813 results about "Direct wave" patented technology

A method for tomographic imaging of diffuse medium includes directing waves into a diffusive medium, solving a surface-bounded inversion problem by forward field calculations through decomposition of contributions from the multiple reflections from an arbitrary surface within the diffusive medium or outside the diffusive medium into a sum of different orders of reflection up to an arbitrary order, and using contact or non-contact measurements of waves outside said diffusive medium to generate a tomographic image.

A method is described for the measurement of multidirectional far-field source signatures from seismic surveys whereby a vertical cable acquisition technique is provided, vertical cable data are acquired, the proper receivers are specified to measure the signature, data are sorted into common selected receiver gathers CSRG, the direct wave within common receiver gather is properly windowed, the angles of each direct path are computed and the amplitude of the signatures is normalized, so as to obtain the multidirectional far-field signatures of the seismic source array having the same characteristics as those that generated the seismic reflections.

Geophysical exploration for oil wells, the source from the vertical seismic profile aspect wave data stack depth domain Corridor profile approach is the use of in situ collection of well spacing VSP data, which will all receive points drilling depth of information and hierarchical data with the depth of information, the use of direct wave VSP data travel through and optimization algorithms are highly accurate anti-layer velocity model, the direct wave to the beginning of the reflected wave in the vicinity of the depth and precision homing imaging, further in-depth domain Corridor section and with the superposition of alternative conventional method leveled in the time domain, with corridors and the superposition method, the results can be superimposed for direct comparison with the drilling and seismic data stratified layer identification. More intuitive, but also made full use of VSP data in the depth of information, make geological formation of the earthquake response and drilling, logging data in depth domain direct contrast, a more intuitive geological layer and the relationship between seismic horizon, thereby enabling layer of identification and calibration more reliable.

A head-related transfer function (HRTF) convolution method arranged, when an audio signal is reproduced acoustically by an electro-acoustic conversion unit disposed in a nearby position of both ears of a listener, to convolute an HRTF into the audio signal, which allows the listener to listen to the audio signal such that a sound image is localized in a perceived virtual sound image localization position, the method including the steps of: measuring, when a sound source is disposed in the virtual sound image localization position, and a sound-collecting unit is disposed in the position of the electro-acoustic conversion unit, a direct-wave direction HRTF regarding the direction of a direct wave, and reflected-wave direction HRTFs regarding the directions of selected one or more reflected waves, from the sound source to the sound-collecting unit, separately beforehand; and convoluting the obtained direct-wave direction HRTF, and the reflected-wave direction HRTFs into the audio signal.

A method and apparatus for evaluating a bond between a formation and a bonding material. The method includes emitting a shear wave into the tubular, recording the response of the shear wave, and evaluating the response to obtain bond information. The bond information includes bond material thickness and efficacy of the bond between cement and formation. The method includes studying and utilizing the time lag of the direct wave and wave events, as well as the interference of these waves on a spectral graph. A calibration method is included as well.

The invention discloses a passive coherent location radar direction finding system based on an Adcock antenna, mainly solving the problem that angles are precisely measured in an environment with strong direct waves and multi-path interferences. The system mainly comprises a signal branch route signal antenna, a receiver A, a signal processor, a constant false alarm rate (CFAR) and track association module and an angle measurement module. The signal antenna applies the Adcock antenna for receiving moving target echo, direct wave and multi-path. The received signal is filtered and amplified by the receiver A, and is transmitted to the signal processor; an analogue intermediate frequency signal is converted into a digital base-band signal via the signal processor, channel adjustment, clutter canceling and range-Doppler two-dimensional correlation are carried out, and the result is transmitted to the CFAR and track association module; the original track is detected by the CFAR and track association module or a target of a new track is formed by the CFAR and track association module, and the angle of the target is measured by the angle measurement module. The invention can realize precisely measurement of angles in an environment with strong direct waves and multi-path interferences.

A method and apparatus for enhancing the moveout between a direct wave and a reflected wave. The method involves transmitting imaging signals into a body to be imaged and receiving the resulting signals propagated from the signal source. The step of receiving the propagated signals includes selectively adjusting the distance between the signal source and the signal receivers between successive signals. The method further comprises separating the reflected signals from the total received signals and enhanced stacking of the measured reflected signals.

A MIMO communication system having deterministic channels the orthogonality of which can be ensured even if a reflected wave other than the direct wave is present during line-of-sight communication is provided. The MIMO communication system is used in a line-of-sight environment and has deterministic channels between the transmission side where a plurality of transmission antennas are arranged and the reception side where a plurality of reception antennas are arranged. The transmission side, the reception side, or both transmission and reception sides of the MIMO communication system have a channel matrix calculation processing means for calculating a channel matrix for establishing an orthogonal channel as a communication channel. The transmission and reception antennas forming the channel matrix are horizontally arranged with respect to the ground.

The invention discloses a method suitable for positioning a hydraulic fracturing micro-seismic source. The method includes: building a micro-seismic-monitoring observation system, acquiring logging information and other seismic data, building an initial speed model, researching and analyzing regional stratum conditions and perforation records, determining background interference and micro-seismic signal features, performing noise compression on fracturing records and performing effective waveform identification on micro-seismic signals, and using methods such as first break picking and manual intervention to pick the first break travel time of a direct wave, wherein the travel time of the perforation records is used for optimizing the speed model, and other effective events are used for the inversion positioning of the seismic source. The method has the advantages that transverse wave travel time is added on the basis that longitudinal wave travel time is used, the micro-seismic source is positioned by using the longitudinal wave travel time and the transverse wave travel time to perform simultaneous constraining, the inversion uses a method combining global searching and local searching, and the method is high in positioning precision and high in calculation efficiency.

An audio signal processing device includes: head related transfer function convolution processing units convoluting head related transfer functions with audio signals of respective channels of plural channels, which allow the listener to listen to sound so that sound images are localized at assumed virtual sound image localization positions concerning respective channels of the plural channels of two or more channels when sound is reproduced by electro-acoustic transducer means; and 2-channel signal generation means for generating 2-channel audio signals to be supplied to the electro-acoustic transducer means from audio signals of plural channels from the head related transfer function convolution processing units, wherein, in the head related transfer function convolution processing units, at least a head related transfer function concerning direct waves from the assumed virtual image localization positions concerning a left channel and a right channel in the plural channels to both ears of the listener is not convoluted.

It is a ultra-wide band earth-probing radar self object identification method based on information integration, which is the following: first to use the large time lag in the relative object signals to the direct wave in the echo-signal of the earth-probing radar and to filter the direct wave; to use the bandwidth relative process to filter wave and to extract typical data and to improve the signal to noise ratio of the signal and to extract the longitudinal and transverse typical data to object shape identification and to extract typical echo-duct data for Welch power spectrum valuation; to use RBF web to classify the object material and finally to integrate the results of the object shape identification and material identification to achieve the complete and effective automatic identification of the underground object of different materials.

A positioning apparatus and method for accurately determining a current position of a mobile station. The current position of the mobile station is determined utilizing radio waves arriving from a plurality of base stations installed in a communication area. For calculating a propagation range of a radio wave arriving from each base station, error correction processing is performed using a predetermined error correction coefficient previously calculated by measuring a radio wave propagation situation around each base station to estimate a propagation range of a direct wave within incoming radio waves. The current position of the mobile station is determined using the estimated propagation range and the positions of the respective base station.

The invention relates to a multi-scale seismic full-waveform inversion method based on a local adaptive convexification method. The method comprises steps: pre-processing is carried out, a zero value sequence serves as an initial value, and an initial speed model serves as a starting value; direct wave information is intercepted; forward modeling direct waves are obtained; an objective function inverted by a seismic source function is built; a direct wave residual and a direct wave residual back propagation wave field are obtained; an updating gradient and an updating direction of the seismic source function are calculated, and a step length is searched; the high-precision seismic source function obtained through inversion is outputted; attenuation time window processing is carried out; seismic data in the time window are simulated; local convexification processing and separation processing are carried out; a high-frequency component in an observation record is removed; a least square objective function is built, and a wave field residual is obtained; a residual back propagation wave field of the model space is obtained; the model updated gradient is obtained; the model updated direction is calculated, and the step length is searched; a multi-scale seismic full-waveform inversion result is outputted; and a final inversion result is outputted. The method is widely applied in the technical field of seismic exploration.

The invention discloses a super-resolution height measuring method based on topographic matching for a digital array meter wave radar, which is mainly used for solving the problem of high height measuring error of a fluctuating position in the prior art. The method comprises the following implementation steps of: performing clutter cancellation and interference cancellation processing on a targetsignal received by the radar to obtain a cancelled target signal; roughly measuring a target elevation angle by using a beam forming method; determining a maximum likelihood search range according tothe roughly-measured elevation angle and searching in the search range; computing a ground reflection point coordinate corresponding to each array element and a direct wave path and a reflection wavepath of each target relative to each array element according to a search elevation angle; computing a corresponding direct steering vector and a multipath steering vector by using the direct wave path and the reflection wave path; constructing a synthetic steering vector and computing a projection matrix of the synthetic steering vector; and performing maximum likelihood estimation to obtain a target accurate elevation angle. In the method, an altitude parameter of a radar position and the synthetic steering vector are introduced into super-resolution height measurement, so that the measuringaccuracy is increased; and the method can be applied to target tracking.

Methods and related systems are described for processing surface seismic data. Surface seismic data representing seismic signals detected at a plurality of surface locations is wavefield deconvolved using a combination of direct wave travel times estimated from borehole seismic data, and wavefield energy estimated from the surface seismic data.

The invention relates to the field of passive radar, in particular to a software radio conception based broadband cognitive passive radar system architecture which has an environmental perception capability, a broadband sampling capability, a high-performance digital signal processing capability and a dynamic receiver parameter regulation capability. The method includes: step one, establishing a signal model which comprises non-orthogonal transmission signals, fading channels and direct wave and target echo receiving signals; step two, unifying a fuzzy function, Cramer-Rao bound and detection performances to a general detection theoretical framework; step three, assessing results based on a performance bound given by an assessment system; step four, improving signal quality of a direct wave channel and a target echo channel according to own characteristics of a mobile communication irradiation source. The method is mainly applied to design and manufacture of passive radar systems.

A directional sound wave logging while drilling device comprises a drill collar special for the directional sound wave logging while drilling device and a directional sound wave while drilling sonic system installed on a drill collar upper centralizer and composed of a single-transmitting four-receiving probe, and adopts a groovy sound insulator on the drill collar to inhibit drill collar direct waves from a transmitting probe to a receiving probe, wherein the transmitting probe and the receiving probe are respectively powered on by a special power supply battery. A measurement and control circuit receives acquired waveform data to perform real-time calculation treatment, communication interfaces are provided for a measurement while drilling system (MWD) and a ground processing system, the power supply battery and the measurement and control circuit are arranged in a compression resistance barrel in a special drill collar mud flowing channel special for sound waves, and upper and lower flow guiding sleeves are connected with the sonic system. The stratum rock longitudinal and transverse sound velocity measured in the drilling process in real time can be used for lithological identification, porosity degree calculation, rock mechanical parameters, well opening stability prediction and the like.

The invention relates to a system utilizing CMMB (China mobile multimedia broadcasting) signals to detect a target and a method thereof. The system comprises a receiving antenna, an analog chassis with a signal simulating and receiving component, a CPCI (compact peripheral component interconnect) chassis with a signal acquisition and processing component, at least one disc array chassis with a signal storage component, a switchboard and a signal process for signal processing, which are connected in sequence. The analog reception adopts a scheme of secondary mixed frequency and fixed medium frequency; the data acquisition adopts a scheme of medium-frequency bandpass sampling and digital down-conversion; the data storage adopts a high-speed disc array; and the data processor is used for implementing such operations as signal reconstruction, channel correction, direct wave suppression, digital beam formation, inter-ambiguity function, peak detection, constant false alarm detection, positioning and tracking and the like, and final output of information of the target distance, speed and direction. The system has the following advantages of no need for frequency distribution, no electromagnetic pollution, high signal randomness, high signal interception performance, large signal bandwidth, high distance resolution, low research and maintenance cost, and high mobility.

Disclosed herein is a wireless transmission system. Transmission antennas are provided on a first communication apparatus while reception antennas individually corresponding to the transmission antennas are provided on a corresponding second communication apparatus. Each reception antenna receives a desired wave from a corresponding transmission antenna as a direct wave and receives an unnecessary wave from a different transmission antenna as a direct wave. The first communication apparatus modulates only the amplitude of a carrier signal for all channels. The second communication apparatus demodulates composite waves of desired waves and unnecessary waves received by the reception antennas by envelope detection or square-law detection and carries out correction operation for the demodulation signals based on transmission characteristics of transmission spaces between the transmission and reception antennas to acquire transmission subject signals.

The invention which discloses a radar remote sensing method for detecting the distribution of the water content in soil in a depth direction relates to the radar remote sensing detection technology. The method comprises the following steps: 1, respectively adopting two modes of horizontal polarization and vertical polarization to measure the scattering field of the soil under multiple visual angle and multiple frequency observation; 2, filtering out components of direct waves in radar echoes; 3, scaling echo data; and 4, utilizing the scattering model and the dielectric constant of the soil to obtain the distribution of the water content in the soil in the depth direction. The radar remote sensing method for detecting the distribution of the water content in the soil in the depth direction of the invention allows the distribution of the water content in soil with the depth under the soil surface of 0-3m to be detected, and can be applied to ground, air and space base remote sensing monitoring platforms.

A method of processing seismic data obtained using a seismic vibrator that includes estimating travel times of direct wave arrivals between the seismic vibrator and an array of seismic receiver locations and wavefield deconvolving the seismic data using the direct wave arrival travel times. Also a related method of producing a high-frequency geological subsurface image that includes acquiring seismic data having significant harmonic energy using a seismic vibrator, estimating direct wave arrival travel times between the seismic vibrator and an array of seismic receiver locations, wavefield deconvolving the seismic data using the estimated direct wave arrival travel times, and using the wavefield deconvolved seismic data to produce a high-frequency geological subsurface image. A further related computer useable medium having computer readable program code means embodied therein practicing the inventive method.

The invention discloses a radar target detection method based on a communication satellite radiation source. The method comprises the steps of determining a radar, wherein a scene on which the radar is located comprises a communication satellite, and the communication satellite radiates an electromagnetic wave signal to the radar so as to respectively obtain a direct wave signal and a target echo signal and respectively obtain a direct wave digital signal and a target echo digital signal; respectively obtaining N direct wave digital signal sections and N' target echo digital signal sections; sequentially carrying out direct wave interference cancellation processing and delay-Doppler migration calibration on the N' target echo digital signal sections to obtain N' target echo digital signal sections subjected to delay-Doppler migration calibration, and to further obtain a coherent accumulating delay-Doppler cross-correlation three-dimensional diagram; carrying out constant false alarm detection on the coherent accumulating delay-Doppler cross-correlation three-dimensional diagram to obtaining R' targets and further obtain doppler frequency shift information corresponding to the R' targets and delay information corresponding to the R' targets.

The invention discloses a exploration method for transmitting and receiving dipole transverse waves in a well. The remote exploration method comprises the following steps of: setting a sub dipole sound source in the well; controlling the frequency of a dipole sound wave excited by the sub dipole sound source so as to enable a dipole sound source to transmit the dipole sound wave in the well below a bending wave cut-off frequency; filtering received waveform signals of a direct wave in the well and a reflected wave outside the well through a filter; adjusting the signals through programmable gain controlled by a micro-processor and a receiving control system to an amplitude suitable for a subsequent analogue / digital converter; after digitally sampling the signals through the analogue / digital converter, transmitting the signals to the micro-processor; and storing digitized data by the processor and transmitting the digitized data to a ground acquisition system. The technical problem of difficulty in measurement and processing because sound wave signals of a receiver reflected to the well are very weak in the traditional dipole transverse wave method can be solved by the method disclosed by the invention.

The invention discloses a self-adapting wave form retrieval method through utilization of zero offset vertical seismic profile (VSP) data to estimate speed and Q value. The method includes a first step of selecting undisturbed a segment of a first-motion wave in a self-adapting mode to the maximum extent according to the signal to noise ratio of the actual VSP data and the degree of a direct wave disturbed by an upward traveling wave, and fully utilizing effective information to construct an objective function, a second step of improving the sensitiveness of the objective function to changes of the Q value through proper construction of a data weighting matrix according to the feature that the Q value is more difficult to estimate than other parameters; a third step of adopting a recently developmental self-adapting multiplication regularization method to improve the ill-conditional problem of nonlinear inversion, and limiting the value range of the unknown parameters through nonlinear transformation, and a fourth step of inferring analytical expressions of elements of a jacobian matrix so as to decrease the calculated amount of inverse problems. Compared with a spectrum ratio method and a wavelet envelope peak value instantaneous frequency method, the method is relatively smaller in influence of the upward traveling wave, stronger in anti-noise performance, and higher in accuracy of inverse parameters.

Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

The invention discloses a method for fast realizing the signal processing of passive radar based on a GPU (Graphics Processing Unit). The method comprises the following steps of at a link of direct wave and clutter suppression, dividing whole data into N data blocks and dividing the data blocks into L data segments, wherein the number of data points within each data segment is M; splicing the data with the same data segment number, of each data block together in a way that the current segment of the No. N data block is spliced with the next segment of the first data block; enabling M*N threads by the GPU for parallel processing; at a link of coherent accumulation and walk correction, segmenting the data in a way that all the data are divided into n segments; grouping the continuous segments in a way that every DIM segments form one group; splicing the all groups of data together in sequence and storing such data in a continuous address space of a GPU video memory; and finally, carrying out GPU parallel processing on the each group of data. The method for fast realizing the signal processing of the passive radar based on the GPU is more applicable for the GPU parallel processing, and the higher speedup ratio can enable real-time processing demands to be met.

Method for correcting OBC or deep-towed seismic streamer data for surface-related multiple reflections. The measured pressure data, preferably after conditioning (71), are simulated using a forward model that includes a water propagation operator between source locations and receiver locations and a term representing primary impulse responses (72). Other terms include direct arrivals and source wavelets. Iterative optimization of an objective function is used to minimize the difference between measured and simulated data, updating the primary impulse response term and optionally the source wavelets term each iteration cycle (73). The converged primary impulses (74) are used to construct simulated multiples and direct arrivals (75), which can be subtracted from the measured data. Optionally the measured data might be blended during the forward simulation (72), to save computational costs in the forward simulation (72) and in the inversion (73).

The invention discloses a single-station user terminal locating method and a system. The method comprises that position information of a plurality of known points in a community is obtained, the position information comprises a signal reaching angle, time advance and longitude and latitude information; information of the signal reaching angle and the time advance of a point to be located is obtained; at least one known point with the signal reaching angle and the time advance most approximate to the signal reaching angle and the time advance of the point to be located is found according to the position information of the known point; and the longitude and latitude information of the point to be located is calculated according to the longitude and latitude information of at least one found known point. According to the single-station user terminal locating method, at least one known point near to the point to be located is found, and longitude and latitude of the point to be located are calculated through the longitude and latitude of at least one known point. The single-station user terminal locating method can solve the problem that a traditional locating method is not accurate caused by multi-diameter or non-direct waves, and can locate accurately under the condition of many obstacles including buildings and the like.