WO2022201330A1 - 信号処理方法及び信号処理装置 - Google Patents
信号処理方法及び信号処理装置 Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
- G01B9/02002—Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies
- G01B9/02003—Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies using beat frequencies
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
- G01B9/02012—Interferometers characterised by controlling or generating intrinsic radiation properties using temporal intensity variation
- G01B9/02014—Interferometers characterised by controlling or generating intrinsic radiation properties using temporal intensity variation by using pulsed light
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02041—Interferometers characterised by particular imaging or detection techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02055—Reduction or prevention of errors; Testing; Calibration
- G01B9/02075—Reduction or prevention of errors; Testing; Calibration of particular errors
- G01B9/02078—Caused by ambiguity
- G01B9/02079—Quadrature detection, i.e. detecting relatively phase-shifted signals
- G01B9/02081—Quadrature detection, i.e. detecting relatively phase-shifted signals simultaneous quadrature detection, e.g. by spatial phase shifting
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02083—Interferometers characterised by particular signal processing and presentation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B2290/00—Aspects of interferometers not specifically covered by any group under G01B9/02
- G01B2290/45—Multiple detectors for detecting interferometer signals
Definitions
- the present invention relates to a signal processing method and a signal processing device.
- Non-Patent Document 1 As a means of measuring the distribution of physical vibration applied to an optical fiber in the longitudinal direction of the optical fiber, pulsed test light is incident on the optical fiber to be measured, and DAS (Distributed Detector) detects backscattered light due to Rayleigh scattering.
- DAS Distributed Detector
- a technique called Acoustic Sensing is known (see, for example, Non-Patent Document 1).
- the DAS captures the change in the optical path length of the optical fiber due to the physical vibration applied to the optical fiber, and senses the vibration. By detecting the vibration, it is possible to detect the movement of an object around the optical fiber to be measured.
- DAS-I DAS-intensity
- DAS-intensity measures the scattered light intensity from each point of the optical fiber under test and observes the change in the scattered light intensity over time.
- DAS-I has the feature that the device configuration can be simplified, but it is a qualitative measurement method because it is not possible to quantitatively calculate the change in the optical path length of the fiber due to vibration from the scattered light intensity (for example, non-patent literature 2).
- DAS-P DAS-phase
- DAS-phase DAS-phase
- the phase changes linearly with respect to changes in the optical path length of the fiber due to vibration, and the rate of change is the same in the longitudinal direction of the optical fiber.
- the vibration can be quantitatively measured, and the vibration applied to the optical fiber to be measured can be faithfully reproduced (see, for example, Non-Patent Document 2).
- a light pulse is injected into the optical fiber to be measured, and the phase of the scattered light at the time t when the light pulse is injected is distributed in the longitudinal direction of the optical fiber. That is, the phase ⁇ (l, t) of the scattered light is measured, where l is the distance from the incident end of the optical fiber.
- the time at which the point at distance l is measured is delayed from the time at which the pulse is incident by the time it takes for the light pulse to propagate from the incident end to distance l. Furthermore, it should be noted that the measuring time is delayed by the time required for the scattered light to return to the incident end.
- Non-Patent Document 1 As a device configuration for detecting the phase of the scattered light, there is a direct detection configuration in which the backscattered light from the optical fiber to be measured is directly detected by a photodiode, etc. There are configurations using detection (see, for example, Non-Patent Document 1).
- the mechanism that performs coherent detection and calculates the phase is subdivided into two: a software-based processing mechanism using the Hilbert transform and a hardware-based processing mechanism using a 90-degree optical hybrid. Also in the method, the in-phase component I(l, nT) and the quadrature component Q(l, nT) of the scattered light are obtained, and the phase is calculated by Equation (2).
- the output value by the four-quadrant arctangent operator Arctan is in the range of (- ⁇ , ⁇ ] in radian units, and m is an arbitrary integer, 2m ⁇ + ⁇ cal (l, nT) are all in the same vector direction on the xy plane Therefore, an uncertainty of only 2m ⁇ exists in the above-calculated ⁇ cal (l, nT), so the phase ⁇ cal (l+ ⁇ l, nT) at distance l+ ⁇ l and the phase ⁇ cal ( The difference ⁇ cal (l, nT) calculated from (l, nT) is also affected by the uncertainty.
- phase unwrapping is further performed as a more accurate evaluation method for .delta..theta.(l, nT).
- ⁇ (l, nT) be the actual phase change to be measured
- ⁇ cal (l, nT) be the measured value of the phase change calculated from the measurement results.
- the unwrapped phase ⁇ cal unwrap (l, nT) obtained by equation (3) is obtained when the absolute value of the phase change between adjacent times of ⁇ is smaller than ⁇ radian at an arbitrary time and place, and ⁇ .delta..theta.(l,nT) can be determined accurately only in the ideal case where cal (l,nT) is free from noise.
- phase unwrapping processing failures also occur due to noise accompanying ⁇ cal (l, nT).
- instrument noise such as thermal noise of the PD for detecting light, noise in the subsequent electrical stage, and shot noise due to light.
- l, nT) and the quadrature component Q(l, nT) are accompanied by noise
- ⁇ cal (l, nT) is also accompanied by noise
- ⁇ cal (l, nT) is also accompanied by noise.
- Noise in ⁇ cal (l,nT) introduces a probability of wrong choice of the proper integer q.
- the conventional technology has the problem that in the phase measurement data measured for a long period of time, there is a possibility of erroneously detecting large apparent vibrations due to the failure of the phase unwrapping process.
- a signal processing method is a signal processing method executed by a signal processing device, wherein phase a phase unwrapping processing step of performing unwrapping processing, and a phase value for each position in the space along a predetermined direction of the space for a predetermined time out of the plurality of times based on the result of the phase unwrapping processing; a first correction step of performing outlier correction of the phase value at a time other than the predetermined time for each position targeted for correction by the first correction step among the positions in the space and a second correction step of performing correction.
- FIG. 1 is a diagram illustrating a configuration example of a signal processing system according to the first embodiment.
- FIG. 2 is a flow chart showing the processing flow of the signal processing system according to the first embodiment.
- FIG. 3 is a diagram showing an example of the calculation result of the phase before correction.
- FIG. 4 is a diagram showing an example of the calculation result of the corrected phase.
- FIG. 5 is a diagram showing an example of a computer that executes a signal processing program.
- FIG. 1 is a diagram showing a configuration example of a signal processing system according to the first embodiment.
- the signal processing system 1 of FIG. 1 implements DAS-P by coherent detection using a hardware-based processing mechanism using a 90-degree optical hybrid in the receiving system.
- the signal processing system 1 functions as a phase OTDR (Optical Time Domain Reflectometer).
- the signal processing method in the first embodiment reduces erroneous detection of apparent large vibrations due to failure of phase unwrapping processing, and is different from the conventional DAS-P.
- a signal processing method equivalent to that of the first embodiment may be implemented on a software basis using the Hilbert transform.
- FIG. 1 it has a light source 11, a coupler 12, an optical modulator 13, a 90-degree optical hybrid 14, a circulator 15, an optical fiber 16 to be measured, a balance detector 17, a balance detector 18, and a signal processing device 19.
- the light source 11 emits continuous light of a single wavelength with a frequency of f0 .
- the light source 11 is a CW (Continuous Wave) light source.
- the coupler 12 splits the continuous light emitted by the light source 11 into reference light and probe light.
- the optical modulator 13 generates an optical pulse with a pulse width of W from the probe light split by the coupler 12 .
- the pulse width W is a value corresponding to the spatial resolution of measurement in the longitudinal direction of the optical fiber.
- the optical frequency of the optical pulse is set to a value obtained by shifting the frequency f0 by the shift frequency.
- the optical pulse generated by the optical modulator 13 does not have to be a single-frequency pulse, as long as the method is used to finally measure the phase change. It is possible.
- f i is selected so that the scattered light intensities at each time and each point are sufficiently separated to the extent that different i can be regarded as uncorrelated.
- optical modulator 13 Any type of optical modulator 13 may be used as long as it generates an optical pulse as described above, and the number thereof may be plural.
- the optical modulator 13 may be an SSB (single side-band) modulator, a frequency-variable AO (Acousto-Optics) modulator, or the like.
- the optical modulator 13 may perform intensity modulation using an SOA (Semiconductor Optical Amplifier) or the like in order to increase the extinction ratio in pulsing.
- SOA semiconductor Optical Amplifier
- the optical pulse generated by the optical modulator 13 is incident on the optical fiber 16 to be measured via the circulator 15 as probe light.
- light scattered at each point in the longitudinal direction of the optical fiber 16 to be measured returns to the circulator 15 as backscattered light and enters one input of the 90-degree optical hybrid 14 .
- the reference light split by the coupler 12 enters the other input of the 90-degree optical hybrid 14 .
- the 90-degree optical hybrid 14 has a coupler 141, a coupler 142, a shifter 143, a coupler 144 and a coupler 145.
- the backscattered light from the optical fiber 16 to be measured enters the input of the coupler 141 with a branching ratio of 50:50. Furthermore, the scattered light branched by the coupler 141 enters the inputs of the coupler 145 with a branching ratio of 50:50 and the coupler 144 with a branching ratio of 50:50.
- the reference light from coupler 12 enters the input of coupler 142 with a branching ratio of 50:50. Furthermore, one of the reference beams split by the coupler 142 is incident on the input of the coupler 144 as it is.
- the shifter 143 shifts the phase of the other reference light split by the coupler 142 by ⁇ /2. Then, the reference light phase-shifted by the shifter 143 enters the input of the coupler 145 .
- balance detector 17 detects the two outputs of coupler 144 and obtains electrical signal 171 whose analog in-phase component is I analog .
- Balance detector 18 also detects the two outputs of coupler 145 and obtains electrical signal 181 whose analog quadrature component is Q analog .
- the electric signal 171 and the electric signal 181 are sent to the signal processing device 19.
- the signal processing device 19 has an AD conversion functional element 191 , an AD conversion functional element 192 , a phase calculation section 193 and a post-processing section 194 .
- the AD conversion functional element 191 digitizes the analog in-phase component I analog to obtain I digital .
- the AD conversion functional element 192 digitizes the analog quadrature component Q analog to obtain Q digital .
- the phase calculator 193 performs phase calculation using the digitized in-phase component I digital output from the AD conversion functional element 191 and the quadrature component Q digital output from the AD conversion functional element 192 .
- the phase calculator 193 can calculate the phase using Equation (2).
- phase calculator 193 may perform appropriate preprocessing. For example, the phase calculator 193 filters the signals of the in-phase component I digital and the quadrature component Q digital using a digital band-pass filter having a signal bandwidth centered on the shift frequency at the time of modulation of the optical pulse, and then uses the formula ( 2) may calculate the phase.
- the phase calculator 193 can use any method that can accurately separate I i measure and Q i measure from I digital and Q digital .
- the phase calculator 193 passes I digital and Q digital through a digital band-pass filter having a center frequency of f i and a passband of 2/W, respectively, and then guarantees a phase delay, so that I i measure and Q i measure can be calculated.
- the phase calculator 193 can calculate the phase based on I i measure and Q i measure by using, for example, the averaging of different optical frequency multiplexed signals described in Patent Document 1, or the like.
- the post-processing unit 194 performs processing for reducing erroneous detection of such apparently large vibrations.
- FIG. 2 is a flow chart showing the processing flow of the signal processing system according to the first embodiment.
- the post-processing unit 194 performs a phase unwrapping processing step of performing phase unwrapping processing on positions in space and phase values for a plurality of times, and based on the results of the phase unwrapping processing, a first correction step of performing outlier correction of the phase value for each position in the space along a predetermined direction in the space at a predetermined time in the space; and a second correction step of correcting the phase value for a time other than the predetermined time for each of the target positions.
- phase unwrapping process corresponds to steps S101 and S102. As described above, unwrapping is an example of phase unwrapping.
- a first correction step corresponds to step S104.
- a second correction step corresponds to step S105.
- the post-processing unit 194 calculates the phase change applied to the section having a width of about the spatial resolution for each point of the distance r ⁇ l from the incident end on the optical fiber 16 to be measured using the equation (4). (step S101).
- Step S101 will be described in detail.
- the post-processing unit 194 sets the phase at the time nT of the distance l obtained as the output of the phase calculation unit 193 to ⁇ cal (l, nT), the phase ⁇ cal (l+ ⁇ l, nT) at the distance l+ ⁇ l and the distance l ⁇ cal (l, nT) is calculated as the difference from the phase ⁇ cal (l, nT) of .
- the value of ⁇ l is set to a value approximately equal to the spatial resolution.
- the signal processing system 1 includes the AD conversion function element 191 so that the interval of the distance l, that is, the sampling period in the longitudinal direction determined by the reciprocal of the sampling rate in the longitudinal direction can be set to a numerical value smaller than ⁇ l. and the AD conversion functional element 192 are operated at a high sampling rate.
- the optical pulse width is 50 ns, so a sampling rate of 20 MHz is sufficient from the viewpoint of spatial resolution. It is assumed that the AD conversion functional element 191 and the AD conversion functional element 192 are operating at the same rate.
- This operating condition is satisfied, for example, in the case of frequency multiplexing, in order to separate each frequency component by a digital bandpass filter as described above.
- the optical pulse width of each frequency is 50 ns and the optical frequency multiplexing number is set to 5, the signal of each optical frequency occupies a band of 40 MHz.
- the AD conversion functional element 191 and the AD conversion functional element 192 are operated at a sampling rate of 400 MHz or higher. 400 MHz is greater than 20 MHz.
- the integer D is set to a value of 2 or more because the AD conversion functional elements 191 and 192 are operated at a high sampling rate.
- the integer D can be set to 20.
- processing such as reducing the number of sampling points by decimating the phase obtained by the phase calculation unit 193 can be performed as long as the increment of the distance l after processing is smaller than the spatial resolution. It is possible to calculate the above integer D after processing.
- the post-processing unit 194 calculates the phase change applied to the section having a width of about the spatial resolution of the distance r ⁇ l using time zero as a reference, as shown in Equation (4).
- the post-processing unit 194 can calculate the phase values of the positions in the range based on the spatial resolution.
- the post-processing unit 194 performs phase unwrapping processing on ⁇ cal ( r ⁇ l , nT) in the time direction for each point on the optical fiber under test at a distance r ⁇ l from the incident end. ) is calculated (step S102).
- Step S102 will be described in detail.
- FIG. 3 shows how such erroneous detection occurs.
- FIG. 3 is a diagram showing an example of the calculation result of the phase before correction.
- the vertical axis is time nT and the horizontal axis is distance l.
- the color gradient indicates the value of ⁇ cal unwrap (r ⁇ l, nT).
- n is incremented by 1 from 1 to n last (steps 103, S106, S107), and the post-processing unit 194 calculates ⁇ cal unwrap (r ⁇ l, nT) for each n , step S104 and step S105 are executed.
- step S104 the post-processing unit 194 performs outlier correction (for example, using a Hampel identifier) for the longitudinal phase change ⁇ cal unwrap (r ⁇ l, nT) at time nT.
- outlier correction for example, using a Hampel identifier
- Step S104 will be described in detail.
- the post-processing unit 194 performs outlier correction processing on the phase change ⁇ cal unwrap (r ⁇ l, nT) in the longitudinal direction at time nT. As described above, the locations where phase unwrapping failures occur are random. Therefore, by detecting and correcting outliers in the longitudinal direction, phase unwrapping failures at time nT can be corrected.
- an outlier processing method for example, a method using a Hampel identifier can be used.
- the Hampel identifier if the number of left and right phases ⁇ cal unwrap (r ⁇ l, nT) in the longitudinal direction r ⁇ l is referred to as an outlier or not is k, the numerical value of k is D can be used as a guideline.
- k ⁇ D/2 can be set. This is because the fiber section [(r ⁇ k) ⁇ l, (r ⁇ k+D) ⁇ l] observed by ⁇ cal unwrap ((r ⁇ k) ⁇ l, nT) is observed by ⁇ cal unwrap (r ⁇ l, nT).
- the standard deviation evaluated from the median value and the median absolute deviation of the phase values between (rk) ⁇ l and (r + k) ⁇ l, which is the range of interest, is calculated, ⁇ cal unwrap (r ⁇ l, nT) is replaced with the median value when it has increased from the median value by C times the standard deviation.
- this numerical value can also be optimized to an optimal numerical value according to the object being measured.
- the post-processing unit 194 calculates the uncorrected phase value ⁇ cal unwrap (r h ⁇ l, nT) of the point recognized as an outlier (the distance r h ⁇ l from the incident end) and the corrected phase value
- a process of adding to (r ⁇ l, pT) and updating as a new value of ⁇ cal unwrap (r ⁇ l, pT) is performed for all r h that required correction.
- Step S105 will be described in detail. Let r h ⁇ l be the distance from the incident end to the point where correction is actually required in step S104, and let ⁇ cal unwrap,h (r h ⁇ l, nT) be the value after correction. At this time, ⁇ cal unwrap,h ( r h ⁇ l, nT) ⁇ cal unwrap (r h ⁇ l, nT) can be regarded as a correction value for correcting the failure of the phase unwrapping process. Add ⁇ cal unwrap,h (r h ⁇ l,nT) ⁇ cal unwrap (r h ⁇ l,nT) for all phase values after time (n+1)T in ⁇ l.
- FIG. 4 shows an example of final phase calculation obtained by repeating steps S104 and S105 above.
- FIG. 4 is a diagram showing an example of the calculation result of the corrected phase.
- the erroneous detection of apparent large vibration seen in FIG. 3 is corrected.
- step S101 the post-processing unit 194 calculates ⁇ cal (r ⁇ l, nT) with time n′T as the reference time, and in step S102, the phase unwrapping process is performed with n′ as the starting point and n becomes smaller. It is also possible to perform both in the direction in which n increases and in the direction in which n increases.
- the post-processing unit 194 also performs step S104 in the order in which n increases from (n′ ⁇ 1)T and in the order of n decreases from (n′+1)T, when viewed on the time axis. in both directions.
- the post-processing unit 194 performs correction by adding the correction value to the phase value for the first time that is earlier than the reference time.
- a correction can be made by adding a correction value to the value.
- the post-processing unit 194 performs a correction by adding a correction value to the phase value for a second time later than the reference time, and the second correction step is performed for each time later than the second time. Correction can be performed by adding the correction value to the phase value in order from the first.
- AD conversion functional element 191 and AD conversion functional element 192 sample faster than the constraint dictated by spatial resolution to use outlier correction and cause phase unwrapping failures. False detection of apparently large vibrations can be reduced. On the other hand, since such a sampling condition is naturally satisfied when frequency multiplexing or the like is performed, the first embodiment can be realized without changing the conventional apparatus configuration.
- the condition that the AD conversion functional element 191 and the AD conversion functional element 192 sample at a higher speed than the constraint determined by the spatial resolution is also satisfied when the change in the vibration to be measured is gentler than the spatial resolution. It may not be required.
- outlier correction may be performed at the data points included in the spatial range in which the vibration to be measured does not change in step S104. Sampling slower than the constraint dictated by may still provide enough data points to perform outlier correction.
- the first embodiment can be implemented by sampling faster than the change in vibration to be measured.
- each component of each device illustrated is functionally conceptual, and does not necessarily need to be physically configured as illustrated.
- the specific form of distribution and integration of each device is not limited to the illustrated one, and all or part of them can be functionally or physically distributed or Can be integrated and configured.
- all or any part of each processing function performed by each device is realized by a CPU (Central Processing Unit) and a program analyzed and executed by the CPU, or hardware by wired logic can be realized as Note that the program may be executed not only by the CPU but also by other processors such as a GPU.
- CPU Central Processing Unit
- the signal processing device 19 can be implemented by installing a signal processing program for executing the above signal processing as package software or online software in a desired computer.
- the information processing device can function as the signal processing device 19 by causing the information processing device to execute the signal processing program.
- the information processing apparatus referred to here includes a desktop or notebook personal computer.
- information processing devices include mobile communication terminals such as smartphones, mobile phones and PHS (Personal Handyphone Systems), and slate terminals such as PDAs (Personal Digital Assistants).
- the signal processing device 19 can also be implemented as a signal processing server device that uses a terminal device used by a user as a client and provides the client with the service related to the above signal processing.
- the signal processing server device is implemented as a server device that provides a signal processing service having the output from the balance detector as input and the result of phase calculation as output.
- the signal processing server device may be implemented as a web server, or may be implemented as a cloud that provides services related to the above signal processing through outsourcing.
- FIG. 5 is a diagram showing an example of a computer that executes a signal processing program.
- the computer 1000 has a memory 1010 and a CPU 1020, for example.
- Computer 1000 also has hard disk drive interface 1030 , disk drive interface 1040 , serial port interface 1050 , video adapter 1060 and network interface 1070 . These units are connected by a bus 1080 .
- the memory 1010 includes a ROM (Read Only Memory) 1011 and a RAM (Random Access Memory) 1012 .
- the ROM 1011 stores a boot program such as BIOS (Basic Input Output System).
- BIOS Basic Input Output System
- Hard disk drive interface 1030 is connected to hard disk drive 1090 .
- a disk drive interface 1040 is connected to the disk drive 1100 .
- a removable storage medium such as a magnetic disk or optical disk is inserted into the disk drive 1100 .
- Serial port interface 1050 is connected to mouse 1110 and keyboard 1120, for example.
- Video adapter 1060 is connected to display 1130, for example.
- the hard disk drive 1090 stores, for example, an OS 1091, application programs 1092, program modules 1093, and program data 1094. That is, a program that defines each process of the signal processing device 19 is implemented as a program module 1093 in which computer-executable code is described. Program modules 1093 are stored, for example, on hard disk drive 1090 .
- the hard disk drive 1090 stores a program module 1093 for executing processing similar to the functional configuration of the signal processing device 19 .
- the hard disk drive 1090 may be replaced by an SSD (Solid State Drive).
- the setting data used in the processing of the above-described embodiment is stored as program data 1094 in the memory 1010 or the hard disk drive 1090, for example. Then, the CPU 1020 reads the program modules 1093 and program data 1094 stored in the memory 1010 and the hard disk drive 1090 to the RAM 1012 as necessary, and executes the processes of the above-described embodiments.
- the program modules 1093 and program data 1094 are not limited to being stored in the hard disk drive 1090, but may be stored in a removable storage medium, for example, and read by the CPU 1020 via the disk drive 1100 or the like. Alternatively, the program modules 1093 and program data 1094 may be stored in another computer connected via a network (LAN (Local Area Network), WAN (Wide Area Network), etc.). Program modules 1093 and program data 1094 may then be read by CPU 1020 through network interface 1070 from other computers.
- LAN Local Area Network
- WAN Wide Area Network
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Abstract
Description
また、図示した各装置の各構成要素は機能概念的なものであり、必ずしも物理的に図示のように構成されていることを要しない。すなわち、各装置の分散及び統合の具体的形態は図示のものに限られず、その全部又は一部を、各種の負荷や使用状況等に応じて、任意の単位で機能的又は物理的に分散又は統合して構成することができる。さらに、各装置にて行われる各処理機能は、その全部又は任意の一部が、CPU(Central Processing Unit)及び当該CPUにて解析実行されるプログラムにて実現され、あるいは、ワイヤードロジックによるハードウェアとして実現され得る。なお、プログラムは、CPUだけでなく、GPU等の他のプロセッサによって実行されてもよい。
一実施形態として、信号処理装置19は、パッケージソフトウェアやオンラインソフトウェアとして上記の信号処理を実行する信号処理プログラムを所望のコンピュータにインストールさせることによって実装できる。例えば、上記の信号処理プログラムを情報処理装置に実行させることにより、情報処理装置を信号処理装置19として機能させることができる。ここで言う情報処理装置には、デスクトップ型又はノート型のパーソナルコンピュータが含まれる。また、その他にも、情報処理装置にはスマートフォン、携帯電話機やPHS(Personal Handyphone System)等の移動体通信端末、さらには、PDA(Personal Digital Assistant)等のスレート端末等がその範疇に含まれる。
11 光源
12、141、142、144、145 カプラ
13 光変調器
14 90度光ハイブリッド
15 サーキュレータ
16 被測定光ファイバ
17、18 バランス検出器
19 信号処理装置
143 シフタ
171、181 電気信号
191、192 AD変換機能素子
193 位相計算部
194 後処理部
Claims (6)
- 信号処理装置によって実行される信号処理方法であって、
空間内の位置及び複数の時刻ごとの位相値に対して、位相接続処理を行う位相接続処理工程と、
前記位相接続処理の結果を基に、前記複数の時刻のうちの所定の時刻について、前記空間の所定の方向に沿って前記空間内の位置ごとに位相値の外れ値補正を行う第1の補正工程と、
前記空間内の位置のうち、前記第1の補正工程による補正の対象となった位置のそれぞれについて、前記所定の時刻以外の時刻について位相値の補正を行う第2の補正工程と、
を含むことを特徴とする信号処理方法。 - 前記第1の補正工程は、基準時刻よりも早い第1の時刻について位相値に補正値を加算する補正を行い、
前記第2の補正工程は、前記第1の時刻よりも早い時刻のそれぞれについて、遅い方から順に、位相値に前記補正値を加算する補正を行うことを特徴とする請求項1に記載の信号処理方法。 - 前記第1の補正工程は、基準時刻よりも遅い第2の時刻について位相値に補正値を加算する補正を行い、
前記第2の補正工程は、前記第2の時刻よりも遅い時刻のそれぞれについて、早い方から順に、位相値に前記補正値を加算する補正を行うことを特徴とする請求項1に記載の信号処理方法。 - 前記第1の補正工程は、ハンペル識別子を利用した補正を行うことを特徴とする請求項1から3のいずれか1項に記載の信号処理方法。
- 信号処理装置によって実行される信号処理方法であって、
前記位相接続処理工程は、光ファイバに光パルスを入射させて得られる前記光ファイバ上の位置であって、空間分解能に基づく範囲の位置、及び複数の時刻ごとの位相値に対して、位相接続処理を行い、
前記第1の補正工程は、前記位相接続処理の結果を基に、前記複数の時刻のうちの所定の時刻について、前記光ファイバの長手方向に沿って前記光ファイバ上の位置ごとに位相値の外れ値補正を行い、
前記第2の補正工程は、前記光ファイバ上の位置のうち、前記第1の補正工程による補正の対象となった位置のそれぞれについて、前記所定の時刻以外の時刻について位相値の補正を行うことを特徴とする請求項1から4のいずれか1項に記載の信号処理方法。 - 空間内の位置及び複数の時刻ごとの位相値に対して、位相接続処理を行う位相接続処理部と、
前記位相接続処理の結果を基に、前記複数の時刻のうちの所定の時刻について、前記空間の所定の方向に沿って前記空間内の位置ごとに位相値の外れ値補正を行う第1の補正部と、
前記空間内の位置のうち、前記第1の補正部による補正の対象となった位置のそれぞれについて、前記所定の時刻以外の時刻について位相値の補正を行う第2の補正部と、
を有することを特徴とする信号処理装置。
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