247 results about "Echo time" patented technology

The invention relates to the technical field of quality detection, in particular to a medical refrigerator body manufacturing detection system and method, and the system comprises a coating reflection detection module, a sound wave response measurement module, an optical signal fluctuation analysis module, a surface defect recognition module and a structural feature state evaluation module. According to the method, the reflection amplitude gradient change of the adjacent scanning areas is compared with the spectral curve continuity, so that the sensing precision of the surface reflection distribution continuity is improved, the recognition capability of weak anomalies is enhanced, and the internal potential defects are accurately captured in combination with the sound wave echo time and structural stability analysis of a specific part; a light intensity gradient model is constructed according to a sound wave analysis result, a splicing seam and a light intensity jump area of a sunken area are identified, abnormal forms such as scratches and bubbles are further extracted, coordinates are marked, the whole process depends on dynamic feedback and multi-signal linkage calibration, the identification precision and the coverage rate are improved, and medical box body quality global efficient detection is achieved.

The invention relates to a magnetic resonance imaging method and device and a storage medium, and the method comprises the steps: scanning a target region through employing a first magnetic resonance sequence, setting a plurality of echo times, and collecting a plurality of spin echo images; recording a plurality of echo times and corresponding dispersion sensitivity coefficients according to the first magnetic resonance sequence; scanning the target area by using the second magnetic resonance sequence to obtain an apparent dispersion coefficient; and according to the plurality of spin echo images, the plurality of echo times, the dispersion sensitivity coefficient and the apparent dispersion coefficient, fitting to obtain a transverse relaxation time constant quantitative image for correcting the dispersion influence. According to the method and the device, the problem of dispersion when a magnetic resonance transverse relaxation time constant quantitative image is obtained through a variable echo time spin echo method in the prior art is solved, and the beneficial effect of effectively improving the quantitative accuracy is achieved.

The invention provides an electromagnetic ultrasonic bolt stress detection system based on a space-time complementation algorithm, and the system comprises the steps: carrying out the multi-channel ultrasonic signal collection of a to-be-detected bolt, and obtaining a multi-channel echo signal group; performing time-varying attenuation compensation and adaptive entropy weight denoising on the multi-channel echo signal group to obtain a denoised echo signal group; extracting echo time-domain features from the de-noised echo signal group, performing segmented time-frequency feature extraction on the de-noised echo signal group based on a short-time sliding window to obtain echo time-frequency features, and fusing the echo time-domain features and the echo time-frequency features into ultrasonic time-frequency features; performing wave field reconstruction on the de-noised echo signal group to obtain a spatial ultrasonic energy diagram, and extracting ultrasonic spatial features of the spatial ultrasonic energy diagram based on a self-attention map convolutional network; performing correlation detection and space-time complementary modeling on the ultrasonic time-frequency features and the ultrasonic space features to obtain ultrasonic space-time joint features, and performing stress analysis on the ultrasonic space-time joint features to obtain bolt stress data.

The invention belongs to the technical field of marine surveying and mapping, and discloses an airborne marine laser radar underwater weak echo signal detection method and system. According to the method, a waveform rising edge is determined by constructing a standard deviation curve, a water surface echo moment is accurately extracted, and two water surface geometric elements of a water surface point and a refraction vector are calculated on the basis; constructing a time-space constrained waveform superposition model, taking the Euclidean distance between the two water surface geometric elements as a neighbor discrimination standard, and screening and superposing neighbor waveforms by using a K neighbor judgment method to obtain a superposed pseudo waveform with a high signal-to-noise ratio; and finally, an improved normalized saliency peak detection method is utilized to judge the underwater echo position step by step and obtain the final underwater echo moment. After the model constructed by the invention is used for processing, the underwater weak echo detection of the airborne ocean laser radar is effectively realized, the maximum sounding performance of the airborne ocean laser radar is improved, and an effective technical support and a solution are provided for sounding data processing and application.

The invention relates to the technical field of water level online measurement, and discloses a water level measurement method and system based on ultrasonic waves. According to the invention, a variable time-sharing amplification circuit with a dynamic range is adopted, and the amplification times of echoes with different distances are automatically changed, so that the amplitude of an echo signal is kept to be more than five times of that of noise, and the influence of the noise on the measurement precision is effectively avoided; the method comprises the following steps of: receiving an echo signal, carrying out digital shaping on the echo signal according to a standard echo waveform near an echo peak value, and taking time corresponding to a waveform vertex after shaping as echo time, so that the influence of the measurement accuracy of echo waveform distortion is eliminated through the technology; meanwhile, the method that optimization is carried out after continuous three times of measurement is adopted, and the accidental phenomena of no echo and measurement value jumping can be effectively eliminated.

The invention provides an in-service closed metal structure internal detection method and device and electronic equipment, and relates to the technical field of ultrasonic detection. The method comprises the following steps: acquiring geometric parameters of a metal structure; wherein the geometric parameters comprise the wall thickness and the outer diameter of the metal structure; controlling the high-frequency ultrasonic probe to emit high-frequency ultrasonic waves and receive first echoes; determining echo time according to the geometric parameters, and judging whether the working condition inside the metal structure is liquid or not according to the echo time and the first echo amplitude; when the working condition in the metal structure is non-liquid, the first low-frequency ultrasonic probe is controlled to emit, and the second low-frequency ultrasonic probe is controlled to receive a second echo; determining the internal working condition of the metal structure according to the second echo and the discrimination line of each working condition; wherein the working conditions comprise air, ice and concrete. The internal working condition of the closed metal structure can be rapidly detected.

The invention discloses a current transformer oil level monitoring system based on ultrasonic echo detection, which relates to the technical field of electric power monitoring and comprises the following steps: acquiring original echo time sequence data; calculating the distance between the transmitting end and the top of the metal expander by combining the propagation velocity of the ultrasonic waves in the air; and when the oil level height value is lower than a set threshold value, an alarm signal is triggered. According to the invention, the problems of easy clamping stagnation, complex installation, large temperature drift and environmental interference and the like of the traditional float-type, pressure-type and window observation methods are effectively overcome, remote uploading and local acousto-optic prompt are supported, and intelligent inspection and fault pre-warning identification under unattended operation are realized; and the operation safety, the monitoring reliability and the operation and maintenance intelligent level of the oil-immersed current transformer are remarkably improved.

The invention provides a circumferential synthetic aperture radar imaging method, which comprises the following steps: acquiring a transmitting signal and an echo signal of radar circular motion, and preprocessing the transmitting signal and the echo signal to obtain a preprocessed echo signal; a compressed sensing method is adopted to convert a signal estimation and recovery problem into a norm minimization problem for signal filtering, and a target echo signal is obtained; dividing a plurality of sub-apertures by adopting a back projection algorithm, carrying out gridding processing on an imaging region, and calculating echo time delays of points in a grid and each position of the radar; and performing signal compensation on a target echo signal according to the echo time delay, performing azimuth focusing through coherent superposition processing to generate a plurality of corresponding sub-images, and performing step-by-step non-coherent fusion on the plurality of sub-images to obtain a circumferential SAR image. According to the invention, a small amount of effective data can be fully utilized for high-quality imaging, and high-resolution image quality is maintained while the imaging speed and the processing efficiency are improved.

The invention relates to the technical field of fault detection, in particular to a steel belt fault detection method for spindle conveying, and the method comprises the steps: collecting echo signals received after an ultrasonic probe transmits ultrasonic waves to a steel belt in an operation process; obtaining each return band; calculating the echo time difference of each echo band; acquiring a peak-to-peak delay coefficient of each echo band; calculating an echo consistency coefficient of each echo band; obtaining all first quartered return bands; acquiring a steel belt echo attenuation value of the echo signal; after wavelet decomposition is carried out on the echo signal, a defect noise estimated value of each wavelet coefficient is obtained; and further obtaining a self-adaptive wavelet threshold value of each wavelet coefficient, and carrying out fault detection on the spindle transportation steel belt. According to the invention, the fault detection precision of the ultrasonic transmission mode is improved.

The invention relates to the technical field of bridge detection, in particular to an existing bridge pile foundation detection method and device based on a phase difference method, and the method comprises the following steps: obtaining a first signal and a second signal detected by two acceleration sensors which are vertically arranged at an interval after a pile foundation is knocked; finding out an effective extreme value in the first signal and the second signal; obtaining a periodic phase difference between the effective extreme value in the first signal and the nearest effective extreme value in the second signal; and according to the abnormal change of the periodic phase difference, determining echo time so as to determine a defect position or a pile length. The problem that signal feature recognition and defect distinguishing are limited due to asymmetry of excitation positions and existence of an upper structure in the prior art can be solved.

The invention discloses a sonar target motion identification method based on a low-frame-rate bright spot structure sequence. The sonar target motion identification method comprises the steps of 1, roughly intercepting a bright spot structure; 2, accumulating a bright spot structure, sonar platform information and tracking information; step 3, motion compensation of the sonar platform; 4, accurately intercepting a bright spot structure; and 5, searching the optimal radial speed. According to the method, target radial motion parameters are extracted by means of distance steep motion of a sonar target among multiple frames of echoes, and a speed estimation loss function based on bright spot structure global optimal estimation is innovatively designed for the problems that the time interval between adjacent echoes of a low-frame-rate sonar target is long and the bright spot structure fluctuates greatly. According to the method, the global similarity between input period bright spot structures is fully utilized, the distance steep motion measurement precision is improved, the radial speed of the sonar target can be given at the same time, and the motion identification precision and stability of the sonar target are improved.

The invention discloses an SAR noise frequency modulation saturation interference suppression method based on time-frequency characteristics, and belongs to the technical field of radar signal processing, and the method comprises the steps: building an SAR echo model under the condition of NFM saturation interference, carrying out the short-time Fourier transform of the interfered SAR echo, carrying out the fundamental wave and high-order harmonic detection, carrying out the notch filtering in each STFT window, and carrying out the noise modulation saturation interference suppression. And converting back to an echo time domain, and finally obtaining SAR echo data after interference suppression. According to the method, NFM saturation interference can be effectively suppressed, the effectiveness of the proposed method is verified through semi-actual measurement data of Radarsat-1, and compared with a time domain cancellation method, the method has better saturation interference suppression capability.

The invention belongs to the field of ocean wave feature extraction, and particularly relates to a sea wave feature inversion method based on reverse echo measurement, which comprises the following steps of: acquiring an echo signal from a seabed to an ocean surface, and performing adaptive time window smoothing processing on the echo signal to obtain an echo signal; carrying out abnormal value identification and missing data filling on the smoothed data; removing abnormal values by adopting an improved Tukey method, and filling missing data by adopting a segmented cubic spline interpolation method; through high-pass filtering and detrending processing, sea wave echo signals with low-frequency trends removed are obtained; and selecting a proper time window to calculate the dispersion of echo time, establishing a mathematical relationship between the dispersion and the significant wave height through a regression algorithm, and substituting observation data into an equation to obtain an inversion result of the significant wave height. According to the method, the sea waves are subjected to feature inversion based on the reverse echo measurement technology, the precision of sea wave feature extraction is effectively improved, the field measurement cost is reduced, and the stable and low-cost sea wave measurement method is provided.

The invention relates to the field of bridge damage detection, in particular to a municipal bridge damage defect detection method and system. The method comprises the following steps: carrying out edge detection and connected domain extraction on an acquired bridge surface grey-scale map to obtain a plurality of edge pixel points and a plurality of connected domains, and calculating the regularity of a target area; constructing a gray scale run-length matrix of the target rectangle, and calculating the texture confusion degree of the target area according to the gray scale run-length matrix; carrying out weighted summation on the regularity and the texture confusion degree, carrying out normalization, and taking a normalization result as the initial abnormal degree of the bridge; ultrasonic pulses are transmitted to the target area to obtain echo time and echo intensity, the echo time and the echo intensity serve as correction factors to correct the initial anomaly degree of the bridge to obtain a bridge damage index, and defect detection is completed. According to the technical scheme, the bridge defect detection efficiency and accuracy can be improved.

The invention discloses an audio-based information hidden transmission method, an audio decoding method and electronic equipment, which are applied to the field of communication. The audio-based information hidden transmission method comprises the following steps: acquiring to-be-embedded original information; generating symbol information according to the original information; obtaining a time delay corresponding to each symbol in the symbol information, obtaining an original audio carrier, and sequentially embedding the time delay corresponding to each symbol into the original audio carrier to generate an echo frame; and combining the echo frame and the original audio carrier to obtain a target audio. The original information to be embedded is embedded into the original audio carrier in the form of echo time delay, so that the confidentiality and security of the communication process are improved, and even if the target audio is accidentally recorded by third-party recording equipment, the embedded original information can still be analyzed from the recorded audio so as to trace the leakage source.

The embodiment of the invention provides a natural gas leakage detection method and device, electronic equipment and a storage medium. The natural gas leakage detection method comprises the steps that all leakage areas of natural gas in a station are recognized; directionally transmitting an ultrasonic detection signal to each leakage area, and calculating the position information of each leakage area according to the echo time of the ultrasonic detection signal in each direction; calculating the natural gas concentration of the corresponding leakage area according to the gas temperature and the gas molecular weight of each leakage area; and displaying the position information and the natural gas concentration of each leakage area in a detection map of the station. According to the embodiment of the invention, through automatic and remote monitoring technologies, the exposure time of personnel on site is reduced, the safety risk is remarkably reduced, and powerful support is provided for emergency rescue work through accurate monitoring and visualization means.

The invention discloses a bolt pre-tightening force prediction method based on ultrasonic echo time-frequency characteristics, and the method comprises the steps: S1, carrying out the ultrasonic excitation of a target bolt, obtaining an ultrasonic echo signal generated by the bolt, and carrying out the time-frequency analysis, and forming an initial time-frequency characteristic matrix; s2, according to a bolt material characteristic database, determining characteristic parameters of ultrasonic echo propagation corresponding to a target bolt material, and performing weighting processing on the initial time-frequency characteristic matrix to obtain a weighted time-frequency characteristic matrix; s3, extracting a time-frequency characteristic index through the weighted time-frequency characteristic matrix, and forming a target characteristic vector; and S4, inputting the target feature vector into the trained double-branch prediction model, outputting a pre-tightening force energy feature value and a pre-tightening force state change value, inputting the pre-constructed neural network model, and outputting a bolt pre-tightening force prediction value. According to the method, the bolt pre-tightening force can be predicted with high precision and high reliability, and the technical problems of low prediction precision and great environmental influence are solved.

The invention relates to a cable accessory-based insulation silicone rubber thermal aging state detection method, apparatus and device. The method comprises the steps of obtaining a correlation model and a to-be-detected sample; transmitting ultrasonic waves to the to-be-detected sample for aging test to obtain a primary echo time domain signal; processing the primary echo time domain signal to obtain a spectrogram, and extracting a fundamental wave amplitude and a second harmonic amplitude from the spectrogram; calculating a relative nonlinear coefficient according to the fundamental wave amplitude and the second harmonic amplitude; and inputting the relative nonlinear coefficient into the correlation model for analysis to obtain the thermal aging degree. The method comprises the following steps: transmitting and receiving ultrasonic waves to and from a sample to be detected to obtain a primary echo time-domain signal, processing the primary echo time-domain signal to obtain a relative nonlinear coefficient, and inputting the relative nonlinear coefficient into a correlation model to analyze and evaluate the thermal aging degree of the identified thermal aging state of the sample to be detected. The microstructure change of the to-be-detected sample caused by thermal aging can be accurately captured, and the thermal aging state can be accurately evaluated.

The invention provides a method and a system for identifying environment abnormity in a direct-current battery swap station. The method comprises the following steps: fusing multi-source images acquired by the direct-current battery swap station; determining at least one suspected abnormal region based on the fused image; constructing a three-dimensional structure model of an object in the suspected abnormal area based on reflection deformation information of structured light projected into the suspected abnormal area for multiple times; determining reflection change information of the object in the suspected abnormal area based on reflection echo intensity and reflection echo time of the obtained ultrasonic wave on the surface of the object in the suspected abnormal area; and performing logic correlation analysis based on the three-dimensional structure model and the reflection change information, and determining a target abnormal region in the to-be-identified direct-current battery swap station. According to the method and the system, the capability of identifying tiny and hidden abnormal objects of the direct-current battery swap station is greatly improved, missed judgment is effectively reduced, the accuracy and the reliability of environment abnormity identification in the direct-current battery swap station are improved, and stable operation of the battery swap station is guaranteed.

A method for acquiring a magnetic resonance image dataset of a field-of-view using a gradient-echo imaging protocol includes acquiring additional k-space lines within a central region of k-space at intervals throughout the imaging protocol, wherein the additional k-space lines are used for estimating motion parameters of the field-of-view. The imaging protocol has been amended by inserting additional gradient blips after at least some of the RF excitations, such that at least one additional gradient echo is generated, allowing the acquisition of at least one additional k-space line during one echo time.

The invention relates to the technical field of ultrasonic wind measurement, in particular to a high-precision wind measurement system and method based on double-frequency ultrasonic waves, and the method comprises the steps: deploying an orthogonal double-frequency ultrasonic transducer array in a horizontal plane, capturing an echo timestamp, and solving the wind speed through the dynamic changes corresponding to the high and low frequency characteristics; according to the forward and reverse wind round-trip time difference of the double-frequency ultrasonic waves on the X axis and the Y axis, the real-time temperature obtained through temperature compensation is combined, the wind speed components of the high-frequency ultrasonic waves and the low-frequency ultrasonic waves are calculated according to a forward and reverse wind formula, the X-axis final wind speed component and the Y-axis final wind speed component are obtained through weighted averaging, the wind direction angle is calculated according to an arc tangent function, and wind speed and direction results are output after quadrant correction; the wind speed and direction data obtained through calculation are preprocessed, and finally the processed data are stored in an internal storage. Double-frequency ultrasonic waves are adopted, high frequency is used for capturing rapid wind speed changes, low frequency is used for long-distance propagation to reduce environmental noise influences, the wind speed is solved in combination with a sound velocity formula, temperature compensation and a propagation equation, and high-precision measurement can be achieved.

The invention discloses a submarine topography surveying and mapping method and system based on an underwater robot, relates to the technical field of underwater robots, and provides reliable basic data for measurement based on an original measurement point sound wave data set S, and extracts a multipath disturbance feature set F of each sonar scanning point; the multi-path interference in the underwater environment is effectively identified and represented, data are clustered through density clustering analysis, dense clusters and discrete points are successfully identified, then a disturbance residual Cc is obtained and compared with a preset interference judgment threshold Omap, each sonar scanning point is endowed with a multi-path label, and the multi-path interference in the underwater environment is effectively identified and represented. According to the method, the time sequence and the amplitude sequence of sonar scanning points are combined, the main path echo time of each measuring point is accurately obtained, the continuity of landforms is effectively judged, and high precision and stability of underwater topographic survey are ensured, especially in the aspects of multi-path interference elimination, main path reconstruction judgment and final accurate topographic reflection.

The invention provides a water quality pollution tracing method and system applied to a wave radar sea area, and the method comprises the steps: firstly obtaining a sea area polarization echo time sequence set captured by a wave radar and a sea area pollutant characteristic set measured synchronously, and then carrying out the polarization characteristic deconstruction processing of the sea area polarization echo time sequence set; a polarization characteristic parameter set of each sea area block is obtained, then a pollutant molecular structure and a polarization reflection coefficient in the sea area pollutant characteristic set are associated and adapted with the polarization characteristic parameter set to generate a pollution polarization association map, and a polarization-driven pollution traceability model is constructed based on the pollution polarization association map. The method comprises the steps of inputting a pollution polarization correlation map and preset sea area ocean current parameters, outputting a traceability path set of pollutants and an initial pollution area boundary, finally analyzing an original diffusion starting point of the pollutants according to a polarization-driven pollution traceability model, and generating a pollution traceability report containing information such as coordinates of the initial pollution area. Therefore, a sea water quality pollution source can be accurately positioned.

The invention discloses an ultrasonic imaging system and method based on a heart surface, a medium and a product, the system comprises an ultrasonic detection assembly and an imaging terminal which are in communication connection, an ultrasonic transducer is packaged at the head end of an attached ultrasonic probe in the ultrasonic detection assembly, and an acoustic window on the ultrasonic transducer is planar; the ultrasonic transducer is used for being attached to the surface of the heart or the aorta, and the plane of the ultrasonic transducer is parallel to the plane of the acoustic window; and the imaging terminal is used for generating a sound velocity mask pattern according to the reference ultrasonic image, determining echo time delay data according to the sound velocity mask pattern, synthesizing and reconstructing the radio frequency signal data according to the echo time delay data to obtain an ultrasonic image, performing motion compensation on the image sequence, performing multi-modal fusion on the ultrasonic image subjected to motion compensation, and obtaining a final ultrasonic image. The problem of acoustic interference of anatomical structures such as the chest wall and the esophagus in a traditional echocardiography technology is solved, and real-time and high-quality image support is provided for cardiac surgery.

The invention discloses a magnetic resonance 3DTOF angiography method based on variable echo time. The method comprises the following steps: step 1, respectively applying a magnetization transmission pulse and a saturation pulse to an imaging area; step 2, calculating the coding gradient lobe area of the imaging region to obtain the time of flow compensation, and determining the specific change condition of the echo time of the imaging region; 3, adopting a 3DTOF gradient echo sequence to obtain a final scanning sequence time sequence, and scanning to obtain magnetic resonance angiography data; and S4, performing filtering processing on the obtained magnetic resonance angiography data, performing reconstruction, generating a DICOM image, performing MIP three-dimensional reconstruction, and finally obtaining a three-dimensional image of the blood vessel. A variable echo time method is adopted, the closer to the center of a k space, the shorter the echo time is, the fewer signal errors are caused by blood flow, meanwhile, more sufficient time is provided for gradient compensation, artifacts caused by blood flow are reduced, and a higher-quality magnetic resonance blood vessel image is obtained.

The invention relates to a magnetic resonance imaging electromagnetic parameter distribution scanning and calculation method, which comprises the following steps that a fast spin echo sequence I is adopted to scan a target body, parameters are (alpha1, TE0, TR0 and Bw1), alpha is a deflection angle, TE is echo time, TR repetition time and Bw receiving bandwidth; scanning a target body by adopting a fast spin echo sequence II, wherein parameters are (alpha2, TE0, TR0 and Bw1); scanning a target body by adopting a fast spin echo sequence III, wherein parameters are (alpha2, TE0, TR0 and Bw2); and scanning the homogeneous water model by adopting the fast spin echo sequences I, II and III. And under the condition that the magnetic vector precession meets the conditions that the amplitudes are comparable when the phases are the same and the phases are differentiable when the amplitudes are the same, each magnetic field and electric field parameter is calculated based on the homogeneous water model data. According to the invention, decoupling of the proton density and the sensitive field of the signal is realized, so that magnetic resonance weighted quantization imaging becomes possible.

The invention discloses a radar target detection method based on graph node dual-channel feature attention fusion, and belongs to the technical field of radar signal detection, and the method comprises the following steps: 1, carrying out the graph node division of received frame radar echo data; 2, respectively extracting time domain amplitude and time frequency characteristics from echo time sequence data corresponding to each graph node; step 3, establishing a feature preprocessing sub-network; step 4, constructing a node feature fusion sub-network; 5, constructing a signal classification graph neural sub-network; 6, connecting the feature preprocessing sub-network, the node feature fusion sub-network and the signal classification graph neural sub-network in series to form a radar target detection neural network; and 7, inputting the test set into the trained radar target detection neural network, and outputting a dichotomy result of which the corresponding node is a target or clutter signal. Through the scheme, the target detection capability of the radar in the clutter environment can be improved.

The present invention discloses a multi-channel ultrasound monitoring system and method based on data analysis, which relates to the technical field of data analysis and signal processing. The method comprises the following steps: S100, acquiring original ultrasound signals from each channel through a wearable flexible ultrasound monitoring array; S200, performing denoising and filtering processing on the original ultrasound signals received from each channel, and extracting key characteristic parameters through a signal processing algorithm; S300, analyzing the extracted signal characteristics, and using a signal classification algorithm to determine whether the current signal comes from a target area; S400, performing cardiac pulsation analysis based on A-ultrasound signals, calculating the dynamic displacement of cardiac tissue through changes in echo time, and generating a time-displacement curve of cardiac pulsation in combination with multiple frames of A-ultrasound signals; S500, adjusting the monitoring strategy through real-time monitoring data. The present invention solves the disadvantage that a single array element easily deviates from the target by switching multiple array elements.

The present invention belongs to the technical field of maritime target detection, and particularly relates to a two-dimensional constant false alarm target detection method and detector based on dual-observation-channel data. The method includes: obtaining the echo time series transmitted on each observation channel and received on each range cell; the observation channels include two observation channels of the cell to be detected and two observation channels of the reference cell; respectively performing square-law detection on the received echo time series to obtain detection statistics; calculating the estimated values of the clutter power levels of the two observation channels respectively based on the samples after square-law detection of the echo data of the reference cell; calculating the normalization factor according to the preset false alarm probability; and performing target detection according to the detection statistics, the estimated values of the clutter power levels, and the normalization factor, in combination with the two-dimensional constant false alarm adaptive decision criterion. It reduces the missed detection or misjudgment caused by the limitation of single-channel information, and improves the accuracy of judging the presence or absence of a target.

Embodiments of the present invention provide a method for measuring the time-of-flight of a low-signal-to-noise ratio ultrasonic echo signal, relating to the field of measurement technology. The method comprises the steps of acquiring an echo signal; performing noise reduction and reconstruction on the acquired echo signal using an empirical wavelet transform to obtain a reconstructed echo signal; obtaining a preset reference echo peak value and a reconstructed echo peak value, and calculating the echo characteristic peak of the echo signal using a preset characteristic peak location algorithm; obtaining echo characteristic points of the echo; and measuring the echo time-of-flight based on the obtained echo characteristic points according to a preset measurement algorithm. This method can achieve higher-precision time-of-flight measurements of ultrasonic echo signals using a simpler calculation method.