, a zero value is used as the Doppler frequency shift value of the invalid echo, and by means of the interpolation method, frequency and height data in nonstandard format vertical sounding ionogram data are transformed according to standard format requirements; by means of the normalization method, echo amplitude and echo Doppler frequency shift data in the nonstandard format vertical sounding ionogram data are transformed according to the standard format requirements, and the nonstandard format vertical sounding ionogram data are converted into standard ionogram data files. By means of the method, the different nonstandard format vertical sounding ionogram data are converted into current international standard data formats, and the purpose that the data are processed though international vertical sounding ionogram data processing software which is matured, universal and complete in function is achieved.