45 results about "Echo doppler" patented technology

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 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 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 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 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.

Aiming at the failure of the fractional-order Fourier transform algorithm in the impulsive noise environment, the present invention utilizes a nonlinear transform-Sigmoid transform to suppress the interference of the impulsive noise, and utilizes the energy aggregation characteristics of the fractional-order Fourier transform to propose a A new method for joint estimation of Doppler frequency shift spread factor and time delay for LFM pulsed radar. First, the Sigmoid transform is combined with the fractional Fourier transform, and a sigmoid-based fractional Fourier transform (Sigmoid‑FRFT) is proposed. Next, the joint estimation of Doppler frequency shift spreading factor and time delay is realized by Sigmoid‑FRFT peak point search. This method does not require prior knowledge of noise, and has strong tolerance to noise with low signal-to-noise ratio. Experimental results show that the method has higher parameter estimation accuracy and lower computational complexity under impulse noise.