242 results about "Pulse compression" patented technology

The invention provides a target positioning method and system based on a distributed networking radar system, and belongs to the technical field of radars, and the method comprises the steps: controlling a plurality of radar nodes to transmit stepping linear frequency modulation continuous wave pulse signals, and collecting target echoes; carrying out band-pass filtering, pulse compression and fast time synchronization processing on the echoes, and generating interference-free data through a moving target extraction algorithm; realizing cross-node clock synchronization based on a moving target behavior cognition model and a template matching algorithm; constructing a multi-node distance estimation equation set, generating an accurate distance value through calibration broadband synthesis and FFT, and determining a target three-dimensional coordinate; and generating a motion track and speed prediction through Kalman filtering based on the target position sequence. The system comprises a signal emission and acquisition module, a signal processing module, a clock synchronization module, a distance estimation and coordinate fusion module and a trajectory prediction module. The method supports multi-target tracking, improves positioning precision and time synchronization precision, has few errors, and is compatible with any node deployment form.

The invention provides an ultrasonic detection method for internal defects of an insulating part of a power system based on a piezoelectric ultrasonic transducer, and belongs to the technical field of insulating part detection. After wavelet denoising and deep attenuation compensation are carried out on echo signals, sound path distance time delay and sound pressure amplitude parameters are extracted, defect identification and position estimation are carried out by utilizing a layered variational auto-encoder, a high-frequency transducer is switched to aiming at tiny defects, a harmonic component is extracted by adopting a nonlinear ultrasonic method, and a characteristic size is calculated; a defect distribution space feature matrix is generated based on a synthetic aperture focusing technology, a unified or personalized processing strategy is selected according to an acoustic characteristic homogenization degree evaluation value, a complete defect detection result is output, and the technical problem that deep weak defects in the electric insulation part are difficult to accurately detect and recognize is solved.

The invention relates to a tunable high-repetition-frequency high-power multi-wavelength optical pulse generation system, which belongs to the technical field of optoelectronic equipment and is structurally characterized in that the output end of a seed pulse source (1) is connected with the input end of a repetition-frequency multiplication module (2), and the output end of the repetition-frequency multiplication module (2) is connected with the input end of a shaping optical path module (3); the output end of the shaping light path module (3) is connected with the input end of the power amplification module (4), and the output end of the power amplification module (4) is connected with the input end of the pulse compression module (5); a multi-wavelength pulse seed source is designed by using a plurality of hybrid filters, and tunable multi-wavelength, high-repetition-frequency and high-power narrow pulse output is realized by using technologies such as an MZI-Sagnac hybrid repetition-frequency multiplication structure and the like.

The invention particularly relates to an airborne SAR distance compressed domain sea clutter suppression method based on generalized gamma distribution, and the method comprises the steps: carrying out the range pulse compression processing of an echo signal received by an airborne SAR, and extracting a pure sea clutter sample from compressed data through employing a non-local sampling strategy; then, a generalized gamma distribution model is quickly fitted for the clutter samples by using an analytical method based on a second type logarithmic cumulant, and a self-adaptive detection threshold is solved through an incomplete gamma function based on the model and a set false alarm probability. And finally, according to the threshold value, carrying out judgment and filtering on distance compressed domain data, suppressing clutter regions lower than the threshold value, and meanwhile, retaining potential target signals, thereby realizing efficient and steady clutter suppression under complex sea conditions.

The invention discloses a non-contact method for measuring a three-dimensional flow velocity field in a pipeline based on acoustic Doppler, and the method comprises the steps: transmitting a focused sound beam into the pipeline, receiving an echo signal reflected by a scatterer in fluid, and generating a Doppler echo signal set covering different angles and depth positions; performing pulse compression and time-frequency analysis on the Doppler echo signal set, and calculating the sight flow velocity component of each point along the sound beam direction; calculating a three-dimensional flow velocity vector of each sampling point based on the coordinate position of each space sampling point and the corresponding sight line flow velocity component, and realizing decoupling of the flow velocity direction and size; according to the spatial distribution of the three-dimensional flow velocity vector on the section of the pipeline, a three-dimensional flow velocity field model in the pipeline is generated through interpolation fitting, and section flow and flow state characteristic parameters are calculated according to the model. According to the embodiment of the invention, the limitation that only two-dimensional or one-dimensional flow velocity can be measured in a traditional method can be broken through, and the spatial resolution and measurement precision of flow velocity field reconstruction in a complex flow state are improved.

According to the megawatt-level half-cycle power generator based on the magnetic pulse compression system, by designing the constant-current magnetic switch reset circuit and the PID voltage stabilization charging technology, the pulse jitter characteristic within 10 ns can be achieved on the premise that megawatt-level power is output, the control precision is greatly improved, and stable output of high-power pulses is achieved. The problem that pulse generated by a traditional magnetic pulse compression amplifier is large in delay jitter is solved, high-precision output of megawatt-level pulses can be achieved, the high-precision magnetic pulse compression amplifier can be applied to a high-power transmitter needing to accurately control pulse output time, the high switching frequency and high switching efficiency of an MOS tube and the pulse compression characteristic of a magnetic switch are combined, and the high-precision magnetic pulse compression amplifier is achieved. The magnetic pulse power source has the advantages of high output power and high efficiency, improves the amplitude and phase stability of the output pulse compared with the traditional magnetic pulse power source, and expands the application scene and platform.

The invention belongs to the technical field of image processing, and discloses a three-dimensional radar sub-aperture imaging deformation monitoring device and method, and the device comprises a radar which is used for collecting echo signals passing through a preset position, processing the echo signals according to frequency mixing and analog-to-digital conversion, obtaining a three-dimensional echo matrix, and outputting the three-dimensional echo matrix; the three-dimensional echo matrix and a sampling ending signal are sent to a motion compensation module; the motion compensation module is used for resampling the azimuth direction of the three-dimensional echo matrix by adopting an interpolation algorithm; the distance matching filtering module is used for performing pulse compression on the distance direction of the three-dimensional echo matrix; the migration correction module is used for carrying out migration correction on the distance direction of the three-dimensional echo matrix after pulse compression; the sub-aperture imaging module is used for calculating a three-dimensional echo matrix after migration correction according to a sub-aperture imaging algorithm; and the deformation monitoring module is used for performing interference difference processing on the three-dimensional complex image to obtain deformation data. The imaging quality and the deformation monitoring precision can be improved.

The invention discloses a pulse compression radar accelerator generation method based on model driving, and relates to the technical field of pulse radars, and the method comprises the steps: based on a pulse compression radar signal processing flow, splitting operators according to calculation, interconnection and storage dimensions, and extracting features; defining 9 types of core components to form a parameterized component library; the components and the connection relation are combined, and an architecture description graph in a JSON format is generated; analyzing the ADG through an architecture interpreter to obtain a standardized parameter, and generating an RTL code based on a Chisel hierarchical architecture; performing simulation verification on the RTL code, pre-estimating the resource if the simulation verification is passed, and returning an error if the simulation verification is not passed; injecting expert configuration and combining with Latin hypercube sampling to obtain an initial solution set, iteratively searching a high-quality solution cluster by a TPE algorithm, resetting a parameter boundary and then switching to an ILS algorithm, and combining with a hardware rule to obtain a global optimal solution; and repeatedly executing the steps until the end conditions that the resources reach the standard and iteration reaches the upper limit are met, and outputting the accelerator architecture with the optimal resources under the target application constraint and the complete RTL code.

The invention belongs to the technical field of inverse synthetic aperture radars, and particularly relates to a tidal deformation dynamic modeling and parameter inversion method based on hybrid GRFT. The specific process is as follows: dynamic slope distance and echo modeling: aiming at each scattering point of a target celestial body, combining a radar position and introducing three-dimensional rotation correction caused by rotation to calculate a dynamic slope distance, and simulating a radar echo signal based on the dynamic slope distance; echo processing based on mixed GRFT: performing pulse compression on echo signals, compensating phase errors caused by rotation and deformation in sub-apertures by using the mixed GRFT, and performing non-coherent superposition on GRFT output of each sub-aperture; searching parameters: setting a search range of initial height and dynamic viscosity of each scattering point, setting a fitness function as non-coherent superposition energy synthesis of each scattering point, and searching in the search range until a termination condition is met; and tide deformation quantity calculation: calculating the tide deformation quantity according to the estimated values of the initial height and the dynamic viscosity of the searched scattering points.

The invention provides a mid-infrared optical frequency comb. The mid-infrared optical frequency comb comprises a near-infrared optical frequency comb seed source of a polarization-maintaining all-fiber structure; the all-fiber nonlinear amplification and pulse compression module is connected with the near-infrared optical frequency comb seed source through a polarization maintaining fiber and is used for amplifying the power of the seed light and compressing the pulse width after generating a linear chirped pulse; the all-fiber nonlinear spectrum broadening module is connected with the all-fiber nonlinear amplification and pulse compression module through a polarization maintaining fiber and is used for broadening a laser spectrum; the difference frequency module is used for receiving the laser pulse processed by the all-fiber nonlinear spectrum broadening module and generating an intermediate infrared laser pulse through intra-pulse self-difference frequency; wherein the seed source, the all-fiber nonlinear amplification and pulse compression module and the all-fiber nonlinear spectrum broadening module are connected through a polarization maintaining fiber to form an all-fiber integrated structure. By adopting the scheme, the anti-interference capability of the system can be enhanced, miniaturization and high operation reliability are realized, the debugging process is simplified, and the difference frequency efficiency is improved.

The invention belongs to the technical field of terahertz, relates to terahertz communication, and particularly discloses a quasi-optical resonant cavity and a terahertz pulse compression system. According to the invention, the pulse generation module and the coupling compensation module are connected in parallel and are connected to the common reflector through the common coupler, so that function decoupling is realized. In a pulse compression stage, the common coupler introduces an incident terahertz wave beam into two optical paths, and destructive interference occurs between two paths of leakage signals by adjusting the coupling compensation module, so that zero coupling loss is realized, and the problem of large energy loss is solved. Meanwhile, the pulse generation module can independently adjust the optical path of the pulse generation module to control the pulse width, and the adjustment process does not affect the optimized interference condition, so that the high robustness of adjustment is ensured. In the output stage, energy is released by switching the state of the common coupler. Compared with the prior art, low-loss accumulation and robust pulse width continuous adjustment are realized at the same time, so that the terahertz pulse compression effect is remarkably improved.

This invention discloses a phase compensation method for ship targets using ISAR based on block phase gradient autofocus. The steps include: pulse compression; range cell migration correction; range-oriented block segmentation; block phase compensation; calculation of the offset between adjacent image blocks; and image block alignment and stitching. This invention performs range-oriented block segmentation of the target echo, overcoming the shortcomings of existing technologies that ignore the spatial variation of rotational phase error, leading to defocusing in ship imaging, thus improving the accuracy of phase compensation and achieving good image focusing effect. Because this invention uses a phase gradient autofocus algorithm to compensate for the phase error within each block, and then uses a cross-correlation method to align and stitch the images of each block region, it overcomes the shortcomings of parameter estimation methods, such as complexity, time consumption, and poor real-time performance, and has the advantages of simple implementation, high efficiency, and strong real-time performance.

A pulse modification apparatus includes at least one pulse stretcher for dispersive stretching of laser pulses and / or at least one pulse compressor for dispersive compression of the laser pulses, an actuator for setting a dispersion of the at least one pulse stretcher or a dispersion of the at least one pulse compressor by setting at least one manipulated variable, a controller for controlling the actuator based on a measurement signal, and an ambient sensor for detecting at least one ambient parameter as the measurement signal. The dispersion of the at least one pulse stretcher or the dispersion of the at least one pulse compressor is dependent on the at least one ambient parameter.

The utility model discloses a femtosecond laser pulse compression device. The femtosecond laser pulse compression device comprises an amplifier, a first half-wave plate, a compressor, a second half-wave plate, a plano-convex lens and a solid sheet group which are sequentially arranged along a light path, laser pulses output by the amplifier enter the compressor after the polarization state of the laser pulses is adjusted by the first half-wave plate, the compressor is used for pre-compensating negative dispersion, the laser pulses output by the compressor enter the plano-convex lens after the polarization state of the laser pulses is adjusted by the second half-wave plate, and the laser pulses are focused by the plano-convex lens, enter the solid sheet group, are compressed and then are output; wherein the laser pulse generates a self-phase modulation effect in the solid sheet group, and the pre-compensation negative dispersion can counteract the positive dispersion generated by the self-phase modulation effect. According to the technical scheme, a chirp mirror does not need to be arranged, the cost can be reduced, and system operation is stabilized.

The invention discloses a ground-based radar space object long-time energy accumulation method based on an orbital element model, and the method comprises the following implementation steps: 1, building an orbital element parameter space, and mapping the grid points of the parameter space into the distance between a target and a radar; and step 2, calculating an envelope position and a phase which need to be compensated according to the mapped distance history at each parameter space grid point. And step 3, compensating a corresponding phase for the echo signal after pulse compression along the calculated envelope position, and then performing coherent superposition, thereby realizing long-time coherent accumulation of echo energy. According to the method, the orbital elements are adopted to construct the parameter space, energy accumulation is carried out in the parameter domain, due to the fact that the orbital elements can better represent the actual motion of a space object, the energy accumulation effect can be improved, meanwhile, the orbital elements are small in parameter space dimension, and the algorithm calculation amount can be greatly reduced.

The application discloses a method for sidelobe suppression of single-bit quantization Chirp signal, and the main technical content of the method comprises sidelobe suppression of single-bit quantization Chirp signal based on a convolution window function. The technical content performs sidelobe suppression through the following steps: step S1, generating a Chirp echo signal; step S2, single-bit quantization of the Chirp signal; step S3, single-bit quantization of a Chirp signal matching filter and adding a convolution window; and step S4, pulse compression of the single-bit quantization Chirp signal. The application can achieve a good compromise between quantization order and pulse compression effect, single-bit quantization can reduce quantization complexity to the maximum extent, and the sidelobe suppression method based on the convolution window function can effectively solve the problem of the decrease of the main sidelobe ratio caused by single-bit quantization. For Chirp signals and other radar signals with large time-bandwidth product, the application can improve the pulse compression effect, improve the range resolution of the radar system, and has certain reference significance for improved design in radar engineering technology.

The invention discloses a broadband radar distance extension target detection method and device, a terminal and a medium, and relates to the technical field of radar signal processing, and the method comprises the steps: obtaining each linear frequency modulation pulse radio frequency signal transmitted by a radar; in a walking and stopping mode, performing pulse compression on each linear frequency modulation pulse radio frequency signal by adopting pulse dechirp processing, and determining each dechirp processing signal; coherent energy accumulation is carried out according to the dechirp processing signals, and coherent accumulation signals are determined; converting the coherent accumulation signal to a frequency domain, and determining a dechirp pulse amplitude spectrum; and performing target detection according to the dechirp pulse amplitude spectrum, and determining a target detection result. According to the method, pulse dechirp processing and coherent energy accumulation are carried out on each received linear frequency modulation pulse radio frequency signal to obtain a coherent accumulation signal for subsequent target detection, so that the problem that in the prior art, when the signal-to-noise ratio is reduced, better anti-noise performance is difficult to realize with smaller calculation amount can be effectively solved.

The invention discloses an SAR intermittent sampling forwarding interference suppression method and system based on pulse compression and time-frequency analysis, and a storage medium, and the method comprises the following steps: carrying out the range pulse compression of SAR echoes containing interference pulse by pulse, so as to accurately obtain an interference-containing pulse sequence; and then, carrying out short-time Fourier transform on the pulse with interference after pulse compression and the nearest pulse without interference, and carrying out superposition and differential operation of two different dimensions to realize time-frequency domain positioning of the 2D-ISRJ. And designing a time-frequency domain filter, and carrying out time-frequency domain wave trapping on the positioned 2D-ISRJ. And finally, recovering the missing part of the signal after wave trapping by using the time-frequency data containing the interference pulse and the nearest non-interference pulse after pulse compression. According to the invention, the interference detection precision of typical two-dimensional intermittent sampling forwarding interference forwarding types can be relatively high under the condition of relatively weak interference, and the suppression method not only can achieve a relatively good suppression effect, but also can better protect useful signals.

This invention discloses a method and system for resisting slice reconstruction interference based on alternating frequency modulation slope polarity and time-series agility. It mainly addresses the problems of high complexity, poor real-time performance, and high dependence on prior information and training data in existing technologies. The scheme is as follows: At the transmitting end, a joint agile transmission signal is established based on the number of sub-pulses, sub-pulse duration, sub-pulse interval, sub-pulse bandwidth, and sub-pulse frequency modulation slope; at the receiving end, the received signal is segmented according to the recorded sub-pulse timing to obtain each segment signal, and pulse compression and delay compensation for both matched and mismatched channels are performed simultaneously; dynamic weights are generated based on the energy of the two compensated channels; an anomaly suppression factor is constructed based on the energy of the matched channels of each segment, and the output of each segment's matched channels is weighted and accumulated using this factor and the dynamic weights to obtain a one-dimensional range profile result. This invention does not require a large amount of training data or estimation of interference parameters, has low computational complexity, can suppress false targets generated by slice reconstruction interference while maintaining the energy of the real target, and can be used for target detection.

The application discloses a reflection type volume grating uniformity improving device and method, which adopts a double-system cooperative structure of axial exposure dose compensation and double-beam interference exposure. The axial exposure dose compensation system compensates the non-uniform axial exposure dose distribution caused by energy attenuation through laser irradiation of a photosensitive wave band of a recording medium and multi-axis rotation of the recording medium. The double-beam interference exposure system generates two collimated coherent lights with adjustable polarization states and powers by using laser of a high-transmittance wave band of the recording medium and a polarized beam splitter, and accurately controls the interference angle by adjusting the mirror posture, so that the high-contrast grating structure is written in the recording medium subjected to the axial exposure dose compensation. The application can effectively solve the non-uniform exposure dose distribution problem caused by laser energy attenuation in the traditional preparation process, thereby guaranteeing the consistency of the axial performance of the volume grating, and effectively promoting the development of the fields of high-performance laser beam combination, pulse compression and optical communication filter which need high-uniformity volume grating.

The application relates to the technical field of radar detection, in particular to a pulse compression ultra-low sidelobe nonlinear frequency modulation waveform design method based on dimension layering and two-stage optimization, which comprises the following steps: given signal parameters, GA parameters and a coefficient vector; the coefficient vector is initialized, a global search is performed by using a GA algorithm, genetic operations are performed, and after being crossed and mutated, energy projection normalization is performed to meet an energy constant constraint; when a termination condition is met, the global search is stopped and a candidate solution set is output; on the basis of the candidate solution set, a parameter space distance threshold is introduced to perform diversity screening, K candidate solutions which are dispersed from each other and excellent in performance are extracted and are zero-padded and dimensioned to obtain K seed vectors; the seed vectors are taken as initial values, a quasi-Newton method is respectively run to perform local optimization and finishing, a coefficient vector corresponding to an initial value which makes the sidelobe energy minimum is selected as an optimal coefficient vector, and a nonlinear frequency modulation waveform with the characteristics of an ultra-low sidelobe is generated based on the optimal coefficient vector.

The invention particularly relates to a weak target multi-station radar airspace accumulation method based on coherent receiving and transmitting channel matching, which comprises the following steps: a transmitting station transmits a linear frequency modulation pulse signal, and a receiving station receives a target baseband echo and performs pulse compression and discretization processing; the fusion center carries out time and space synchronization on the signals and then groups the receiving and transmitting channels in a search mode; coherent accumulation is adopted in the groups to maximize the cooperative gain, and non-coherent accumulation is adopted between the groups to avoid phase interference; and finally traversing the search unit and judging whether the target exists or not through threshold detection. The method can dynamically adapt to the echo correlation difference, achieves the optimal airspace accumulation gain, accurately detects a weak target in a low signal-to-noise ratio scene, greatly shortens the accumulation time, improves the early warning efficiency, is compatible with an existing multi-station radar architecture, and is high in engineering application value.

The application discloses a kind of synthetic aperture assisted multi-channel radar forward-looking learning imaging method, first, the echo data of the region to be imaged is acquired, the data obtained is compressed in distance direction pulse, then the echo data after pulse compression is imaged using the synthetic aperture assisted depth unfolding iterative shrinkage threshold algorithm ISTA network, i.e. in real aperture dimension, the imaging problem is converted into the estimation problem of target scattering coefficient, the target function is solved using the depth unfolding ISTA network, then the azimuth focusing is carried out using back projection BP algorithm in synthetic aperture dimension, then the synthetic aperture dimension result and the ISTA network result are fused to obtain the left-right unambiguous super-resolution imaging result.The method of the application overcomes the problem of left-right ambiguity and low resolution of single-base radar forward-looking imaging, realizes multi-channel radar forward-looking high-resolution imaging, and through depth learning, the parameter setting step is saved, the efficiency is improved, and the problem of signal-to-noise ratio sensitivity is overcome.

The invention discloses a time sequence generation and phase calibration method for a cooperative external radiation source radar system, and belongs to the field of radar signal processing, and the method comprises the steps: receiving a direct wave signal from a transmitting station in the cooperative external radiation source radar system, and determining a direct wave pulse pressure peak value position of a current PRT; when the last PRT of the current CPI is not reached, the sampling starting time of the next PRT is determined by utilizing the direct wave pulse pressure peak value position so as to sample echo data, the echo data are returned and processed continuously until echo signals of the whole CPI are obtained, and a fast-slow time dimension two-dimensional matrix is reconstructed; performing pulse compression on each PRT along a fast time dimension to obtain a fast-slow time dimension two-dimensional matrix after pulse compression; a smoothed phase sequence is obtained by extracting the maximum peak phase of each PRT; and compensating the phase difference of each PRT by taking the first PRT as a reference so as to finish phase correction. According to the invention, system inconsistency caused by asynchronous clock sources between double bases can be corrected.

An off-axis single-grating multi-pass pulse compressor disclosed by the present invention comprises a compression module and at least one group of mirror groups, the mirror groups are used for increasing dispersion compensation of the compression module, and the compression module comprises a D-shaped reflector, a grating, a plane reflector, a first horizontal mirror and a first high-low mirror. Each group of mirror group comprises two mirrors, one mirror of each group of mirror group is located at the laser output end of the compression module, and the other mirror of each group of mirror group is located above the first high-low mirror, or the other mirror of each group of mirror group is located above the second high-low mirror. And the other mirror of each mirror group is positioned on one side of the first high-low mirror and has the same height with the horizontal plane. According to the off-axis single-grating multi-pass pulse compressor, a multi-pass single-grating compressor can be achieved, the total dispersion compensation amount is greatly increased, the advantages of low cost and small size of a transmission-type single-grating compressor can be reserved, and the compression requirement of ultra-large chirped pulses can be met.

The application relates to the field of ultra-wideband radar imaging and optical computing technology, in particular to a light computing real-time processing method for ultra-wideband radar imaging. The method comprises core steps of signal receiving and electro-optical modulation, optical pulse compression, initial phase compensation based on Kalman filtering, envelope alignment, coherence recovery and two-dimensional grid projection. Based on the ultrafast linear processing advantage and algorithm optimization principle of light computing, the application utilizes optical finite impulse response filters and adjustable delay line technology to disassemble and reconstruct the traditional imaging method, and reduces the end-to-end processing delay to the sub-millisecond level. The application breaks through the real-time processing bottleneck of ultra-wideband radar imaging, provides effective theoretical support and method basis for developing a full real-time ultra-wideband two-dimensional fine imaging system, and is widely applicable to application fields with high real-time requirements such as military reconnaissance and geological exploration.

The invention discloses an efficient space-time processing method for multi-channel radar foresight imaging, which comprises the following steps of: firstly, acquiring multi-channel foresight radar echo data of an area to be imaged, and performing range pulse compression and range migration correction on the acquired data; the method comprises the following steps: firstly, carrying out space-time super-resolution and space-time beamforming on each channel, then separating echoes along a track area and deviating from a track area in each channel by using Doppler differences of different areas, finally, constructing different space-time guide matrixes for different echo data, respectively realizing imaging through space-time super-resolution and space-time beamforming processing, and further obtaining a final imaging result through splicing processing. According to the method, the calculation burden of multi-channel radar foresight super-resolution imaging is remarkably reduced, the space-variant problem of a point spread function is indirectly solved, and excellent imaging performance can be obtained.

This invention provides a semiconductor mode-locked laser and its fabrication method, relating to the field of optoelectronics. It addresses the problem in existing technologies where femtosecond pulses are difficult to output due to self-phase modulation and dispersion effects, thereby avoiding the use of external pulse compression technology and reducing production costs. The semiconductor mode-locked laser includes a mirror region, a gain region, and a saturable absorption region. The gain region is located between the mirror region and the saturable absorption region and is connected to both regions. The semiconductor mode-locked laser also includes a substrate, and a chirped grating layer and an active layer disposed on the same side of the substrate. The chirped grating layer is located in the mirror region and includes multiple gratings with a grating period linearly decreasing along the emission direction of the semiconductor mode-locked laser. The active layer is located in the gain region and the saturable absorption region, and the distance between the chirped grating layer and the substrate is greater than the distance between the active layer and the substrate.

One aspect of the invention relates to method and system for increasing signal-to-noise ratio (SNR) and suppressing range lobe artifacts in ultrasound imaging or sensing, active sonar, LIDAR, and / or radar. The method includes forming a coded excitation waveform with a chip waveform and a binary sequence; transmitting the coded excitation waveform into a medium of interest, and receiving signals generated from the medium of interest responsive to excitation of the coded excitation waveform; and performing pulse compression on the received signals using a decoding filter to increase the SNR and suppress the range lobe artifacts.

The invention particularly relates to a multi-dimensional suppressing interference rapid interception response signal processing method, which comprises the following steps of: setting energy and frequency detection after echo sampling, setting energy and frequency detection after digital down-conversion, setting signal feature detection after pulse compression and moving target indication, and setting statistical detection after CFAR (Constant False Alarm Rate) detection. Signal feature detection is set after moving target detection and SAR imaging. And based on the score of each detection module, control enabling of different priorities on the anti-interference function of the system, including an immediate dimension, a short-time dimension and a long-time dimension, is generated, so that the aim of rapidness is fulfilled. According to the method, the suppression interference is accurately and quickly identified in combination with the judgment standards of multiple dimensions, the anti-interference response is carried out at the fastest speed, and the anti-interference response is carried out at the fastest speed. The application can be well embedded into a conventional radar signal processing system, has the characteristics of strong universality, good real-time performance and high accuracy, and can be widely applied to the field of digital signal processing products.