82 results about "Impulse detection" patented technology

The invention discloses a radio frequency voltage sensor and a plasma source system. The radio frequency voltage sensor comprises a signal acquisition module and a signal processing circuit. The signal processing circuit comprises a rectangular wave pulse detection module, a signal conversion module, a peak holding module and an operation output module; the input end of the rectangular wave pulse detection module receives a pulse synchronization signal; the signal conversion module is connected with the output end of the signal acquisition module; the first input end of the peak holding module is connected with the output end of the signal conversion module, and the second input end of the peak holding module is connected with the output end of the rectangular wave pulse detection module; and the operation output module is connected with the output end of the peak holding module. According to the radio frequency voltage sensor and the plasma source system provided by the invention, the peak voltage corresponding to the single-stage pulse can be accurately detected, the peak voltage corresponding to the multi-stage pulse can also be stably detected, the output is prevented from jumping to zero during the pulse closing period, and the stability and practicability of measurement are improved.

The invention discloses a partial discharge intelligent detection method and a partial discharge intelligent detection system. The method comprises the following steps: firstly, synchronously acquiring a multi-channel ultrasonic signal and a surface infrared image sequence of to-be-detected power equipment; performing pulse detection, cross-channel clustering based on a sliding time window and time difference positioning on the ultrasonic signal to obtain a preliminary discharge point; the multi-moment infrared images are intelligently selected and fused based on the ultrasonic pulse active time period, and a target surface infrared image highlighting the abnormal temperature rise area is generated; performing spatial aggregation on the ultrasonic positioning point and the infrared abnormal region to form a suspected sound-heat associated discharge source; respectively extracting waveform features and temperature features from the aggregated ultrasonic pulse set and the infrared region, fusing the waveform features and the temperature features, and inputting the fused features into a dual-channel neural network model; and finally, the model outputs a discharge type identification result and a discharge intensity evaluation value of the suspected discharge source. According to the invention, through deep space-time fusion and feature level fusion, the positioning precision and identification accuracy of partial discharge detection are significantly improved.

The invention discloses a full-localization ultra-high-speed multi-channel ADC (Analog to Digital Converter) acquisition and processing platform, and relates to the technical field of signal processing. The platform comprises a high-stability clock distribution calibration module, a synchronous acquisition and pulse injection module, a pulse detection and integer deviation module, a coarse-grained translation alignment module, a sub-sampling phase extraction module, a fractional delay interpolation alignment module, a hierarchical storage and flow control module and a high-speed interface synchronous output module. Multi-channel sampling clock synchronization is realized through FPGA dynamic phase adjustment; performing coarse-grained translation by injecting calibration pulses to detect integer deviation, extracting a sub-sampling phase difference, and adopting fractional delay filtering to realize sub-sampling precision alignment; hierarchical storage and intelligent flow control are carried out according to priorities, and synchronous data flow is output through a domestic high-speed interface; through a full-flow domestic chip and a synchronous correction technology, sub-sampling precision alignment and hierarchical flow control output of a multi-channel ADC at an ultrahigh sampling rate are realized.

The invention discloses an SAR interference suppression method based on echo asynchronous pulse detection, and the method comprises the steps: constructing a local odd-even channel comparison mode or a global reference pulse comparison mode, directly carrying out the processing in a time domain of an SAR echo data matrix, determining a corresponding mode through the energy characteristics of an interference signal, and carrying out the detection of the interference signal. Constructing a channel difference mask and an outlier mask in the corresponding mode, and finally obtaining an interference mask in each mode; establishing a mask matrix based on the interference mask, and processing the amplitude matrix to obtain an amplitude matrix after interference suppression processing; and combining the phase matrix to obtain a final non-interference SAR echo data matrix. According to the method, interference artifacts brought to SAR image data by the forwarding type coherent interference can be suppressed, and the phenomenon of sidelobe deterioration of strong scattering points in the image after frequency domain notch is eliminated, so that the forwarding type coherent interference existing in the SAR echo data is effectively suppressed.

The invention discloses a high-voltage positive and negative pulse detection circuit, which relates to the technical field of signal conditioning, and is characterized in that a voltage division circuit is responsible for attenuating input pulse signals, a switching diode is responsible for rectification and inputting positive and negative pulse signals into corresponding conditioning circuits respectively, and a charging circuit is responsible for maintaining pulse width characteristics of the signals; and the steepness of the signal edge is ensured by the comparator, and FPGA identification can be realized. Uncertain high-voltage pulse signals can be processed, and application scenes are diversified. The edge characteristic, pulse width and pulse direction of the pulse signal can be identified, and the signal processing capability is prominent.

The invention discloses an acoustic signal partial discharge detection system of a distribution network transformer, which is characterized by comprising a multi-sensor acquisition unit, a synchronous clock control unit, a signal preprocessing unit, an edge calculation processing unit and a communication and storage unit, the edge calculation processing unit integrates a cross-band denoising module, a multi-scale feature extraction module, a lightweight neural network diagnosis module and a diagnosis result fusion module, wherein the cross-band denoising module is used for performing joint denoising on audible sound and ultrasonic frequency band signals. According to the invention, a set of partial discharge detection scheme for a distribution network transformer scene is established, and the scheme flow comprises denoising, feature extraction, neural network training and diagnosis. According to the scheme, audible audio frequency band and ultrasonic frequency band data are covered, and interference generated by mechanical vibration of the transformer in the ultrasonic frequency band is removed through a soft threshold value of wavelet transformation and a pulse detection denoising algorithm.

This invention relates to a radar pulse signal detection method and apparatus based on sparse spectrum sensing. The radar pulse signal detection apparatus based on sparse spectrum sensing includes a sparse spectrum sensing module, a dynamically adjusted adaptive filtering module, and a dual-threshold pulse detection module. The sparse spectrum sensing module performs single-bit sampling on the original signal to obtain the signal frequency and bandwidth. The dynamically adjusted adaptive filtering module filters the signal according to the signal frequency and bandwidth. Utilizing the sign bit of the AD data for spectral sensing, the system monitors and tracks the input spectral distribution in real time. Compared to the traditional short-time Fourier transform, this significantly reduces the resources required for signal processing and increases the processing bandwidth. During filtering, based on the pulse signal center frequency and bandwidth obtained from the spectral monitoring module, the dynamically adjusted adaptive filtering module adjusts the filter's center frequency to achieve tracking and filtering of the radar pulse signal.

The invention discloses an intelligent control system and method for a high-power laser driving power supply, and relates to the field of laser control, the method comprises the following steps: transmitting pulse detection laser, presetting the pulse width, repetition frequency and monopulse energy, calculating the loss ratio of a spectroscope through an integrated infrared temperature sensor, an optical power meter and the spectroscope, and calculating the power consumption of the spectroscope; basic parameters such as the initial temperature, the reflection power, the melting temperature and the temperature reflection correlation parameters of the reflecting material are obtained, and a database is built; emitting continuous working laser, calculating an energy density conversion coefficient and a reflection power peak value, and performing associative storage; detecting the center temperature of a material light spot in real time, predicting real-time reflection power by combining a reflection power peak value, and dynamically adjusting the actual power of working laser according to the temperature, a reflection power threshold value and an adjustment coefficient; and monitoring the temperature change rate and the reflection power, and if the temperature change rate and the reflection power exceed a safety threshold, early warning and stopping laser. According to the method, reflected laser dynamic control is achieved, laser energy output stability and machining precision are improved, and reliable system operation is guaranteed.

An ADC (50) is disclosed. It has two VTCs (110a, 110b) for converting a first and a second input voltage, respectively, to pulses with delays corresponding to the magnitudes of these voltages. It further has a pulse-detector circuit (120) coupled to outputs (114a, 114b) of the two VTCs (110a, 110b). The pulse-detector circuit (120) is configured to make a transition from a first logic state (‘0’) to a second logic state (‘F) at a first output (124a) of the pulse-detector circuit (120) in response to the start of the pulse from one of the VTCs (110a) and to make a transition from the first logic state (‘0’) to the second logic state (‘F) at a second output (124b) of the pulse-detector circuit (120) in response to the start of the pulse from the other VTC. Furthermore, the pulse-detector circuit (120) is configured to reset both the first and the second output (124a, 124b) to the first logic state (‘0’) in response to both the first output (124a) and the second output (124b) of the pulse-detector circuit (120) being set in the second logic state (‘1’). The ADC (50) further has a first TDC (130a) coupled to the first output (124a) of the pulse-detector circuit (120) and a second TDC (130b) coupled to the second output (124b) of the pulse-detector circuit (120).

The invention discloses an aircraft fuel quantity measurement self-adaptive filtering method, system and device based on multi-dimensional statistic dynamic adaptation and a medium. The method comprises the following steps that S01, signals are collected and preprocessed; dividing a fuel quantity digital signal output by a sensor into continuous time blocks according to a fixed time window; s02, calculating a multi-dimensional statistical magnitude; comprising the mean value, variance and kurtosis of the current time block; s03, performing multi-stage filtering processing; s04, performing data fusion and conversion; and keeping the original value of the data pulse point, and combining the original value with the fine filtering result of the non-pulse point to obtain a complete filtered signal. By monitoring the multi-dimensional statistical characteristics (mean value, variance and peak value) of a fuel quantity signal in real time and combining a coarse filtering-pulse detection-fine filtering multi-stage structure, filtering parameters are dynamically adjusted, efficient suppression of mixed noise (low-frequency shaking, Gaussian noise and pulse noise) is achieved, and the precision of fuel measurement under complex working conditions is improved.

The application provides a high duty cycle signal discrimination and suppression method for a wide bandwidth space receiver, comprising the following steps: step 1, background noise statistical processing; step 2, amplitude calculation and peak searching processing; step 3, peak signal space resolution; step 4, single beat statistical quantity generation; step 5, multi-beat statistical quantity generation; step 6, duty cycle calculation and cross-frequency point merging; step 7, high duty cycle signal judgment; and step 8, high duty cycle signal suppression threshold generation and output. The high duty cycle signal discrimination result and the high duty cycle signal suppression threshold generated by the application play a role before the generation of the pulse level detection result, are a beneficial supplement to the traditional background noise statistical threshold and the CFAR threshold, can filter out the high duty cycle signal in the pulse detection stage, can greatly reduce the processing pressure of the subsequent pulse pretreatment and signal sorting, and can improve the interception quality of the receiver to the normal radar pulse signal.

This invention discloses a radiation source signal classification method based on pulse-level multi-source separation, mainly addressing the problem of poor radiation source signal classification performance in complex electromagnetic environments using existing technologies. The implementation steps are as follows: 1) Receiving broadband intermediate frequency or baseband signals and performing pulse detection; 2) Estimating the direction of arrival and constructing pulse descriptors for the detected pulses based on a multi-element antenna structure; 3) Modeling a pulse-level multi-dimensional feature space and performing density peak clustering based on temporal consistency constraints within this space; 4) Adaptively estimating the number of radiation sources and reconstructing the pulse sequence, performing multi-physical domain feature extraction; 5) Fusing the multi-physical domain features to complete the classification and identification of radiation source signals. This invention can effectively distinguish pulses from different radiation sources in complex electromagnetic environments, while effectively reducing the system's storage and computing resource consumption while ensuring high recognition performance.

The invention discloses a second pulse detection protection circuit, system and method and a vehicle. The second pulse detection protection circuit comprises a second pulse transmission module, an input signal detection module and an output signal detection module. The second pulse transmission module outputs a second pulse signal, the input signal detection module outputs a second pulse sampling signal I, the input end of the output signal detection module is connected with the output end of the second pulse transmission module, and the output signal detection module outputs a second pulse sampling signal II; the positioning module is used for judging whether to generate the second pulse signal based on the second pulse sampling signal I and selecting to generate the second pulse signal, and judging whether to stop generating the second pulse signal and whether to output the second pulse signal based on the second pulse sampling signal I and the second pulse sampling signal II. According to the invention, accurate second pulse signals can be obtained in real time.

A brain measurement apparatus includes: a static magnetic field forming unit for forming a static magnetic field in a measurement area; a gradient magnetic field coil for forming a gradient magnetic field in the measurement area; a transmission coil for transmitting a transmission pulse toward a subject in the measurement area; a detection coil for detecting a nuclear magnetic resonance signal generated in the subject by transmission of the transmission pulse; and a generator for generating an MR image based on the nuclear magnetic resonance signal detected by the detection coil.

A method and system for inspecting polarization in a fibered optical path. The method being executed by a computer-implemented system comprising a controller and at least one detector communicatively coupled to the controller, the computer-implemented system being operatively connected to the fibered optical path, including: causing a laser to emit at least one optical pulse into the fibered optical path; detecting a plurality of reflected optical signals from the fibered optical path; determining a plurality of experimental correlation values based on the plurality of reflected optical signals and a reference signal function; and in response to a given experimental correlation value of the plurality of experimental correlation values being less than a threshold, identifying a mechanical disturbance caused by birefringence in the fibered optical path, the mechanical disturbance being located at a location of the plurality of locations corresponding to the given experimental correlation value.

The application discloses a kind of wafer defect detection device and method, comprising: detection module, processing module and image reconstruction module;Detection module includes: laser emission unit, transmission lens group, photoacoustic conversion unit and sound-electricity conversion unit;Laser emission unit is launched to the surface of the wafer to be measured with pulse detection laser, pulse detection laser generates optical signal with defect characteristic information after passing through wafer to be measured, photoacoustic conversion unit converts optical signal into acoustic signal;Sound-electricity conversion unit converts acoustic signal into electrical signal;Processing module extracts the defect characteristic information of wafer to be measured according to electrical signal;Image reconstruction module determines the defect of wafer to be measured according to defect characteristic information.The defect detection device provided in the application converts the optical signal scattered after wafer to be measured into electrical signal by the cooperation of photoacoustic conversion unit and sound-electricity conversion unit, so as to analyze and process the defect of wafer to be measured, so as to efficiently and accurately detect the defect on the surface of wafer to be measured.

Systems and methods for detecting a timing interval in which a light pulse is received by a photodetector array comprising: receiving, by a plurality of photosensitive elements of the photodetector array, electromagnetic radiation from a field of view, accumulating, by each of the plurality of photosensitive elements, an electrical charge proportional to an intensity of received electromagnetic radiation during an integration time period, and performing a search on signals converted from the accumulated electrical charge to detect a light pulse appearance with a predefined precision. Performing the search may include performing a fine search stage including: controlling the duration of the integration time period for each of the plurality of photosensitive elements and a temporal relationship between the integration time periods of the photosensitive elements. The temporal relationship between the integration time periods of the photosensitive elements may define a distinct temporal pattern corresponding to each timing interval within the duration of the integration time period. Detecting a timing interval in which a light pulse is received from the field of view by identifying the distinct temporal pattern corresponding to that timing interval.

The invention relates to an LED lamp light decay compensation method based on pulse driving and an intelligent range hood. The method comprises the following steps: acquiring a pulse detection signal output by a photoelectric detection module under test light of an LED lamp; the test light is generated by controlling the LED lamp through a pulse driving signal; calculating a response delay index based on the pulse detection signal and the pulse driving signal; and compensating the original driving current of the LED lamp based on the response delay index to obtain a new driving current, thereby solving the problem of poor reliability of LED attenuation compensation, and using the time response characteristic of the signal as the basis for judging the LED attenuation state, not only realizing adaptive compensation, but also improving the accuracy and reliability of LED light attenuation compensation.

In one embodiment, a lidar system includes a light source configured to emit (i) local-oscillator light and (ii) pulses of light. Additionally, the light source is configured to impart a spectral signature of one or more different spectral signatures to each of the emitted pulses of light, where the emitted pulses of light include an emitted pulse of light having a particular spectral signature of the one or more different spectral signatures. The lidar system also includes a receiver configured to detect the local-oscillator light and a received pulse of light, the received pulse of light including a portion of the emitted pulse of light scattered by a target located a distance from the lidar system. The receiver includes a detector configured to produce a photocurrent signal corresponding to the local-oscillator light and the received pulse of light. The receiver also includes a pulse-detection circuit and a frequency-detection circuit.

The application discloses a kind of fast autonomous detection guiding interference methods based on ZYNQ platform, applied to detection guiding interference system, comprising: the main channel radio frequency signal is sent into high-speed single-bit ADC, and after PL end receives high-speed single-bit ADC data, real-time pulse detection and rough frequency measurement;By rough frequency measurement result, each channel radio frequency signal is input after frequency conversion, and corresponding intermediate frequency ADC is input;PL end is according to rough frequency measurement result, after the signal of each intermediate frequency ADC is received differentially, pulse parameter is measured after frequency conversion, and pulse description word is sent into PS end;PS end uses pulse description word to match radar library, and pulse description word is sorted and calculated, and the calculation result is sent to peripheral equipment, and the calculation result is updated radar library, and the corresponding interference strategy is selected by the radar characteristic parameter matched, and the interference parameter is sent to PL end;PL end generates interference signal according to the pulse parameter of each signal and interference parameter, and after processing, interference signal is sent.The application can real-time self-adapting radar signal fast reconnaissance and guiding interference.

Techniques are provided for non-linear filtering of a signal for improved pulse detection and pulse width discrimination. A system implementing the techniques according to an embodiment includes a first linear filter configured to filter an in-phase component of a received signal to a downsample bandwidth and a second linear filter configured to filter a quadrature phase component of the received signal to the downsample bandwidth. The system also includes a magnitude calculation circuit coupled to outputs of the first linear filter and the second linear filter and configured to generate a magnitude signal based on the filtered in-phase component and the filtered quadrature phase component of the received signal. The system further includes a median filter processor coupled to an output of the magnitude calculation circuit and configured to apply a median filter to the magnitude signal to generate a filtered signal having reduced noise while maintaining sharp edge transitions.

The embodiment of the present specification provides an auxiliary card searching module, method and near field communication device. Wherein, the auxiliary card searching module comprises a pulse detection unit, a control unit and a modulation unit; the control unit is connected with the pulse detection unit and the modulation unit respectively; the pulse detection unit is used for generating a trigger signal within a preset time length based on a response signal of a device antenna of the slave device; the response signal is generated by the device antenna of the slave device in response to the radio frequency signal sent by the master device; the preset time length is less than the pulse time length of one radio frequency signal sent by the master device; the control unit is used for controlling the modulation unit to switch states according to the trigger signal, so as to promote the master device to enter the polling mode.

The invention discloses a nuclear spin precession observation device and method based on a differential enhanced atom magnetometer, and the method comprises the steps: introducing two beams of detection light with opposite frequency detuning amounts into a 2 * 2 optical switch, and generating two pulse detection light beams with the phase difference of 180 degrees; the two beams of light are used for replacing direct-current and same-frequency detection light used in traditional differential detection, the two beams of detection light generate rotation angles with opposite symbols and equal sizes when penetrating through the polarized alkali metal atom gas chamber at the same time, and the rotation angle signal intensity is amplified by two times by differentiating the rotation angles with the opposite symbols. Meanwhile, a phase-locked amplification technology and a differential measurement method are applied, and the differential enhanced atom magnetometer has the advantages of isolating low-frequency electric noise, inhibiting common-mode noise and being high in measurement signal-to-noise ratio, thereby constructing the differential enhanced atom magnetometer. A differential enhanced atom magnetometer is placed around a polarized inert gas chamber, and the nuclear spin precession process of the inert gas is observed by measuring the periodic change of the macroscopic magnetic moment of the inert gas in a magnetic field.

This invention discloses a fault mode-driven multi-mode intelligent anomaly diagnosis method and system for power automation systems. The method includes offline learning and online detection phases. In the offline phase, detection knowledge items, including purified historical statistical baselines and ramp-up discrimination models, are periodically generated and stored. In the online phase, the data is preprocessed and adapted, and corresponding dedicated detection operators are activated according to the indicator type, combined with the detection knowledge items for analysis. The dedicated detection operators include ramp-up detection operators for resource-related indicators, pulse detection operators for performance-related indicators, and trend change point detection operators for disk-related indicators. The ramp-up detection operators employ a parallel fusion structure of seasonality analysis and model discriminant analysis. Candidate events output by the detection are converted into alarm records after suppression judgment. This invention achieves accurate and interpretable intelligent fault diagnosis through a closed loop of "offline baseline purification, online mode adaptation, and diagnostic output."

This invention discloses a radio frequency (RF) voltage sensor and a plasma source system. The RF voltage sensor includes a signal acquisition module and a signal processing circuit. The signal processing circuit includes a rectangular wave pulse detection module, a signal conversion module, a peak hold module, and a computational output module. The input terminal of the rectangular wave pulse detection module receives a pulse synchronization signal. The signal conversion module is connected to the output terminal of the signal acquisition module. The first input terminal of the peak hold module is connected to the output terminal of the signal conversion module, and the second input terminal of the peak hold module is connected to the output terminal of the rectangular wave pulse detection module. The computational output module is connected to the output terminal of the peak hold module. The RF voltage sensor and plasma source system provided by this invention can accurately detect the peak voltage corresponding to a single-stage pulse, and can also stably detect the peak voltage corresponding to multiple-stage pulses, while avoiding the output jumping to zero during pulse shutdown, thus improving the stability and practicality of the measurement.

The invention relates to a signal pulse width detection and splicing method based on a sliding window and a double-threshold state machine, and the method comprises the steps: carrying out the pulse detection of an electromagnetic pulse signal currently collected by electronic reconnaissance equipment, determining whether the electromagnetic pulse signal is an effective signal, and configuring a flag bit according to the detection result of the effective signal; at the rising edge of the clock, the sliding window shift register is used for storing the electromagnetic pulse signal; calculating the sum of corresponding signal flag bits and the sum of effective data amplitudes based on the data stored in the sliding window shift register; comparing the sum of the signal flag bits with a preset threshold value, and determining a corresponding signal state; when the signal state is a high level state, determining a corresponding signal amplitude average value based on the ratio of the sum of the effective data amplitudes to the sum of the signal flag bits; and constructing effective signals based on the signal amplitude average value and outputting the effective signals so as to splice the effective signals. According to the method, the problems of inaccurate signal pulse width detection and incomplete splicing in a complex electromagnetic environment are solved.

The invention discloses a broadband radar signal reconnaissance and parameter estimation system and method and a storage medium. The system comprises a frequency spectrum reconnaissance module used for performing Fourier transform on reconnaissance channel input data and detecting a first carrier frequency and a bandwidth of a signal in a frequency domain; the signal processing module is used for carrying out self-adaptive frequency conversion and filtering on the input data according to the parameters; the pulse detection module is used for performing pulse detection on the filtering signal and finely estimating a second or third set of carrier frequency and bandwidth parameters of the frequency modulation or phase modulation type signal; the direction-finding data FFT module is used for performing FFT conversion on the lateral channel data to extract phase information; and the packaging module is used for packaging the pulse detection result and the phase information into pulse description words and outputting the pulse description words. According to the invention, the integrated processing of the broadband radar signal from rapid reconnaissance, precise processing, modulation identification to direction finding information fusion is realized, and the real-time processing capability of the system, the throughput of the broadband signal and the parameter estimation precision are obviously improved.

The application provides a wide dynamic pulse laser ranging method and system of a neural network, comprising the following steps: S1, collecting echo signals after a laser radar transmits laser signals; S2, extracting characteristic parameters of the transmitted and received waveforms; S3, detecting rising edges and falling edges of the characteristic parameters, and if both the rising edges and the falling edges are valid, the pulse detection is successful; S4, calculating a time difference of corresponding positions of a seed light waveform of the transmitted signals and a waveform of the echo signals; and S5, obtaining a distance between the laser radar and a target by a time-of-flight ranging method. The application has reduced operation amount, high measurement accuracy and strong adaptive capacity. The wide dynamic ranging can be realized by a single-channel ADC acquisition module. The system has few channels, a simple circuit structure and low power consumption. The trained neural network can accurately predict the ranging result according to the input waveform characteristics.

The application discloses a kind of explosion vibration source positioning method, system and computer program product based on machine learning classification and guided pulse detection, it is related to signal processing and target positioning technical field, solve the problem of insufficient robustness of existing detection method in complex environment.It includes the following steps: step S1, multi-channel signal is synchronously collected, and the multi-channel signal is pretreated;Step S2, pulse detection is carried out to the multi-channel signal after pretreatment, and TOA sequence is formed;Step S3, preliminary detection is carried out to TOA sequence, and after extracting features, the features are input into machine learning model for classification, and the output category is explosion, then enter positioning solution;Step S4, positioning solution is carried out, and the solution result is output.

This invention relates to fiber optic gyroscopes, specifically to a method, processing circuit, and fiber optic gyroscope for reducing scaling factor error. It addresses the shortcomings of fiber optic gyroscopes, such as fiber ring aging during prolonged operation, which alters the scaling factor compensation model across the entire temperature range, leading to decreased long-term scaling factor stability and limiting gyroscope applications. The method for reducing scaling factor error involves using a pulse detection circuit between the PIN-FET photodetector output and the FPGA input to measure transit time error. This error is then used to correct the modulation time, ensuring the fiber ring length is under closed-loop control.