19 results about "Frequency agility" patented technology

The invention discloses a wide-area radar system combining satellite-borne mechanical scanning and phase scanning. The wide-area radar system is composed of a central processing unit, a servo controller, an active phased-array antenna and a scanning mechanism. The servo controller is mounted on the platform cabin, is rigidly connected and does not rotate; the central processing unit and the active phased-array antenna are installed on the load cabin, the load cabin is connected with the platform cabin through the scanning mechanism, and the servo controller controls the whole load cabin to rotate around the center of the load cabin. According to the method, a brand new satellite-borne wide-area radar system architecture is constructed, mechanical scanning and electric scanning characteristics are combined, flexible control of beam broadening, tracking staring, wide-area searching, frequency agility, power control and the like of a radar system is supported, and the method has an application mode integrating detection, tracking, imaging and recognition.

The invention discloses an interference signal suppression method and device based on an inter-pulse carrier frequency agility short pulse signal, a computer readable storage medium and computer equipment, relates to the technical field of communication, and mainly aims to solve the problem that an existing agility system radar is still poor in anti-interference capability in a complex electromagnetic environment and poor in interference performance. And the requirement of effectively detecting a detection target in a strong confrontation environment cannot be met. Comprising the steps that after radar equipment transmits an inter-pulse carrier frequency agile short pulse signal and receives an echo signal, a baseband echo matrix is acquired, and an interference judgment threshold value is determined based on the baseband echo matrix; when the variance of the distance unit of the baseband echo matrix is greater than the interference judgment threshold, determining that the distance unit contains an interference signal; and performing zero setting operation on the distance unit to obtain an echo signal after interference suppression.

The application provides a multi-station frequency agile radar anti-interference and synergistic method, through two short baseline pulse interval frequency agile radars receiving echo signals and carrying out mixing processing and pulse compression; interference pulses of an echo data matrix are removed and the remaining pulses are combined to obtain a new echo data matrix; a distance-speed two-dimensional redundant dictionary matrix corresponding to the new echo data matrix and matched with target information is constructed in combination with transmission parameters; then a compressed sensing model is constructed and a reconstruction result of an original signal is obtained by solving.The application selects two pulse interval frequency agile radars to work synergistically, which can effectively improve signal processing gain, has strong electronic countermeasure capability, good target detection capability and excellent electromagnetic compatibility; by utilizing the characteristic that only some pulses of echo of the pulse interval frequency agile radar may be interfered, the interfered pulses are directly removed in the echo data matrix, and complex matrix operation is not involved, so that the calculation complexity is low and the running speed is fast.

The invention discloses an intelligent frequency agility method and system based on frequency spectrum cognition and deep learning, and the method comprises the steps: generating a plurality of baseband linear frequency modulation signals with different center frequencies, and obtaining a broadband radio frequency linear frequency modulation signal set; inputting the signals into a digital phased array receiving channel at the same time to obtain a multi-path baseband data set; according to the real-time total delay of the receiving channel, performing integral multiple clock period delay on each signal data in the baseband data set to obtain a delay linear frequency modulation signal set; according to the multi-path baseband data set and the delay linear frequency modulation signal set, determining a peak position of each datum in the correlation peak data set through a peak search algorithm model, and further calculating a phase difference set; and removing a first-order linear component and a direct-current component in the phase difference set by adopting a dechirp algorithm to obtain a phase nonlinear set of the digital phased array receiving channel. According to the invention, nonlinear, efficient, accurate and low-cost measurement of the phase of the digital phased array receiving channel can be realized.

The invention discloses a folding clutter suppression method based on a frequency agility radar, and the method comprises the steps: setting the pulse number of a frequency agility pulse sequence, a frequency hopping interval and a frequency hopping coefficient of each frequency agility pulse signal, and transmitting a plurality of frequency agility pulse signals; calculating the carrier frequency of the echo signal received by the frequency agility radar according to the frequency hopping interval and the frequency hopping coefficient; filtering the echo signal by using a frequency domain filter corresponding to the echo signal carrier frequency, and outputting the filtered echo signal; respectively performing impulse response and convolution processing on the time domain and the frequency domain of the filtered echo signal by using a matched filter, and outputting the echo signal after matched filtering; and sparse reconstruction is carried out on observation signals in the sparse reconstruction model by using an orthogonal matching pursuit algorithm or an alternating direction multiplier method to obtain sparse vectors, so that target signal energy is enhanced, non-matching interference components are suppressed, significant enhancement of weak and small targets is realized, and folding clutters and noise are suppressed.

A system and method for testing coherent and frequency agility characteristics of a radar echo simulation device, the system comprising: a local oscillator signal generation module for generating a frequency agile local oscillator signal; a signal transmission module for generating a modulated transmit baseband signal; upconverting the modulated signal and transmitting to the device under test, outputting the phase and frequency of the transmit baseband signal to a phase difference calculation module and a frequency difference calculation module; a signal reception module for receiving a signal returned by the device under test, downconverting the received signal based on the frequency agile local oscillator signal to obtain a receive baseband signal, outputting the phase and frequency of the receive baseband signal to the phase difference calculation module and the frequency difference calculation module; a phase difference calculation module for calculating the phase difference between the receive baseband signal and the transmit baseband signal; a frequency difference calculation module for calculating the frequency difference between the receive baseband signal and the transmit baseband signal; a testing module for determining the coherent characteristic and the frequency agility characteristic of the device under test based on a plurality of sets of phase difference values and a plurality of sets of frequency difference values, respectively.

The invention belongs to the field of radar signal processing, discloses a method for acquiring a one-dimensional range profile of a high-speed moving target by sub-pulse linear frequency modulation emission and inter-pulse frequency agility radar, and realizes frequency agility waveform echo high-speed target detection and correction based on sparse representation. In the prior art, distance and Doppler parameter estimation of target echoes can be generally realized by adopting sparse representation and sparse processing, and orthogonal matching pursuit (OMP) is one of common solution algorithms. The carrier frequency of a frequency agility radar jumps randomly between pulses, and the acquisition of a one-dimensional range profile of a high-speed moving target not only needs to correct inter-pulse range migration, but also needs to compensate intra-pulse range-Doppler coupling generated by the change of the carrier frequency. According to the method, firstly, compensation of intra-pulse distance-Doppler coupling is carried out, then distance migration correction is carried out on each frequency agility pulse based on a KeyStone method, sparse processing is carried out on a corrected echo signal by adopting an orthogonal matching pursuit algorithm, and a high-resolution one-dimensional distance image of a target is obtained. Experimental results show that the one-dimensional range profile processing method for performing inter-pulse range migration correction through the KeyStone algorithm is beneficial to target detection in high-speed motion.

The invention provides an anti-severe environment wireless sensing system for a spacecraft. A multi-mode energy collection subsystem is used for collecting heat energy from a spacecraft structure in a high-temperature pneumatic heating environment and converting the heat energy into electric energy; the high-temperature energy storage subsystem is used for storing continuous low-power and transient high-power electric energy and providing transient high-power support for frequency agile communication and acoustic standby communication during sudden communication; the plasma self-adaptive frequency agility communication system is used for realizing self-adaptive wireless radio frequency communication in a plasma sheath layer; the acoustic standby communication subsystem is used for providing an independent structure guided wave acoustic communication channel when all radio frequency bands are shielded by plasma; the multi-parameter sensing subsystem is used for realizing measurement and data preprocessing of multiple physical quantities such as temperature, pressure and acceleration in a high-temperature environment; and the functionally graded material packaging structure is used for buffering thermal expansion mismatch under the conditions of high temperature and strong thermal cycle and integrally packaging the subsystems.

The application relates to a long-time accumulation and parameter estimation method under a frequency agile radar system, which comprises the following steps: radar echo signal down-conversion and pulse compression; search parameter interval and search interval initialization; non-uniform frequency domain generalized Radon Fourier transform is adopted to complete distance correction, Doppler phase compensation and hopping phase elimination under specific search parameters, and coherent accumulation is completed; search parameters are traversed, constant false alarm detection is carried out after signal energy is projected to the search parameter domain, if there is a target, the target motion parameters are determined according to the position of the energy peak, and the target motion track is output. The application effectively improves the echo signal-to-noise ratio of a complex maneuvering target and has target detection capability under a strong noise background.

The application provides a frequency-adjustable energy selection unit and surface, comprising a three-layer metal unit, a diode combination and a dielectric substrate design, realizes a working frequency agility function based on manual control through an applied bias voltage and an energy selection function controlled adaptively through sensing spatial energy, and has multiple functions of working frequency selection, working frequency band agility and spatial energy selection. The application solves the problem of unadjustable working frequency of the energy selection surface, so that the energy selection surface can not only realize strong electromagnetic protection, but also resist electronic interference, greatly expanding the function of the energy selection surface.

A radio frequency (RF) communications system may include a first RF node that transmits data, including a new frequency of operation, and a sequence of pilot symbols spread with a complex spreading code sequence. A second RF node may receive an incoming signal from the first RF node and perform despreading for N sample offset delays to generate N despreading sequences for the sequence of pilot symbols. The second RF node may perform a cross-correlation to select a desired despreading sequence from the N despreading sequences, determine a phase offset and timing offset, process the incoming signal based upon the desired despreading sequence, phase offset and timing offset, and switch to the new frequency of operation.

The invention discloses a software and hardware design method of a radar frequency agility control system based on an RFSoC, and the method employs a ZYNQ chip and a radio frequency front-end receiving and transmitting assembly to carry out the design of a radar system, and employs an upper computer to carry out the control and transmission of frequency agility parameters. Waveform generation is carried out through a ZYNQ chip, AD / DA conversion is carried out, frequency agility control is carried out through a control radio frequency front-end transceiving assembly, and rapid response to interference changes can be realized through efficient processing and real-time control. According to the RFSoC-based radar frequency agility control system digital signal processing platform, radar waveform generation and inter-frame agility, inter-pulse agility and shield agility of radio frequency can be realized according to radar application scene requirements.

The invention relates to the technical field of signal measurement, and particularly discloses a power and spectrum characteristic measurement method based on a pulse modulation signal, which comprises the following steps of: performing parallel acquisition on the pulse modulation signal, and extracting amplitude envelope data and instantaneous phase data; performing numerical analysis on the instantaneous phase data to obtain a carrier frequency deviation value, and comparing the carrier frequency deviation value with a preset frequency point set to generate a carrier frequency matching flag bit; detecting the arrival time of a pulse rising edge according to the amplitude envelope data, and performing combined judgment with the carrier frequency matching flag bit to output a frequency selective trigger signal; dynamically adjusting a center frequency and a gating window of frequency domain measurement according to the trigger signal, and collecting frequency domain spectrum data; carrying out time sequence association on the carrier frequency value, the time domain envelope parameter and the frequency domain spectrum data, and constructing a multi-dimensional association data chain; according to the invention, accurate screening measurement of specific frequency points in the frequency hopping pulse sequence is realized, and the problems of gating mismatch and time-frequency correlation fracture in a frequency agility scene are solved.

This invention discloses a design method for anti-jamming strategy of frequency-modulated agile signal based on DQN. First, the interaction process between the radar and the jammer is modeled as a Markov decision process. Then, the frequency modulation slope in the radar's transmitted waveform is used as the action, and the sequence of frequency modulation slopes in the radar and jammer's transmitted waveforms from the previous and current moments is used as the state. Next, a positive reward function is designed based on the correlation peak values ​​of the jamming and target signals, and a negative reward function is designed based on the signal energy and the probability of signal interception. Finally, the optimal SV-LFM signal slope variation strategy is learned through a deep Q-network. This method allows the radar to learn the optimal anti-jamming strategy without any prior information, enabling the radar system to adaptively suppress jamming while avoiding low signal-to-noise ratio and high interception probability caused by drastic pulse width changes.

This invention discloses a radar timing processing method based on wide-speed coverage, belonging to the field of radar signal processing technology. It aims to solve the problems of poor clutter suppression, limited velocity measurement range, and severe range-folded clutter interference in complex clutter environments by traditional moving target indication (MTI) filters. This method achieves wide-speed coverage at three times the speed of sound and effectively suppresses range-folded clutter through a timing design that alternates between positive and negative frequency modulation slopes and uses carrier frequency agility, combined with a genetic algorithm-optimized staggered pulse repetition period (PRT) and MTI filter weight coefficients. Experimental results show that this method can reduce the average amplitude of folded clutter by approximately 45 dB, successfully separate target signals obscured by clutter, and significantly improve the radar's target detection performance in complex environments.

The invention relates to a ship target identification method and device based on a frequency agility radar, and the method comprises the steps: transmitting a frequency agility waveform through the radar, obtaining a distance and speed distribution diagram of a target through a high-resolution distance and speed processing method, carrying out the feature extraction of the measured distance and speed distribution diagram, inputting the feature into a classification network, and carrying out the identification of a ship target. The ship target and the passive interference false target are effectively classified, and the classification performance of the ship target and the passive interference false target is improved. Therefore, the problems that in an existing ship target recognition technology, high-resolution range profile features are prone to being interfered by visual angles, micro-motion features excessively depend on long-time observation, and the classification performance of ship targets and passive interference false targets is greatly affected are solved.

This invention provides a networked radar decision-making method based on an improved MADDPG, which balances resolution and anti-interference performance, and relates to the field of radar anti-interference technology. First, an adversarial scenario is constructed between the networked radar and a multi-point broadband frequency-sweeping jammer, signal distribution is analyzed, and overlap coefficients are established. Second, the radar cooperative scheduling process is modeled as a multi-agent partially observable Markov decision process, constructing a composite reward function that balances detection resolution and anti-interference performance. Then, a multi-agent deep deterministic policy gradient algorithm is used for network training, and a self-attention mechanism is introduced in the value evaluation to extract mutual interference topology features, obtaining the frequency agility strategy for each radar. This invention overcomes the limitations of traditional discrete frequency hopping, enabling the radar to adaptively utilize fragmented spectrum to elastically expand bandwidth under conditions of no online communication, effectively achieving a comprehensive improvement in high-precision detection and high anti-interference survivability.

The application discloses a direct frequency synthesis frequency converter, which is used for solving the problem of how to obtain optimal phase noise through a single programmable frequency divider, and comprises a frequency mixing and frequency dividing circuit and a control circuit; the frequency mixing and frequency dividing circuit comprises a frequency divider circuit and a frequency mixer circuit; the application utilizes a programmable FPGA to control internal registers of an AD9516 through an SPI port, configures internal channel frequency divider values of the AD9516, realizes multiple frequency dividing functions, and the FPGA has a programmable function and cooperates with other modules of a radar to realize frequency agility controlled by a terminal program; an external clock of 1.2 GHz is used as an input clock source of distribution, and an internal VCO does not need to work. The AD9516 provides three level selections of LVPECL, LVDS and CMOS, and different frequency words are used to realize safe shutdown and value change control.