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 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 method for detecting terrain obstacles with an unmanned vehicle-borne radar based on echo characteristics. Through the echo Doppler frequency shift characteristics and the high-resolution range profile characteristics of the terrain obstacles, detection and recognition on slopes and ditches are achieved. The method is suitable for being applied to the small unmanned vehicle-borne millimeter-wave radar. Compared with the prior art, the unmanned vehicle-borne anti-collision radar designed through the method has the advantages that radar miniaturization is achieved conveniently, detection on the directions and pitching information of the obstacles can be achieved through a one-dimensional linear array, and a complex servo system is eliminated. The millimeter-wave radar is used for detecting the terrain obstacles, the influence of smoke, dust, rain, fog and other bad weather can be overcome, and the all-day working capacity of the radar is enhanced.

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 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 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 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 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 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.