194results about How to "Shorten capture time" patented technology

The invention relates to a data processor system for space-based measurement and control of a high-speed aircraft. The data processor system comprises a power supply module, an interface module, a control module, an encryption module, a forward processing module and a reverse processing module, wherein the power supply module is used for providing the secondary power source for the other modules; the control module is used for receiving control instructions, and sending the control instructions to the other modules; the encryption module is used for encrypting the reverse data stream and decrypting the forward data stream respectively; the forward processing module is used for receiving the mid-frequency signal, completing the receiving and processing link, recovering forward information, and outputting the forward information to an external device through the interface module; the reverse processing module is used for receiving image data, flight state information and remote measurement information, generating the mid-frequency signal after completing the launching and processing link to output the mid-frequency signal to an external radio frequency front end, and eventually sending the mid-frequency signal to a ground system. The data processor system supports the carrier high-dynamic measurement and control of the aircraft, is large in region coverage, supports multiple users, can realize real-time two-way communication with the aircraft, and has certain interference capability.

The invention discloses a high-dynamic weak-signal rapid capture method for a direct sequence spread spectrum system, belonging to the field of radio communication. Because a spread spectrum carrier has a chirp signal characteristic under the condition of high-dynamic motion (high-speed and high-acceleration), the high-dynamic weak-signal rapid capture method comprises the steps of: firstly, carrying out carrier Doppler frequency compensation by using a time frequency focusing characteristic of fractional order Fourier transform; secondly, carrying out incoherent accumulation on a spread frequency signal by using an order resolving capacity of the fractional order Fourier transform; and finally, carrying out capture judgment on the signal in an order Fourier domain by using a constant false alarm rate detection technology. According to the invention, the difficulty of incapability of long-time coherent accumulation under the high-dynamic condition in the traditional Fourier transform based rapid capture method is solved; and under the condition of high dynamicity and low signal to noise ratio, the signal to noise ratio is effectively increased and the signal capture time is shortened. In addition, a rapid algorithm exists in the invention and is easy to realize on the engineering in real time.

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 fully-digital direct sequence spread spectrum communication system and a rapid pseudo code capturing method thereof. A digital signal is processed by using an FPGA (Field Programmable Gate Array) which comprises a pseudo code capturing module, a sampling signal of an ADC (Analog To Digital Converter) is subjected to frequency mixing with a signal of a local carrier NCO (Numerically Controlled Oscillator) and filtered to obtain a baseband signal, residual carrier Doppler frequency is eliminated from the baseband signal by adopting a differential multiplying mode, thus the phase deviation of a receiving signal and a local pseudo code is further obtained through an FFT (Fast Fourier Transform) algorithm without scanning on a carrier frequency domain; and when the phase deviation of the pseudo code is obtained, a local pseudo code phase is modified and is subjected to correlation degree of dissociation with the receiving signal, and the carrier Doppler frequency is figured out by using the FFT algorithm, and is compensated to a carrier NCO and a pseudo code NCO, thus carrier frequency capturing and pseudo code capturing are realized.

Described herein are variants of alpha-hemolysin having at least one mutation selected from T12R, T12K, N17R, N17K or combinations of T12 and N17 mutations. The variants in some embodiments may further comprise H144A. The α-hemolysin variants have a decreased time to thread.

The invention discloses a method and a system for rapidly capturing a relay satellite measurement and control system signal. The method comprises the following steps: S1, analog-to-digital conversion: performing band-pass sampling on an analog intermediate-frequency signal through a high-speed analog-to-digital converter by comprehensive digital baseband equipment to obtain a digital intermediate-frequency signal; S2, down-sampling processing; S3, implementation of a capturing time shorter than a data sampling time: controlling two memories to implement seamless caching of data streams, wherein a caching depth is a sampling number of coherent integration, and a switching interval between the two memories is a sampling time of captured data; and S4, implementation of a search of a signal dynamic range: converging a Doppler frequency range by adopting a two-round frequency search according to a speed of outputting a frequency search unit result in a data sampling period, and obtaining a code phase offset of cached data in a third-round phase search. The system is used for implementing the method. The method and the system have the advantages of easiness in implementation, high accuracy, capability of satisfying a current engineering condition, and the like.

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 provides a long distance and high accuracy oriented compound laser range finding method and system. According to the range finding method, the transmitting terminal uses two independent light sources with different wavelengths to generate two channels of range finding signals for performing range finding through a pulse coding method and a phase method respectively. The pulse coding method is a combination of a low order pseudo code signal with an impulse method. The range finding system includes two continuous lasers, an m-sequence signal modulation unit, a phase modulation unit, a pair of optical antennas, two photoelectric detectors, a pulse code processing module, a phase processing module and a range finding result calculation unit. According to the range finding system, two channels of range finding signals can be independently measured, free of interference by a pulse coding method and a phase method respectively; and the range finding results from these two methods are compounded for higher range finding accuracy. Also in the invention, the accuracy advantage of the pseudo-code range finding method is introduced into a conventional impulse method, which increases the measuring accuracy. Compared to the conventional impulse method, the method of the invention can better cope with interference. It takes a shorter pseudo-code acquisition matching time than the pseudo-code range finding method.

The application discloses a method for detecting and eliminating narrow-band interference by a GNSS (Global Navigation Satellite System) receiver. The method comprises the steps as follows: firstly, the receiver converts received time-domain signals into frequency-domain signals through FFT (Fast Fourier Transform); secondly, frequency points of narrow-band interference signals are found in the frequency-domain signals and are set as a blocking frequency of a wave trapper; and finally, the receiver filters and eliminates the narrow-band interference signals from the received time-domain signals through the wave trapper. The application has the advantages of simplicity in implementing the technology, smaller calculated amount, high real-time performance and good flexibility.

The invention relates to a GPS weak signal capturing method based on a sequential probability ratio. The method comprises the steps of: (1) performing parallel code domain planar search on a sampled and quantized intermediate frequency digital signal which is output by the front end of a receiver, (2) calculating a threshold value corresponding to different unrelated accumulation times under a preset condition of false-alarm probability, (3) calculating a probability density function contained in an assumed signal, (4) calculating a probability (5) that the assumed signal is more than the threshold value, ending the search stage, if a signal is captured, or repeating the step (3), (4), (5) if no signal is captured, and if the unrelated integral accumulation times M reaches to 100 but still no signal is fund, that means no signal exists, ending the capturing stage as well. The method of the invention can efficiently shorten the capturing time of strong signals, reduce the whole capturing time and increase the capturing property.

The invention aims to provide a fast acquisition system and method based on a laser phased technology. Firstly, the spatial position where a target communication terminal is located is obtained by querying the ephemeris or orbital parameters, and the spatial position serves as the maximum probability position point to be located in the center of an area to be scanned; a coordinate system is built according to the center of the area to be scanned, and an uncertainty area is divided into four sub areas according to the center of the area to be scanned; a beacon light polarized laser, a first liquid crystal optical phased array, a one-half wave plate and a second liquid crystal optical phased array are arranged in sequence, beacon light emitted by the beacon light polarized laser points to the area to be scanned, and the uncertainty area is scanned; a target object is acquired finally. The system and method have the advantage that the acquisition time of the building process of space laser communication links is shortened.

A method for evaluating signals of fluorescence scanning microscopy with simultaneous excitation and detection of fluorescence in different focal planes of a sample by means of confocal laser scanning microscopy. The invention evaluates signals of fluorescence scanning microscopy without the signal losses usually taking place with a confocal aperture, by coupling an illumination beam into a microscope observation beam path which images a measuring volume on a detector array arranged in the image plane, focusing the illumination beam which passes through a beam-forming phase mask for generating an elongated focus in the measuring volume, collecting and collimating fluorescent light generated in the measuring volume and routing it to diffractive optics which split the light beams into different diffraction orders and impress a different spherical phase on the light beams, imaging the different diffraction orders on detector regions of the detector array so that fluorescent light from focal planes at different depths of the measuring volume are associated with different diffraction orders, and associating the fluorescence signals on which crosstalk is superposed from different focal planes of the measuring volume with defined focal planes by means of correlation-based association based on distinguishable blinking behavior of fluorescing dyes.

Whole Doppler range of signal is divided into frequency sweep points. Using united non-coherent detecting energy in parallel de-spread on all frequency sweep points, the method finds out maximum value. Comparing the maximum value with referenced threshold determines whether signal is captured, and carrier frequency and phase of de-spread code. Under limited resources, the method avoids complex calculation, and realizes quick capturing signal. In condition of large frequency deviation and high dynamic signal, the invention guarantees stable, high performance quick operation in whole dynamic range. The invention is applicable to area of satellite communications and wireless communication based on spread spectrum.

The invention relates to a low-orbit satellite spread spectrum communication system signal capturing and tracking system. The system disclosed by the invention has the advantages of interference resistance, high capturing speed and high tracking efficiency. The system is implemented through the following technical schemes, a receiver obtains a digital low-intermediate frequency signal after frequency mixing and filtering through a frequency mixing and filtering module and analog-to-digital AD conversion through an ADC module; a digital baseband signal is obtained through digital down-conversion of an orthogonal down-conversion module and low-pass filtering of a low-pass filtering module, the digital baseband signal is divided into two paths to be sent to a correlation capturing module and a tracking module respectively, the correlation capturing module carries out correlation processing on the digital baseband signal through a parallel capturing algorithm based on FFT, obtains a code phase and a Doppler frequency offset rough estimation value, and captures a carrier frequency and a code starting point of a spread spectrum signal; the tracking module accurately estimates the digital baseband signal; and the correlation capturing module and the tracking module continuously correct the frequency and the phase through carriers NCO and codes NCO to realize synchronization and rapid capturing of the long address codes, and finally the communication information of a satellite signal is obtained through analysis of an information analysis module.

The invention provides a high-dynamic high-sensitivity GNSS signal capturing method, used for satellite navigation signal capture. After downsampling of sampling data is realized by using an overflowbit of the phase accumulator, through a parallel compensation data folding coherent accumulation method, the signal pseudo code search data volume is further compressed, the processing efficiency andcapture speed are improved, pseudo code Doppler compensation and two-stage adder processing are adopted, and incoherent accumulation of Doppler and pseudo code chip two-dimensional correlation valuesis completed. According to the method, the carrier Doppler change rate is calculated through the flight acceleration of the GNSS receiver, dynamic parallel compensation in folding coherent accumulation is achieved in combination with the carrier Doppler value, and pseudo code Doppler compensation in incoherent processing is achieved through pseudo code Doppler. The GNSS receiver high-dynamic high-sensitivity fast capturing method is suitable for capturing other spread spectrum signals.

The invention belongs to the technical field of satellite communication and especially relates to a rapid high-efficiency signal capturing method for a BeiDou navigation satellite system (BDS). For second-generation BeiDou B1 frequency band weak signals, NH code secondary modulation is carried out on local quantified pseudo-random codes, multi-millisecond coherent integration is carried out on the pseudo-random codes and received signals, a frequency domain code phase searching algorithm based on SFT is realized, and the operation complexity and capturing time of the capturing algorithm are further reduced.

The invention discloses a method for fast acquisition of PN codes in a satellite spread spectrum communication system, comprising: S1: determining the frequency search step; S2: sequentially compensating and accumulating frequencies of different step lengths on the local signal frequency; S3: calculating the I channel and the full correlation value of the local mixed frequency signal of channel Q and the received signal; S4: the full correlation value is added correspondingly in the complex number domain, and its modulus value is calculated; S5: the one with the largest peak value, it is judged that the Doppler frequency shift is located at this frequency shift In the compensation module; S6: If the frequency compensation step is greater than the preset frequency compensation threshold, execute S7; otherwise, obtain the frequency shift and phase offset; S7: continue to divide the compensation frequency, reduce the search step length, and return to S2. The present invention divides the frequency compensation continuously, gradually narrows the search range, improves the compensation accuracy, shortens the capture time, and obtains the maximum correlation peak value through the calculation of the correlation value, so that the code phase is compensated, and the PN code and Doppler are realized. Two-dimensional capture of frequency shifts.

The invention discloses a P code catching method and a P code catching device. The method comprises the following steps that IF (intermediate frequency) signals and local carrier signals from a carrier generator are multiplied, and I-Q two-path base band signals with rest Doppler frequency are obtained; the base band signals are extracted to obtain base band data to be processed, and the base band data to be processed is stored according to the sub segment; the local P code is used as a tap coefficient, each sub segment is respectively subjected to partial PMF to obtain accumulation results, and the code phase searching is completed; the filtering results after the PMF processing is subjected to buffer memory, in addition, fast FFT is respectively carried out, the frequency spectrum analysis is realized, and the frequency searching is completed; the accumulation according to points is carried out after the parallel model delivery is respectively carried out on the output results of the FFT processing, M point incoherent accumulation results are obtained, and the caught results are found, wherein the caught results include but are not limited to the maximum correlation value, the second correlation value, the frequency, the phase, the paragraph and the like. The method and the device provided by the invention have the advantages that a PMF and FFT combination mode is adopted, the P code catching sensitivity is improved, and the catching speed is obviously accelerated, so the requirements of actual signals are met.

The invention discloses a GPS (Global Positioning System) signal acquisition method based on an FPGA (Field Programmable Gate Array), which comprises the following steps of: firstly, carrying out down sampling on a medium-frequency acquisition signal by adopting an average sampling method; taking data obtained by averaging the energy of a point during each sampling period as sample data subjectedto down sampling, wherein the averagely-sampled points meet 2FFT (Fast Fourier Transformation) operation; finishing initial acquisition of the GPS signal to obtain an initial phase range of a pseudocode and initial carrier frequency; and carrying out further fine acquisition by using a time domain correlation algorithm to obtain accurate initial phase of the pseudocode and carrier frequency. An FPGA hardware platform is set up in the acquisition system and is combined with a radio-frequency front-end chip of a GSP receiver; and the acquisition system comprises a clock generation module, a main control module realized by a state machine, a GPS signal storage module, a carrier oscillator module, a carrier stripping module, a pseudocode reading module, an average sampling module, an FFT(FastFourier Transformation) / IFFT (Inverse Fast Fourier Transform) module, a threshold decision and initial phase calculation module and a fine acquisition module realized by a correlator.

The invention relates to an adaptive coherent accumulation joint acquisition method under GNSS weak signal, which belongs to the field of signal acquisition. The method preserves the performance of high acquisition probability of the prior coherent accumulation method and avoids the flip effect of navigation data in the piriorcoherent accumulation method. The method uses the coherent accumulation and the differential accumulation, and can detect the flip position of the navigation data in the process of acquisition. Before the flip of the navigation data is detected, the coherent accumulation method is used firstly. After the flip of the navigation data is detected, the differential accumulation method is used. Thus, the method has the advantages of high processing gains of the coherent accumulation and no flip effect of the navigation data on the differential accumulation. In addition, different from the threshold value detected by fixed acquisition in the traditional method, the adaptive coherent accumulation joint acquisition method adjusts the threshold value adaptively according to the noise of a received signal. Compared with the traditional method, the adaptive coherent accumulation joint acquisition method improves the detection probability, shortens the acquisition time and is suitable for accurate positioning in a weak signal environment.

The invention provides a high-dynamic fast acquisition implementation method in spread spectrum measurement and control communication. The method includes the steps of multi-phase rotation, down-sampling data storage, dispreading conducted in segments, HDFT operation conducted in segments, iterative self-adaption threshold calculation, frequency acquisition conducted through threshold judgment, and Doppler frequency offset correction conducted according to the acquired frequency. According to the method, through multi-phase rotation, data pre-storage and offline fast related operation, acquisition time is shortened to a great extent; through HDFT operation and iterative self-adaption threshold calculation, Doppler frequency offset is obtained rapidly and corrected; under the condition that the frequency offset is as high as + / -180kHz and the Doppler frequency change rate reaches 10 kHz / s, acquisition, chip synchronization and Doppler frequency offset correction are conducted on signals by a measurement and control communication receiver within 50 ms, complexity is low, stability and reliability are achieved, and resource consumption is low.

The invention consists of level detection circuit of satellite signal, control and digital signal processor. The output of the control and digital signal processor is divided into three ways and each of them is connected with the pitch control motor and motor control circuit, the directional control motor and motor control circuit, roll control motor and motor control circuit. The other ends of three of them are connected with the level detection circuit of satellite antenna through mechanical drive and speed reduction.

The invention discloses a spread spectrum signal pseudo code rapid capturing device and a spread spectrum signal pseudo code rapid capturing method. The capture device includes: a N-point FFT computing unit, a data caching unit, a pseudo code spectrum storage unit, a weighting coefficient storage unit, a data reading unit, a data processing unit, a B point IFFT calculation unit and a code phase and Doppler estimation unit, the capture device adopts a frequency domain mixed downsampling combined parallel capture method, and signal capture is completed through cooperation of all the units. According to the spread spectrum signal pseudo code rapid capture device and the capture method, a frequency domain mixed downsampling combined parallel capture method is adopted, mixed downsampling is carried out on the frequency domain sequence corresponding to the cross-correlation sequence, the position of a correlation peak can be rapidly estimated at a low calculation cost, and all cross-correlation results do not need to be calculated; and only one N-point FFT calculation unit and one B-point IFFT calculation unit are needed, so that two-dimensional parallel search of a code phase and a carrier frequency can be realized with low hardware overhead, and the pseudo code capturing time is remarkably shortened.

The invention discloses a universal satellite high-speed data transmission signal timing synchronization method, belonging to the technical field of satellite communications. The method comprises following steps of high-speed sampling, signal demodulation, timing error estimation, timing extraction, loop filtering, timing correlation and gating, sampling frequency controlling and sampling frequency synthesization. Due to adoption of an envelope square timing error estimation algorithm and effective A / D sampling frequency controlling, a closed loop timing synchronization loop is formed finally. According to the method, synchronization is simple, timing synchronization of multiple modulation systems like MPSK, MQAM, MAPSK and so on can be realized, so that the method has good universality and greatly improves the use flexibility.

The invention relates to a spatial coherent optical communication high-dynamic carrier capture tracking loop. The carrier capture tracking loop comprises double frequency locked loops and a phase locked loop, wherein a CPAFC (Cross Product Automatic Frequency Control) tracking algorithm and an ODAFC (Overlap Discrete Automatic Frequency Control) tracking algorithm are effectively combined by adopting the double frequency locked loops to perform frequency capture tracking processing; capture tracking can be performed on gradient frequency offset through the CPAFC tracking algorithm, and coarse capture of a large frequency offset can be performed through the ODAFC tracking algorithm; the working states of the two frequency locked loops are controlled according to a locking state; in a stable locking state, capture tracking is performed on gradient frequency by only adopting the CPAFC tracking algorithm; and in a lock losing state and after entrance of the lock losing state, frequency capture tracking is performed by adopting the two frequency locked loops together, so that capture tracking in a large frequency offset range can be realized. Through adoption of the carrier capture tracking loop, the advantages of the two algorithms are combined; the demands of carrier capture tracking processing at different working stages can be met; and stable carrier capture tracking under a high-dynamic condition is realized.

A method for real-time communication of large dynamic Doppler scene of hypersonic aircraft includes steps of: at the sending end, pre-coding a transmitting signal, inserting pilot data and sending; atthat receive end, extracting pilot data; on the one hand, coarsely capturing doppler frequency offset and doppler primary change rate by using pilot information; on the other hand, estimating channelstate information by using pilot information; in the aspect of acquisition, by using the method of fft-based parallel segmentation, accomplishing fast and coarse acquisition; after coarse acquisitionof doppler frequency offset and doppler rate of change, manually shifting the received data, and estimating channel state information and merging diversity. The invention can meet the requirements ofreal-time telemetry communication of a hypersonic aircraft, has the characteristics of short time consumption and low complexity, and has important significance for the real-time communication of thehypersonic aircraft.

The invention discloses a GPS receiver which reduces first positioning time after starting up and the method thereof. The GPS receiver includes positioning unit and non-volatile storage which communicates with the positioning unit. The method which reduces the first positioning time of GPS receiver includes the following steps: reading backup information stored in the non-volatile storage; obtaining current time information; estimating the Doppler shift range; according to the range of Doppler shift, capturing GPS satellite; and calculating the position of the GPS receiver. Because of using the backup information in the non-volatile storage to estimate the range of Doppler shift, even if the system is at low battery condition or powered off, the backup information in the non-volatile storage is still valid, thereby the fast positioning after user turns on the GPS receiver is realized.

Provided is a high-speed GPS receiver signal capture method. A capture loop is assisted through inertia information and ephemeris information, Doppler frequency shift at the next moment is forecasted, the frequency range of GPS signals is estimated in advance, and Doppler frequency is searched for within the range; before a complex signal and a local code sequence of a base band are subjected to FFT operation, extraction processing with the extraction factor of M is performed, and then iteration is performed on the value of M according to the capture result till capture succeeds. According to the method, operand is reduced by reducing the number of operation points of FFT. According to the method, the operand is reduced by reducing the number of operation points of the FFT, meanwhile, the frequency search time is shortened, and high-dynamic GPS signals can be fast captured.

The invention is applicable to the field of satellite positioning and navigation and provides a GNSS satellite signal acquisition method, device and a satellite navigation receiver. The method comprises steps: read signals and address information of a first storage unit storing 2<N> point FFT results are controlled to be outputted; through controlling the address information, data in the first storage unit are subjected to ring shift left readout or ring shift right readout; and according to the read signals and the address information, the data in the first storage unit are read. Thus, shiftof the read data is thus controlled through controlling the address, and movement of a search frequency point is further realized. A large amount of FFT operations can be avoided, the acquisition efficiency is improved, and the acquisition time is shortened.

The invention discloses an INS auxiliary Beidou signal capturing method. The method includes the steps that firstly Doppler frequency generated by movements of a carrier and a satellite is calculated; the Doppler frequency is transmitted to a capturing loop of a receiver, and a carrier NCO of the loop adjusts carrier frequency; frequency mixing is conducted on intermediate frequency signals and local carrier signals to acquire in-phase signals and orthogonal signals, and the in-phase signals and the orthogonal signals correlation operations with local signals conduct respectively; correlation values acquired by each operation are stored in a cache to acquire an M*N matrix; correlation values of the in-phase branch and the orthogonal branch form a plural matrix, and whether the signals enter a tracking module or the signals are recaptured is judged until the signals are captured. The advantage of combining time domain capture and frequency domain capture is fully exerted, and a matching filter set is adopted in the matching process, so that capturing time is saved, and rapid capture of the signals in a high dynamic environment can be rapidly achieved; the correlation values of the in-phase signals and the orthogonal signals are combined in the matrix to conduct FFT conversion, so that hardware resources are saved.