93 results about "Local spread" patented technology

The invention discloses a GPS signal large-scale parallel quick capturing method, which comprises the following steps: configuring a large-scale parallel quick capturing module firmware comprising submodules of multiplier, data block cache, parallel part correlative processing, frequency domain transformation, postprocessing and digital controlled oscillator, code generator and the like in a system CPU; through the calling computation, converting low-medium frequency digital signals into baseband signals in a processing procedure to combine a data block; performing zeroing extension of the length and the data block on each equational data section in the data block; then based on FFT transformation computation, performing parallel part correlative PPC processing on each extended data section and local spreading codes, and performing FFT transformation on each line of a formed PPC matrix to obtain a result matrix; and performing coherent or incoherent integration on a plurality of result matrixes formed by processing a plurality of data blocks to increase the processing gain, improve the capturing sensitivity, roughly determine the code phase and the Doppler frequency of GPS signals, and achieve two-dimensional parallel quick capturing of the GPS signals. The method has high processing efficiency and high capturing speed, and can be applied to various GPS positioning navigation aids.

The invention discloses a circuit for rapidly capturing a long period pseudo random spread spectrum code of a satellite navigation receiver and a capturing method thereof. The circuit comprises: a data preprocessing module, a sampling data control module, a frequency mixing module, a local spread spectrum code generation module and a single capturing engine. The single capturing engine comprises:a local spread spectrum code memory, a first stage coherent integral module, a first stage coherent data memory, a second stage coherent integral module, a third stage incoherent integral module and a threshold control comparison module. An output terminal of the data preprocessing module is connected with an input terminal of the frequency mixing module through the sampling data control module. The output terminal of the frequency mixing module is connected with one input terminal of the first stage coherent integral module. The local spread spectrum code generation module is connected with another input terminal of the first stage coherent integral module. The circuit of the invention has the following characteristics that: integral gain is high; an anti-electromagnetism interference ability is strong; a capturing sensitivity is high; capturing precision is high; a capturing false alarm rate is low; a capturing speed is fast; reliability is high. And there are many other characteristics.

The invention belongs to the time synchronization technical field and discloses a distributed network time synchronization method. The method includes following steps that: the difference of the clock of a center node and the clock of terminal nodes is determined; after receiving time synchronization request signals sent by different terminal nodes through different carrier frequencies, the center node captures, tracks and demodulates the request signals by using a local spread spectrum sequence database so as to obtain terminal node serial numbers, request sign information and terminal node clock information contained in the request signals, and center node clock information is compared with the local clock of the center node, time difference is measured; and offset correction is performed on the local clock of the terminal nodes according to the difference of the clock of the center node and the clock of the terminal nodes. Through synchronization, accuracy can reach a level of several hundreds of nanoseconds or even a level of dozens of nanoseconds.

The invention relates to a GPS rapid hot start method. After being started up by hot start, a receiver utilizes the assist of a local real time clock unit RTC (Real Time Clock) to carry out two-dimension trap of spreading code, i.e. carrier frequency when in a trap state, basically aligns local C/A codes with the received code flow with the deviation within a 0.5 code chip; the deviation between the carrier frequency and the received carrier frequency is not more than 100Hz; once signals are trapped, the bit synchronization is then carried out to find the telegraph bit boundary of 20 ms; once finding telegraph bit boundary is completed, the tracking state is entered in, so that a local spreading code generator and a local carrier generator track the received GPS signals and carrier signals in real time to complete first rapid positioning and directly enter into a positioning resolving link without waiting for the completion of a baseband subframe synchronous process to calculate the on-orbit position and the pseudo-range of a satellite, and resolve the receiver position through a least square method to complete the rapid positioning. The method further ensures the effectiveness through a hot start failure detection mechanism.

The invention relates to the technical field of wireless communication, in particular to a novel digital pseudo code synchronization method for a spread spectrum microwave receiver. The novel digital pseudo code synchronization method for the spread spectrum microwave receiver includes steps that capturing, to be specific, using the auto-correlation features of PN codes to compare a received signal with local PN codes in sequence, performing the correlation operation, after detecting the related results and performing self-adapting threshold detection, regulating the phases of local spread spectrum codes, and turning to a tracking step after meeting the self-adapting threshold requirement through detection and amplitude detection; tracking, to be specific, using the correlation between the phase of the code element advancing the local spread spectrum code sequence by 1/2 and the phase of the code element lagging behind the local spread spectrum code sequence by 1/2 and the received signal to obtain an error control signal, wherein the error control signal is used as a phase discrimination result to be input to a code element clock generator to regulate the PN code phases and keep the rigid synchronization between the local PN codes and the received signal. The novel digital pseudo code synchronization method for the spread spectrum microwave receiver is capable of eliminating the phase error so as to realize the precision of the phases of the local spread spectrum sequence and received sequence and the consistency there-between to realize the best receiving effect.

A method for the acquisition of a radionavigation signal carrying a spreading code with a quasi-infinite period, where the signal is sampled in baseband on a delay line and correlated with a local spreading code replica, the sampled signal is shifted on the delay line from one correlation to the other, where in order to correlate the signal with the local replica of the code, a plurality of sequences of the spreading code are generated, the code sequences being of the same duration, equal to the duration of the signal sampled on the delay line, and associated with the consecutive time ranges in the temporal alignment search space, where each of the code sequences is correlated with the signal sampled in a respective correlation operation, the correlation operations being executed in parallel for the different sequences of code.

The invention relates to a decoding method for a low intermediate frequency receiving system in a short-range wireless network. The method comprises the following steps: firstly, receiving a radio-frequency signal transmitted by a transmitting terminal in the short-range wireless network, and directly sampling a low intermediate frequency signal after down-conversion to obtain a baseband receiving signal; carrying out correlative conjugating operation on a local spread-spectrum modulation complex sequence in the short-range wireless network to obtain a group of weight sequences; carrying out up-conversion on a first sequence of the local frequency-expansion modulation complex sequence to low intermediate frequencies; carrying out conjugate multiplication on the low intermediate frequency local sequence and a synchronous low intermediate frequency receiving signal to obtain a correlation value sequence; carrying out correlative operation on every weight sequence with the correlation value sequence respectively to obtain a group of correlation values; and taking the position of the sequence corresponding to the maximal correlation value as receiving demodulation data. The method has the advantages that secondary down-conversion does not need to be carried out on the receiving signal at a radio-frequency terminal, the complexity and the calculation amount of the system are reduced, image interference introduced by secondary conversion is reduced, conjugate multiplication is carried out only on the receiving signal and a first local sequence when decoding, and the calculation amount is reduced.

The invention discloses a method for determining a webpage theme. The method comprises the following steps that a custom theme and links for acquiring the webpage theme are determined; the links for acquiring the webpage theme comprises link context extraction and the local spread extraction link; the local spread extraction link comprises link context extraction in a theme type semantic block, and link context extraction and webpage link extraction in a catalog type and image type semantic block. According to the method for determining the webpage theme, a classification method of webpage HTML label document based on layout labels are given first, then the idea of blocks is disclosed, position numbering is conducted on classified semantic blocks, a layout label DOM tree with numbers is constructed, and at last theme determination and theme link extraction are conducted based on webpage blocks; a user can acquire theme information quickly, the availability of a Web is expanded, and the series problems of information extraction and the like can be better solved.

The invention relates to a time-frequency synchronizing method with twice correlation in a short-distance wireless network and belongs to the technical field of wireless communication. Firstly, cross-correlation of a received digital signal is implemented by utilizing the periodic repeating characteristic and the well correlation characteristic of training sequences, thus obtaining a group of new receiving related value sequences; the same cross-correlation operation of local spread spectrum modulating sequences is implemented, thus obtaining a group of new local related value sequences; sliding correlation of the receiving related value sequences and the local related value sequences is implemented, thus obtaining a group of sliding related value sequences; and an estimated value of frequency deviation and a synchronizing position of time are determined according to the maximum value of all related values, thus realizing combined time-frequency synchronization. The time-frequency synchronizing method of the invention reduces the calculation amount of time-frequency synchronization and estimation, improves the performance of time synchronization and frequency deviation estimation under the influence of frequency deviation, and leads a receiver to have lower energy consumption and better receiving performance in the situation of larger frequency deviation.

The invention provides a high-precision 3 mm-waveband single-side-band noise coefficient spread spectrum measurement device and method. The device comprises a down converter module, a microwave and local oscillator combining module, a control interface module and a power module. The down converter module is used for achieving input matching, subsection filtering and down converting of 3 mm signals. The microwave and local oscillator combining module comprises a YTO (YIG tuned oscillator) and a drive and control circuit and is used for generating a combined scanning local oscillator signal source. The control interface module is used for achieving information interaction of a microwave noise coefficient analyzer host and a local spread spectrum measurement device through a USB intelligent interface bus. The power module is used for providing various power sources needed by the local spread spectrum measurement device. By the adoption of the device and method, the problems that the system is huge, the measurement accuracy is poor, the measurement repeatability and consistency cannot be guaranteed easily, the purchase and maintenance cost is high and operation is difficult in an existing 3 mm-waveband noise coefficient testing scheme are solved.

This invention discloses a spread spectrum communication system and a centerless wireless network applying different phase sequences of a single spread spectrum code to realize CDMA. Said system includes a satellite receive clock pick-up unit, a clock synchronous unit, a control time-slot generation unit, a match unit a related multipath selection unit, a demodulation unit, a control process unit, a PN code set generator, a code multipath selection unit, a spread spectrum modulation unit and a duplexer, among which, the clock receive unit receives wireless signals for the system, and picks up clocks for the system, the clock synchronous unit generates code slice clock pulses synchronized to the data clock, the match receive unit receives wireless signals to generate multipath matched signals, the related multipath selection unit selects related values in an assigned time slot to be output to the demodulation unit, which finishes the demodulation of the information carried by related peaks, the control unit fetches the related data values in the assigned time slots to deal with data in a period and judge the pulse levels of related peaks and selects suitable phase sequences as the spread spectrum codes for emit signals based on the channel used situation or selects phase sequence as the local spread spectrum code used in the reception.

The invention relates to a maximum ratio channel equalization method of short wave (SW) multiple carrier-code division multiple access (MC-CDMA), which comprises the following steps: firstly, mapping data frames to be sent in a displacement mapping module into cyclic shift with original direct sequences, and delivering the cyclic shift which is subjected to serial-to-parallel conversion to inverse fast Fourier transform (IFFT) so as to be changed into time domain modulating signals; carrying out serial-to-parallel conversion on modulated parallel time domain signals, inserting pilot frequency symbols into the obtained parallel time domain signals after serial-to-parallel conversion, and sending the obtained parallel time domain signals in which the pilot frequency symbols are inserted to a receiving end by a channel; after the signals which are received by the receiving end and comprise the pilot frequency symbols and the data frames are subjected to the serial-to-parallel conversion, firstly sending to fast Fourier transform (FFT) and then evaluating the transmission functions of the SW channel by the received pilot frequency symbols; obtaining equilibrium factors of maximal ratio combining efficiency (MRCE) through the data frames received by the receiving end in accordance with the evaluated the transmission functions of the channel, and then carrying out the maximum ratio channel equalization; and carrying out correlation on each sub-carrier datum subjected to the maximum ratio equalization and sequences generated by local spreading codes, obtaining dispreading data by judgment, and receiving the next data frame by a receiver continuously. The maximum ratio channel equalization method has a preferable bit error ratio and is used to reach an anti-interference effect.

The invention belongs to the technical field of ultra short wave communication systems, and particularly relates to a high data rate burst communication fast acquisition method and a device based on a spread-spectrum technology. The method comprises steps: accumulation down sampling is carried out on base band data with twice the spread-spectrum code rate as accumulation zero clearing signals; down sampling base band signals and spread-spectrum codes sampled at the twice spread-spectrum code rate are subjected to vector storage, the down sampling base band data slide at the twice spread-spectrum code rate respectively, the phase of the local spread-spectrum codes is fixed and the local spread-spectrum codes do not slide, under the same clock action, the two are grouped for XOR accumulation, an incoherent peak of a half chip is solved and compared until the incoherent peaks of all half chips are compared and the maximum value, the second maximum value, the third maximum value and the code phase are latched, the average value of the incoherent peaks of all code phases is solved, and whether signals are acquired successfully is judged. Thus, acquisition on high data rate ultra short wave burst communication based on the spread-spectrum technology can be quickly realized, and the hardware realization complexity is low.

The invention discloses a fast capturing method for a non-coherent spread spectrum signal, and aims to fast and accurate capturing of spread spectrum code phases and Doppler. The method is implementedthrough the following technical scheme: in a spread spectrum receiving system, a pseudo-code generator generates a local spread spectrum code sequence; the local spread spectrum code sequence is sentto a parallel processing unit for performing multipath parallel processing; frequency slot division is carried out according to slot division control information sent by a main control unit; carrierDoppler is compensated; matched filtering, coherent integration, zero-padding FFT and non-coherent integration are carried out sequentially; multi-dimensional peak value search is carried out on a plurality of branch signals; a phase capturing result and a carrier frequency rough estimation result are obtained; the obtained phase capturing result and carrier frequency rough estimation result are sent to the main control unit; the main control unit sends selection control information to a branch selection unit; and a received signal aligned to a phase of the local spread spectrum code sequenceis selected and output to an accurate frequency measurement unit for estimating a carrier frequency of the received signal.

The invention provides a capture system for improving weak GNSS (global navigation satellite system) signal processing gain, and aims to provide a processing gain capture system capable of increasing the GNSS processing gain and avoiding related loss of integral operation. The technical scheme includes that an integral extension unit (8) comprising a data storage module (11) and a series combination addition module (12) is arranged between a parallel correlation operation unit (7) and a peak value judgment unit (9), the parallel correlation operation unit (7) is used for performing parallel correlation operation for received signals from a radio frequency processing unit (2) and local spreading codes from a local pseudo-code generator (1), transmitting operation processing results into the integral extension unit (8) for extending integrals, transmitting integral extension results into the peak value judgment unit (9) and comparing the integral extension results with a related peak value judgment threshold set by a threshold circuit, and the peak value judgment unit judges whether capture is finished or not by threshold comparison to capture signals.

The invention discloses an adaptive threshold controller and a control method, a direct sequence spread spectrum signal detection method and a circuit. The adaptive threshold control method comprises the following steps: making a statistic of the number N of signals to be detected of a current group; calculating shift correlation values of the N signals to be detected and a local spread spectrum sequence; judging whether the shift correlation values exceed the threshold, and making a statistic of the number n of the shift correlation values exceeding the threshold; based on the number N of the signals to be detected and the number n of the correlation values exceeding the threshold, selecting a sign function epsilon; and modifying the threshold based on the sign function epsilon, and taking the modified threshold as the threshold of the signals to be detected of a next group. The adaptive threshold control method provided by the invention can make a false alarm probability tend to 0 and a detection probability tend to 1 under the circumstance that the dynamic range of an input signal amplitude is very wide, so that the acquisition performance of a system can be improved.

The invention discloses a low signal-to-noise ratio code capturing method based on a frequency modulation signal. The method comprises steps of receiving a signal obtained by splicing the frequency modulation signal and the spread spectrum modulation signal, performing down-conversion processing on the received spliced signal, performing matched filtering processing on the spliced signal and a local frequency modulation signal, and solving the quadratic sum of in-phase and orthogonal branches of a matched filtering result to obtain judgment data; sending the judgment data to an adaptive constant false alarm rate judgment device, and judging whether the splicing signal is successfully captured or not by adopting a 3/4 judgment strategy; sending the spliced signal subjected to down-conversion processing and judgment data into a spreading code discriminator, judging whether a spreading signal arrives or not, and determining a spliced point of a frequency modulation signal and the spreading modulation signal; and according to the splicing point of the frequency modulation signal and the spread spectrum modulation signal, sending the spread spectrum modulation signal in the spliced signal subjected to down-conversion processing to a dispreading module, and carrying out correlation accumulation with a local spread spectrum code to obtain a dispreading signal. The method has higher detection probability and anti-interference performance.

In a method for estimating a frequency deviation between a received spread-spectrum code signal and a local frequency signal, the received spread-spectrum code signal is despread using a local spread-spectrum code. The despread signal is integrated over a particular integration period. From at least two successively obtained integration values, a phase change value characteristic of the phase change between the two integration values is calculated. From this, the frequency deviation is determined.

A method to counterbalance pilot frequency interference in code division multiple address system is method which can carries on consolidated receiving of multipath signal and also can counterbalance multiple addrss interference caused by pilot frequency channel in each path of signal. First, it uses channel coefficient estimator to obtain the estimation value of time varying multipath fading channel coefficient, and then, to use pilot frequency counterbalancing calculation to calculate out multipe address interference caused by pilot frequency channel on the strengest pass and to eliminate itout from receiving signal. The device includes channel coefficient estimator module, effective arrival path selector module, maximal ratio combining module, to be connected in series by sequence, of which the output ends of channel coefficient estimator module, effective arrival path selector module, maximal ratio combining module and local spread spectrum sequence creator module with be all connected with input end of pilot frequency channel interference counterbalancing module. The input end of base band sampling signal will be an input end of the device and to be connected with input ends of channel coefficient estimator module and maximal ratio combining module separately.

The invention discloses a method for detecting an NR uplink control channel format 1, which comprises the following steps of: receiving data by a base station, extracting and splitting the data, and calculating a target signal by using a frequency domain local spread spectrum sequence and a time domain local spread spectrum sequence of an idle code channel to obtain an interference noise power measurement value, a channel estimation value and a data signal; splicing operation data of different antennas at different frequency hopping RB positions according to a given sequence R to obtain a corresponding data vector, a channel estimation vector and an interference noise matrix; inputting the data vector, the channel estimation vector and the interference noise matrix into a minimum mean square error equalizer to obtain equalized data; and mapping the balanced data to a standard constellation point according to a given decision rule, and demodulating the balanced data into an information bit according to a given bit-constellation point mapping criterion. According to the invention, different antenna signals at different frequency hopping RB positions are spliced and then sent to the MMSE equalizer at one time, so that the performance loss caused by large signal-to-noise ratio condition difference among multiple paths of signals can be effectively overcome.

The invention discloses a frequency hopping spreading code phase tracking method suitable for narrowband interference. The method comprises the following steps: generating a local frequency hopping code word and a local spreading code word; de-hopping received frequency hopping spreading signals; performing low-pass filtering and draw-off on the de-hopped signals to obtain data with a reduced rate; carrying out digital automatic gain control on the data with the reduced rate to obtain data with basically constant amplitude; performing rotation amount control, i.e., controlling the rotation amount of phase rotation; performing the phase rotation on the data with the basically constant amplitude; performing de-spreading on the data after the phase rotation; accumulating the data after the de-spreading, and finding an accumulative mode maximum value and a corresponding phase rotation amount; and performing phase adjustment amount accumulation, i.e., accumulating all phase adjustment amounts, and performing division on an accumulation result and a clock period of a local reference clock to obtain a quotient and a remainder value, for performing overall reference clock period adjustment on a local frequency hopping spreading code phase and performing adjustment within one reference clock period on the local frequency hopping spreading code phase according to the remainder value.

The invention discloses a three-phase potential detecting method of a low-voltage carrier wave power line for communication, aiming at a communication mechanism that a sending end takes one phase electric wave form in three-phase alternating current on a low-voltage power line as a reference, time slots with bad channel characteristics are avoided, and data are non-continuously sent. The method comprises the following steps of: carrying out relevant operations on received signals of a receiving end and received local spread spectrum code words by the receiving end; selecting relevant peak values according to a relevant operational result and a comparison result of a decision threshold; identifying effective peak values in the relevant peak values and obtaining a relevant value sequence reflecting a relative position relation of a data time slot and a space time slot of the receiving end; respectively carrying out relevant operations on the relevant value sequence and an indication code expressing three phase alternating current electric wave forms; and determining a three-phase reference phase taken as a reference by the sending end according to a relevant value. The method can accurately and effectively detect receiving signals and detect out alternating current phases ought to be taken as a reference so as to be convenient for subsequently processing and recovering data.