37results about How to "Good cross-correlation" patented technology

The invention discloses ultrasonic imaging method and device. The method comprises the following steps of: firstly carrying out coded modulation on a pulse generating an acoustic radiation force, and exciting a probe to emit an ultrasonic wave to generate a multi-frequency acoustic radiation force to generate tissue vibration; then adopting the coded modulation different from an exciting pulse for the pulse detecting the tissue vibration, ensuring the good correlation between two code words, and eliminating the interference caused by an exciting pulse echo generating the acoustic radiation force for a detection echo by utilizing a CDMA (Code Division Multiple Access) technology similar to communication, thereby improving the signal-to-noise ratio and increasing the energy of the acoustic radiation force by more fully utilizing the pulse width and the frequency band width resources of a system.

A technique for interference suppression in MC-CDMA systems is proposed which exploits the structural differences in signals that arrive at the receiver with Doppler shifts or carrier offsets. Oversampling the received signal in the frequency domain and properly combining the samples provides the interference suppression. Frequency domain oversampling is accomplished by using a time extension of the conventional MC-CDMA signal. Furthermore, a receiver structure is introduced that despreads and combines groups of samples so that a linear minimum mean-squared error solution for combining the groups is easily found. This combining scheme increases the signal-to-interference ratio (SIR) experienced by the desired user in the MC-CDMA system. In addition, the receiver performs well in severe near-far scenarios when there is sufficient Doppler separation between the signals of the desired user and an interferer. Numerical results show that the proposed receiver significantly outperforms the conventional MC-CDMA receiver.

The invention discloses a real-time absolute ranging method and system based on single-chamber dual-femtosecond optical comb cross-correlation analysis. The method comprises steps: S1, two simultaneously-outputted femtosecond optical combs with different repetition frequencies are generated, the two different repetition frequencies are fr1 and fr2, and the repetition frequencies are locked to an atomic clock by frequency stabilization control; S2, after the beam of the two femtosecond optical combs passes through an interferometer optical path module, the orthogonal polarization components ofoptical comb pulse return light (reference light and measurement light) and local optical comb pulses are measured, and after combination, two groups of femtosecond laser pulse pairs with mutually-perpendicular polarization directions are generated; S3, two-path optical balance cross-correlation signals for reference and measurement are generated, and the signales can be generated by a femtosecondpulse cross-correlation analysis unit in the embodiment of the invention; and S4, the balance cross-correlation signals are subjected to high-speed digital signal analysis processing to obtain a ranging result. The system is the device used for executing the above method. The method and the system disclosed in the invention have the advantages of large ranging range, fast updating speed, high measuring precision and simple operation and the like.

The invention discloses a network coding feedback method for a coordinated multi-point transmission system, which belongs to the technical field of communication. Information such as pre-coding matrix indicator (PMI) information required to be fed back and own information such as reference signal (RS) information periodically to be transmitted are subjected to network coding and then transmitted. A network coding concept is introduced to simultaneously transmit feedback information under the condition of keeping constant conventional uplink transmission overhead. A transmitted information sequence subjected to the network coding still has relatively higher cross correlation and autocorrelativity, so a receiver obtains the PMI information by a correlation detection and minimum Euclidean distance searching method, and own information required to be fed back is hidden in a sounding RS (SRS) sequence subjected to the network coding in a network coding way by taking SRS information required to be transmitted by the system as a carrier to improve the transmission effectiveness and effectively improve the throughput of the system by reducing even eliminating feedback overhead.

The invention discloses a controllable test vector generator based on a linear feedback shift register (LFSR). The controllable test vector generator comprises three sections: 1, a control code sequence generation section comprising a counter and a memory; 2, a sequence pseudo random test vector sequence generation section comprising a inscribe LFSR; 3, a feedback network section formed by n-1 bit input or a non-gate NOR and an exclusive-OR gate XORfb. Depending on the test vectors required to be generated, the control code sequence is acquired, wherein the control code sequence is stored in the memory and is provided for controlling a run of the inscribe LFSR, such that the sequence or jump output pseudo random sequence of the inscribe LFSR is adopted as the test vector. With the present invention, only the control code memory, the counter, the feedback network section formed by the n-1 bit input or the non-gate NOR and the exclusive-OR gate XORfb, and a control exclusive-OR gate XORCTRL are added on the base of the inscribe LFSR, such that hardware expense is few, and test cost is low.

The invention relates to the field of communication, disclosing an information channel evaluating method, a basic training sequence code detecting method and a receiving terminal. The method comprises the following steps of: conjugating with the FreqLocData (i, j) and performing the dot product after offsetting the interference signal of RxMidamb (j) and converting the time frequency domain in each iterating process for evaluating the information channel, wherein the FreqLocData (i, j) is the data that the Middleamble of each co-channel cell is converted to a frequency domain; converting the dot product-performed data FreqH(i, j) into a time frequency signal to denoise; computing the CheOut (i, j) of this iteration according to the denoised signal TimeHCaINoise (i, j) and an information channel evaluating result CheOut (i, j) computed by the last iterating process; and deciding whether to output the result or enter into the next iterating process according to the iterating times. Therefore, the invention can effectively improve the receiving performance of the receiving terminal when the same frequency interference is more serious.

The invention provides a synchronous sequence sending method, and a synchronous detection method and apparatus. The sending method comprises the following steps: setting a target synchronous sequencewith good autocorrelation property, wherein at least a segment of sequence intercepted on the time domain or the frequency domain of the target synchronous sequence is a sub-synchronous sequence, thesub-synchronous sequence has good autocorrelation property, and the sub-synchronous sequences have good cross-correlation property; and sending the target synchronous sequence to a terminal. In the synchronous sequence sending method provided by the embodiment of the invention, for terminals with different bandwidths or terminals with different carrier intervals, after a base station side sends the same target synchronous sequence, the terminals can intercept the corresponding sub-synchronous sequences according to own requirements to perform synchronous detection, thereby not only ensuring the synchronous detection accuracy, but also improving the application range of the target synchronous sequence.

The invention provides an underwater acoustic communication synchronization method based on a Zadoff-Chu sequence and an OFDM technology. The method comprises the following steps of: generating to-be-transmitted signals through the OFDM technology, setting a length N of the Zadoff-Chu sequence to be the number of subchannels of OFDM; generating two segments of identical Zadoff-Chu sequences ZC-sq1 and ZC-sq2 with the length N by the same root sequence, adding the two segments of sequences to the front end of an OFDM signal, and adding one segment of protective interval with the length Ng between the two segments of sequences; respectively capturing the signal through two time windows of which the length is N, and judging whether a peak value greater than a threshold value Delta exists in correlation operation result; respectively locating the peak values greater than the threshold value Delta in the correlation operation result, taking a peak value position of which the peak value is greatest as the peak value position searched this time, respectively recording as N1 and N2; judging whether the distance between the N1 and the N2 is approximate to N+Ng; acquiring signals again and taking N2+Ng as a starting point of an OFDM signal data segment, and thereby completing synchronization. The underwater acoustic communication synchronization method provided by the invention improves precision, reliability and accuracy of synchronization.

The invention relates to a signal sending and receiving method and a device thereof. Wherein the part, carried by a first signal, on a kth subcarrier in an ith subcarrier group in the N subcarrier groups is one of the listed sequences, and the related sequence is one of the listed sequences; the listed sequences are sequences with better cross correlation, so that for the two subcarrier groups, aslong as two of the listed sequences are selected, the better cross correlation between the signals borne by the two subcarrier groups can be ensured, the interference between the signals can be reduced, and the channel estimation performance is improved.

An operating method for an electronic device and a signal processor included in the electronic device are provided. The operating method for an electronic device comprises a descrambling a synchronization signal received from a cell, acquiring a time domain average signal on the descrambled synchronization signal, executing a differential correlation on the time domain average signal by a predetermined reference, and measuring a power of the synchronization signal provided from the cell, using the differential.

The invention provides a waveform design method of an expanding zero-correlation zone; the method includes steps of forming a zero-correlation sequence by applying an initial regular base sequence generating method, introducing a spread spectrum radar polyphase code sequence to perform Kronecher multiplication with the zero-correlation sequence, so that the final sequence has quasi-perfect self-correlation property and perfect cross-correlation property within a certain zone, and has a larger zero correlation zone; thereby effectively reducing the mutual influence of the echo of adjacent distance units and improving the target detecting precision.

The invention discloses a communication coding method for a marine oil exploration acoustic locating transponder, and belongs to the technical field of the seaborne geophysical exploration. The communication coding method for the marine oil exploration acoustic locating transponder comprises the following steps: generating a source code, generating a combination code, and generating a final code, wherein in the step of generating the source code, c is a feedback coefficient and is also a characteristic multinomial coefficient, the values of the coefficients can be ''1'' or ''0'', ''1'' represents that a feedback branch is communicated, ''0'' represents that the branch is cut off, the period of a shifting register output sequence can be changed if the connection states of feedback lines are different, and the value of c determines the feedback connection and the sequence structure of the shifting register; in the step of generating the combination code, firstly, a source code optimization pair is optimized, and the combination code is obtained; and in the step of generating the final code, according to the relevant characteristic, the amount of the combination code and the balance of the combination code, selection is carried out to generate the final code. According to the communication coding method for the marine oil exploration acoustic locating transponder, which is disclosed by the invention, the noise of a receiver is lowered, the signal to noise ratio of the receiver is improved, and meanwhile, the problem of mutual interference due to the fact that a plurality of transponders simultaneously response can be effectively overcome.

The invention provides a transmitting method and a receiving method of a preamble signal in ultra-high-speed mobile broadband communication. The sending method comprises the following steps: generating a time domain leader sequence A with the length of N, generating a time domain preamble symbol D with the length of L, taking D as a minimum unit, cascading and expanding for any length to form a preamble symbol P, cascading data symbols behind the preamble symbol P to form a sending signal baseband frame B, enabling the baseband frame B to pass through a sampling filter to obtain a filtered baseband frame signal S so as to limit the bandwidth of the baseband signal, performing up-conversion on the baseband frame signal S to form a radio frequency signal, and sending the radio frequency signal outwards. Compared with the prior art, the method has a good cross-correlation characteristic under an extremely low signal-to-noise ratio, and the calculation complexity is greatly reduced, so that chip processing resources are saved and the information operation speed is increased.

The invention provides a calculation method and device for PCCPCH (Primary Common Control Physical Channel) carrier and interference ratio. According to the method, PCCPCH_RSCP is calculated by performing descrambling and despreading operation on first data field data and second data filed in TS0. During calculation of PCCPCH_ISCP, when PCCPCH_C/I is not smaller than a preset threshold value, midamble_ISCP is calculated by adopting certain specified taps on an interface between two windows on channel impulsion response, and PCCPCH_ISCP is obtained by means of scale conversion; and when PCCPCH_C/I is smaller than the preset threshold value, midamble_RSCP of a midamble field is calculated through a relevant operation method, midamble_RSCP is subtracted from midamble_RSSI to obtain midamble_ISCP, and new PCCPCH_ISCP is obtained by means of scale conversion. Through adoption of the calculation method and device, the calculation accuracy is increased.