1558 results about "Multiple frequency" patented technology

The invention provides a directional energy multi-target interference system based on an ultra-wideband phased array technology, and the system integrates signal perception, target recognition, interference signal generation and phased array control, so as to achieve the precise interference of an unmanned aerial vehicle cluster. The signal sensing module scans an airspace target through the ultra-wideband phased-array antenna array and obtains spectrum characteristics of a target signal. The target identification module analyzes signal features, identifies an individual target and predicts a motion track and a communication protocol of the individual target. And the phased array control module calculates and adjusts antenna beam forming parameters, and dynamically controls the radiation direction, phase and transmitting power of the antenna. The interference signal generation module generates a matched interference waveform based on the target communication protocol and the trajectory information. The ultra-wideband phased-array antenna array adopts a digital beam forming technology. According to the invention, efficient and accurate directional energy interference can be realized under multiple frequency bands, the confrontation capability of the unmanned aerial vehicle cluster is improved, and the method is suitable for defense tasks in electronic warfare and complex electromagnetic environments.

A method and apparatus for frequency priority for cell reselection in a wireless communication system is provided. A wireless device may receive, from a network, a cell reselection configuration associated with a Non-Terrestrial Networks (NTN) cell. The wireless device may apply the first priority values for the multiple frequencies. The wireless device may determine that the location condition for a specific cell in a specific frequency, among the multiple frequencies, is met. The wireless device may apply a second priority value for the specific frequency.

The invention relates to a lithium battery electrochemical impedance spectroscopy online measurement and estimation method and system based on a charging pile, and belongs to a battery detection technology. The system comprises a measurement module, an estimation module and a result output module. The measurement module comprises a signal generation sub-module, a waveform amplification sub-module and a response processing sub-module; a pulse control signal is inserted into the signal generation sub-module during charging, and is amplified into a measurement excitation signal by the waveform amplification sub-module to be applied to a battery; the response processing sub-module samples the response signal and calculates an impedance spectrum. The estimation module comprises a neural network sub-module and an impedance spectrum estimation sub-module; the neural network sub-module is used for training a physical information neural network by using impedance response to output Randles circuit model parameters to the estimation sub-module, and the change of the electrochemical impedance spectrum is predicted. And the result output module displays and stores the measured and estimated values of the impedance spectrum. According to the invention, the impedance values of the to-be-measured battery pack under multiple frequencies can be measured and estimated on line, and the estimation of the impedance spectrum is physically interpretable.

The invention relates to the technical field of information transmission, in particular to a multi-band processing system for electronic communication, which comprises a signal separation module, a frequency deviation compensation module, an amplitude correction module, a phase correction module and a dynamic feedback adjustment module. According to the invention, a plurality of frequency bands are extracted to execute band-pass filtering to separate signal components, short-time power spectral density is calculated to describe energy distribution, normalization coefficient operation is carried out to enhance frequency domain balance, high-energy component screening is carried out to reduce noise interference, signal effectiveness is improved, and frequency offset compensation calculates a change rate based on adjacent phase data and eliminates abnormal fluctuation. A time domain coefficient is adjusted to correct a frequency offset error, amplitude correction depends on short-time Fourier transform to screen the maximum amplitude to optimize signal consistency, phase adjustment fits a group delay error curve to optimize compensation parameters, dynamic feedback optimizes a strategy according to a signal-to-noise ratio to enhance compensation precision, and signal transmission quality and stability are improved.

The invention relates to the technical field of audio signal processing, and discloses a room sound correction method, device and equipment for audio equipment and a storage medium, which are used for improving the accuracy and correction effect of correction parameters and effectively improving the acoustic effect of the audio equipment in a room. The room sound correction method of the audio equipment comprises the following steps: acquiring response data of a room to a multi-band preset test signal, and extracting room acoustic data by adopting a time-frequency conjoint analysis method, the room acoustic data comprising frequency attenuation, reflection paths, phase shifts and reverberation time information of different bands; based on the room acoustic data, performing compensation processing by using preset microphone calibration data to obtain a calibrated frequency response curve; performing fitting calculation on a preset ideal frequency curve and the calibrated frequency response curve according to an optimization algorithm to obtain specific correction parameters of the room; and correspondingly adjusting the output of the audio equipment according to the correction parameter.

The invention discloses an electroencephalogram signal frequency domain feature extraction optimization method and system, and relates to the technical field of biomedical signal processing, and the method comprises the steps: obtaining a time domain signal; carrying out noise removal processing on the acquired time domain signal by adopting an adaptive noise filtering algorithm to obtain a processed time domain signal; performing spectral analysis on the processed time domain signal through a frequency domain conversion algorithm to generate a frequency domain signal; dividing frequency bands of the frequency domain signal according to different frequency ranges to obtain decomposition signals of a plurality of frequency bands; extracting frequency domain features from the decomposed signals, and summarizing the extracted frequency domain features to generate an initial feature set; performing dimension reduction processing on the initial feature set by applying a dimension reduction technology to obtain an optimized feature set; and classifying the optimized feature set by using a machine learning model suitable for a classification task to obtain a classified feature set. The method solves the problems that in the prior art, the current electroencephalogram signal processing efficiency is poor, and the practical application of the electroencephalogram signals is affected.

The embodiment of the invention relates to the technical field of vehicles, and discloses an atmosphere lamp control method and device, a vehicle and a computer readable storage medium, and the method comprises the steps: obtaining the frequency domain information of a to-be-played audio, then determining the target decibel corresponding to each frequency band range in a plurality of preset frequency band ranges according to the frequency domain information, and obtaining the target decibel corresponding to the target decibel; the multiple frequency band ranges are frequency band ranges obtained by dividing a low-frequency part and a high-frequency part of the audio frequency, the frequency band width of the frequency band range corresponding to the low-frequency part is smaller than that of the frequency band range corresponding to the high-frequency part, and finally the atmosphere lamp is controlled to operate according to the target decibel corresponding to each frequency band range. By applying the technical scheme of the invention, the dynamic change of the atmosphere lamp can be coordinated with the music content, so that the user experience is improved.

The invention relates to the field of surface-mounted metasurface structure design, in particular to a design method and device for a multi-frequency transparent transmission type surface-mounted metasurface structure, and the method comprises the steps: representing a multi-layer structure of a glass surface-mounted metasurface through a cascade transmission matrix; wherein the metasurface comprises a metal layer and a dielectric layer; a corresponding transmission coefficient is calculated by using the represented cascade transmission matrix, and a theoretical optimal transmission coefficient of a target frequency band under the structure is obtained by adjusting the dielectric constant and the thickness of a metasurface dielectric layer and the equivalent impedance of a metasurface metal layer to determine an initial structure and a parameter change interval of a to-be-optimized metasurface unit; simulating to obtain a transmission coefficient under the initial structure of the metasurface; and based on the transmission coefficient under the initial structure of the metasurface, taking a theoretical optimal transmission coefficient as an optimization target, and adopting a quasi-Newton algorithm to optimize metasurface design to obtain a metasurface structure corresponding to the optimal transmission coefficient. Compared with the prior art, the invention has the advantages of greatly and stably improving the transmission performance of multiple frequency bands and the like.

The invention relates to a method and a device for probing a subsurface structure. The method comprises the steps of (a) sending a probe signal as an electromagnetic wave into the structure. (b) receiving an echo signal of the electromagnetic wave from the structure, and (c) processing the echo signal for deriving information about the structure. The step (c) of processing the echo signal comprises sampling the echo signal at a sampling frequency fs. The probe signal comprises multiple discrete frequency components fn,k, wherein at least two of the multiple frequency components fn,k are located in different Nyquist zones. An n-th Nyquist zone covers a frequency range from (n−1)*Tfs / 2 to n*fs / 2 with fs being the sampling frequency and n=1, 2 . . . . Further, k=1 . . . K and K is the number of frequency components fn,k in the n-th Nyquist zone. The method and device facilitate an increase in data acquisition speed without losing information on any of the frequency components.

The invention provides a modified basalt fiber, a basalt fiber shielding material and a preparation method, and relates to the technical field of fiber composites.The modified basalt fiber comprises an activated basalt fiber, an adhesion layer and an electromagnetic shielding layer, and the surface of the activated basalt fiber is sequentially coated with the adhesion layer and the electromagnetic shielding layer; the adhesion layer comprises polydopamine; the electromagnetic shielding layer comprises magnetic Fe3O4 nano particles and a graphene nano sheet; the mass ratio of the activated basalt fibers to the polydopamine to the magnetic Fe3O4 nanoparticles to the graphene nanosheets is 1 to (0.4 to 0.5) to (0.6 to 1) to (0.1 to 0.25). According to the basalt fiber shielding material provided by the invention, the conductive particles and the magnetic particles are combined, and by optimizing the material components and proportion, a very good electromagnetic wave absorption and shielding effect can be achieved, a wider frequency band shielding effect can be provided, and electromagnetic radiation in various frequency ranges can be effectively covered.

The invention provides a power grid cable real-time current detection method and system, and the method comprises the steps: carrying out the multi-frequency-band synchronous collection of the current of a cable shielding layer for a high-voltage DC power transmission system with multiple loops laid in parallel, and obtaining the time-space information data; an electromagnetic coupling transfer function is calculated based on the data, and an electromagnetic coupling coefficient matrix is constructed, so that near-end cross induction current is separated to obtain a real current signal; establishing a cable dispersion model by using a real current signal, and performing fault feature recognition by combining a time domain criterion, a frequency domain criterion and time-frequency joint entropy analysis; and finally, calculating a credibility index by combining the temperature gradient and the electromagnetic environment parameters, correcting a preliminary judgment result and generating a protection control signal. According to the method, the near-end cross induction current and the real fault current can be effectively distinguished, the problem that the protection system of the multi-end high-voltage direct current system operates by mistake or does not operate in the power-on transient period is solved, and the reliability of the system is improved.

The invention discloses a power cable tiny defect positioning method based on a CFI-Z algorithm, and the method comprises the steps: obtaining a reflection coefficient vector of a head end of a power cable obtained through sweep frequency signals based on multiple frequencies, and obtaining a minimum norm least square solution and a closed solution of a power cable fault positioning factor according to a continuous frequency-increasing Z transformation matrix; and obtaining the sparse intensity of the minimum norm least square solution and the closed solution to obtain the final solution of the power cable fault positioning factor, and finally obtaining the position of the power cable defect according to the head end reflection time domain sequence of the power cable to complete the positioning of the early defect of the cable. According to the invention, the problems of insufficient high-frequency components and bandwidth limitation in the injected pulse are solved, so that the defect positioning sensitivity of the power cable is high, the anti-noise capability is strong, the positioning error is small especially under the condition of a long cable or a cable with small defects, and the method has a good effect in early-stage small defect positioning.

The invention discloses a joint estimation method for timing advance and frequency offset based on a conjugate symmetric ZC sequence, which relates to the technical field of wireless communication and comprises the following steps of: inputting a leader sequence extracted from a demodulated received signal; two ZC sequences in the leader sequence are respectively in cross-correlation with a local ZC sequence, and a peak value of a cross-correlation result amplitude is obtained; iteratively performing fractional frequency offset compensation estimation to obtain a fractional frequency offset estimation value and a compensated leader sequence; performing timing advance estimation and integer frequency offset estimation to obtain a timing advance estimator and an integer frequency offset estimator; obtaining a frequency offset estimation value by combining the decimal multiple and integer multiple frequency offset estimation values; and ending the timing advance and frequency offset estimation, and outputting estimated values of the timing advance and the frequency offset. According to the method, the negative influence of the decimal frequency offset on the ZC sequence is eliminated in a mode of iteratively compensating and estimating the decimal frequency offset, and high-performance timing advance and frequency offset joint estimation with robustness to frequency shift and noise is realized based on the structure of the conjugate symmetric ZC sequence; the method is suitable for a non-ground network communication scene with large Doppler frequency shift and low receiving signal-to-noise ratio.

The invention provides an OFDM signal receiving and processing system and method suitable for an NAVDAT system. According to the method, the characteristics that NAVDAT system signals have synchronous headers, pilot frequencies and the like are fully considered, firstly, the synchronous headers are used for carrying out correlation operation on received data to search a frame starting point, and a signal frame to be demodulated and decoded is obtained in combination with a constant false alarm detection algorithm; and subsequently, carrying out symbol synchronization to determine the FFT window position. Secondly, in combination with a discrete pilot signal, estimating an integral multiple frequency offset error, namely coarse synchronization, and further realizing estimation of a decimal multiple frequency offset error, namely fine synchronization, so as to realize frequency synchronization. And then, channel estimation is carried out by using the pilot signal and adopting a least square method to obtain the channel frequency response of the pilot, the frequency response of the complete signal is obtained through interpolation, and the rough estimation result is further processed through the designed RCAFCN network to obtain accurate channel estimation, so that the original OFDM signal is recovered. And finally, extracting a data part in the OFDM signal according to a frame structure, realizing soft demodulation through a log-likelihood ratio mode, decoding data of a signaling part by using a polarization code, and decoding data of a service part by using a low-density parity check code, thereby realizing complete demodulation and decoding. The method provided by the invention can effectively reduce inter-symbol interference and inter-carrier interference existing in OFDM signals, compensate channel distortion, reduce noise influence, improve decoding precision, improve communication quality, realize optimization of NAVDAT system baseband processing, and guarantee sailing safety of ships on the sea by combining with an existing marine broadcast system.

The invention provides a sleep staging detection method and a sleep staging detection device.The method comprises the steps that a polysomnogram of a target object within a preset time period is obtained; inputting the plurality of physiological signals into a first model to obtain frequency signals under different frequency characteristics; the multiple frequency signals are input into a second model to obtain two intermediate layer signals, the second model comprises a character string operation module and two first channels, the character string operation module is used for integrating the multiple frequency signals into a target frequency signal, and the two first channels are used for receiving the target frequency signal; the input of each first channel is a target frequency signal received from the character string operation module, and the output of each first channel is a corresponding first intermediate layer signal; and inputting the two first intermediate layer signals into a third model to obtain a sleep staging result of the target object. According to the sleep staging method and device, the physiological signals in the polysleep map are processed and analyzed, and the accuracy of the sleep staging result is improved.

This disclosure describes systems, methods, and devices for configuring sounding reference signal resources across multiple frequency locations for device positioning. A device may encode for transmission a sounding reference signal (SRS) including a first set of SRS resources for a first transmission by a user equipment (UE) device to the node B network device at a first time and a second set of SRS resources for a second transmission by the UE device to the node B network device at a second time; decode the first transmission received from the UE device using the first set and a first bandwidth at the first time; decode the second transmission received from the UE device using the second set and a second bandwidth at the second time; and combine the first transmission and the second transmission for a device positioning estimation based on the first bandwidth and the second bandwidth.

The invention relates to the technical field of optics, and discloses a microscopic imaging system. The system comprises a light source module used for generating a laser beam; the radio frequency drive generation module is used for generating radio frequency drive signals with various frequencies; the heterodyne interference light path module is used for respectively performing optical heterodyne interference processing on the laser beams according to the radio frequency driving signals with various frequencies, respectively forming a light spot array and a reference light source and then combining the light spots and the reference light source, and generating combined light beams to be incident on a sample to be detected; wherein different light spots in the light spot array correspond to different light frequencies; the spectral data receiving module is used for collecting light data generated after the combined light beam is reflected by the to-be-detected sample; wherein the to-be-detected sample is subjected to fluorescence labeling in advance; and the image inversion module is used for receiving the optical data and carrying out image inversion processing on the optical data to generate imaging data of the sample to be detected. According to the scheme, the microscopic imaging response speed is increased, the efficiency is high, and the accuracy is good.

The invention discloses a Fourier transform and S transform combined battery impedance spectroscopy measurement method and device, and aims to improve the precision, speed and reliability of impedance measurement of a battery energy storage system. According to the method, a multi-frequency component excitation signal is generated through a controllable current source, and current and voltage response signals of a battery are synchronously acquired and are respectively input into a Fourier transform module and an S transform module for frequency domain analysis. The Fourier transform module extracts impedance spectrums of low and medium frequency bands, and the S transform module extracts impedance spectrums of medium and high frequency bands through Gaussian window time-frequency analysis. And a data fusion algorithm is adopted to perform composite processing on results of the two modules, including a direct selection method, an arithmetic average method, an amplitude and phase calibration method and a weighted average method, so that smooth transition and optimization between frequency bands are realized, and finally the electrochemical impedance spectrum is generated. Through collaborative analysis of Fourier transform and S transform, parameter optimization and a fusion algorithm, the efficiency and accuracy of impedance spectroscopy measurement are remarkably improved, and the method is suitable for rapid monitoring and diagnosis of the battery state.

The invention discloses an electroencephalogram signal automatic feature extraction method based on a convolutional neural network, which comprises the following steps of: acquiring original electroencephalogram signal data, and performing adaptive artifact suppression and channel amplitude dynamic re-calibration based on a channel spectrum curvature change rate; executing frequency band deformation reconstruction, determining a frequency band boundary according to the frequency spectrum curvature change rate sequence, and constructing a frequency deformation mapping function to generate a plurality of frequency band component tensors; inputting the frequency band component tensor into an improved ConvNeXt model, and extracting a multi-dimensional electroencephalogram feature tensor; cross-frequency-domain attention fusion is executed, and a fused electroencephalogram feature vector is constructed; performing task reasoning, and outputting an electroencephalogram task response result; and performing feature feedback reconstruction according to the frequency deformation consistency index and the prediction offset degree, and jointly updating deformation convolution kernel parameters. According to the method, the accuracy and stability of electroencephalogram feature extraction are improved, and the method is suitable for various electroencephalogram intelligent processing scenes such as cognitive state recognition and medical auxiliary analysis.

A power converting apparatus includes a rectifier unit that rectifies first alternating-current power supplied from a commercial power supply, a capacitor connected to an output end of the rectifier unit, an inverter connected across the capacitor to generate second alternating-current power and output the second alternating-current power to a motor, and a control unit that controls an operation of the inverter and an operation of the motor using a dq-rotational coordinate system rotating in synchronization with a rotor position of the motor. The control unit extracts multiple frequency components from a q-axis current pulsation, which is a pulsatile component of a q-axis current, and limits the amplitude value of each of the extracted frequency components to control the amplitude of the q-axis current pulsation.

The invention provides a dark crack detection method of an ultrahigh-strength steel plate stamping part for a new energy automobile, and relates to the technical field of stamping part detection, and the dark crack detection method comprises the following steps: obtaining a detection area and a reference area of a to-be-detected stamping part; injecting a group of same multi-frequency alternating-current excitation signals into the detection area and the reference area of the to-be-detected stamping part at the same time, and synchronously acquiring a first electrical response signal of the detection area under the multi-frequency alternating-current excitation signals and a second electrical response signal of the reference area under the multi-frequency alternating-current excitation signals; based on the first electrical response signal and the second electrical response signal, calculating a conductivity difference value of the detection area and the reference area at the same frequency point, and obtaining a conductivity difference value-frequency curve comprising a plurality of frequency points; and based on the conductivity difference-frequency curve, whether dark cracks exist in the detection area is judged. According to the detection method, the defect degree can be quantitatively evaluated, and the strict requirement of the new energy automobile industry for quality consistency is met.

The invention relates to the technical field of water treatment equipment, in particular to an ultrasonic water treatment equipment control method and system based on variable-frequency vibration waves. According to the method, based on preset fluid working condition parameters, ultrasonic frequency conversion vibration wave signals covering multiple frequency bands are dynamically generated, and a vibrator array is driven to generate a composite sound field; a cavitation effect and an activation effect are synchronously excited in a fluid medium through variable-frequency vibration wave signals, so that physical form depolymerization and surface charge distribution change of scale forming substances occur; a shearing effect is formed on a fluid-pipe wall boundary layer, an attached state biological membrane structure is stripped, and the microscopic binding force of a crystallized scale body is loosened; monitoring the dispersion degree of scale-forming substances in the fluid and the state of a boundary layer, and adjusting the frequency band combination and energy distribution of variable-frequency vibration waves to maintain scale inhibition; and continuously optimizing the frequency conversion strategy and the sound field intensity according to the feedback data of the scale inhibition maintenance state. Through intelligent multi-band frequency conversion control of the ultrasonic water treatment equipment, efficient and environment-friendly water treatment and scale prevention effects are realized.

The invention relates to the technical field of communication technologies and navigation systems, and discloses a multi-channel narrowband data link comprehensive processing module, which comprises a radio frequency transceiver module which comprises a radio frequency transceiver and is used for converting a received radio frequency signal into a baseband signal and converting the baseband signal into a radio frequency signal; the analog channelization module is connected with the radio frequency receiving and transmitting module and used for receiving the baseband signals converted by the radio frequency receiving and transmitting module, carrying out preliminary channel division on the signals and dividing the signals into a plurality of frequency band signals; and the digital channelization processing module is connected with the analog channelization module and is used for carrying out digital processing on the signal after analog channelization. By adopting a zero intermediate frequency architecture, a multi-stage channelization design, cooperative work of the FPGA and the SOC, precise clock synchronization and an anti-interference technology, the multi-channel signal processing precision and the system stability are improved, and meanwhile, the power consumption and the hardware complexity are reduced.

Disclosed are techniques for wireless communication. In an aspect, a user equipment (UE) receives, during a first state, a configuration of a sounding reference signal (SRS) resource or SRS resource set, obtains an association between the SRS resource or SRS resource set and a group of random access channel (RACH) resources, and transmits, while outside the first state, a group of RACH signals using transmission properties based on the association between the SRS resource or SRS resource set and the group of RACH resources, wherein the group of RACH resources spans a plurality of adjacent frequency resources over a single time resource, or the group or RACH resources spans the plurality of adjacent frequency resources over a plurality of time resources.

The invention belongs to the field of wireless communication, and particularly relates to a low-loss leaky coaxial cable and a manufacturing method thereof. The leaky coaxial cable comprises an inner conductor, a composite insulating layer, an outer conductor and a sheath layer which are coaxially arranged in sequence, and each layer forms a concentric cylindrical structure by taking an axis as a center. The outer surface of the inner conductor and the outer surface of the outer conductor of the leaky coaxial cable are respectively roughened, so that the contact between the inner conductor and the insulating layer and the contact between the outer conductor and the sheath layer are improved, meanwhile, a solid inner skin layer originally used for bonding the inner conductor and the insulating layer is omitted, the signal transmission performance is improved, and the service life of the leaky coaxial cable is prolonged. And the transmission loss is reduced. Compared with an existing product, the leaky coaxial cable with the surfaces of the inner conductor and the outer conductor, provided by the invention, has the advantages that the attenuation index is integrally optimized by 2.6%-5.8% under multiple frequency bands of 900 MHz to 2700 MHz on the premise of meeting the test requirements of adhesive force, standing wave and insulating dielectric strength between the insulating layer and the inner conductor.

The invention provides a feature extraction method for an electroacoustic background interference signal of operation power transformation equipment, which belongs to the technical field of power transformation equipment, and comprises the following steps: acquiring an electroacoustic signal, preprocessing the electroacoustic signal, and generating a controlled interference signal at the same time; and performing time-frequency analysis on the preprocessed electroacoustic signal and the controlled interference signal, and optimizing the interference signal parameter to enable the interference signal parameter to be highly similar to the electroacoustic signal. And constructing a wavelet basis function library based on the optimized controlled interference signal, and performing wavelet packet decomposition on the electroacoustic signal to obtain a plurality of frequency band sub-signals. A self-adaptive threshold model is established by using a controlled interference signal, and soft threshold denoising processing is performed on sub-signals. Time-frequency features of the denoised sub-signals and the controlled interference signals are extracted, a feature mapping relation is established, and an initial feature set is obtained; and performing nonlinear dimensionality reduction on the initial feature set by adopting principal component analysis to obtain a dimensionality-reduced feature set. And an improved support vector machine model is adopted to evaluate the importance of dimension reduction features, and an optimal feature set is selected as an electroacoustic background interference signal feature.

The invention provides a non-invasive multi-frequency dessert displacement monitoring method, which comprises the following steps of: setting an excitation frequency set and a frequency switching interval through an upper display control machine, and controlling a lower embedded system to switch different frequencies in real time according to the set interval, thereby realizing real-time switching of multiple frequency points; the lower embedded system collects electrocardiosignals and cardiac impedance signals of a monitored object and transmits the electrocardiosignals and the cardiac impedance signals to the upper display and control machine through wired or wireless WIFI / Bluetooth. And the upper display control machine performs corresponding filtering and wavelet transform analysis on the cardiac impedance signal and the electrocardiosignal, extracts important feature points of the signals and calculates a cardiac displacement index. The lower embedded system is controlled by the upper display and control machine to monitor multi-frequency excitation of a human body, interference of different-frequency noise on measured electrocardio and cardiac impedance signals in different environments is avoided, and non-intrusive continuous cardiovascular monitoring can be realized. And more accurate hemodynamic parameters are provided for clinical diagnosis and treatment.

The invention discloses a frequency domain ground penetrating radar transmitting source coding and receiving signal synthesis method and system. The method comprises the following steps: constructing a frequency domain coding continuous wave ground penetrating radar transmitting signal by extracting amplitude and phase information of multiple frequency points of a time domain ultra-wideband transmitting pulse; adopting a fast forward modeling method based on impulse response to realize forward modeling of a coding source emission signal of the typical geoelectric model; in-phase components and orthogonal components of all frequency points are extracted, frequency responses are synthesized into responses of quasi-time-domain transmitted pulses through an inverse Fourier transform method, the high resolution equal to that of time-domain ultra-wideband transmitted signals is obtained, and higher anti-noise performance is achieved. According to the invention, the amplitude phase coding continuous wave transmitting signal is adopted, so that the frequency spectrum shaping of the quasi-time domain pulse of the transmitting frequency spectrum is realized, the resolving power of the synthetic signal is improved, and a theoretical basis is laid for signal synthesis of frequency domain ground penetrating radar hardware design.

The invention discloses a gas pipeline leakage source positioning method, and relates to the field of gas leakage detection. According to the method, acceleration signals and sound wave signals are collected through sensors arranged at detection points, peak value extraction is carried out in respective corresponding frequency domain complex spectrums through data preprocessing, and main frequency signals and frequency multiplication signals are obtained; distinguishing real leakage and interference signals according to the stable frequency integral multiple relation characteristic and time sequence consistency of the two signals; the phase difference is calculated by extracting the phase of the dominant frequency signal and the phase of the corresponding frequency multiplication signal, and the position of the leakage source relative to the detection point is calculated by combining the path sound velocity. The method can capture small distance differences, effectively improves the precision and robustness of leakage positioning, and is suitable for online leakage monitoring and diagnosis of gas or liquid medium pipelines.

Disclosed herein is an optical frequency comb generator for a distributed acoustic anomaly detection system. The system can include a continuous wave frequency modulated laser source configured to generate a laser signal. The system can include an acousto-optical modulator configured to modulate the laser signal by altering an amplitude and / or frequency of the laser signal based on an RF drive signal applied to the AOM, and to output an optical pulse with multiple frequency sidebands based on the modulation. The output can form an optical frequency comb usable detecting and locating acoustic anomalies within a structure under observation.