113 results about "Pulse repetition frequency" patented technology

The invention relates to the technical field of synthetic aperture radars, and discloses a dechirp strip SAR waveform design method based on time domain azimuth ambiguity, and the method comprises the steps: obtaining the azimuth output maximum width and synthetic aperture length of an SAR image through calculation; respectively calculating the minimum value and the maximum value of the pulse repetition frequency through the scene size and the synthetic aperture length so as to determine the initial selection range of the pulse repetition frequency; constructing a time domain azimuth ambiguity function, presetting a time domain azimuth ambiguity value, and traversing all pulse repetition frequency values in the pulse repetition frequency initial selection range through the time domain azimuth ambiguity function to obtain a candidate pulse repetition frequency set; in the candidate pulse repetition frequency set, the minimum value of the pulse repetition frequency is used as the final pulse repetition frequency, and the technical problems that the existing time domain azimuth ambiguity is not fully constrained, so that the SAR image has fuzzy artifacts, the imaging quality is influenced and the like are solved.

The invention relates to the technical field of intelligent sensors, in particular to an unmanned aerial vehicle track intelligent tracking method based on a millimeter-wave radar, which comprises the following steps: receiving echo signals collected by the front end of the millimeter-wave radar, carrying out constant false alarm rate detection and Doppler frequency shift extraction on the echo signals, generating an unmanned aerial vehicle target space coordinate set, and carrying out target tracking on the unmanned aerial vehicle. And mapping the target space coordinate set of the unmanned aerial vehicle to a three-dimensional Euclidean space. According to the method, a non-convex optimization objective function containing beam switching time cost and precision constraint is constructed, and mathematical optimal solution of radar beam resources is realized. The generated adaptive scheduling instruction is used for adjusting the pulse repetition frequency and the beam residence time, it is ensured that radar front-end parameters dynamically evolve along with the target state, overall centroid tracking is emphasized for rigid body formation so as to save resources, independent high-frequency refreshing is emphasized for discrete targets so as to ensure the precision, and the accuracy is improved. And the continuity and robustness of trajectory tracking of the unmanned aerial vehicle in a complex electromagnetic environment are improved.

A method of measuring a delay time of a propagation of a signal in a line in a circuit structure, the method comprises irradiating the line by pulses of a charged particle beam, wherein a pulse repetition frequency of the pulses of the charged particle beam is varied. The method further comprises measuring, for each of the pulse repetition frequencies, a secondary charged particle emission responsive to the irradiating the line by the pulses of the charged particle beam at the respective pulse repetition frequency, and deriving the delay time of the line based on the secondary charged particle emission responsive to the varying of the pulse repetition frequency.

For shear wave imaging with ultrasound, the apparent pulse repetition frequency is increased by combining displacements from different lateral locations. Different combinations based on different shear wave velocities and corresponding time shifts and / or attenuations and corresponding scalings are tested to find a smooth displacement profile for the combination. Once the smooth displacement profile is found, the corresponding shear wave velocity is estimated or determined.

The embodiment of the application provides a parameter inversion method, device and electronic equipment, wherein the parameter inversion method comprises: performing interference suppression on a received incomplete SAR signal to obtain a non-interference signal matrix; wherein the non-interference signal matrix comprises a plurality of non-interference pulse signals with time sequence continuity, and the incomplete SAR signal represents that the SAR signal is incomplete; sequentially performing data processing on each non-interference pulse signal to obtain pulse parameters of each non-interference pulse signal; the pulse parameters at least comprise a stationary phase center position, a termination point, a pulse bandwidth, a pulse signal frequency modulation rate and a peak position; based on the pulse parameters of each non-interference pulse signal, signal parameters of the incomplete SAR signal are inverted to obtain transmission parameters of the incomplete SAR signal; the signal parameters at least comprise a pulse width, a bandwidth, a frequency modulation rate, a pulse repetition interval and a pulse repetition frequency.

FIELD: protective coatings.SUBSTANCE: method for forming a protective oxide-ceramic coating on the surface of products made of valve metals and alloys by the plasma electrolytic oxidation method involves immersing the product as an electrode together with a counter electrode in a bath filled with an aqueous alkaline electrolyte, and supplying rectangular pulses of anodic and cathodic voltage to the electrodes using a pulsed power source. Anode and cathode voltage pulses are supplied with a current-free pause between them, the value of which is 4.8 times the duration of the anode pulse. The amplitude values of the cathode voltage pulses range from 85 to 149 V with a pulse repetition frequency from 1000 Hz to 4000 Hz, while the current pulse repetition frequency is additionally regulated.EFFECT: obtaining oxide-ceramic coatings with specified properties under reduced energy conditions, with lower values of cathode voltage.1 cl, 2 ex

A laser system for multiphoton microscopy comprises a seeder oscillator, fast modulator, amplifier, second modulator, and optical parametric amplifier configured to produce pulses with variable pulse spacing temporally synchronized to a scanner having sinusoidal motion. The variable pulse spacing ensures each pixel receives substantially the same number of laser pulses, eliminating uneven energy distribution of fixed repetition rate systems. The scanner operates at 4-12 kHz frequencies while the seeder oscillator produces femtosecond pulses at 10-100 MHz with 10-100 ns pulse spacing. The optical parametric amplifier outputs wavelengths from 600-1900 nm, with 1300-1700 nm optimized for three-photon microscopy. Methods include synchronizing pulse timing to scanner motion and varying interpulse intervals across scan lines. For 8 kHz scanners with 512 pixels per line, the system achieves 32% energy reduction compared to constant pulse spacing while maintaining 100-150 mW average power on biological samples, preventing thermal damage and enabling video rate imaging.

A first radar transmitter capable of transmitting a pulse-modulated radar signal to a target, a second radar transmitter capable of transmitting a radar signal to the target, a radar receiver capable of simultaneously receiving a radar signal transmitted by the first radar transmitter and reflected by the target and a radar signal transmitted by the second radar transmitter and reflected by the target, and a signal control unit to control one or more of a carrier frequency, a pulse recurrence frequency, and a duty ratio of a pulse-modulated radar signal, and a carrier frequency of a non-pulse-modulated radar signal with respect to the first radar transmitter or the first radar transmitter and the second radar transmitter are provided.

For shear wave imaging with ultrasound, the apparent pulse repetition frequency is increased by combining displacements from different lateral locations. Different combinations based on different shear wave velocities and corresponding time shifts and / or attenuations and corresponding scalings are tested to find a smooth displacement profile for the combination. Once the smooth displacement profile is found, the corresponding shear wave velocity is estimated or determined.

The application provides a pulse repetition frequency type recognition method and device based on graph domain mapping and feature enhancement, and relates to the technical field of radar signal processing. The method comprises the following steps: determining a pulse repetition frequency sequence corresponding to a screened pulse repetition frequency; taking the reciprocal of the pulse repetition frequency sequence to obtain a pulse repetition interval sequence; dividing the pulse repetition interval sequence into multiple subsequences according to a preset length; transforming the multiple subsequences into a Gram difference angle field image according to a graph domain mapping algorithm, and dividing the image into training samples and test samples; constructing a pulse repetition frequency type recognition network, inputting the training samples into the pulse repetition frequency type recognition network, training the pulse repetition frequency type recognition network, and obtaining a trained pulse repetition frequency type recognition network; and inputting the test samples into the trained pulse repetition frequency type recognition network to recognize multiple pulse repetition frequency types. In this way, the recognition accuracy and robustness of the pulse repetition frequency type are improved in a complex non-ideal scene with a high proportion of missed pulses and false pulses.

The application discloses an engine rotor multi-parameter measurement system and method, and the system comprises a first optical comb, a second optical comb, a polarization maintaining optical fiber amplifier, a polarization maintaining optical fiber beam splitter, an integrated polarization maintaining optical fiber ring, an integrated polarization maintaining optical fiber beam combiner, a plurality of high-temperature-resistant optical fiber probes, a high-speed photoelectric detector and a data acquisition and processing system; the pulse repetition frequency of the first optical comb is greater than that of the second optical comb, and the two have a high repetition frequency difference; the plurality of high-temperature-resistant optical fiber probes respectively generate reference light pulses and measurement light pulses; the scanning light pulses emitted by the second optical comb respectively interfere with the plurality of reference light pulses and the plurality of measurement light pulses to generate double-comb interference reference signals and double-comb interference measurement signals; through processing of the reference signals and the measurement signals of each channel, the engine rotor speed, the blade tip clearance, the blade tip timing and the blade vibration parameters are obtained. The application has the advantages of high measurement speed, high measurement accuracy and multi-parameter synchronous measurement.

The present application relates to radar target recognition tracking technical field, especially in the field of phased array radar multi-target adaptive identification method and system, including: first, the radar echo and platform attitude data are acquired, the velocity distribution is extracted and the target is divided into two groups of high speed / low speed; for high speed group, the displacement prediction parameter is extracted to adaptively adjust the beam pointing sequence, for low speed group, the pulse repetition frequency is determined based on the residence time window and the frequency shift characteristics, and the resource allocation scheme is generated; then the attitude correction result is integrated into the beam control parameter, the adaptive observation sequence is generated combined with the resource scheme, and the trajectory information is tracked in real time; again, the Doppler shift deviation is estimated according to the trajectory, the gain / bandwidth and other signal processing parameters are compensated online, and the corrected target position and velocity are output. The present application realizes three-dimensional high-precision identification, continuous stable tracking and efficient resource utilization in complex dynamic scene.

The invention relates to the technical field of space imaging, and provides a space target space-based microwave imaging parameter optimization method and device. According to the method, through predicting a target intersection section of a detection satellite and a space target, an average relative speed, a minimum intersection distance and an orbit prediction error component of the detection satellite and the space target are extracted from the target intersection section; determining the optimized detection time length and the optimized detection frequency of the detection satellite at least based on the minimum intersection distance and the orbit forecast error component, and determining the optimized imaging time length of the detection satellite at least based on the average relative speed and the minimum intersection distance, and multi-constraint cooperative solution is carried out on the pulse repetition frequency PRF of the detection satellite at least based on the average relative speed and the minimum intersection distance to obtain the optimized PRF, microwave imaging parameter optimization design of quantitative model and actual scene constraint is realized, the efficiency is high, the application scene is wide, and the method is suitable for large-scale popularization and application. And powerful support is provided for precision improvement and engineering landing of a space-based microwave imaging technology.

The present application relates to a dual-comb laser, and in particular to a direction-polarization multiplexing single-cavity dual-comb laser, which solves the technical problems of the prior art that pulse components in different polarization directions are difficult to separate, leading to high difficulty in dual-polarization mode locking, harsh implementation conditions, or difficulty in adjusting the pulse repetition frequency difference, and the numerical value is small, or the mutual coherence of the output pulse sequence is low, and the signal-to-noise ratio is low. The present application adopts a full polarization maintaining optical fiber resonant cavity with a polarization beam splitter as a central node and a double-linked ring cavity structure composed of ring structure A and ring structure B. The laser transmitted in the counterclockwise direction in the ring structure A is cut off, and the laser transmitted in the clockwise direction is separated by the polarization beam splitter and transmitted in the opposite direction in the ring structure B, partially output, and partially returned to the ring structure A, thereby realizing cyclic oscillation.

The present specification describes a system for eliminating X-ray crosstalk between a plurality of X-ray scanning systems and passive radiation detectors. The system includes a frequency generator for generating a common operational frequency, a high-energy X-ray source or scanning system coupled with the frequency generator for receiving the common operational frequency and configured to modify the pulse repetition frequency of the high-energy X-ray source or scanning system in order to synchronize with the common operational frequency and a low-energy X-ray scanning system and / or passive radiation detection system coupled with the frequency generator for receiving the common operational frequency and having a processing module configured to remove data associated with the common operational frequency at an instance of time if the high-energy X-ray source or scanning system has emitted X-rays at the instance of time.

The application discloses an interferometric SAR synchronization method of radar inter-satellite link combined with Ka-band link cross correction, and aims at the problems of interrupting normal SAR imaging or existing initial phase winding in the existing synchronization link method, and proposes a cross correction scheme of X-band radar inter-satellite link combined with Ka-band high-precision synchronization link. The system adopts a common reference source to ensure the phase correlation, and different synchronization time sequences are designed, that is, the X-band link is synchronized at a low frequency to eliminate the initial phase winding, and the Ka-band link is synchronized at a high frequency same as the SAR pulse repetition frequency (PRF) to realize high-precision phase measurement. During ground processing, the initial phase error of the Ka-band compensation function is corrected by using the X-band synchronization data, so that a high-precision phase synchronization compensation function is obtained, and the echo of the secondary satellite is compensated. The application solves the problem of initial phase winding under the premise of not interrupting the normal SAR imaging time sequence, and significantly improves the phase synchronization precision, image quality and absolute height measurement reliability of the dual-satellite interferometric SAR system.

The method for avoiding third-order intermodulation based on radar waveform generation of the application comprises the following steps: obtaining image test results under different radar parameters based on a standard radar test, adjusting the relationship of the different radar parameters by a frequency spectrum analyzer, determining the relationship between the pulse repetition frequency (PRF) and the frequency difference of different radar signals, and the radar parameters including the radar pulse repetition frequency and the frequency difference between different radar signals; suppressing the third-order intermodulation when the radar transmits and receives multiple signals; after suppressing the third-order intermodulation, sending the generated signal carrier frequency information to the radar radio frequency part, generating corresponding multiple signals and radiating. In a manner without reducing the signal-to-noise ratio, the influence of the third-order component is avoided, thereby improving the signal detection performance of the radar.

Devices for providing an acoustic wave to a target location include at least one transducer device and at least one beam-forming processor to cause the at least one transducer device to produce a first acoustic wave, the first acoustic wave includes a plurality of pulses having a pulse repetition frequency, where a pulse width of each pulse is in a range of 10 ns to 10 μs and the pulse repetition frequency is in a range of 1 Hz to 50 Hz, receive data associated with a second acoustic wave, wherein the second acoustic wave is a reflection of the first acoustic wave, determine a characteristic of the second acoustic wave, and determine whether to change a beam path of an acoustic wave produced by the at least one transducer device based on the characteristic of the second acoustic wave. Methods and computer program products are also disclosed.

The application provides a kind of lossless echo spaceborne radar high-resolution wide swath timing design method, zebra chart is drawn using spaceborne radar parameters;The gap between the bands in the zebra chart selects the scene echo limiting area, thereby selecting the pulse repetition frequency range;Randomly select the pulse repetition frequency of each group in the pulse repetition frequency range to form a pulse repetition frequency sequence, and in turn judge whether the distance ambiguity corresponding to the pulse repetition frequency of adjacent two groups is consistent, if not consistent, then according to the pulse repetition frequency from small to large and from large to small, redesign the pulse repetition frequency at the connection of the group pulse repetition frequency sequence to obtain the designed pulse repetition frequency sequence. Through the fine timing design of the pulse repetition frequency sequence, the grouping pulse repetition frequency agile sequence without losing echo is obtained, which still uses the non-uniform undersampling method to ensure the high-resolution wide swath imaging requirements, and at the same time, it does not produce the collision of the transmit-receive timing, ensuring the integrity of the target information. In addition, the design also considers avoiding the influence of the nadir echo, ensuring the subsequent imaging quality.

The application relates to the field of artificial rainfall, and relates to a method for artificial rainfall by using silver iodide nanoparticles and a scattering device. The main purpose is to overcome the problems of low nucleation efficiency caused by the dependence of traditional artificial rainfall technology on explosives, low utilization rate of silver iodide and uncontrollable particle size. The main scheme comprises the following steps: generating a pulsed laser beam by a laser generator; adjusting the energy density of the laser beam to 1-100 J / cm 2 , the pulse width is nanosecond to femtosecond level, the pulse repetition frequency is 10-100 kHz, the laser beam is focused on the surface of a silver iodide target material; the transient photo-thermal effect of the laser beam is utilized to cause the silver iodide target material to be non-decomposable gasified to generate silver iodide vapor; the silver iodide vapor is condensed into 10-1000 nm silver iodide nanoparticles in the air through high-altitude low-temperature high-speed airflow to form artificial condensation nuclei; and the silver iodide nanoparticles are released to the top or inside of a target cloud layer to promote the condensation of water vapor in the cloud and the formation of precipitation.

The application provides a spaceborne bistatic SAR imaging system and method, comprising: a transmitting signal adopts a coded signal pulse sequence as a periodic transmitting sequence, and the relationship between any pulses is orthogonal; a pulse repetition frequency is set based on a bistatic configuration, and the adopted pulse repetition frequency should make the space-to-space direct wave and the bistatic SAR ground echo be received simultaneously, and the corresponding radar transmitting signal waveforms of the two are different; based on the setting of the coded signal pulse sequence and the setting of the pulse repetition frequency, the space-to-space direct wave and the bistatic SAR echo of an observation area which are mixed together in time are obtained, and the space-to-space direct wave and the bistatic radar echo signal obtained at the same time are orthogonal; based on the obtained space-to-space direct wave and the bistatic SAR echo of the observation area which are mixed together in time, the space-to-space direct wave and the bistatic SAR echo of the observation area are extracted respectively, and the function of spaceborne bistatic SAR imaging under space-to-space direct wave suppression is realized.

The invention provides a medium-high repetition frequency velocity measurement method and system based on a height-finding radar, and relates to the technical field of data processing and signal processing. According to the method, the target point track distance obtained through data processing is used as prior information, the number of target distance folding times is calculated, and the problem of range finding ambiguity caused by medium-high repetition frequency is solved; a medium-high repetition frequency mode is adopted for tracking speed measurement, and the problem that the low repetition frequency speed measurement range is small is solved; a multi-frequency mode is adopted, the prior information of the track speed of a target point is utilized, and corresponding pulse repetition frequency and emission frequency are calculated and selected, so that the blind speed problem is solved; the interference problem of ground clutter and meteorological clutter is solved by adopting multi-dimensional CFAR (Constant False Alarm Rate) processing and a method of narrowing a target search range through acquired priori information such as target point track distance and point track speed; a point track velocity measurement and Doppler velocity measurement combined processing method is adopted to solve the problem of velocity measurement resolution of monopulse radar.

The invention discloses a medium pulse repetition frequency set selection method based on an ant colony optimization algorithm and a storage medium, an optimal selection problem of a medium pulse repetition frequency set is modeled as a combinatorial optimization problem, and by introducing the ant colony optimization algorithm, on the premise of satisfying distance and speed fuzzy elimination constraints, the optimal selection problem of the medium pulse repetition frequency set can be solved. And the blind area proportion in the radar measurement space is minimized. According to the method, the optimization efficiency of the medium pulse repetition frequency set can be effectively improved, the blind area of the distance-Doppler two-dimensional space is remarkably reduced, the convergence speed and the global optimization capability of the algorithm are improved, and the method has good practical value and popularization prospect and is suitable for improving the target detection performance of a pulse Doppler radar system.

Disclosed is a real-time representation device for the GHz pulse repetition frequency based on dual-optical-comb spectroscopy. The device comprises a signal optical comb light source, a first polarization controller, a polarization beam splitter, a local oscillator optical comb light source, a first optical coupler, a second optical coupler, a first photoelectric detector, a third optical coupler, a second photoelectric detector, a high-speed oscilloscope, and a data processing module; real-time measurement of GHz pulse repetition frequency dynamics is realized; dual-optical-comb spectroscopy measurement technology is used to carry out real-time measurement on the spectral characteristics of the GHz pulse repetition frequencies of different soliton types; and the device has the advantages of high spectral resolution, high refresh rate, system integration, and the like, and solves the problems of the soliton evolution phenomenon of optical fiber lasers of special wavebands such as 2 μm, and transient changes of GHz pulse repetition frequency dynamics being difficult to effectively represent by means of a traditional average measurement method, and the like.

The invention particularly relates to a multi-beam phased array radar array plane control method, which comprises the following steps that a radar array plane is initialized after a first state machine is electrified, a timing module generates a first reset signal based on wavefront pulse to reset the first state machine, and a second reset signal is generated by dynamic delay to reset a second state machine and a third state machine; the first state machine loads the beam address and the forming data in parallel, completes beam storage mapping and automatically resets the address; the second state machine dynamically selects a reset strategy to realize time sequence connection, and beam switching is synchronized through a handshake protocol; a third state machine monitors a time sequence signal in real time and triggers protection when the time sequence signal exceeds a threshold value; the system circularly executes resetting, wave beam presetting, time sequence switching and thermal monitoring processes, adaptively adjusts parameters, and automatically cuts off a transmission time sequence when abnormity occurs. Through cooperative control of the multi-state machine, high-precision and high-reliability multi-beam dynamic management is realized, any number of beams, time sequence configuration and pulse repetition frequency are supported, and the flexibility and stability of a radar system are improved.

The invention relates to the technical field of optical fiber sensing, and provides a high-spatial-resolution distributed Raman optical fiber temperature measurement system and method. The system comprises a pulse laser, an avalanche photoelectric detector, a signal acquisition module and an upper computer, the pulse laser outputs high-repetition-frequency narrow-pulse laser which is injected into the sensing optical fiber to excite a back Raman scattering effect; the avalanche photoelectric detector converts the scattered light into an electric signal; the signal acquisition module adopts an asynchronous equivalent time sampling technology, an ADC module is controlled by an FPGA module to acquire signals point by point at a low sampling rate, a high-resolution waveform is recombined by using a small frequency difference between a sampling clock and a laser pulse repetition frequency, and a signal-to-noise ratio is improved through a plurality of times of cumulative average algorithm; and the upper computer reconstructs a complete time domain waveform and demodulates the temperature information of each position of the optical fiber. The high spatial resolution of 10cm is realized, the cost and complexity of the system are reduced, and the system is suitable for high-precision temperature measurement scenes.

A radiation system for controlling pulses of radiation comprising an optical element configured to interact with the pulses of radiation to control a characteristic of the pulses of radiation, an actuator configured to actuate the optical element according to a control signal received from a controller, the control signal at least partially depending on a reference pulse repetition rate of the radiation system and, a processor configured to receive pulse information from the controller and use the pulse information to determine an adjustment to the control signal. The radiation system may be used to improve an accuracy of a lithographic apparatus operating in a multi-focal imaging mode.

Bipolar high voltage bipolar pulsing ablation systems, devices, and methods are disclosed that include power supplies that can produce high voltage bipolar pulses with a positive high voltage pulse greater than about 200 V followed by a negative high voltage pulse less than about −200 V with a positive to negative dwell period between the positive high voltage pulse and the negative high voltage pulse. A high voltage bipolar pulsing power supply, for example, can reproduce high voltage pulses with a pulse repetition frequency greater than about 10 kHz.

The invention discloses an interference SAR (Synthetic Aperture Radar) synchronization method combining a radar inter-satellite link with Ka-band link cross correction, and provides a cross correction scheme combining an X-band radar inter-satellite link with a Ka-band high-precision synchronization link in order to solve the problem that normal SAR imaging is interrupted or initial phase winding exists in an existing synchronization link method. According to the system, a common reference source is adopted to ensure coherence, and different synchronization time sequences are designed: an X-band link is synchronized at a relatively low frequency and is used for eliminating initial phase winding; the Ka-band link is synchronized at the same high frequency as the SAR pulse repetition frequency (PRF) for high precision phase measurement. During ground processing, the initial phase error of the Ka frequency band compensation function is corrected by using X frequency band synchronization data, so that a high-precision phase synchronization compensation function is obtained, and auxiliary satellite echoes are compensated. According to the method, the problem of initial phase winding is solved on the premise of not interrupting a normal SAR imaging time sequence, and the phase synchronization precision, the image quality and the absolute elevation measurement reliability of a double-star interference SAR system are remarkably improved.