48 results about "Correlation integral" patented technology

A method for estimating and compensating of frequency deviation (FD) of random access channel includes carrying out preset FD compensation and correlation integration as well as non-correlation integration on leading part of random access channel to confirm a pre-selected multi-path, carrying out FD pre-compensation and correlation as well as non-correlation integration on DPCCH at pre-selected multi-path, canceling multi-path with integration valve being less than threshold, using residual FD estimation value to carry out residual FD compensation on DPPCH and FD pre-estimation value and residual FD estimation value to carry out FD compensation on DPDCH.

Techniques are provided for aiding in acquiring a signal using the data bit information that is associated with each signal source. One aspect of the invention is to use the data bit information that is associated with each signal source when calculating the In Phase and Quadrature correlation integrals by using the sampled data associated with the received signal. By using the data bit information that is associated with each signal source, coherent correlation may be performed by breaking the signal into data blocks and performing calculations on a block-by-block basis. Coherent correlation is the calculation of In Phase and Quadrature correlation integrals for sampled data that is associated with the received signal.

The invention relates to a threshold detection method for weak satellite signal acquisition. The signal comprises pseudo range measuring codes. The method comprises the following steps: A, carrying out correlation integration on every possible satellite for N milliseconds, and carrying out M-times difference accumulation on the obtained result; B, determining whether a satellite signal exists or not according to the preset upper limit and lower limit of threshold; C, if the detected signal-to-noise ratio is greater than the upper limit of the threshold, then judging that a strong signal exists; D, if the detected signal-to-noise ratio is less than the lower limit of the threshold, then judging that no signal exists; E, if the detected signal-to-noise ratio is between the two thresholds, then carrying out near-far effect elimination algorithm on the detected strong signal, and detecting the processed data again; and F, and calculating the upper limit of the threshold after the strong signal is eliminated, and if the detected signal-to-noise ratio is greater than the threshold, then judging that a signal exists. The method considers the influence of near-far effect on weak satellite signal acquisition and introduces the concept of detection after the strong signal is eliminated. Compared with the traditional method, the invention reduces the false-alarm probability.

The invention designs a GPS software receiver, which is suitable for various working environments with low signal to noise ratio, high dynamic, assistance of an inertial navigation system (INS) or independent working and the like, automatically regulates performance as required to adapt to different working environments and achieves the optimal information utilization to the fullest extent as possible. An implementation method for the GPS software receiver comprises the following steps of: independently regulating the tracking bandwidth of each tracking channel according to signal strength; combining the advantages of long-term noncorrelation integral and short-term correlation integral to design a tracking loop with high-sensitivity real-time output; realizing real-time estimation of a receiver crystal frequency error model by using a method for estimating fixed intervals; and finally, based on the deep combination, improving capture velocity and tracking dynamic performance of a weak signal. The implementation method for the GPS software receiver can fully use all detectable satellite signals, can improve the tracking dynamic performance of the weak signal by utilizing auxiliary information of INS information, and also accelerates new star search when INS information assistance exists.

The invention discloses an extraction method of a multi-scale characteristic and a fluctuation parameter of a sea wave based on EMD (Empirical Mode Decomposition). The method comprises the steps of reading in a sea wave time sequence measured at a fixed point or a simulated sea wave sequence, determining and analyzing the sea wave scale according to the demand of data analysis, decomposing the sea wave time sequence by an EMD method to obtain a plurality of IMF (Intrinsic Mode Function) sequences, computing a fractal characteristic of an IMF component by a q-order correlation integral and differential box counting method, computing a statistical characteristic of the IMF component by a moment estimation method, and computing the fluctuation parameter of the IMF component by a spectrum method. The fractal characteristic, statistical characteristic and fluctuation parameter of the IMF component can disclose an internal structure and an external representation characteristic of the sea wave. The method can be used for modeling, analyzing and predicting the sea wave.

The invention discloses a GPS weak signal tracking system based on I/Q branch correlation integral observation filtering. A receiver is used for receiving a satellite signal which is converted into an intermediate frequency signal through down conversion and transmitted to a frequency mixer. The frequency mixer is also used for receiving local sine and cosine reproduction carrier signals outputted by a local carrier digital-controlled oscillator, and outputting a I-branch output signal and a II-branch output signal to a correlation arithmetic unit. The correlation arithmetic unit also receives a local advanced C/A code, an instant reproduction C/A code and a lagged reproduction C/A code, wherein the local advanced C/A code, the instant reproduction C/A code and the lagged reproduction C/A code are generated by a code generator. Results are outputted to an integral eraser, and six-way relevant integral values are generated and outputted to a Kalman filter. The Kalman filter obtains an estimated carrier phase difference, an estimated carrier frequency difference and an estimated code phase difference, and the estimated carrier phase difference, the estimated carrier frequency difference and the estimated code phase difference are transmitted to the local carrier digital-controlled oscillator and the code generator. The system effectively reduces the noise intensity of the satellite signal, can trace the satellite signal better in a weak-signal environment, and improves the tracing precision.

A method of acquisition of a received signal received from a global navigation satellite system, includes: obtaining a snapshot of the received signal; correlating the snapshot with a locally-generated signal, wherein the correlating includes: trying a phase delay value indicative of a hypothesized phase delay of the locally-generated signal with respect to the snapshot; and obtaining a partition of the snapshot and the locally-generated signal into corresponding pluralities of blocks, and calculating partial correlation integrals for each block of the plurality of blocks. The corresponding pluralities of blocks each include a first block having a time duration related to the phase delay value.

The invention discloses a synchronization method. The bit synchronization method and device of a compatible Beidou satellite navigation system and a global position system (GPS) is characterized in that correlation integral data of I branch of a channel and data of Q branch can be read; supposing that 20 conceivable bit boundaries exist and can generate stripping codes of NH codes so as to strip the NH code of the Beidou satellite navigation system, but the GPS does not need to be operated in that way; detection of data jumping is carried out and the detection result need to be compared to decide that the maximum conceivable boundary of the data jumping number is a boundary of a real sign bit. The invention further discloses a synchronization device . By means of the above-mentioned method and the device, the bit synchronization of the Beidou satellite navigation system and signals of the GPS can be carried out at the same time. In addition, sensitivity of the bit synchronization of navigation signals can be improved by adjusting the time of the bit synchronization, and therefore the bit synchronization method and device of the compatible Beidou satellite navigation system and the GPS has higher military and commercial value.

The invention discloses an optical IQ modulator arbitrary bias point control method and system. The control method comprises: calculating a first type of correlation integral coefficient by using a first disturbance signal and a second disturbance signal; obtaining the characteristic voltage rough values of respective modulators according to a relationship between bias voltages and the first typeof correlation integral coefficients; obtaining the characteristic voltage accurate values of respective modulators by using an iterative method and the characteristic voltage rough values of respective modulators; calculating the bias voltages required to be loaded onto respective modulators at a target bias point, and correspondingly setting the bias voltages required to be loaded onto respective modulators; calculating the value of a second type of correlation integral coefficient by using a third disturbance signal, and accordingly calculating a reference correlation coefficient vector; obtaining a real-time correlation coefficient vector, calculating an error voltage, and then correspondingly adjusting the bias voltages of respective modulators by using the error voltage. The method and system can control any bias point of an optical IQ modulator and maintain the stability of the bias point.

This invention discloses a multi-path search device and a method for random accessed channels in WCDMA access system, which first of all carries out precursor test and correlated and non-correlated integral and takes multiple paths P exceeding the first threshold value as the pre-selected paths, then to plug 1/4 code into the front and back of each of the multi-path in equal distance to get 3p multiple paths and then compares the non-correlated accumulated value of the control part DPCCH of random accessed channel information with a set second threshold to eliminate fake paths reported by the precursor test ( multi-path smaller than the second threshold) and keep the multi-path exceeding the second threshold value then to select an information demodulation multi-path.

Techniques are provided for fine-tuning estimates of a delay value for a sampled signal. One aspect of the invention is to perform, for the sampled signal, coarse-grained calculations of the In Phase and Quadrature (I and Q) correlation integrals at a limited number of points, wherein the calculations are performed over a range of hypothesized delay values. A range of delay values of interest are then determined from the coarse-grained calculations of the I and Q correlation integrals. A subset of I and Q values based on the coarse granularity calculations of the I and Q correlation functions is used to perform a time-domain interpolation to obtain fine-grained values of the I and Q integrals in the range of the delay values of interest. Magnitude calculations are performed based on the fine-grained values of the I and Q integrals. Fine-tuned estimates of delay value are based on the magnitude calculations. Alternatively, fine-tuned estimates of delay value are based on the template-matching approach.

The present invention discloses a Beidou weak signal capture method based on a difference correlation integral. The Beidou weak signal capture method is obtained through improvement of the traditional difference correlation integral algorithm, the difference correlation integral operation is performed through adoption of the sample point delay mode to weaken the influences of Beidou signal NH code hopping and bit hopping; and the integral time is prolonged to improve the signal-to-noise ratio of signals; and moreover, the FFT algorithm is employed to realize the parallel searching of the code phases and the carrier frequency so as to greatly shorten the capture time compared to the traditional capture algorithm. The Beidou weak signal capture method based on the difference correlation integral is suitable for all the Beidou civil signals with no need for considering the difference of the GEO and non-GEO navigation message.

The invention discloses a double-base foresight synthetic aperture radar moving-target speed error function construction method. According to the method, first, the Doppler barycenter and the Doppler adjustable frequency of a moving target are deduced in a double-base foresight SAR mode, and the orientation signals of the moving target are constructed; then the reference functions with speed estimation errors and the bearing signals of the moving target are used for correlation integral processing; finally, the largest value of the correlation integral results under different moving target speed estimation errors are respectively extracted to construct the speed error function. The speed error function can be used for comprehensively conducting quantitative analysis and research on the influence of movement of the moving target on imaging, and also can be used for completing double-base SAR moving target moving compensation, determining orientation self-focusing optimized long selection and the like, so that the focusing imaging of the double-base foresight SAR moving target can be realized in an efficient and high-precision mode.

The invention relates to a double differential coherent detection method for capturing a weak satellite signal. The signal comprises a pseudorange measurement code. The method comprises the following steps that: A. total quantity of search units is determined according to an inputted signal sampling rate and a correlation integral time; B. each potential satellite and each search unit are undertaken the correlation integral with the length of N millisecond, and relevant results of homodromous and orthogonal branch circuits are respectively recorded; C. data processed in step B is inputted into a double differential device to obtain a single differential result of each search unit; D. the result which is obtained in step C is accumulated for M times; E. the search unit corresponding to the maximum value of the outputted result in step D is found out; F. a signal-to-noise ratio corresponding to the result in step E is solved and is compared with a threshold to judge whether the signal exists or not. The double differential coherent detection method overcomes the phase influence in the traditional differential accumulation, has higher noise resistant performance compared with the traditional double differential method, and can improve the detected signal-to-noise ratio.

A real-time operating optimized method of multi-input and multi-output continuous manufacture procedure includes steps as follows: first, using plurality of pivotal operation conditions in the manufacture procedure as optimized variables, and using the technical target associating with the pivotal operation conditions as the objective function, then, calculating on line the grades vector between pivotal operation conditions and the technical target at current time according to historical data of pivotal operation conditions and the technical target, using correlation integral method or other methods, at last, using this grades vector to define the adjustment direction of the operation conditions. When the grades vector is positive or negative, the pivotal operation conditions should be adjusted in order to change the grades vector to zero.

The invention provides an envelope detection method and system based on matching with correlation integral. The method includes: step 101) based on a Nyquist sampling theorem, sampling a carrier signal whose center frequency is f with sampling frequency f<s> and sampling time t<samp>, and obtaining N discrete data; step 102) generating a sine or cosine signal whose frequency is f, sampling the sine or cosine signal according to the sampling frequency f<s> and integral time t, obtaining N<samp> sampled discrete data, then performing M times of circumferential shifting on elements in a sine sample set, and obtaining M shifting sample signal sets in total; step 103) selecting N<samp> continuous discrete data from the N discrete data, solving dot products of the discrete data and the sine sample set and the M shifting sample signal sets, obtaining M+1 dot product values, and taking a maximum value of these dot product values as an envelop value corresponding to the N<samp> discrete data; and repeating step 103) for several times, obtaining envelope values of a plurality of sets of N<samp> continuous discrete data, and completing detection.