908 results about "Self correlation" patented technology

The present invention relates to a method for generating and apparatus for employing code families having desirable correlation properties. Regardless of code length, maximum autocorrelation of the codes is 4 for any nonzero offset and maximum cross-correlation of any two codes from a code family is 4 for any offset. The codes can be used in impulse radio systems and non-impulse radio systems including CDMA, TDMA, FDMA, OFDM and various other frequency hopping and direct sequence systems. The codes can be used to specify various impulse radio and non-impulse radio signal characteristics including pulse position in time, amplitude, width, type, phase, phase difference, frequency, spreading code, etc. The codes have the unique property that they can specify as many as two components in which a signal is not present. A method of code compression is provided.

A method for calibrating an impulse radio distance measuring system comprising an impulse radio transceiver by conducting a pulse through a transmit receive switch to an antenna, receiving return energy which has been discharged across the transmit receive switch, determining a time of arrival of the return energy. The return energy is comprised of two distinct pulses, one of which represents discharge of the transmit switch as the original pulse travels to the antenna, the second represents energy reflected from the antenna and again discharged across the transmit receive switch while the switch is in the transmit position. The timing of the un-reflected energy is determined then the timing of the reflected energy relative to the un-reflected energy is determined through auto-correlation of the time domain scan of the received composite waveforms.

A method and apparatus for microlithography. The method and apparatus include optimizing illumination modes based on characteristics of a specific mask pattern. The illumination is optimized by determining an appropriate illumination mode based on diffraction orders of the reticle, and the autocorrelation of the projection optic. By elimination of parts of the illumination pattern which have no influence on modulation, excess DC light can be reduced, thereby improving depth of focus. Optimization of mask patterns includes addition of sub-resolution features to reduce pitches and discretize the probability density function of the space width.

An embodiment of the present invention provides an automatic gain control system for a wireless receiver that quickly differentiates desired in-band signals from high power out-of-band signals that overlap into the target band. The system measures power before and after passing a received signal through a pair of finite impulse response filters that largely restrict the signal's power to that which is in-band. By comparing the in-band energy of the received signal after filtering to the total signal energy prior to filtering, it is possible to determine whether a new in-band signal has arrived. The presence of this new in-band signal is then verified by a multi-threshold comparison of the normalized self-correlation to verify the presence of a new, desired in-band signal.

A hearing aid comprises at least one microphone (M) for converting input sound into an input signal, a subtraction node for subtracting a feedback cancellation signal from the input signal thereby generating a processor input signal, a hearing aid processor (G) for producing a processor output signal by applying an amplification gain to the processor input signal, a receiver (R) for converting the processor output signal into output sound, an adaptive feedback cancellation filter for adaptively deriving the feedback cancellation signal from the processor output signal by applying filter coefficients, calculation means for calculating the autocorrelation of a reference signal, and an adaptation means for adjusting the filter coefficients with an adaptation rate, wherein the adaptation rate is controlled in dependency of the autocorrelation of the reference signal.

A packet detection apparatus detects a packet from a received signal by using a preamble containing an established, repeating training sequence. A first autocorrelation calculator computes a first autocorrelation of the received signal over a first interval. A first determining unit determines packet discovery by comparing the first autocorrelation to a first autocorrelation threshold value. A second autocorrelation calculator computes a second autocorrelation of the received signal over a second interval equivalent to the interval length for packet discovery announcement. A second determining unit determines packet discovery announcement by comparing the second autocorrelation to a second autocorrelation threshold value lower than the first autocorrelation threshold value.

A method of localizing signals utilizing auto-correlation functions and cross correlation functions includes: collecting data at a plurality of input channels; filtering the data collected from the plurality of input channels in order to identify a primary signal; identifying at least two lags and at least one reference lag in a function of the data; and estimating relative travel times of the data.

The invention discloses a self-correlation optical fiber communication system based on mode division multiplexing. The self-correlation optical fiber communication system based on mode division multiplexing comprises an optical carrier input unit, optical signal modulation units, a wavelength division multiplexing unit, a mode division multiplexing and demultiplexing unit, a wavelength division multiplexing unit and coherent reception units. The mode division multiplexing and reconciliation multiplexing unit comprises a mode multiplexer and mode demultiplexer, and the mode multiplexer and the mode demultiplexer are connected through few-mode optical fibers. The optical carrier input unit is connected with each optical signal modulation unit, the wavelength division multiplexing unit and the mode multiplexer through single-mode optical fibers. The mode multiplexer is connected with the mode demultiplexer through few-mode optical fibers. The mode demultiplexer is connected with the wavelength division multiplexing unit and each coherent reception unit through single-mode optical fibers. The optical carrier input unit is further connected with the wavelength division multiplexing unit. The self-correlation optical fiber communication system based on mode division multiplexing eliminates an expensive narrow line width adjustable local oscillator light source which is arranged at a reception end, enables a laser to be conveniently managed and maintained, is free from using frequency offset estimation in a digital signal processor (DSP) and phase retrieval algorithm, reduces complexity of the DSP and has the advantages of being high in spectrum effectiveness and big in nonlinearity tolerance.

A time reference system for generating a time reference from signals produced by a global navigation satellite constellation has a satellite signal receiver to receive and down-convert code-modulated signals from a plurality of satellites and a correlator to track and decode the down-converted signals to provide signals containing partial pseudo-range measurements for respective satellites. A data processing arrangement receives assistance data from an external source and performs data-bit synchronisation in which bit edges of a low frequency data bit stream carried by the received satellite signals are identified, to perform a preliminary position-velocity-time solution to provide an approximate time reference, and to perform auto-correlation of pre-selected data sequences in the data stream to resolve time ambiguities thereby to compute a precise time reference signal in weak received signal conditions. The pre-selected data sequences may be the repeated data preamble in the GPS navigation message constituted by the data stream.

A method for detecting signal and estimating symbol timing is provided. The method is applicable to the receiver in an OFDM system. The method uses the autocorrelation of the short preamble of input signals to detect signals, and performs the coarse frequency offset compensation at the same time. Then, the end of the short preamble for the input signals is detected by the signal detection. The compensated signals are cross-correlated with the portion of the long preamble or that of guard interval together with the long preamble. In addition, the method uses the information for the end of the short preamble to find out a range of the sliding window for estimating symbol timing. In such a manner, the method can make sure of the accuracy for the symbol timing.

A synchronization timing detecting apparatus includes a correlation calculator configured to generate a first correlation value by calculating a cross-correlation between an input signal being sampled and a reference signal or an auto-correlation of the sampled input signal, an interpolation processor configured to generate a second correlation value interpolating a plurality of the first correlation values having a different combination of sampling points of the input signal, and a detector to detect a synchronization timing based on the first and the second correlation values.

A music-synchronized display apparatus includes a beat extractor configured to detect a portion in which a power spectrum in a spectrogram of an input music signal greatly changes and to output a detection output signal that is synchronized in time to the changing portion in synchronization with the input music signal; a tempo value estimation section configured to detect the self-correlation of the detection output signal from the beat extractor and to estimate a tempo value of the input music signal; a variable frequency oscillator in which an oscillation center frequency is determined on the basis of the tempo value from the tempo value estimation section and the phase of the output oscillation signal is controlled on the basis of a phase control signal; a phase comparator; a beat synchronization signal generation and output section; an attribute information storage section; an attribute information obtaining section; and a display information generator.

A system, method, and signal are disclosed for line probing. The invention provides an improved signal for line probing having desirable characteristics. In various embodiments the signal comprises a periodic sequence having good autocorrelation characteristics. The periodic sequence of the invention provides a faster and more accurate evaluation of the channel. Another embodiment of the invention comprises processing of the received sequence to determine a desired or maximum data rate for the line or channel. The invention also provides an evaluation and calculation of the noise on the line or channel.

The invention discloses a mine micro-quake signal P wave first arrival moment joint pickup method and mainly solves the technical problems that a single PAI-K and AIC method is high in pickup precision but is unstable in pickup of low signal to noise ratio, spike, tail shock and pure noise signals. The method comprises the following steps: extracting mine micro-quake signal waveform data; carrying out maximum kurtosis value arrival time (K1) pickup; carrying out minimum self-correlation value arrival time (K2) pickup; and judging whether | k1-k2 | is larger than a threshold value L, if so, abandoning the micro-quake signals, or otherwise, outputting P wave arrival time k=k2. Through PAI-K_AIC joint identification, interference of low signal to noise ratio, spike, tail shock and pure noise signals is effectively eliminated, mistake pickup rate is greatly reduced, and P wave pickup stability is enhanced. The method has the advantages of simple processing, high applicability and high accuracy and the like.

The invention relates to a method for predicting city traffic accidents based on time-space distribution characteristics. The method comprises: first, in combination of the case information and the space information, creating a case space database and performing pretreatment to the data; then, based on surface area statistics, analyzing the traffic accidents' time-space distribution characteristics; using the global and local self-correlation method to realize the analyzing of the aggregate state; based on the case happening point data, analyzing the traffic accidents' time-space distribution characteristics; through the hierarchical clustering analysis, expressing the distribution rule of the cases hierarchically; through the nuclear density estimation method, expressing the continuous changes and accurate gathering center of the traffic accidents' happening distribution; and finally, utilizing the BP neural network prediction algorithm, using the time-space distribution characteristics of the already happened cases to predict the time-space distribution areas of traffic accidents in the future. According to the invention, in combination with the time-space distribution and through the utilization of big date excavation BP neural network prediction algorithm and the time-space distribution characteristics of the already happened cases to predict the time-space distribution areas of traffic accidents in the future, it is possible to increase the precision, the timeliness and reduce the manual cost.

The invention provides a target tracking method based on multi-characteristic adaptive fusion and kernelized correlation filtering technology. The method comprises steps of according to target position and the dimension of the previous frame tracking, acquiring a candidate region of target motion; extracting histogram characteristics and color characteristics in the gradient direction of the candidate region, fusing the two kinds of characteristics, carrying out Fourier transform so as to obtain a characteristic spectrum and then calculating kernelized correlation; determining the position and the dimension of the target at the current frame, and acquiring a target region; extracting histogram characteristics and color characteristics in the gradient direction of the target region, fusing the two kinds of characteristics, carrying out Fourier transform so as to obtain a characteristic spectrum and then calculating kernelized self-correlation; designing the adaptive target correlation and training a position filter model and a dimension filter model; and using a linear interpolation method to update the characteristic spectrums and the related filters. According to the invention, the discrimination capability of the models is improved; robustness of the target tracking of the target in a complex scene and the appearance change is improved; calculation complexity is reduced; and tracking timeliness is improved.

The invention relates to a time-frequency synchronization joint estimation method based on a multi-carrier receiver of a digital television media broadcast (DTMB) system. The method is characterized by comprising the following steps: step 1, carrying out frame header mode recognition and frame header position coarse estimation; step 2, generating a pseudorandom noise (PN) sequence A of a zero phase matched with the frame header mode by a local PN generator, and carrying out carrier frequency offset estimation by utilizing a step-variable frequency sweeping method; step 3, correlating received data with the PN sequence A after compensation carrier is subjected to large frequency offset, so as to estimate a serial number of a frame; generating a PN sequence B of a matched phase matched with the frame header mode, and then correlating the PN sequence B with the received data so as to obtain a frame header position fine estimation value; and step 4, carrying out self-correlation on the frame header position according to the frame header position fine estimation value so as to obtain a carrier frequency offset fine estimation value, and summarizing a carrier frequency large offset estimation value and the carrier frequency offset fine estimation value so as to obtain a final carrier frequency offset estimation value. In the invention, the time-frequency synchronization joint estimation method based on the multi-carrier receiver of the DTMB system is used, thereby facilitating the realization of share of operation data and parameters and reducing the arithmetic labor.