35 results about "Doppler tolerance" patented technology

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 relates to a noise-like Chirp-based Q-CCSK (Quadrature-Cyclic Code Shift Keying) spread spectrum communication method, and belongs to the technical field of wireless communication. According to the method provided by the invention, due to the good autocorrelation characteristic of noise-like Chirp signals and the mutual correlation characteristic of the noise-like Chirp signals at different frequency modulation rates, the noise-like Chirp signals are used as a base function of Q-CCSK spread spectrum modulation; therefore the Doppler tolerance is greater, and the great Doppler frequency offset can be resisted, so that the signal capturing time under a high dynamic environment is shortened, and the safety of the wireless communication is improved; as the information is carried for signal sectional cyclic displacement through a Q-CCSK modulation technique, the frequency band utilization rate of spread spectrum communication is effectively improved.

The invention discloses an SAR imaging method based on the LFM-PC composite modulation signal and polar coordinate format algorithm, which uses the phase coded signal modulated LFM signal to obtain a new composite modulation signal of LFM-PC signal wherein the LFM-PC composite modulation signal is used as a radar transmitting signal and PFA is used for imaging processing. As the phase modulation function of LFM-PC signal obtained from the phase coded signal modulated LFM signal is continuous, the SAR imaging method based on the LFM-PC composite modulation signal and polar coordinate format algorithm becomes feasible. At the same time, the Doppler tolerance of LFM-PC signal is greatly improved compared with the phase coded signal. Therefore, the invention can achieve a good imaging effect and good an anti-interference performance under small inclined perspective.

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, and a 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.

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 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 discloses a complementary waveform construction method and module, a cognitive radar system and a waveform emission method, solves the problem that an existing complementary waveform construction method cannot provide enough and flexible Doppler tolerance, and belongs to the technical field of radar emission. The waveform construction method comprises the steps of determining input parameters according to requirements, and constructing a constant vector and a constant matrix; under given high-order Doppler frequency spectrum zero constraint and energy constraint, constructing a constraint optimization problem by taking maximization of similarity between a received pulse weight and a given window function as an optimization target; solving to obtain a transmitting sequence vector and a receiving pulse weight vector, and further constructing a transmitting pulse string and a receiving reference signal to complete complementary waveform construction. According to the method,a complementary waveform construction module is obtained by using a computer, a cognitive radar system is formed by combining the radar and the waveform, and the waveform transmitting method can intelligently select to transmit a common pulse string and a Doppler-tolerant complementary waveform pulse string to realize target detection.

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 provides a method for determining an LFM waveform of a distributed spaceborne radar based on different frequency modulation slopes of the same bandwidth. A linear frequency modulation signal of the same carrier frequency, the same time width and the same bandwidth is equally divided into two segments on the time axis, each segment is modulated by using a different frequency modulation slope k, a transmitting signal model of different frequency modulation slopes of the distributed system radar is established to analyze the influence of differences of the frequency modulation slopes on the waveform orthogonality and Doppler sensitivity, autocorrelation, cross-correlation and Doppler tolerance and other parameters of the transmitting waveform are set via theoretical analysis, double-segment transmitting waveform parameters of each radar unit are determined, the quasi-orthogonality and low Doppler sensitivity between multiple double-slope LFM signals are achieved at last, andthe demands of the distributed system radar for the transmitting waveform are met without increasing the bandwidth of the radar system. The method provided by the invention is simple in operation, and can be used for significantly improving the orthogonality of the transmitting waveform of the distributed spaceborne radar system, and reducing the crosstalk between the radar units and the requirements of the distributed system for the system bandwidth B.

The invention discloses an automatic detection and judgment method for a vector hydrophone line spectrum, relates to the technical field of underwater acoustic signal processing and signal detection,and the method can be used to judge the existence of a moving target through change of amplitude and orientation and effectively exert the due effect of underwater target line spectrum detection, andis reliable in detection technology and low in false alarm rate. According to the technical scheme, the method comprises the following steps that each frame of vector data received by a vector hydrophone is obtained, the average sound intensity spectrum of each frame of quantity data is solved, a slope threshold and a peak height threshold are adopted to extract a line spectrum from the average sound intensity spectrum, and the line spectrum is composed of line spectrum frequency; from the second frame of vector data, the line spectrum frequency of each frame of vector data is compared with the line spectrum frequency of the previous frame of vector data, and the line spectrum frequency meeting the Doppler tolerance is classified as the line spectrum of the same target. The line spectrum frequency belonging to the same target is compared and judged, it is judged that the target exists if the forward amplitude change and the monotonous orientation change exist, and an alarm signal is sent.

The invention discloses a method for designing a zero-setting waveform of an LFM signal of an MIMO radar. The method comprises: step one, establishing an MIMO radar model; step two, initializing an LFM signal frequency interval and an initial phase; step three, calculating the center frequency of each LFM transmitting signal; step four, calculating a frequency modulation slope of each initial LFMsignal; step five, generating a matrix of the LFM signals; step six, calculating a covariance matrix of the LFM signal matrix; step seven, calculating the zero-falling depth of the LFM signal in the direction of radar interference; step eight, calculating the zero-falling depth of the LFM signal in the direction of radar interference; step nine, optimizing a waveform frequency interval and an initial phase of the LFM signal; and step ten, acquiring the optimized LFM signal waveform. The designed waveform has the advantages of good Doppler tolerance and no radiation power to the interference direction.

The invention discloses an LFM-PC signal and an ambiguity function optimization method thereof. The method comprises the steps that an optimization model is established based on a minimum peak sidelobe level criterion, the ambiguity function is optimized by adopting a sequential quadratic programming method, and the practicability of the method is examined through simulation. According to the LFM-PC signal and the ambiguity function optimization method thereof, a set of orthogonal phase-encoded signals are used as radar transmitted signals to improve anti-jamming performance of an SAR; compared with an LFM, the new signal has better anti-jamming performance, and compared with the phase-encoded signal, the new signal has a larger Doppler tolerance; the minimum peak sidelobe level criterionis adopted, and the ambiguity function is optimized by adopting the sequential quadratic programming method, so that the Doppler tolerance of the signal is enlarged.

The invention provides a satellite navigation signal design method based on pseudo-random Chirp. A navigation signal reference signal of each satellite is formed by splicing two sections of Chirp signals with the same symbol duration, the same frequency spectrum width and completely opposite modulation frequencies, and each section of Chirp signal is formed by splicing two sections of Chirp signals with the same modulation frequency and different initial frequencies; pseudo-random phase modulation of the reference signal of each satellite is carried out; the coded navigation message is modulated to the designed pseudo-random Chirp signal to obtain a satellite navigation signal. The method has the characteristics of large Doppler tolerance, multiple access and physical layer security. The method can fundamentally reduce the dimension of the receiver capture process into time domain one-dimensional search, shortens the capture time, improves the dynamic stress of a receiver, meets the carrier phase estimation requirements under high dynamic conditions, and is suitable for the fields of satellite navigation systems, pseudo-satellite positioning auxiliary systems, indoor positioning systems and the like.

The invention relates to a genetic-algorithm-based quadrature phase coding waveform design method. The method comprises: step one, an initial sample signal is generated; step two, fitness of an initial sample is calculated; to be specific, fitness of each individual sequence is calculated by using an MPSR as a fitness function; the MPSR is compared with a design threshold, an algorithm is completed on the condition that the MPSR threshold is met and an individual number reaches a need, and otherwise, execution is carried out continuously; with an optimal reserving method, an individual with the highest fitness in the sample is reserved and is used for replacing an individual with the lowest fitness; pairwise matching is carried out on individuals in the sample randomly, matched parent individuals are replaced based on a certain crossover probability and recombination is carried out to generate new individuals; and on the basis of a certain mutation probability, a code value of a certain individual in the sample changes. Therefore, the formed signal has high correlation, high frequency resolution ratio, high Doppler tolerance, and good anti-reverberation capability. The method is suitable for an acoustic positioning system; and continuous and high-precision positioning is realized.

The invention provides a Doppler compensation method for a phase-coded signal based on tracking information. The Doppler compensation method comprises the following steps: estimating a Doppler compensation range of a target echo; performing sliding window detection on the target echo in the Doppler compensation range to obtain phase information, and comparing a differential mean value result of the phase information with a threshold value; when the differential mean value result is larger than the threshold value, obtaining the actual position of the target echo, determining whether the difference value between the target speed information and the target speed predicted by the tracking algorithm is within the Doppler tolerance bandwidth or not, and performing Doppler compensation on the target echo according to the judgment result; and when the differential mean value result of the phase information is less than or equal to the threshold, performing Doppler compensation on the target echo by using the target speed in the Doppler compensation range. According to the technical scheme provided by the invention, the Doppler compensation problem of the multi-target phase encoding echo signal is effectively solved.

The invention provides a sparse moving target detection method based on a slow time sliding window filter. The method belongs to the field of radar moving target detection methods, and comprises the following steps: designing a pulse repetition interval sequence optimization problem with optimal regional Doppler tolerance accumulation as a criterion based on a generalized fuzzy function, and obtaining an optimal solution through problem conversion and a gold region search method. The invention aims to provide a brand-new radar moving target detection method in a sparse target environment. A concept of a generalized fuzzy function is introduced, and a secondary modulation pulse repetition interval sequence and a corresponding slow time matching filter are designed, so that a moving target detection processing flow is simplified, and meanwhile, the sparse moving target detection capability of a given Doppler range is enhanced.

The invention discloses an NC-CE-OFDM radar communication integrated waveform design method, and the method comprises the steps: setting a signal parameter, and initializing a target state; determining a subcarrier position and a PAPR condition of an unoccupied frequency band through a dynamic spectrum sensing and channel estimation technology; the PAPR is reduced by using a phase technology, and communication information is modulated on a subcarrier which does not occupy the bandwidth for transmission; solving the error rate of the discontinuous constant envelope integrated signal in the additive white Gaussian noise channel; solving a fuzzy function in the radar communication integrated signal; and solving the distance resolution, Doppler resolution and Doppler tolerance characteristics of the integrated signal waveform according to the fuzzy function. According to the method, the discontinuous OFDM signal and the phase modulation technology are combined, the problem of spectrum resource shortage can be relieved, and the maximum utilization rate of the discontinuous OFDM signal spectrum is achieved.

The invention discloses a dual matched filtering method and device and electronic equipment. The method comprises the following steps: acquiring an echo signal of a preset signal sent to a moving target; according to the echo signal, obtaining a Doppler channel signal where the target is located; obtaining a delay signal group according to the Doppler channel signal; obtaining a reference signal group according to the Doppler channel signal and the delay signal group; performing matched filtering on the reference signal group to obtain a matched filtering result of the reference signal group; and performing transformation processing on the matched filtering result of the reference signal group to obtain a detection result of the target. According to the method, pulse pressure distortion caused by Doppler frequency shift of signals in conventional matched filtering is eliminated, Doppler tolerance of the signals is eliminated, and a technical basis is provided for improving low-interception anti-interference performance of a radar and improving high-speed small target detection capability; the method can be applied to various types of radars, sonars and navigation equipment, and has popularization and application values.

The invention relates to a method for improving Doppler tolerance of slow time phase-coded signals of sky wave radar and particularly relates to a method for improving Doppler tolerance of slow time phase-coded signals of sky wave radar. The method aims to solve a problem of low Doppler tolerance caused by LFMCW (Linear Frequency Modulation Continuous Wave) slow time phase coding of the existing sky wave radar. The method comprises the following steps of 1, setting that a sky wave MIMO radar transmitting station has M transmitting array elements, detecting periodic signals to form a group of slow time phase coded signals, and setting the signal transmitted by the mth transmitting array element as sm(t); 2, determining a slow time phase code; 3, determining the pulse width of the fast time phase coded signal; 4, calculating the number of the fast time orthogonal signals; 5, calculating the code element width of the fast time phase coding signal; 6, calculating the number of code elements of fast time phase coding; 7, obtaining a phase matrix of the optimized fast time orthogonal coding multi-phase set; and 8, obtaining a final transmitting signal of the MIMO radar. The invention relates to the field of radar communication.

The invention discloses an optimization design method of an LFM-PC composite modulation signal. The method comprises the following steps: constructing a discrete model of a fuzzy function of the LFM-PC composite modulation signal; constructing an optimization model based on the discrete model; and solving the optimization model through an ADMM algorithm, wherein the composite modulation signal is obtained through intra-pulse linear frequency modulation and intra-pulse phase coding composite modulation. The optimized LFM-PC signal obtained by the optimization design method of the invention has a lower normalized sidelobe while maintaining wide Doppler tolerance, and has a higher radar detection capability.