91 results about "Autocorrelator" patented technology

Interferometers and autocorrelator based sensors are disclosed that are configured to have multiple sample arms which can be scanned and the backscattered low coherence source light from a sample resolved in a single sweep of one or more variable delays of the sensor. Borescopes and catheters capable of scanning multiple sections or areas of materials and tissues using these sensors are described.

A radar based sensor detection system comprises a microwave source operative to provide a continuous wave signal at an output. A pulse-former is coupled to the output of the source and is operative to provide at an output a variable length pulse that increases the transmitted energy of the radar system according to the range of object detection. A modulator is coupled to the output of the pulse-former for providing a modulated pulse signal when required. A transmit/receive switch coupled to the output of the modulator is selectively operative between a first transmit position and a second receive position. A transmit channel coupled to the transmit/receive switch transmits the pulse signal when the switch is operated in the transmit position. A receiving channel coupled to the transmit/receive switch receives the modulator signal when the switch is operated in the receive position. First and second voltage multipliers each have a local oscillator input for receiving the modulator signal in the receive position, and each have an input signal port, and an output port. A receiver channel receives a reflected transmitted signal from an object and applies the received signal to the receive signal input ports of the voltage multipliers. An autocorrelator coupled to the output ports of the voltage multipliers correlates the received signal to produce an output signal indicating the detection and position of the object.

An autocorrelator apparatus and method for economically measuring physical properties of an object where the measurement path is at least semi-translucent to light, such as thicknesses in multilayered optical structures, group index of refraction, and distance to a surface. The apparatus includes a non-coherent light fiber interferometer and an optional coherent light fiber interferometer in association so as to share PZT fiber modulators. Thickness and boundary extent measurements can be made, for example, of solids, liquids, liquids moving along a horizontal plane, or liquids flowing down a plane.

Provided are a synchronization apparatus and method for improving timing estimation performance in an OFDM-FDMA/CDMA/TDMA system, which can correctly estimate symbol timing through a more correct timing metric using a guard interval of a preamble. The synchronization apparatus includes an auto-correlator for calculating an auto-correlation value of a received signal and a signal delayed by a predetermined time, a power detector for calculating power of the received signal, a timing metric/normalizer for normalizing the auto-correlation value by dividing the auto-correlation value by the calculated power to obtain a timing metric, and a peak detector for finding a peak value of the timing metric to estimate a frame starting position and an initial symbol timing. The auto-correlator calculates an auto-correlation length as long as a length of a guard interval, considering the preamble characteristic that the patterns are repeated in the time domain. The initial symbol timing is set to a position determined by adding the position where the timing metric has a peak value to the length of the guard interval and subtracting the maximum value of the expected channel delay spread from the result value.

The invention discloses a weak signal detection method based on joint denoising and frequency modulation, and belongs to the technical field of signal processing. The method comprises the steps that 1) partial noise suppressing is carried out on low signal to noise ratio signals which are to be detected and are mixed with noise through an autocorrelator; 2) wavelet threshold transforming is carried out on the signals which are processed in the step of 1) and are to be detected, so as to remove residual noise after signal autocorrelation; 3) a modulatable standard signal is used to modulate the frequency of the signals output in the step of 2), so that the modulated signal frequency can meet the detection condition of a dual Duffing oscillator difference system, and high frequency signals in the modulated signals are filtered out through a low pass filter; 4) the signals output by the low pass filter in step of 3) are input into the dual Duffing oscillator difference detection system, and initial state parameters of the system are set; and 5) whether the dual Duffing oscillator difference detection system has the phenomenon of regular intermittence chaos is judged, and if the phenomenon of regular intermittence chaos occurs, a continuous zero method is used to acquire an intermittence chaos period and the frequency of the signals to be detected. Compared with a traditional detection method, the method can be used to detect the weak signals of any frequency in a background with strong noise, and is of great significance in practical application.

The present invention provides nano particle size measuring method and device with scattered dynamic low-strength laser. The method includes: radiating liquid sample with monochromic laser beam of proper length to produce scattered light signal; collecting and transmitting to light signal with single-modular fiber with gradient refractive index; recording with single-photon counter module the scattered photons and converting into output electric pulse signal; and processing the signal in an autocorrelator. The device includes: light source, polarizer, focusing lens, two-layered refractive index sample matching pool, fiber, single-photon counter module, autocorrelator and computer. The present invention can measure nano particle size fast and accurately.

A base station apparatus, communication terminal apparatus, communication system, and communication method are provided that enable the data part transmission amount to be increased, that are resistant to frequency selective fading, and that enable a BS with low transmission loss to be selected. An OFDM transmitting apparatus 100 sets a power measurement pilot as one OFDM symbol in one frame, assigns power measurement pilot subcarrier numbers to base station apparatuses, and transmits a power measurement pilot according to common frame timing among the base station apparatuses, and a communication terminal apparatus 200 is equipped with an autocorrelator 210 that outputs a symbol synchronization signal, an autocorrelator 220 that finds an autocorrelation characteristic of a repeat waveform part that is a repetition of the same waveform having a cycle of ½ effective symbol length or a waveform with the sign reversed having a cycle of ½ effective symbol length from a received power measurement pilot, and an in-phase averaging section 230 that performs in-phase averaging in frame units of an autocorrelation characteristic of the repeat waveform part and detects the positional frame timing of a power measurement pilot on the time axis.

The invention provides an optical path autocorrelator for distributed optical fiber strain sensing measurement, which is formed by sequentially connecting a broad spectrum light source (1), an annular multibeam generator (2), an optical path autocorrelation detecting unit (3), a transmission optical fiber (4) and an optical fiber sensor array (5) end to end; the annular multibeam generator (2) comprises a 2*2 optical fiber coupler (21), a first three-port optical circulator (22), an optical fiber collimator (23) and a movable optical reflector (24); and the optical path autocorrelation detecting unit (3) comprises a second three-port optical circulator (31), an optical detector (32) and an interference signal detecting and processing unit (33). The invention can realize real-time monitoring and measurement of physical quantities, such as multi-point strain or deformation, and the like,solve the problems of overlarge light source power loss and superlow light source utilization ratio when a plurality of sensors are multiplexed in an optical fiber and the problem of measurement precision reduction caused by the existence of light source feedback light and improve the stability of a system.

The invention relates to the technical field of high-precision time delay measurement, in particular to a method and device for measuring optical delay with an optical autocorrelation method. The method for precisely measuring the delay based on optical autocorrelation is provided to solve the problems in the prior art, the time delay smaller than 10 picoseconds can be measured, the largest measuring range is determined by the measuring range of an autocorrelator, and relative measuring precision is superior to 1%. The method and device are achieved through the cooperation of a pulse laser, a first optical fiber coupler, a delay line device, a second optical fiber coupler, the autocorrelator, a processor and the like. The method and device are suitable for the precise measurement of subnanosecond time delay in the optical fiber and free space optical field.

An optical performance monitor (OPM) adapted to (i) sample an autocorrelation function corresponding to an optical signal transmitted in an optical network and (ii) based on the sampling, characterize two or more impairments concurrently present in the optical signal. In one embodiment, the OPM has an optical autocorrelator (OAC) coupled to a signal processor (SP). The OAC receives the optical signal from the network, generates two or more samples of its autocorrelation function, and applies said samples to the SP. The SP processes the samples and generates two or more signal metrics. Based on the signal metrics and reference data corresponding to the impairments, the SP then obtains a measure of each of the impairments.

The invention discloses an autocorrelator for measuring the width of ultra-short laser pulses. The autocorrelator comprises an incidence reference hole, a wedge-shaped spectroscope, a first right-angle reflector, a second right-angle reflector, a scanning device platform, a paraboloidal mirror, a detector and a control device, wherein the incidence reference hole is used for passing to-be-detected lasers which enter horizontally and straightly at equal heights to form an incidence light path; and the wedge-shaped spectroscope is positioned on the incidence light path, and the included angle of the wedge-shaped spectroscope and the incidence light path is 45 degrees. According to the autocorrelator, the wedge-shaped spectroscope is adopted to replace two beam splitting slices in the prior art, and the two sides of each beam slitting slice are parallel to each other, so that a light path structure of the autocorrelator is simple, and interference field signals formed by multiple reflections of two surfaces of the wedge-shaped spectroscope cannot coincide with an emergent light path any more, so that the detector can detect neat autocorrelation signals.

The invention provides a decision method for estimating the frequency deviation of OFDM, which belongs to the technical field of communication and comprises the following steps: setting the correlation length of a short autocorrelator and the correlation length of a long autocorrelator according to the range change of system frequency deviation parameters; operating and working out the peak value of the short autocorrelator and the peak value of the long autocorrelator according to the correlation length of the short autocorrelator and the correlation length of the long autocorrelator; estimating a wide-range frequency deviation estimation gross value according to the peak value of the short autocorrelator; estimating a narrow-range frequency deviation estimation gross value according to the peak value of the long autocorrelator; determining the architecture type and the frequency deviation subsection range of a frequency deviation value determining device; and determining the result of frequency deviation according to the architecture type and the frequency deviation subsection range of the frequency deviation value determining device, the wide-range frequency deviation estimation gross value and the narrow-range frequency deviation estimation gross value. The decision method reduces the operation complexity of a frequency synchronization algorithm.

An optical receiver including an optical divider to divide a signal light from an optical transmission line into two portions, a first and a second dispersion compensators, each dispersion compensator having variable dispersion compensation to compensate chromatic dispersions of each of the two portions of signal light output from the optical divider, and a data demodulator to demodulate a data carried by a signal light output from the first dispersion compensator. The optical receiver further includes an optical autocorrelator to operate on a signal light output from the second dispersion compensator and a controller to control the second dispersion compensator to increase autocorrelation of the optical autocorrelator, and to control the first dispersion compensator according to the result of said controlling the second dispersion compensator.

Provided are an apparatus for estimating frequency offset from received signal and method for the same. The apparatus and method estimates frequency offset precisely without increment of autocorrelator by performing moving average filtering on a noised signal to thereby alleviate jitter. The frequency offset estimating apparatus includes: moving average filter for alleviating jitter of received signal; multiplier for multiplying a filtered signal by conjugate complex operanded pilot signal; phase-rotation value calculator for calculating a phase-rotation value from multiplicand operanded signal by using of symbol delay and an autocorrelation function; frequency offset estimator for estimating frequency offset from the phase-rotation value based on a smoothing function multiplication.

The invention discloses a signal source positioning method of a Duffing-Lorenz-based chaotic system. Signal receivers at three different positions form a group of receiving base stations and consist of same auto-correlators and Duffing-Lorenz circuits; before a weak signal is received, the Duffing-Lorenz circuits are adjusted to guarantee that output voltage waveforms of the circuits are chaotic waveforms; when the weak signal is received by the three signal receivers at different times respectively, the signal is denoised by the respective auto-correlator to serve as an input signal to be introduced into the respective Duffing-Lorenz circuits; the change of the voltage waveforms output by the three Duffing-Lorenz circuit circuits from the chaotic waveforms to large periodic waveforms is detected by using the detector and mutant site times t1, t2 and t3 are recorded; the mutant site times t1, t2 and t3 are input into a computer; the position of a signal source is calculated by using the computer. The method has the advantages of high sensitivity, accurate detection and positioning of the weak signal and the like.

The invention provides an integrated optical autocorrelator based on molybdenum selenide double-photon absorption and a measuring method. The integrated optical autocorrelator comprises a substrate, an input waveguide, a splitter, a connection waveguide, a fixed time delayer, an adjustable time delayer, an adjustable time delayer interface, a first connector, a combiner, an output waveguide, a molybdenum selenide thin film, an on-chip electrode, a second connector and a controller. According to the integrated optical autocorrelator, on-chip integration of the optical autocorrelator and measurement of the on-chip pulse width can be realized through a simple structure by employing the double-photon absorption characteristic of a molybdenum selenide material.