35 results about "Doppler tolerance" patented technology

The invention discloses a related waveform design method for an MIMO radar part based on an LFM fundamental wave beam, and mainly solves a problem that the transmission directional diagram performance of waveform and the Doppler tolerance cannot be considered at the same time in the prior art. The method comprises the implementation steps: setting a waveform parameter and an expected directional diagram, and obtaining all fundamental wave beams and the time width of each chirp signal group; constructing all chirp signal modules according to the fundamental wave beams and the time width of each chirp signal group; and synthesizing a transmission waveform through the combination of all chirp signal groups. According to the invention, the method constructs a transmission directional diagram close to the chirp signal groups of the fundamental wave beams, synthesizes the transmission waveform through the combination of all chirp signal groups, enables the transmission directional diagram of the waveform to be able to approach the expected directional diagram, guarantees that the waveform has higher Doppler tolerance, and can be used for the design of the transmission waveform of the MIMO radar.

The invention discloses a radar waveform design method restrained by autocorrelation, orthogonality and Doppler tolerance. Firstly, a cost function with stable properties and with overall consideration of the autocorrelation, the cross correlation and the Doppler tolerance of wave forms is designed. Secondly, by using a Greedy random search optimization algorithm, repeated iterations are carried out until a system no longer receives any phase change, and the wave form design meeting the requirements of the full polarization measurement of radar is obtained.

The invention discloses a method of inhibiting direct wave interference by employing code phase modulation signals. The method comprises the steps of determining central frequency, bandwidth and pulse width of code phase modulation signals; adjusting coding forms and phase information of the code phase modulation signals, generating all candidate emission signals, calculating autocorrelation coefficients, screening the candidate emission signals and obtaining a preliminary emission signal set; calculating cross correlation characteristics of all signals in the set for the preliminary emission signal set, further screening the emission signals and obtaining a new emission signal set; and calculating fuzziness functions of signals in the emission signal set, obtaining doppler tolerance through the fuzziness functions, converting the doppler tolerance into theory velocity measurement precision, comparing the theory velocity measurement precision of each signal in the emission signal set with an allowed velocity variation scope of an active sonar task target and then selecting suitable emission signals in the emission signal set based on a comparison result.

The invention provides a multi access detection method used for Doppler tolerance, comprising the steps as follows: 1) at the emission end, a driving waveform used for detection is formed and emitted out; the driving waveform cuts the wideband hyperbolic frequency modulation waveforms into N sub-pulses; subsequently, the waveform is composed according to HFM-Costas formed by the resorting of N-order Costas coding sequence; 2) at the receiving end, the echo receiving detection of the driving waveform is carried out. The method of the invention has the technical effects that: compared with the driving waveform compared with the traditional multi access detection method, the HFM-Costas composite waveform in the novel method has better detection robustness on the Doppler tolerance; aiming at the interference-non-interference mixed detection receiving machine of the composite waveform, the Doppler passage searching is not needed, the structure is simple and the hardware cost is low.

The invention provides a quadrature encoding waveform determination method applied to a satellite-borne high-resolution wide-width SAR. First, preset input parameters are determined according to user requirements and constraint conditions of the satellite-borne high-resolution wide-width SAR; second, the Doppler tolerance fD of a transmitted waveform of the satellite-borne high-resolution wide-width SAR is determined; third, linear frequency modulation signal bandwidth BL of a quadrature encoding waveform and bandwidth BP and code length N of binary phase codes are determined through the Doppler tolerance fD, range resolution Rho r and pulse width T; fourth, the encoding group number M and system pulse repetition frequency (PRF) are determined according to azimuth resolution Rhoa and a satellite-borne striped SAR wave potential design formula; finally, the quadrature encoding waveform is designed according to the conditions obtained in the previous steps. When the quadrature encoding waveform determination method is adopted for realizing the satellite-borne high-resolution wide-width SAR, complexity of a system or complexity of an imaging method is not increased, and the requirement for system hardware is low; the image mode is simple, the imaging algorithm is mature, and large images of continuous scenes can be obtained; a novel SAR system wave potential design effort is created.

The invention relates to the field of underwater acoustics and more particularly to the field of signal processing in a low frequency (LF) active sonar system.The present invention makes it possible to decrease the false alarm rate while retaining the classification of the objects.The subject of the invention is a method of processing signals received corresponding to a signal emitted comprising by recurrence two pulses, a first Doppler tolerant broadband pulse of HFM type in particular and a second Doppler intolerant broadband pulse of BPSK type in particular, comprising:a step of detecting objects performed on the part of the signal received corresponding to the first pulses and providing an alarm for each object detected, anda step of classifying the objects detected performed on the part of the signal received corresponding to the second pulses for the alarms satisfying at least one predetermined criterion.