The modified atomic transformations are constructed and proved.On their basis the new complex analytic wavelets are obtained.The proof of the Fourier transforms existence in L1 and L2 on the basis of the theory of ato...The modified atomic transformations are constructed and proved.On their basis the new complex analytic wavelets are obtained.The proof of the Fourier transforms existence in L1 and L2 on the basis of the theory of atomic functions(AF)are presented.The numerical experiments of digital time series processing and physical analysis of the results confirm the efficiency of the proposed transforms.展开更多
In recent years, explosively increasing data traffic has been boosting the con?tinuous demand of high speed optical interconnection inside or among data centers, high performance computers and even consumer electronic...In recent years, explosively increasing data traffic has been boosting the con?tinuous demand of high speed optical interconnection inside or among data centers, high performance computers and even consumer electronics. To pursue the improved intercon?nection performance of capacity, energy efficiency and simplicity, effective approaches are demonstrated including particularly advanced digital signal processing (DSP) meth?ods. In this paper, we present a review about the enabling adaptive DSP methods for opti?cal interconnection applications, and a detailed summary of our recent and ongoing works in this field. In brief, our works focus on dealing with the specific issues for short-reach interconnection scenarios with adaptive operation, including signal-to-noise-ratio (SNR) limitation, level nonlinearity distortion, energy efficiency consideration and the de?cision precision.展开更多
This paper proposes the design and development of virtual experimental projects in the Digital Signal Processing course,using MATLAB,Proteus,and CCS platforms to develop a library of typical experimental cases for bio...This paper proposes the design and development of virtual experimental projects in the Digital Signal Processing course,using MATLAB,Proteus,and CCS platforms to develop a library of typical experimental cases for biomedical engineering majors and discusses the design process.Based on these typical cases,this paper explores the secondary design for innovative engineering practice case teaching,which can promote students’understanding and mastery of digital signal processing theories,algorithms,and technologies in an intuitive,flexible,and efficient way;quickly build new innovative engineering case models and further cultivate students’engineering application ability as well as innovative thinking.展开更多
We experimentally built a photonics-aided long-distance large-capacity millimeter-wave wireless transmission system and demonstrated a delivery of 40 Gbit/s W-band 16-ary quadrature amplitude modulation(QAM)signal ove...We experimentally built a photonics-aided long-distance large-capacity millimeter-wave wireless transmission system and demonstrated a delivery of 40 Gbit/s W-band 16-ary quadrature amplitude modulation(QAM)signal over 4600 m wireless distance at 88.5 GHz.Advanced offline digital signal processing algorithms are proposed and employed for signal recovery,which makes the bit-error ratio under 2.4×10^(−2).To the best of our knowledge,this is the first field-trial demonstration of>4 km W-band 16QAM signal transmission,and the result achieves a record-breaking product of wireless transmission capacity and distance,i.e.,184(Gbit/s)·km,for high-speed and long-distance W-band wireless communication.展开更多
Programmable photonic waveguide meshes can be programmed into many different circuit topologies and thereby provide a variety of functions.Due to the complexity of the signal routing in a general mesh,a particular syn...Programmable photonic waveguide meshes can be programmed into many different circuit topologies and thereby provide a variety of functions.Due to the complexity of the signal routing in a general mesh,a particular synthesis algorithm often only accounts for a specific function with a specific cell configuration.In this paper,we try to synthesize the programmable waveguide mesh to support multiple configurations with a more general digital signal processing platform.To show the feasibility of this technique,photonic waveguide meshes in different configurations(square,triangular and hexagonal meshes)are designed to realize optical signal interleaving with arbitrary duty cycles.The digital signal processing(DSP)approach offers an effective pathway for the establishment of a general design platform for the software-defined programmable photonic integrated circuits.The use of well-developed DSP techniques and algorithms establishes a link between optical and electrical signals and makes it convenient to realize the computer-aided design of optics–electronics hybrid systems.展开更多
Since Pulse Code Modulation emerged in 1937, digitized speech has experienced rapid development due to its outstanding voice quality, reliability, robustness and security in communication. But how to reduce channel wi...Since Pulse Code Modulation emerged in 1937, digitized speech has experienced rapid development due to its outstanding voice quality, reliability, robustness and security in communication. But how to reduce channel width without loss of speech quality re-mains a crucial problem in speech coding theory. A new full-duplex digital speech communication system based on the Vocoder of AMBE- 1 000TM and microcontroller ATMEL 89C5 1 is introduced. It shows higher voice quality than current mobile phone system with only a quarter of channel width needed for the latter. The prospective areas in which the system can be applied include satellite communication, IP Phone, virtual meeting and the most important, defence industry.展开更多
A control system for correction mechanisms through the whole trajectory is proposed based on the principle of one-dimensional trajectory correction projectile. Digital signal processing( DSP) is utilized as the core c...A control system for correction mechanisms through the whole trajectory is proposed based on the principle of one-dimensional trajectory correction projectile. Digital signal processing( DSP) is utilized as the core controller and gobal positioning system( GPS) is used to measure trajectory parameters to meet the requirements of calculating ballistics and system functions. Firstly,the hardware,mainly including communication module,ballistic calculation module,boosting& detonating module and data storage module,is designed. Secondly,the supporting software is developed based on the communication protocols of GPS and the workflow of control system. Finally,the feasibility and the reliability of the control system are verified through dynamic tests in a car and live firing experiments. The system lays a foundation for the research on trajectory correction projectile for the whole trajectory.展开更多
Nonlinearity impairments and distortions have been bothering the bandwidth constrained passive optical network(PON)system for a long time and limiting the develop-ment of capacity in the PON system.Unlike other works ...Nonlinearity impairments and distortions have been bothering the bandwidth constrained passive optical network(PON)system for a long time and limiting the develop-ment of capacity in the PON system.Unlike other works concentrating on the exploration of the complex equalization algorithm,we investigate the potential of constellation shap-ing joint support vector machine(SVM)classification scheme.At the transmitter side,the 8 quadrature amplitude modulation(8QAM)constellation is shaped into three designs to mitigate the influence of noise and distortions in the PON channel.On the receiver side,simple multi-class linear SVM classifiers are utilized to replace complex equalization methods.Simulation results show that with the bandwidth of 25 GHz and overall bitrate of 50 Gbit/s,at 10 dBm input optical power of a 20 km standard single mode fiber(SSMF),and under a hard-decision forward error correction(FEC)threshold,transmission can be realized by employing Circular(4,4)shaped 8QAM joint SVM classifier at the maximal power budget of 37.5 dB.展开更多
As an increasingly popular flow metering technology,Coriolis mass flowmeter exhibits high measurement accuracy under single-phase flow condition and is widely used in the industry.However,under complex flow conditions...As an increasingly popular flow metering technology,Coriolis mass flowmeter exhibits high measurement accuracy under single-phase flow condition and is widely used in the industry.However,under complex flow conditions,such as two-phase flow,the measurement accuracy is greatly decreased due to various factors including improper signal processing methods.In this study,three digital signal processing methods—the quadrature demodulation(QD)method,Hilbert method,and sliding discrete time Fourier transform method—are analyzed for their applications in processing sensor signals and providing measurement results under gas-liquid two-phase flow condition.Based on the analysis,specific improvements are applied to each method to deal with the signals under two-phase flow condition.For simulation,sensor signals under single-and two-phase flow conditions are established using a random walk model.The phase difference tracking performances of these three methods are evaluated in the simulation.Based on the digital signal processor,a converter program is implemented on its evaluation board.The converter program is tested under single-and two-phase flow conditions.The improved signal processing methods are evaluated in terms of the measurement accuracy and complexity.The QD algorithm has the best performance under the single-phase flow condition.Under the two-phase flow condition,the QD algorithm performs a little better in terms of the indication error and repeatability than the improved Hilbert algorithm at 160,250,and 420 kg/h flow points,whereas the Hilbert algorithm outperforms the QD algorithm at the 600 kg/h flow point.展开更多
In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbala...In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbalance,carrier wave leakage,etc.These damages result in system performance tremendous degrades.We proposed a semiblind method to estimate the I/Q imbalance of THz orthogonal modulator,based on predefined preamble and pilot symbols for quadrature amplitude modulation(QAM).In this paper,a transmitter with Y band quadrature mixer and 20Gbps base-band signal has been tested.The bandwidth of the baseband signal was 7GHz,and the modulation type was 16QAM.By this method,7dB improvement of the system’s symbol Mean Square Error(MSE)has been got.That means the proposed method can be used to eliminate the I/Q imbalance effectively.展开更多
The growing problems of harmonic pollution on coal mine power lines caused by high-power DC drive systems has increased the use of active power filters.We analyzed compensation errors caused by the time lag in the det...The growing problems of harmonic pollution on coal mine power lines caused by high-power DC drive systems has increased the use of active power filters.We analyzed compensation errors caused by the time lag in the detecting circuits of an active power filter based on DSP control.We derived a mathematical model for the compensation error starting from the error estimation when a single distortion frequency is present.This model was then extended to the case where multiple frequencies are present in the distortion.A formula for a general theory of compensation error with fixed load and fixed lag time is presented.The theoretical analysis and experimental results show that the delay time of an active power filter mainly arises from the sampling time.Lower sampling frequencies introduce larger compensation errors in the active power filter reference current.展开更多
The entire roller inlayed block intelligence cold strip shape meter is developed successfully in this paper,which can stably work chronically in the cold rolling workshop,the independent innovation of the key technolo...The entire roller inlayed block intelligence cold strip shape meter is developed successfully in this paper,which can stably work chronically in the cold rolling workshop,the independent innovation of the key technology of cold strip shape measuring,the foreign technical monopoly and blockade are broken through.The structural form which is different from the international popular segmented detection roller is put forward,the entire detection roller inlayed block is developed,a group of elastic blocks in that the sense organs are installed are inlayed in the radial symmetry rectangular grooves of the detection roller body,the entire roller structure is composed of elastic pieces and the roller body,the scratch of the strip surface due to different thermal expansion of the traditional detection roller measuring unit is avoided effectively.The signal transmission form which is different form the international popular dry slip ring is put forward,the spray wet slip ring is developed,slip ring and detection roller can be taken down and installed as possibly as fast,so the maintain is convenient,while through the section auto-spray cleaning,lubrication and cooling, the service life is remarkable improved and the outside interference signal is reduced.The signal processing form which is different form the international popular gathering card is put forward,the embedded DSP shape signal processing hardware system is developed,the electromagnet,temperature,humidity and vibration’s interference of industry practice to shape transmission signal can be effectively avoided,which can guarantee the instantaneity and measured precision of shape measured signal.The shape signal processing software system whose function contains error compensation,pattern recognition,establishment of the target shape and the closed-loop control calculation is built,the shape meter’ computer human interaction is friendly,and function of shape meter is strong,at the same time the intellectualized level of the shape meter is improved.Now,this shape meter has been successfully applied on the 1 250 mm cold strip mill of Angang Steel Company Limited,the long-term operating testing is done,every guide line achieves the anticipative effect,the measuring precision is high and the measuring signal is stable and reliable,the shape meter is tested on high speed,big tension,changed wrap angle and big depressed complicated working conditions,any scratch of the detection roller surface and the strip surface is not appearing,it can completely adapt well to the industrial production environment,reaching the international advanced level.展开更多
In the step processing a digitalized signal,noises are generated by internal or external causes of the system.In order to eliminate these noises,various methods are researched.Among these noise elimination methods,Fou...In the step processing a digitalized signal,noises are generated by internal or external causes of the system.In order to eliminate these noises,various methods are researched.Among these noise elimination methods,Fourier fast transform(FFT)and short-time Fourier transform(STFT)are widely used.Because they are expressed as a fixed time-frequency domain,they have the disadvantage that the time information about the signal is unknown.In order to overcome these limitations,by using the wavelet transform that provides a variety of time-frequency resolution,multi-resolution analysis can be analysed and a varying noise depending on the time characteristics can be removed more efficiently.Therefore,in this paper,a denoising method of underwater vehicle using discrete wavelet transform(DWT)is proposed.展开更多
In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8...In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.展开更多
In this paper,we propose and experimentally demonstrate a joint shaping technique to improve the performance of a lowresolution transmission system for the first time,to the best of our knowledge.The joint shaping tec...In this paper,we propose and experimentally demonstrate a joint shaping technique to improve the performance of a lowresolution transmission system for the first time,to the best of our knowledge.The joint shaping technique combines probabilistic shaping(PS)and error feedback noise shaping(EFNS).In the 40-Gbaud intensity-modulation direct-detection(IM/DD)experimental transmission system,a bit-error-rate(BER)of 3.8×10^(-3)can be achieved easily with the joint shaping at the physical number of bits(PNOB)of 3.In the 30-Gbaud dual polarization(DP)coherent experimental transmission system,a BER below 1×10^(-3)is easily obtained with a 3-bit quantizer by using joint shaping.The optimization of the shaping degree is also analyzed.展开更多
A numerical simulation study of the performance of encoding and decoding of short optical pulse in OCDMA (Optical Code Division Multiple Access) systems under non-linear optical effects is presented. The performance o...A numerical simulation study of the performance of encoding and decoding of short optical pulse in OCDMA (Optical Code Division Multiple Access) systems under non-linear optical effects is presented. The performance of encoding and decoding short pulses is obtained through use of device FBG (fiber Bragg grating) where the codes are inserted through discrete jumps in the optical phase (±π). The multiuser interference is also the object of the present study, where a figure of merit (interference figure) is used to quantify the interference in multiuser auto and cross correlation. We evaluate the dependence of the multiuser interference for the coupling constant of FBG. Finally, the interference inserted in the autocorrelation due to nonlinear effects generated in the nonlinear switching of the coded pulse in a dual core nonlinear directional coupler is examined, where temporal broadening of pulses decoded is observed.展开更多
Aiming at the problems in a linear frequency modulation continuous wave(LFMCW)ranging lidar system,such as low signal-to-noise in echo beat frequency and difficult extraction of the signal frequency,a method with high...Aiming at the problems in a linear frequency modulation continuous wave(LFMCW)ranging lidar system,such as low signal-to-noise in echo beat frequency and difficult extraction of the signal frequency,a method with high-speed and high accuracy based on field programmable gate array(FPGA)is proposed.Firstly,the laser echo beat signal is sampled by high-speed analog to digital converter(ADC)and then processed in FPGA for data preprocessing.After the signal is processed by the 8192-point FPGA will obtain the frequency spectrum and then apply the frequency spectrum to data processing and adaptive noise signal peak detection.These two steps realize the real-time and accurate extraction process of the target echo beat signal frequency.Finally,the spectrum data is transmitted to the host computer and processed through the external data acquisition board for real-time spectrum display.Experimental results show that data preprocessing and spectrum data processing can effectively suppress DC bias and system modulation noise.Adaptive noise peak detection can accurately divide the threshold contour according to the dynamic noise of the system and realize the detection of target signal peak.When the sampling clock of the system is 100 MHz,the time needed for each calculation of the spectrum is 81.92μs,and the refresh rate of the spectrum reaches 12.2 kHz,which meets the real-time requirements of the system.展开更多
Optical spectral measurements are crucial for optical sensors and many other applications,but the prevailing methods,such as optical spectrum analysis and tunable laser spectroscopy,often have to make compromises amon...Optical spectral measurements are crucial for optical sensors and many other applications,but the prevailing methods,such as optical spectrum analysis and tunable laser spectroscopy,often have to make compromises among resolution,speed,and accuracy.Optical frequency combs are widely used for metrology of discrete atomic and molecular spectral lines.However,they are usually generated by optical methods and have large comb spacing,which limits the resolution for direct sampling of continuous spectra.To overcome these problems,this paper presents an original method to digitally generate an ultrafine optical frequency comb(UFOFC)as the frequency ruler for spectral measurements.Each comb line provides one sampling point,and the full spectrum can be captured at the same time using coherent detection.For an experimental demonstration,we adopted the inverse fast Fourier transform to generate a UFOFC with a comb spacing of 1.46 MHz over a 10-GHz range and demonstrated its functions using a Mach–Zehnder refractive index sensor.The UFOFC obtains a spectral resolution of 0.01 pm and response time of 0.7 μs;both represent 100-fold improvements over the state of the art and could be further enhanced by several orders of magnitude.The UFOFC presented here could facilitate new label-free sensor applications that require both high resolution and fast speed,such as measuring binding kinetics and single-molecule dynamics.展开更多
We propose an alternative approach to compensation of intermodal interactions in few-mode optical fibers by means of digital backpropagation.Instead of solving the inverse generalized multimode nonlinear Schr?dinger e...We propose an alternative approach to compensation of intermodal interactions in few-mode optical fibers by means of digital backpropagation.Instead of solving the inverse generalized multimode nonlinear Schr?dinger equation,we accomplish backpropagation of the multimode signals with help of their near-field intensity distributions captured by a camera.We demonstrate that this task can successfully be handled by a deep neural network and provide a proof of concept by training an autoencoder for backpropagation of six linearly polarized[LP]modes of a step-index fiber.展开更多
The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed,axial compressor.The flat-baffles with different span heights are used to simulate d...The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed,axial compressor.The flat-baffles with different span heights are used to simulate different distorted inflow cases.Compared with auto-correlation and root-mean-square analysis,cross-correlation analysis used to predict early stall warning does not depend on the distortion position.Hence,the cross-correlation coefficient was used to monitor the stable status of the compressor and provide the feedback signal in the active control strategy when suffering from different distortions.Based on the stall margin improvement of tip air injection obtained under different distorted inflow cases and the sensitivity analysis of cross-correlation coefficients to injected momentum ratios,tip air injection was adopted as the actuator for adaptive feedback control.The digital signal processing controller was designed and applied to achieve adaptive feedback control in distorted inflow conditions.The results show that the adaptive feedback control of air injection nearly achieves the same stall margin improvement as steady air injection under different distortion intensities with a reduced injection mass flow.Thus,the proposed adaptive feedback control method is ideal for the engine operation with circumferential distorted inflow,which frequently occurs in flight.展开更多
文摘The modified atomic transformations are constructed and proved.On their basis the new complex analytic wavelets are obtained.The proof of the Fourier transforms existence in L1 and L2 on the basis of the theory of atomic functions(AF)are presented.The numerical experiments of digital time series processing and physical analysis of the results confirm the efficiency of the proposed transforms.
基金This work was supported by National Natural Science Foundation of Chi⁃na(NSFC)under Grant Nos.61935011,61875124 and 61875049.
文摘In recent years, explosively increasing data traffic has been boosting the con?tinuous demand of high speed optical interconnection inside or among data centers, high performance computers and even consumer electronics. To pursue the improved intercon?nection performance of capacity, energy efficiency and simplicity, effective approaches are demonstrated including particularly advanced digital signal processing (DSP) meth?ods. In this paper, we present a review about the enabling adaptive DSP methods for opti?cal interconnection applications, and a detailed summary of our recent and ongoing works in this field. In brief, our works focus on dealing with the specific issues for short-reach interconnection scenarios with adaptive operation, including signal-to-noise-ratio (SNR) limitation, level nonlinearity distortion, energy efficiency consideration and the de?cision precision.
基金the 2021 Experimental Teaching Reform Project of Shanghai University of Medicine&Health Sciences“Digital Signal Processing Course Design”(Project Number:JG(21)04-B4-02).
文摘This paper proposes the design and development of virtual experimental projects in the Digital Signal Processing course,using MATLAB,Proteus,and CCS platforms to develop a library of typical experimental cases for biomedical engineering majors and discusses the design process.Based on these typical cases,this paper explores the secondary design for innovative engineering practice case teaching,which can promote students’understanding and mastery of digital signal processing theories,algorithms,and technologies in an intuitive,flexible,and efficient way;quickly build new innovative engineering case models and further cultivate students’engineering application ability as well as innovative thinking.
基金partially supported by the National Key R&D Program of China(No.2018YFB1800905)the National Natural Science Foundation of China(Nos.61935005,91938202,61720106015,61835002,62127802,and 61805043).
文摘We experimentally built a photonics-aided long-distance large-capacity millimeter-wave wireless transmission system and demonstrated a delivery of 40 Gbit/s W-band 16-ary quadrature amplitude modulation(QAM)signal over 4600 m wireless distance at 88.5 GHz.Advanced offline digital signal processing algorithms are proposed and employed for signal recovery,which makes the bit-error ratio under 2.4×10^(−2).To the best of our knowledge,this is the first field-trial demonstration of>4 km W-band 16QAM signal transmission,and the result achieves a record-breaking product of wireless transmission capacity and distance,i.e.,184(Gbit/s)·km,for high-speed and long-distance W-band wireless communication.
文摘Programmable photonic waveguide meshes can be programmed into many different circuit topologies and thereby provide a variety of functions.Due to the complexity of the signal routing in a general mesh,a particular synthesis algorithm often only accounts for a specific function with a specific cell configuration.In this paper,we try to synthesize the programmable waveguide mesh to support multiple configurations with a more general digital signal processing platform.To show the feasibility of this technique,photonic waveguide meshes in different configurations(square,triangular and hexagonal meshes)are designed to realize optical signal interleaving with arbitrary duty cycles.The digital signal processing(DSP)approach offers an effective pathway for the establishment of a general design platform for the software-defined programmable photonic integrated circuits.The use of well-developed DSP techniques and algorithms establishes a link between optical and electrical signals and makes it convenient to realize the computer-aided design of optics–electronics hybrid systems.
文摘Since Pulse Code Modulation emerged in 1937, digitized speech has experienced rapid development due to its outstanding voice quality, reliability, robustness and security in communication. But how to reduce channel width without loss of speech quality re-mains a crucial problem in speech coding theory. A new full-duplex digital speech communication system based on the Vocoder of AMBE- 1 000TM and microcontroller ATMEL 89C5 1 is introduced. It shows higher voice quality than current mobile phone system with only a quarter of channel width needed for the latter. The prospective areas in which the system can be applied include satellite communication, IP Phone, virtual meeting and the most important, defence industry.
文摘A control system for correction mechanisms through the whole trajectory is proposed based on the principle of one-dimensional trajectory correction projectile. Digital signal processing( DSP) is utilized as the core controller and gobal positioning system( GPS) is used to measure trajectory parameters to meet the requirements of calculating ballistics and system functions. Firstly,the hardware,mainly including communication module,ballistic calculation module,boosting& detonating module and data storage module,is designed. Secondly,the supporting software is developed based on the communication protocols of GPS and the workflow of control system. Finally,the feasibility and the reliability of the control system are verified through dynamic tests in a car and live firing experiments. The system lays a foundation for the research on trajectory correction projectile for the whole trajectory.
文摘Nonlinearity impairments and distortions have been bothering the bandwidth constrained passive optical network(PON)system for a long time and limiting the develop-ment of capacity in the PON system.Unlike other works concentrating on the exploration of the complex equalization algorithm,we investigate the potential of constellation shap-ing joint support vector machine(SVM)classification scheme.At the transmitter side,the 8 quadrature amplitude modulation(8QAM)constellation is shaped into three designs to mitigate the influence of noise and distortions in the PON channel.On the receiver side,simple multi-class linear SVM classifiers are utilized to replace complex equalization methods.Simulation results show that with the bandwidth of 25 GHz and overall bitrate of 50 Gbit/s,at 10 dBm input optical power of a 20 km standard single mode fiber(SSMF),and under a hard-decision forward error correction(FEC)threshold,transmission can be realized by employing Circular(4,4)shaped 8QAM joint SVM classifier at the maximal power budget of 37.5 dB.
基金Project supported by the Scientific Research Project of Shanghai Municipal Bureau of Quality,China and the Technical Supervision Foundation of China(No.2018-05)。
文摘As an increasingly popular flow metering technology,Coriolis mass flowmeter exhibits high measurement accuracy under single-phase flow condition and is widely used in the industry.However,under complex flow conditions,such as two-phase flow,the measurement accuracy is greatly decreased due to various factors including improper signal processing methods.In this study,three digital signal processing methods—the quadrature demodulation(QD)method,Hilbert method,and sliding discrete time Fourier transform method—are analyzed for their applications in processing sensor signals and providing measurement results under gas-liquid two-phase flow condition.Based on the analysis,specific improvements are applied to each method to deal with the signals under two-phase flow condition.For simulation,sensor signals under single-and two-phase flow conditions are established using a random walk model.The phase difference tracking performances of these three methods are evaluated in the simulation.Based on the digital signal processor,a converter program is implemented on its evaluation board.The converter program is tested under single-and two-phase flow conditions.The improved signal processing methods are evaluated in terms of the measurement accuracy and complexity.The QD algorithm has the best performance under the single-phase flow condition.Under the two-phase flow condition,the QD algorithm performs a little better in terms of the indication error and repeatability than the improved Hilbert algorithm at 160,250,and 420 kg/h flow points,whereas the Hilbert algorithm outperforms the QD algorithm at the 600 kg/h flow point.
基金National Key RD Program of China Grant(2018YFB1801504)the President Funding of China Academy of Engineering Physics with No.YZJJLX2018009.
文摘In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbalance,carrier wave leakage,etc.These damages result in system performance tremendous degrades.We proposed a semiblind method to estimate the I/Q imbalance of THz orthogonal modulator,based on predefined preamble and pilot symbols for quadrature amplitude modulation(QAM).In this paper,a transmitter with Y band quadrature mixer and 20Gbps base-band signal has been tested.The bandwidth of the baseband signal was 7GHz,and the modulation type was 16QAM.By this method,7dB improvement of the system’s symbol Mean Square Error(MSE)has been got.That means the proposed method can be used to eliminate the I/Q imbalance effectively.
基金provided by the National Basic Research Program of China (No.2005CB221505)
文摘The growing problems of harmonic pollution on coal mine power lines caused by high-power DC drive systems has increased the use of active power filters.We analyzed compensation errors caused by the time lag in the detecting circuits of an active power filter based on DSP control.We derived a mathematical model for the compensation error starting from the error estimation when a single distortion frequency is present.This model was then extended to the case where multiple frequencies are present in the distortion.A formula for a general theory of compensation error with fixed load and fixed lag time is presented.The theoretical analysis and experimental results show that the delay time of an active power filter mainly arises from the sampling time.Lower sampling frequencies introduce larger compensation errors in the active power filter reference current.
文摘The entire roller inlayed block intelligence cold strip shape meter is developed successfully in this paper,which can stably work chronically in the cold rolling workshop,the independent innovation of the key technology of cold strip shape measuring,the foreign technical monopoly and blockade are broken through.The structural form which is different from the international popular segmented detection roller is put forward,the entire detection roller inlayed block is developed,a group of elastic blocks in that the sense organs are installed are inlayed in the radial symmetry rectangular grooves of the detection roller body,the entire roller structure is composed of elastic pieces and the roller body,the scratch of the strip surface due to different thermal expansion of the traditional detection roller measuring unit is avoided effectively.The signal transmission form which is different form the international popular dry slip ring is put forward,the spray wet slip ring is developed,slip ring and detection roller can be taken down and installed as possibly as fast,so the maintain is convenient,while through the section auto-spray cleaning,lubrication and cooling, the service life is remarkable improved and the outside interference signal is reduced.The signal processing form which is different form the international popular gathering card is put forward,the embedded DSP shape signal processing hardware system is developed,the electromagnet,temperature,humidity and vibration’s interference of industry practice to shape transmission signal can be effectively avoided,which can guarantee the instantaneity and measured precision of shape measured signal.The shape signal processing software system whose function contains error compensation,pattern recognition,establishment of the target shape and the closed-loop control calculation is built,the shape meter’ computer human interaction is friendly,and function of shape meter is strong,at the same time the intellectualized level of the shape meter is improved.Now,this shape meter has been successfully applied on the 1 250 mm cold strip mill of Angang Steel Company Limited,the long-term operating testing is done,every guide line achieves the anticipative effect,the measuring precision is high and the measuring signal is stable and reliable,the shape meter is tested on high speed,big tension,changed wrap angle and big depressed complicated working conditions,any scratch of the detection roller surface and the strip surface is not appearing,it can completely adapt well to the industrial production environment,reaching the international advanced level.
文摘In the step processing a digitalized signal,noises are generated by internal or external causes of the system.In order to eliminate these noises,various methods are researched.Among these noise elimination methods,Fourier fast transform(FFT)and short-time Fourier transform(STFT)are widely used.Because they are expressed as a fixed time-frequency domain,they have the disadvantage that the time information about the signal is unknown.In order to overcome these limitations,by using the wavelet transform that provides a variety of time-frequency resolution,multi-resolution analysis can be analysed and a varying noise depending on the time characteristics can be removed more efficiently.Therefore,in this paper,a denoising method of underwater vehicle using discrete wavelet transform(DWT)is proposed.
文摘In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.
基金supported by the National Key R&D Program of China(No.2019YFB1803504)the National Natural Science Foundation of China(Nos.61821001,61901045,and 61625104)the Fund of State Key Laboratory of Information Photonics and Optical Communication BUPT(No.IPOC2021ZT18)。
文摘In this paper,we propose and experimentally demonstrate a joint shaping technique to improve the performance of a lowresolution transmission system for the first time,to the best of our knowledge.The joint shaping technique combines probabilistic shaping(PS)and error feedback noise shaping(EFNS).In the 40-Gbaud intensity-modulation direct-detection(IM/DD)experimental transmission system,a bit-error-rate(BER)of 3.8×10^(-3)can be achieved easily with the joint shaping at the physical number of bits(PNOB)of 3.In the 30-Gbaud dual polarization(DP)coherent experimental transmission system,a BER below 1×10^(-3)is easily obtained with a 3-bit quantizer by using joint shaping.The optimization of the shaping degree is also analyzed.
基金CNPq,FUNCAP,CAPES,FINEP for the financial support.
文摘A numerical simulation study of the performance of encoding and decoding of short optical pulse in OCDMA (Optical Code Division Multiple Access) systems under non-linear optical effects is presented. The performance of encoding and decoding short pulses is obtained through use of device FBG (fiber Bragg grating) where the codes are inserted through discrete jumps in the optical phase (±π). The multiuser interference is also the object of the present study, where a figure of merit (interference figure) is used to quantify the interference in multiuser auto and cross correlation. We evaluate the dependence of the multiuser interference for the coupling constant of FBG. Finally, the interference inserted in the autocorrelation due to nonlinear effects generated in the nonlinear switching of the coded pulse in a dual core nonlinear directional coupler is examined, where temporal broadening of pulses decoded is observed.
基金Supported by Joint Astronomical Fund of National Natural Science Foundation of China(U1831133)Key Laboratory of Space Active Opto-electronics Technology of Chinese Academy of Sciences(20212DKF4)Shanghai Natural Science Foundation(17ZR1443500)
文摘Aiming at the problems in a linear frequency modulation continuous wave(LFMCW)ranging lidar system,such as low signal-to-noise in echo beat frequency and difficult extraction of the signal frequency,a method with high-speed and high accuracy based on field programmable gate array(FPGA)is proposed.Firstly,the laser echo beat signal is sampled by high-speed analog to digital converter(ADC)and then processed in FPGA for data preprocessing.After the signal is processed by the 8192-point FPGA will obtain the frequency spectrum and then apply the frequency spectrum to data processing and adaptive noise signal peak detection.These two steps realize the real-time and accurate extraction process of the target echo beat signal frequency.Finally,the spectrum data is transmitted to the host computer and processed through the external data acquisition board for real-time spectrum display.Experimental results show that data preprocessing and spectrum data processing can effectively suppress DC bias and system modulation noise.Adaptive noise peak detection can accurately divide the threshold contour according to the dynamic noise of the system and realize the detection of target signal peak.When the sampling clock of the system is 100 MHz,the time needed for each calculation of the spectrum is 81.92μs,and the refresh rate of the spectrum reaches 12.2 kHz,which meets the real-time requirements of the system.
基金Zhaohui Li acknowledges the support of the National Basic Research Programme of China(973)(Project No.2012CB315603)National High Technology 863 Research and Development Program of China(Nos.2013AA013300 and 2013AA013403)+5 种基金the Research Fund for the Doctoral Program of Higher Education of China(20124401110003)National Natural Science Foundation of China(NSFC)(Grant No.61435006)the Program for New Century Excellent Talents in University(NCET-12-0679)in ChinaXuming Zhang acknowledges the NSFC(Grant No.61377068)the Hong Kong Research Grant Council(Grant Nos.PolyU 5327/11E and N_PolyU505/13)the Hong Kong Polytechnic University(Grant Nos.G-YN07,4-BCAL and G-YBBE).
文摘Optical spectral measurements are crucial for optical sensors and many other applications,but the prevailing methods,such as optical spectrum analysis and tunable laser spectroscopy,often have to make compromises among resolution,speed,and accuracy.Optical frequency combs are widely used for metrology of discrete atomic and molecular spectral lines.However,they are usually generated by optical methods and have large comb spacing,which limits the resolution for direct sampling of continuous spectra.To overcome these problems,this paper presents an original method to digitally generate an ultrafine optical frequency comb(UFOFC)as the frequency ruler for spectral measurements.Each comb line provides one sampling point,and the full spectrum can be captured at the same time using coherent detection.For an experimental demonstration,we adopted the inverse fast Fourier transform to generate a UFOFC with a comb spacing of 1.46 MHz over a 10-GHz range and demonstrated its functions using a Mach–Zehnder refractive index sensor.The UFOFC obtains a spectral resolution of 0.01 pm and response time of 0.7 μs;both represent 100-fold improvements over the state of the art and could be further enhanced by several orders of magnitude.The UFOFC presented here could facilitate new label-free sensor applications that require both high resolution and fast speed,such as measuring binding kinetics and single-molecule dynamics.
文摘We propose an alternative approach to compensation of intermodal interactions in few-mode optical fibers by means of digital backpropagation.Instead of solving the inverse generalized multimode nonlinear Schr?dinger equation,we accomplish backpropagation of the multimode signals with help of their near-field intensity distributions captured by a camera.We demonstrate that this task can successfully be handled by a deep neural network and provide a proof of concept by training an autoencoder for backpropagation of six linearly polarized[LP]modes of a step-index fiber.
基金co-supported by the National Natural Science Foundation of China(No.51922098)the National Science and Technology Major Project of China(No.2017-Ⅱ-0004-0017)the Special Fund for the Member of Youth Innovation Promotion Association of CAS(No.2018173).
文摘The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed,axial compressor.The flat-baffles with different span heights are used to simulate different distorted inflow cases.Compared with auto-correlation and root-mean-square analysis,cross-correlation analysis used to predict early stall warning does not depend on the distortion position.Hence,the cross-correlation coefficient was used to monitor the stable status of the compressor and provide the feedback signal in the active control strategy when suffering from different distortions.Based on the stall margin improvement of tip air injection obtained under different distorted inflow cases and the sensitivity analysis of cross-correlation coefficients to injected momentum ratios,tip air injection was adopted as the actuator for adaptive feedback control.The digital signal processing controller was designed and applied to achieve adaptive feedback control in distorted inflow conditions.The results show that the adaptive feedback control of air injection nearly achieves the same stall margin improvement as steady air injection under different distortion intensities with a reduced injection mass flow.Thus,the proposed adaptive feedback control method is ideal for the engine operation with circumferential distorted inflow,which frequently occurs in flight.
