49 results about "Differential space time" patented technology

A differential space-time block coder produces successive space-time blocks of symbols from M-PSK symbols to be encoded, in accordance with an orthogonal matrix and a normalization factor. Differentially encoded space-time output blocks, for transmission via a plurality of transmit antennas (16, 18) of a wireless communications system, are produced by multiplying (42) each space-time block from the space-time block coder (40) by the respective previous (44) differentially encoded space-time output block. Decoding is independent of channel estimation, and the arrangement is simple, avoids error propagation, and is applicable to different numbers of transmit antennas.

A method and apparatus are provided for combining pilot symbols and Transmit Parameter Signalling (TPS) channels within an OFDM frame. The method uses Differential Space-Time Block Coding to encode a fast signalling message at an OFDM transmitter. At an OFDM receiver, the encoded fast signalling message can be decoded using differential feedback to recover information about the channel responses that would normally be carried by pilot symbols. In wireless data transmission employing adaptive modulation and coding, an instantaneous channel quality measurement, independent of the origin of interference for example, neighboring-cell interference, white thermal noise, or residual Doppler shift is provided. Using the correlation between a signal which has been symbol de-mapped, and one which has also been soft decoded and re-encoded, a channel quality indicator is produced. Another embodiment uses TPS data as pilot symbols by decoding TPS and then re-encoding.

The invention discloses a complex lithology natural gas reservoir interval transit time discriminating method, and belongs to the technical field of acoustic logging information application. Formation lithology mineral composition, porosity, water saturation and formation water electrical resistivity factors are utilized to calculate an interval transit time theoretical value curve, the interval transit time theoretical value curve obtained through calculation is compared with an interval transit time curve measured actually, and a natural gas reservoir is discriminated according to the different features of the interval transit time theoretical value curve obtained through the calculation and the interval transit time curve measured actually. The complex lithology natural gas reservoir interval transit time discriminating method is especially suitable for being used in discrimination of natural gas reservoirs of clastic rock, carbonate rock, igneous rock and the like, good in application prospect and capable of improving discriminating effect of the natural gas reservoirs.

The invention discloses a differential encoding space-time-frequency modulation method, and belongs to the technical field of wireless communication. The method comprises that: a mobile terminal of a communication system performs space-time encoding on an information bit sequence required to be transmitted to generate a unitary matrix code word sequence; the unitary matrix code word sequence is subjected to differential modulation to generate a matrix sequence to be transmitted; symbols in the matrix sequence to be transmitted are respectively mapped to a space domain, a time domain and a frequency domain so as to acquire a group of space-time-frequency three-dimensional signals; a plurality of groups of transmission signals are acquired through OFDM modulation, and each group of transmission signals is transmitted through a transmitter antenna; and the OFDM modulation and differential demodulation are directly carried out a receiving end, and required information is acquired. Through differential space-time-frequency block code mapping or differential space-time-frequency cyclic code mapping, the encoding and the differential modulation are respectively carried out at different dimensionalities, so that a requirement of a channel on relevance of the time domain and the frequency domain is reduced, and a requirement of reliable signal transmission in high-speed mobile environment in a wideband communication system can be met.

A differential STBC transmitting/receiving apparatus in a multiple antenna system using eight or less transmit antennas is provided. In the differential STBC transmitting apparatus, a symbol mapper receives binary data and generates a number of symbols from the binary data, each symbol having a number of bits. A space-time block encoder generates an STBC by encoding the symbols. A differential processor differentially encodes the STBC through feedback and delay. A distribution matrix processor substitutes the differentially coded STBC into a distribution matrix preset according to the number of transmit antennas, and outputs the differential STBC code of the distribution matrix to the transmit antennas.

The invention provides a geology single-layer data depth time conversion method and device for seismic data explanation. The geology single-layer data depth time conversion method includes: using a seismic marker bed position nearest to the upper portion of a target series of strata as the initial position of calculating to extract time and depth initial values; obtaining the geology single-layer depth values to be calculated from an oil filed geology stratified data table to serve as the target depth values in deep time conversion; adopting an interval transit time curve, performing depth time conversion calculation from the initial depth downwards in a point-by-point recurrence mode until reaching the target depth, and solving the time value corresponding to the target geology single layer; and using the seismic data explanation layer position under the target series of strata as the reference, comparing errors between time values of well logging speed calculation and actual seismic wave travel time values, performing error correction in an error averaging method, and outputting the rectified results to obtain the final geology single-layer time values.

The invention relates to a method for reconstructing an interval transit time curve by virtue of multiple logging curves. The method mainly comprises the steps of selecting a plurality of logging curves obvious in response to reservoir characteristics by performing reservoir sensitivity and correlation analysis on the logging curves; performing discrete wavelet decomposition on the logging curves together with a sonic wave curve to form 8 decomposition layers; enabling all the layers of high-frequency decomposition results of other logging curves except the sonic curve to form matrices respectively, obtaining the corresponding characteristic values and characteristic vectors of the matrices; taking the characteristic vectors corresponding to different characteristic values as new components, which, at the moment, have orthogonality (correlation ); performing multivariate regression analysis on the high-frequency components of the corresponding layer of wavelet decomposition of the sonic curve by utilizing characteristic vectors of each layer, calculating a weighting coefficient corresponding to each vector, returning a regression significance analysis result and determining the quality of regression; next, determining the number of layers of the sonic high-frequency components to be reconstructed by virtue of the characteristic vectors according to the regression significance analysis result, selecting multiple regression results as the high-frequency components for a part having more layers than selected layers, and remaining the high-frequency decomposition results of the sonic logging curves for a part having less layers than the selected layer, and then carrying out curve reconstruction by using the low-frequency components of the sonic logging curves and the high-frequency components obtained through regression so as to obtain a final sonic reconstructed curve.

The invention provides a system for a differential space time transmit diversity in a multicarrier modulation system and an implement method thereof, wherein the implement method comprises the following steps: A, a modulation signal is subjected to differential coding by a differential space time coder and is output to two paths; and B, one path of signal in the step A passes through an OFDM modulator and a cyclic prefix insertion device and is transmitted by an antenna, the other path of coding signal passes through another OFDM modulator and is transmitted to a time delay delta unit, after the signal is subjected to cyclic time delay with delta delayed time, the signal is transmitted to the cyclic prefix insertion device, inserted with cyclic prefix and transmitted by an antenna. On the premise of ensuring the transmission speed, the system can obtain high space time diversity gain and effectively improve system performance.

The invention discloses a method for obtaining the undercompaction overpressure in a stratum. The method comprises the steps that 1, firstly, according to the difference change characteristics of theaverage interval transit time, the average stratum density and the average neutron porosity of a mudstone section along with the average buried depth, the normal compaction section and the undercompaction section are determined; 2, then the index relation of the acoustic wave velocity and the vertical effective stress is fitted by utilizing a scatter diagram of the acoustic wave velocity and the vertical effective stress of the normal compaction section; 3, due to the fact that change of the vertical effective stress and the acoustic wave velocity of the undercompaction section needs to fall on a change trend curve of the acoustic wave velocity and the vertical effective stress of the normal compaction section, the acoustic wave velocity of the undercompaction section is substituted into the index relation obtained in the step 2, and the vertical effective stress of the undercompaction section is obtained; and 4, finally, the overpressure value in the undercompaction section is obtained by combining the relation of the vertical effective stress of the undercompaction section and the overpressure. The magnitude of the undercompaction overpressure can be accurately obtained only through logging data, the characteristics of rapidity, simpleness, convenience and accuracy are achieved, and the evaluation efficiency on the undercompaction overpressure is improved.

Disclosed is a differential space-time block coding apparatus with a high transmission rate in a wireless communication system employing multiple transmit antennas and a method thereof. The differential space-time block coding method includes the steps of, when elements of a transmission matrix B₄₃^v are transmitted in a predetermined block (a v^th block) through a predetermined transmit antenna at a predetermined time, modulating a symbol S_v of inputted binary data to a symbol S_v+1, creating a matrix S₄₄^v+1 in a block (a (v+1)^th block) following the predetermined block by substituting the modulated symbol for the matrix P₄₄, and then, in order to perform a differential encoding function, multiplying the matrix B₄₃^v by the matrix S₄₄^v+1 so as to calculate a new matrix B₄₃^v+1 to be transmitted in the (v+1)^th block.

The invention relates to a blind detection method for differential space-time coding signals. The method includes the process that the input differential space-time coding signals are separated via a JADE method to obtain signal components transmitted by antenna array elements, each signal component is processed via a modulation mode recognition algorithm to recognize a modulation mode, the signal components with the same frequency band and the same modulation mode are extracted, the extracted signal components are detected by the aid of a differential space-time coding signal detection method to recognize differential space-time coding signals, the differential space-time coding signals with continuous time span are selected to perform statistical analysis so as to realize effective evaluation of a differential space-time coding matrix. By the method, the JADE algorithm, the modulation mode recognition algorithm and the differential space-time coding signal recognition algorithm are combined for the first time, and differential space-time coding signal recognition and differential space-time coding matrix evaluation under the condition of no priori knowledge is realized.

The invention belonging to the field of radar technology discloses a space-based multi-channel moving target radar receiving and processing system so that a problem of the great influence on the dynamic range of the system by strong clutters in stealth target monitoring can be solved. The system is composed of M antenna sub arrays, M radio-frequency receiving channels, M first real-time delay units, M second real-time delay units, and M-1 operational amplifiers that are arranged in sequence along the moving direction of a satellite platform, wherein the M is larger than or equal to 2. Each antenna sub array sends a received echo signal to one corresponding radio-frequency receiving channel; the radio-frequency receiving channels carry out down conversion on the echo signals to obtain intermediate-frequency signals, divide the signals into two paths, and output the processed signals to the operational amplifiers by a delay way, wherein the delay difference of the two paths is 1/PRF; theoperational amplifiers carry out cancellation on adjacent pulse signals of the adjacent channels to reduce the strength of clutters entering the data acquisition system. Therefore, the requirement for high-order-digit AD chips is reduced; the high effective precision of echo data is ensured; and weak target detection by a space-based early-warning radar is guaranteed.

The invention discloses a Distributed orthogonal decode transmitting difference space-time coding decoding scheme based on a wireless sensor network, comprising the following steps: 1) in a narrowband wireless sensor network, two information source nodes synergetically transmit information to a same information destination node to determine an one by one mapping relationship between difference coefficient pairs and primitive symbol pairs based on a phase modulation module and a primary reference phase; 2) based on the determined mapping relation, the two information source nodes perform a differential coding to the respective primitive transmitting symbol to map on a differential coding symbol set; 3) the transmission of a set of information has three time slots, wherein, in the first and second time slots, the two information source nodes broadcast and transmit differential coding symbols respectively, and at the same time, process a receiving signal of the other information source to form an orthogonal space-time code structure for transmitting by using a decode transmitting cooperative scheme; 4) in the third time slot, the two information source nodes normalize the receiving signal firstly, and then transmit a treated signal to the information destination node at the same time in a same power; 5) the information destination receives signal of the three time slots to add the first and the second time slot signals and combining the receiving signal of the third time slot, and the difference coefficient pairs relative to the corresponding primitive transmitting symbol can be decoded by using the difference decode arithmetic of the invention; 6) based on the mapping relationship between the primitive symbol and the difference coefficient pairs, the primitive transmitting symbol can be inverse mapped , and at least, the primitive transmitting bit can be obtained by demodulation.

The invention relates to the field of microseismic event identification, in particular to an automatic identification method of microseismic events based on inter-channel energy superposition. The method comprises the steps that a perforation signal first arrival time difference file deltati is calculated; multi-channel microseismic signals are corrected by using the first arrival time differencefile deltati; corrected multi-channel microseismic signal energy is summed to obtain a high signal-to-noise ratio model trace M(i); identification of the microseismic events is conducted by adopting an STA/LTA method based on a model trace energy envelope E(i). By means of the method, reliability and correctness of the automatic identification method of the microseismic events are improved aimingat defects of a conventional microseismic signal first arrival picking method.

Provided is an apparatus and method for receiving a differential space-time block code (STBC) without estimating a channel characteristic using an additional training sequence in a wireless communication system using a plurality of transmission/reception antennas. The apparatus for receiving a differential STBC includes a detector for detecting a symbol from a received differential STBC using a trellis diagram and a Viterbi algorithm, a deinterleaver for deinterleaving the detected symbol, and a decoder for decoding a signal deinterleaved by the deinterleaver.

A point target movement velocity detection method based on multiple linear moveout scanning, extending and sampling comprises the following steps: (1) establishing a multiple linear moveout scanning detection device; (2) using each linear detector to detect point targets in an extending and sampling manner; (3) processing Nt groups of image data acquired by each linear detector to obtain sub-pixel images; (4) performing non-uniformity correction and sub-pixel match on two sub-pixel images processed by the two adjacent processed linear detectors, then performing difference computation to complete the background subtraction; (5) performing threshold filtering on difference images processed by the two adjacent processed linear detectors, extracting positive and negative point pairs in the difference images by adopting the neighborhood constraint criterion, so as to complete the target detection and extraction of moving points in once scanning process; (6) marking regions of paired positive and negative points extracted in the step (5) respectively, calculating movement velocity and movement directions of the targets according to the position relation of the marked regions of the positive and negative points; (7) averaging the movement velocity and the movement directions obtained in the step (6) to obtain the velocity and the direction of a detected target.

The invention relates to a relay closing moment detecting method. Timing is started from the moment that a relay control chip gives out a closing instruction, the difference value delta U on the two sides of a relay is detected in real time, if delta U is smaller than a threshold value for a certain continuous time, it is regarded that the relay is closed, the time value corresponding to the moments with delta U smaller than the threshold value serves as the time delay difference of the relay for the control chip to calculate the moment for sending a closing instruction when the relay is closed next time, it is guaranteed that the relay is closed at the zero crossing point of an alternating current source and the surge current is minimum, and therefore the service life of a machine is prolonged.

The invention belongs to the technical field of wireless mobile communication, and discloses a Short burst MIMO-OFDM communication system and method based on differential coding. The method includes:inputting a short burst data stream to be sent; performing channel coding; carrying out constellation mapping; based on a differential coding mode, adopting a method for carrying out difference on OFDM subcarriers; carrying out OFDM modulation; after the receiving end receives the signal, carrying out OFDM demodulation, removing a cyclic prefix, and then carrying out fast Fourier transform (FFT);performing differential space-time frequency decoding; performing constellation inverse mapping; performing channel decoding; and obtaining the output required data. According to the method, the problem caused by channel estimation is solved, pilot frequency does not need to be added into a frame structure, and the utilization rate of data symbols in a short frame structure is improved; the adopted differential space-time-frequency coding method can reduce redundant data under short burst and can obtain the maximum diversity; and channel coding is further added, so that the system reliabilitycan be further improved.

The invention belongs to the technical field of wireless communication, and relates to an in-phase/quadrature (IQ) imbalance compensation method for a differential encoding orthogonal frequency division multiplexing (OFDM) system. The method mainly utilizes compensating parameters of a subcarrier and a mirror image subcarrier to perform combined estimation, thus compensating the IQ imbalance in the system. The IQ imbalance compensation method for the differential space-time encoding OFDM system comprises the steps of estimating the compensating parameters in the subcarrier and a subcarrier mirror image, updating a compensation matrix, and using the compensation matrix to compensate an original carrier. According to the method, the data of the two subcarriers is used for estimating a compensation vector together while the accuracy is not lost, and the convergence rate of the algorithm doubles that of a generalized linear algorithm.

The invention discloses a differential space-time coding and orthogonal frequency division multiplexing encoding method for an LEO system based on double sampling. The method comprises the following steps of firstly, constructing an asynchronous double relay network model under an LEO satellite channel; secondly, carrying out differential DTSC-OFDM encoding; thirdly, constructing a double sampling receiver; and lastly, carrying out differential decoding through a receiving end. The double sampling method based on a differential DSTC-OFDM encoding condition can overcome intersymbol interference caused by frequency selective fading, and meanwhile, complicated channel estimation is removed from transmitting and receiving ends; the transmitting end adopts a double sampling way to improve an average received signal to noise ratio of the receiving end, so that the system performance reduction caused by delay inequality of decimal parts is avoided. Compared with the prior art, when the system has the delay inequality of the decimal parts, the bit error rate performance can be well improved.

The invention provides a method and device for determining reservoir lithology. The method comprises the steps that whether a reservoir to be determined is a sand-mudstone formation; under the condition that the reservoir to be determined is the sand-mudstone formation, the stratum correction constant quantity of the reservoir to be determined is obtained; the low-frequency component of an interval transit time curve and the shale content of the reservoir to be determined are obtained; according to the stratum correction constant quantity, the shale content and the low-frequency component of the interval transit time curve of the reservoir to be determined, a reservoir characteristic curve of the reservoir to be determined is obtained through calculation; and according to the reservoir characteristic curve, the reservoir lithology of the reservoir to be determined is determined. In the embodiment, the distinguishing precision of sand shale is greatly improved, and therefore the purpose of improving the reservoir predicting effect is achieved.