1639 results about "Frequency shift" patented technology

The invention provides a time division duplex multi-carrier synchronous transmission method based on 5G, which is used for solving the problems of inflexible carrier time slot allocation and inaccurate time delay compensation in synchronous transmission. By dynamically adjusting time slot allocation and working frequency bands of carriers in a network control center, the method optimizes network loads and reduces cross interference; the time delay of each carrier is compensated in real time by adopting a synchronous signal calibration algorithm, so that strict alignment of transmission time slots is ensured; the transmitting end dynamically adjusts the transmitting power according to link state information, and the receiving end reduces interference and signal attenuation through a multi-carrier cooperative interference management and multi-path delay compensation mechanism; and a receiving end performs joint decoding based on channel estimation and integrates demodulation signals of all carriers, so that the transmission efficiency and the signal quality of the 5G network are improved. The method is suitable for a base station system and a base station and repeater extension coverage system, and is especially suitable for a distributed wireless system including an optical fiber remote distributed system, a cable remote frequency shift repeater system and the like.

The invention provides a tunnel deformation parameter inversion method and device based on distributed optical fibers, and relates to the technical field of tunnel deformation parameter inversion, and the method specifically comprises the steps: selecting a monitoring point in a tunnel, arranging an optical fiber sensor, and obtaining a Brillouin scattering signal generated by the optical fiber sensor under the stress effect of the corresponding monitoring point; extracting a Brillouin frequency shift corresponding to the monitoring point, and determining an environmental effect frequency shift correction value by using the temperature change data, the humidity change data and the service time of the optical fiber sensor; determining the structural strain of the monitoring point according to the Brillouin frequency shift and the environmental effect frequency shift correction value, generating a three-dimensional strain field cloud picture, performing spatial registration on the three-dimensional strain field cloud picture and the geometric topology of the model, and performing three-dimensional grid division; the structure strain of the monitoring point is mapped to the grid node at the corresponding position, the structure strain of other grid nodes is determined based on the space distance attenuation law, inversion of the whole tunnel deformation parameters is completed, and the tunnel deformation monitoring precision and efficiency are improved.

The invention relates to the technical field of unmanned aerial vehicle autonomous decision, provides an unmanned aerial vehicle autonomous decision reinforcement learning method, system and device based on multi-objective optimization, and a storage medium, and solves the problems of limited dynamic task distribution capability and poor decision capability of an unmanned aerial vehicle. The method comprises the steps that based on infrared data and radar data, a moving track prediction sequence of a suspicious target in a target area is generated, a moving probability thermodynamic diagram is constructed, and the target area comprises a patrolled area; performing Doppler frequency shift analysis on the radar data to generate a target velocity vector field; and in combination with the position data of the unmanned aerial vehicle, outputting an unmanned aerial vehicle autonomous decision reinforcement learning result of a dynamic segmentation scheme containing an unpatrolled region through a region re-division reinforcement learning model based on a reward function for multi-objective optimization. The reward function is used for reflecting area coverage rate maximization, target tracking success probability maximization and path energy consumption minimization. According to the invention, autonomous intelligent decision-making of the unmanned aerial vehicle on the unpatrolled area is realized.

The present disclosure provides a wireless receiver having a Delay Doppler channel detector. The Delay Doppler channel detector includes a Delay Dopper domain channel estimator and a detector and demodulator. The Delay Doppler domain channel estimator is configured for estimating a channel gain, a delay, and a Doppler frequency shift of a path of a channel of data received via the channel. The detector and demodulator is configured for extracting a symbol sequence of the received data based on the estimated channel gain, the estimated delay, and the estimated Doppler frequency shift of the path of the channel.

The invention discloses a laser radar test method based on a long-distance target distance measurement result, and the method comprises the following steps: obtaining a laser radar echo signal, and extracting the frequency spectrum information of the echo signal; doppler frequency shift characteristic parameters are extracted according to the frequency spectrum information, and the relative speed of the target is calculated based on a preset frequency shift calculation model; acquiring multi-source sensor data associated with the laser radar test platform, and fusing to construct a dynamic ranging reference coordinate system; performing dynamic motion compensation on a laser ranging result according to the relative speed of the target to obtain a target initial measurement distance after Doppler correction; mapping the target initial measurement distance after Doppler correction to the dynamic distance measurement reference coordinate system to obtain a remote target final distance measurement result aligned with a test platform coordinate system; and outputting the accurate position and moving state information of the target in the three-dimensional space according to the final distance measurement result. According to the invention, the ranging precision and stability can be improved.

The invention relates to the technical field of deformation monitoring, in particular to a mountain tunnel surrounding rock deformation monitoring method and system based on distributed optical fiber sensing. The method comprises the following steps that Brillouin frequency shift original data and center wavelength original data are collected, tunnel construction progress data and surrounding rock geological survey data are obtained at the same time, format standardization and time sequence alignment processing is carried out, and preprocessed optical fiber sensing basic data, construction time sequence data and geological attribute data are generated; surrounding rock deformation characteristic parameters are extracted based on the optical fiber sensing basic data, and surrounding rock deformation multi-dimensional characteristic vectors are constructed; performing deformation mode density clustering and surrounding rock deformation dynamic prediction based on the surrounding rock deformation multi-dimensional feature vector to generate a surrounding rock deformation dynamic prediction value; and carrying out comparison and iterative correction on the dynamic prediction values of the surrounding rock deformation, and carrying out regionalized polymerization to generate a mountain tunnel surrounding rock deformation spatial and temporal distribution visualization result. According to the invention, full-time-space accurate monitoring and early warning of tunnel surrounding rock deformation can be realized.

The invention provides a tunnel deformation monitoring system and method based on a distributed optical fiber sensing technology, and relates to the technical field of tunnel monitoring. A spiral winding type optical fiber is arranged in the longitudinal axis direction of the surface of a tunnel lining, a transverse optical fiber is arranged on a key section, and the data acquisition frequency is set to be 1Hz. Dividing the optical fiber into a plurality of data acquisition points at equal intervals, obtaining the real-time temperature and Brillouin frequency shift change of each point, measuring the temperature and strain sensitivity coefficient, and calculating the total strain; calculating long-term temperature strain compensation based on the long-term temperature component, generating an instantaneous temperature difference through the real-time temperature and the long-term temperature component, further calculating instantaneous temperature strain compensation, subtracting the two kinds of strain compensation from the total strain to obtain stress strain, and evaluating the deformation level of the tunnel based on the stress strain. And the accuracy of evaluation is judged through clustering analysis.

The invention relates to the technical field of structural stress precision measurement, in particular to a distributed optical fiber sensing-based steel structure stress monitoring method, which comprises the following steps of: 1, constructing a sensing optical fiber array in a steel structure node area; 2, injecting optical pulses into the sensing optical fiber array, and synchronously collecting Brillouin frequency shift signals and Raman scattering signals of all points; 3, temperature and mechanical strain are separated based on the reference optical fiber signals, global temperature compensation is adopted for the first optical fiber set, and temperature gradient compensation along the optical fiber path is adopted for the second optical fiber set; 4, decomposing the compensated mechanical strain into multidirectional strain components according to the spatial orientation of the optical fiber, and reconstructing a three-dimensional stress field through strain component fusion; and 5, dynamically judging the damage risk according to the local stress concentration coefficient and the change rate thereof in the stress field. And through the temperature compensation technology, the influence of the environment temperature change on the strain data is eliminated, and the reliability of the monitoring result is improved.

The invention discloses a fringe projection three-dimensional shape measurement method based on frequency domain and time domain joint coding, and the method comprises the following steps: firstly, embedding a multi-frequency three-step phase shift fringe pattern in the vertical direction based on multi-scale region division, introducing four-step phase shift and complementary Gray code joint coding in the horizontal direction, generating a coding pattern set, and carrying out the projection; after an image is collected, frequency domain transformation and time domain decoding are carried out respectively, and a vertical dominant frequency position, a horizontal period number and a wrapped phase are obtained; then, combining a main frequency position in the vertical direction with a period number and a wrapped phase in the horizontal direction, and extracting a space coordinate of a direct illumination component based on frequency position invariance; and finally, establishing a pixel homonymy point mapping relation between the projector and the camera, and realizing high-precision three-dimensional reconstruction. Compared with a traditional frequency shift method, the method has the advantages that projection patterns are greatly reduced, reconstruction precision and anti-interference performance are improved, and the method is suitable for dynamic three-dimensional measurement under complex illumination conditions such as specular reflection, semitransparent shielding and subsurface scattering.

The invention discloses an optical cable icing galloping online monitoring system based on a BOTDR, and belongs to the technical field of distributed optical fiber sensing. The system comprises an optical module, a signal processing module and a data processing module, the optical module is used for generating a detection light signal and interacting with a sensing optical fiber to obtain a Brillouin scattering signal, and then the Brillouin scattering signal is converted into an electric signal; the signal processing module is used for performing frequency down-conversion, signal filtering and digital acquisition on the electric signal to obtain multiple groups of Brillouin scattering signal data; the data processing module is used for processing the multiple groups of Brillouin scattering signal data and extracting a Brillouin frequency shift center frequency; temperature and strain distribution along the optical cable is obtained according to the frequency shift, and temperature and strain states are transmitted to a QT upper computer through PCIE for real-time display. According to the invention, high-precision and long-distance optical cable icing galloping monitoring can be realized, reliable early warning and safety guarantee are provided, and technical support is provided for maintenance and management of an electric power system.

The invention provides a frequency-modulated continuous wave laser ranging device based on frequency shift double optical combs, which integrates frequency-modulated continuous wave and double optical comb technologies and comprises an FMCW light source, a beam splitter, a detection and reference light channel, a beam combiner, a photoelectric detector and a processing module. The FMCW light source outputs linear frequency sweeping laser which is divided into two paths through the beam splitter, and the detection light channel detects a target through the first optical comb generator and the circulator. The frequency fFS of the reference optical channel is increased through a frequency shifter, optical combs with different comb tooth intervals are generated by a second optical comb generator, and the fFS and the repetition frequency difference delta fR are in a non-integer multiple relation, so that interference is effectively avoided. After being combined by the beam combiner, the two paths of signals are converted into beat frequency signals by the photoelectric detector, and then time domain signals are spliced by the processing module by using coherence, so that the distance measurement precision is improved. According to the invention, the frequency shift double-optical comb technology improves the precision and anti-interference performance; an efficient data processing algorithm ensures rapid measurement and a wide range of application.

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 discloses an off-network block sparse orthogonal matching pursuit underwater acoustic time delay Doppler domain channel estimation method, and belongs to the technical field of underwater acoustic channel estimation. The method solves the problems that a channel estimation method based on traditional orthogonal matching pursuit cannot estimate frequency shift parameters on non-grid points and is high in calculation complexity. According to the method, channel parameters of integer grid points are obtained based on a BOMP algorithm, and then residual Doppler factors on non-grid points are subjected to further fine estimation based on maximum likelihood criterion fitting. The problem that a traditional OMP channel estimation method in underwater OTFS communication can only estimate channel parameters on grid points is solved, and the estimation precision of channel frequency shift parameters is further improved by estimating frequency shift parameters on non-grid points; and meanwhile, a fractional order dictionary is prevented from being established in a channel parameter process, so that the system complexity is reduced to a certain extent. The method can be applied to underwater sound time delay Doppler domain channel estimation.

The invention discloses a regional adjustable intermittent sampling interference method and system for an unmanned aerial vehicle SAR platform, and the method specifically comprises the steps: generating radar original data according to an intercepted unmanned aerial vehicle carried SAR signal; adopting a Bernoulli mapping sequence to carry out intermittent sampling on SAR signals of the unmanned aerial vehicle, and generating a randomly distributed non-uniform false target group; according to the generated intermittent sampling signal controlled by the Bernoulli mapping sequence, the distance direction and the azimuth direction of the SAR signal are interfered by using a distance direction frequency shift and false motion target characteristic modulation method, and a smart interference signal controlled by the Bernoulli mapping sequence after modulation is generated, so that the interference signal has a false motion characteristic; and after digital-to-analog conversion, low-pass filtering and up-conversion processing are carried out on the generated interference signal, the interference signal is sent by using a transmitting antenna, and interference on the SAR platform radar of the unmanned aerial vehicle is completed. The real moving target in the specific area is protected, and the method has the advantages of being simple, high in real-time performance and good in interference effect.

Disclosed are systems and techniques for wireless communications. For example, a first network device can transmit, to second network device(s), a first information signal including information indicating a frequency for a backscattered signal. The first network device can transmit, to a third network device, a second information signal including information indicating a frequency shift for shifting a reference signal to produce the backscattered signal. The first network device can transmit the reference signal to the third network device. The first network device can select, based on channel reports received from the second network device(s), the energy harvesting waveform and at least one second network device for providing the energy harvesting waveform to the third network device. The first network device can transmit, to the at least one second network device, a scheduling signal including scheduling instructions to transmit the energy harvesting waveform to the third network device.

The invention relates to the technical field of radar, and discloses a three-dimensional positioning life detection radar system, and the radar system comprises a phased array antenna unit which is used for transmitting radar waves and dynamically adjusting the wave beam direction according to the target position; the signal receiving unit is used for receiving a radar signal reflected by a target; the Doppler frequency shift analysis module is used for analyzing the frequency change of the received radar signal and extracting a micro-motion signal of the target; the target motion analysis module is used for tracking the motion of the target through a Kalman filtering technology; the three-dimensional reconstruction module is used for reconstructing the three-dimensional position of the target through an electromagnetic field integral equation and multi-source sensor information fusion according to the received signals; and the deep learning module is used for identifying the micro-motion signal and optimizing target classification. By adopting the phased-array antenna unit and the beam forming technology, the technical effects of carrying out accurate three-dimensional scanning and rapid dynamic beam adjustment on the target are achieved.

The invention discloses a secondary modulation interference signal generation method and device, a storage medium and equipment, and belongs to the technical field of radar countermeasure. The method comprises the following steps: a jammer processes a target SAR signal to obtain a digital SAR signal and calculates a signal parameter; generating a distance-direction phase modulation signal, a distance-direction sine function modulation signal, a distance-direction frequency shift modulation signal, an azimuth-direction phase modulation signal, an azimuth-direction sine function modulation signal and an azimuth-direction frequency shift modulation signal according to the signal parameters by combining a required interference type; according to the generated signals and the digital SAR signals, range direction modulation and azimuth direction modulation are completed, and finally digital interference signals are obtained; and converting the digital interference signal into an analog interference signal and forwarding the analog interference signal to the target SAR system, and generating different types of interference effects through imaging processing. According to the invention, nine different types of two-dimensional interference effects can be flexibly generated, and the central position of the interference result can be accurately controlled.

The invention discloses an SER6 Pro antenna with adaptive beam forming capability, comprising: a generation module for generating an initial beam directional diagram based on spatial-temporal correlation analysis of multipath signals; the calculation module is used for updating beam direction parameters in real time by using a Doppler frequency shift estimation algorithm so as to adapt to Doppler frequency shift change of a high-speed mobile user; the suppression module is used for carrying out noise suppression on the beam signal in a frequency domain by adopting an adaptive filter; and the optimization module is used for dynamically adjusting the beam forming matrix and optimizing the beam direction and intensity through an iterative optimization algorithm. The method has the beneficial effects that the problem of inaccurate beam direction identification caused by excessive reflected and scattered signals in a complex multi-path propagation environment is solved; the problem of unstable beam tracking caused by significant change of Doppler frequency shift in a high-speed mobile user scene is solved; and the problem that the signal-to-noise ratio is reduced due to the strong external noise source in a high-interference environment is solved.

The invention discloses an intelligent control method and system for a motor driver, and the method comprises the steps: building an acoustoelectric incidence matrix through collecting harmonic current and sound pressure fluctuation data in the operation process of a motor, and forming a fault feature library; identifying an available fault mode to determine an energy collection point, and performing phase deviation processing on the collection point to generate an auxiliary driving signal; performing spectrum analysis on the sound pressure fluctuation data to obtain an acoustic characteristic spectrum, extracting an efficiency indication tone through characteristic decomposition, mapping the efficiency indication tone into a torque optimization parameter, and establishing a noise reduction control table; performing spectrum analysis on the enhanced control domain to identify a high-energy frequency band, executing a frequency shift operation to generate a safety frequency band signal, and forming a multi-frequency band management strategy in combination with a noise reduction control table; a management strategy is decomposed into parallel control flows for sequential staggered arrangement, and an energy-saving control matrix is generated; and generating a PWM control signal based on the matrix, carrying out edge reconstruction, and obtaining a softened edge waveform through an anti-resonance injection technology to complete intelligent control of the motor driver.

The invention discloses a two-dimensional modulation interference signal generation method and device, a storage medium and equipment, and belongs to the technical field of radar countermeasure. The method comprises the following steps: a jammer detects and receives a target SAR signal and converts the target SAR signal into a digital SAR signal; generating a phase coding modulation signal and a distance direction frequency shift modulation signal according to the required interference type and the signal parameter; generating an azimuth sine function secondary modulation signal and an azimuth frequency shift modulation signal according to a required interference type and a signal parameter; based on the various generated modulation signals and the digital SAR signals, range modulation and azimuth modulation are completed, and digital interference signals are obtained; and converting the digital interference signal into an analog interference signal, and forwarding the analog interference signal to the target SAR system. According to the invention, distance-direction phase coding modulation, azimuth-direction quadratic sine function modulation and two-dimensional frequency shift modulation are combined, six different types of two-dimensional interference effects can be flexibly generated, and the central position of the interference result can be accurately controlled.

This power cable monitoring system includes: a power cable including a power transmission cable provided at an inner circumferential part, an armoring wire provided at an outer circumferential part, and sensor ropes having an optical fiber to detect a physical quantity of a measurement target; and a backscattering light measurement device which measures distribution of the physical quantity of the measurement target, using backscattering light from the optical fiber, wherein distribution of temperature and strain of the power cable is obtained from a frequency shift signal of Rayleigh backscattering light obtained by the backscattering light measurement device on the basis of a signal detected by the sensor ropes, and a polarization distribution signal obtained from the Rayleigh backscattering light.

A metrology system including a heterodyne light source is provided. The heterodyne light source includes a first light source, an acousto-optic modulator and a source optical arrangement. The acousto-optic modulator receives at least one wavelength laser beam from the first light source and generates at least one corresponding frequency shifted laser beam (e.g., with orthogonal polarization). The source optical arrangement includes a receiving optical element portion and a birefringent optical element portion. The receiving optical element portion receives the wavelength laser beam(s) and the corresponding frequency shifted laser beam(s) and directs the beams along an optical path toward the birefringent optical element portion. The birefringent optical element portion combines the beams to output a combined beam (e.g., which may be utilized as part of a measurement process to determine at least one measurement distance to at least one surface point on a workpiece, etc.).

The invention discloses an SAR sea surface flow velocity inversion method based on physical guidance and data driving fusion, and relates to the field of flow velocity inversion, and the method comprises the steps: carrying out the non-geophysical Doppler frequency shift correction of the Doppler frequency shift observed by a spaceborne synthetic aperture radar, and obtaining the geophysical Doppler frequency shift; predicting based on a wave-induced Doppler frequency shift model according to a radar incident angle, reanalyzed wind direction data, a sea surface 10-meter height wind speed inverted by an SAR (Synthetic Aperture Radar), a simulated wind wave parameter, a simulated surge parameter and a simulated maximum wave parameter to obtain a wave-induced Doppler frequency shift; the wave-induced Doppler frequency shift model is obtained based on physical guidance and data-driven modeling; doppler frequency shift generated by sea surface flow is determined according to the geophysical Doppler frequency shift and the wave-induced Doppler frequency shift; according to the method, the Doppler frequency shift generated based on the sea surface flow is converted to obtain the sea surface radial flow velocity, the wave-induced Doppler frequency shift is accurately removed, and reliable inversion of the sea surface flow velocity is realized.

The invention relates to the technical field of satellite communication signal processing, and discloses a broadband satellite signal blind demodulation reconstruction method and system based on sparse representation. The method comprises the following steps: carrying out frequency domain transformation on broadband satellite mixed signals to extract pilot frequency features to construct a beam state feature matrix, inputting the matrix into an adversarial network to generate a beam adaptive sparse dictionary, constructing a topological relation graph according to a Doppler frequency shift set, and carrying out collaborative sparse decomposition to obtain a sparse coefficient matrix; and extracting a code rate candidate set to execute parallel sparse reconstruction, determining an actual code rate through self-consistency verification to obtain a complete signal, analyzing a switching instruction, extracting time sequence statistical characteristics, predicting target domain characteristics, generating a switched sparse dictionary, and executing demodulation. The sparse decomposition precision, the code rate blind estimation accuracy, the cooperative processing efficiency and the switching continuity of the broadband satellite mixed signals are improved.

The invention relates to the technical field of wireless communication, in particular to a multimode chip core architecture system realized based on a software radio technology, which comprises an anti-interference module used for executing real-time optimization on a multi-system compatible baseband data stream and calling a dynamic compensation mechanism based on dynamic frequency shift characteristics in an environment characteristic data set, adjusting a local frequency source and a channel equalization parameter through multi-stage compensation operation to obtain an anti-interference enhanced data stream; and the packaging module is used for packaging the anti-interference enhanced data stream and the positioning data into a time-hopping pulse-direct sequence code division multiple access fusion frame structure and sending the fusion frame structure through a radio frequency unit. Through an ASIC and SDR hybrid architecture and a four-level hierarchical design, a multi-system communication function is integrated, and the hardware efficiency is improved and the power consumption is reduced.

The invention provides an intelligent optical cable performance prediction method and system for a data center, and relates to the technical field of data center performance analys.The intelligent optical cable performance prediction method comprises the steps that firstly, an optical cable microstructure disturbance quantization model is constructed, and an optical cable is divided into a plurality of virtual quantization units in the longitudinal direction; each unit packages a real-time stress-strain state parameter and a response sensitivity coefficient of the basic structure unit, inputting a Brillouin scattering spectrum frequency shift data flow collected in real time into the model for disturbance source analysis, generating a physical excitation decomposition sequence, driving a virtual quantization unit to perform state evolution iterative operation according to the physical excitation decomposition sequence, and obtaining a Brillouin scattering spectrum frequency shift data flow model; a stress-strain state evolution track set is obtained, a time-space correlation network of optical cable link disturbance propagation is constructed according to the stress-strain state evolution track set, network flow characteristic analysis is conducted on the time-space correlation network, an early warning node set is extracted, the future evolution trend of the early warning node set is calculated, and serialized optical cable performance abnormity early warning information is generated. The optical cable performance abnormity can be predicted in advance, and stable operation of the data center optical cable is guaranteed.

The invention provides a channel estimation method of a multi-user uplink low earth orbit satellite wireless communication system, which is used for transmitting signals by adopting an OTFS (Over The Over The Fine Switching) modulation technology aiming at a low earth orbit satellite rapid moving scene, and provides a low-complexity uplink channel estimation method combining path number, time delay, Doppler and channel fading. The method comprises the following steps: firstly, designing different pilot symbol grid positions of multiple users in a time delay-Doppler domain; then, performing energy threshold detection on all time delay domains of low-orbit satellite receiving signals to estimate the total number of paths and the time delay value of each path; then, giving a closed expression of channel fading by using a maximum likelihood estimation method, and estimating Doppler frequency shift by using a one-dimensional search method; through simulation verification, the provided uplink joint channel estimation method can effectively realize channel detection, can be further applied to ergodic capacity derivation work, and has relatively good practicability and performance.

The invention provides a distributed optical fiber sensing system based on AOM frequency shift and a vibration positioning method, and relates to the technical field of optical fiber sensing, probe light emitted by a light source is divided into two branch light beams, one branch light beam is input into a first interferometer structure after frequency shift, and the other branch light beam is input into a second interferometer structure. The two split light beams are coupled in the interferometer structure to obtain sensing light and reference light, and the sensing light is coupled with the reference light in the light demodulation element after passing through the sensing optical fiber to obtain interference light. The two paths of interference light are converted into electric signals, then the signal processing assembly is used for eliminating Rayleigh backscattering noise signals, and the vibration position in the sensing optical fiber is determined according to the phase delay inequality between the two electric signals. According to the invention, the interference of Rayleigh backscattering is avoided, the sensing distance is increased, the signal-to-noise ratio of the system is improved, an additional light source is not needed, only a single optical fiber is used for transmission, and the cost is reduced.

The invention relates to the field of electric field quantum measurement, in particular to a low-frequency electric field measurement method and a three-photon Rydberg system. The low-frequency electric field measurement method comprises the following steps: moving an atom gas chamber containing cesium atoms to a low-frequency electric field to be measured; cesium atoms are driven by probe light to transition from a ground state 6S1 / 2 to an excited state 6P1 / 2; driving cesium atoms to jump from an excited state 6P1 / 2 to an excited state 9S1 / 2 through decoration light; driving the cesium atoms to transition from an excited state 9S1 / 2 to a higher Rydberg state nP3 / 2 through coupled light to obtain Rydberg atoms; a photoelectric detector is adopted to detect the absorption condition of the detection light; based on the absorption condition, an oscilloscope is adopted to observe EIT spectrum change; based on the EIT spectrum change, obtaining a spectrum frequency shift amount; and the electric field intensity of the low-frequency electric field to be measured is calculated through the spectral frequency shift amount and the polarizability of the Rydberg atoms, so that the shielding problem of the atomic air chamber to the low-frequency electric field can be reduced, the spectral line width is narrower, and the electric field measurement resolution is greatly improved.

The invention relates to the field of ocean current remote sensing, and relates to a vector flow inversion method combining a single-station ground wave radar and a satellite-borne SAR, and the method mainly comprises the steps: calculating the frequency deviation of a first-order Bragg peak of the ground wave radar, carrying out the inversion of the sea surface radial flow of the ground wave radar, and carrying out the inversion of the sea surface radial flow of the SAR through employing a Doppler centroid anomaly method; interpolating a ground wave radar radial flow result to an SAR data grid through bilinear interpolation; inverting a single-station vector flow based on a ground wave radar radial flow result, projecting single-station vector flow data with high confidence coefficient to an SAR range direction, calculating a difference mean value of a projection flow velocity and an SAR radial flow velocity, and further calibrating the SAR radial flow; and combining a ground wave radar radial flow result with the calibrated SAR radial flow to invert a vector flow. According to the method, the defect of ocean current observation through a single means is overcome, high-precision inversion of the combined vector flow is achieved, and the method has important significance on ocean environment monitoring, disaster forecasting, shipping safety and the like.