Digital Processing Algorithms Research Articles

Towards a more efficient and durable load classifier using machine learning analysis of electrical data generated by self-sensing asphalt mixtures

Real-time weighing plays a crucial role in various applications in the road infrastructure field, such as pavement design, pavement monitoring systems, and the development of digital twins. Innovative sensing technologies offer solutions to the limitations of traditional sensors, enhancing durability and cost-effectiveness. Current research on self-sensing technologies primarily focuses on material manufacturing, electrode embedding, and testing of piezoresistive properties. However, there is limited investigation of innovative methods for processing and analyzing electrical signals from self-sensing materials for load classification. The novelty of the present paper lies in the development of a machine learning-based load classifier using electrical data from laboratory self-sensing asphalt mixtures with carbon fibers (CFs). Specimens underwent repeated cyclic dynamic loads, and electrical signals were recorded and processed using a customized digital processing algorithm. Artificial Neural Network (ANN) and decision tree algorithms were employed to develop load classification models. Results indicate that the addition of CFs strengthens the asphalt mixture, converting it into a piezoresistive material with load-sensing capabilities. Conclusions show that while the machine learning algorithms performed satisfactorily, further research is required for optimization purposes.

Influence of Front-End Electronics on Metrological Performance of QCM Systems.

Quartz Crystal Microbalances (QCMs) are versatile sensors employed in various fields, from environmental monitoring to biomedical applications, owing mainly to their very high sensitivity. However, the assessment of their metrological performance, including the impact of conditioning circuits, digital processing algorithms, and working conditions, is a complex and novel area of study. The purpose of this work is to investigate and understand the measurement errors associated with different QCM measurement techniques, specifically focusing on the influence of conditioning electronic circuits. Through a tailored and novel experimental setup, two measurement architectures-a Quartz Crystal Microbalance with dissipation monitoring (QCM-D) system and an oscillator-based QCM-R system-were compared under the same mechanical load conditions. Through rigorous experimentation and signal processing techniques, the study elucidated the complexities of accurately assessing QCM parameters, especially in liquid environments and under large mechanical loads. The comparison between the two different techniques allows for highlighting the critical aspects of the measurement techniques. The experimental results were discussed and interpreted based on models allowing for a deep understanding of the measurement problems encountered with QCM-based measurement systems. The performance of the different techniques was derived, showing that while the QCM-D technique exhibited higher accuracy, the QCM-R technique offered greater precision with a simpler design. This research advances our understanding of QCM-based measurements, providing insights for designing robust measurement systems adaptable to diverse conditions, thus enhancing their effectiveness in various applications.

Разработка и исследование подхода к обработке сигналов цифровых измерительных трансформаторов тока и напряжения

During the development of secondary systems of stations and substations, including relay protection, automation, control, electricity metering, etc., qualitative changes have recently occurred due to the introduction of digital technologies. The introduction of digital technologies is supported by innovative development programs such as “Digital Transformation 2030”. The introduction of digital technologies is associated with the use of digital data transmission channels according to uniform standards. Projects of “digital substations” are being actively implemented with the transmission of digital information at all levels, including the primary equipment, the transmission of information both from current and voltage measuring transformers, and from switching devices. Currently, digital instrument transformers are actively being developed and implemented, in which information about measured currents and voltages is presented in digital code. New approaches to measure primary currents and voltages, and transmit information pose new challenges, and open prospects for improving signal processing methods used for relay protection purposes. Thus, the relevant aim of the study is the development and research of approaches to digital processing of signals of digital instrument current and voltage transformers. To solve the problems posed within the framework of this study, analytical and numerical solution methods have been used. Numerical methods are applied using software products such as MathCAD and the Python programming language to generate signals and display them on graphs. To substantiate the reliability, verification of the results obtained by different methods is carried out. The authors have formulated an approach to digital processing of signals obtained using current sensors of a digital instrument transformer. The authors have studied the approach to determine synchronized current vector values by processing information received from primary current converters. The characteristics of the algorithm for obtaining a vector have been analyzed and the dependences of errors on the influence of distorting factors have been plotted. The proposed approach is a development of the existing approach to obtain a vector by getting information from current sensors operating on different physical principles. The results show the advantages of the proposed method. The proposed digital signal processing algorithm is more technically expensive since it contains at least two metrologically calibrated measuring channels instead of one. However, all other things being equal, it allows to increase the accuracy and speed of the digital processing algorithms taken as a prototype. The results obtained can be used to formulate algorithms for measuring relay protection devices.

The influence of digital media technology on immersive animation design

To improve the effect of immersive animation design, this paper combines digital media technology (DT) to establish an immersive animation design system and analyzes the media digital signal data processing algorithm. According to the advantages and disadvantages of the FHT algorithm and probabilistic algorithm, this paper proposes the FHT-SLM algorithm and the FHT-IPTS algorithm. Moreover, this paper analyzes the basic principle of TPWC transform and M-TPWC and the CO-OFDM system of cascaded FHT algorithm and M-TPWC algorithm. Finally, this paper simulates the CO-OFDM simulation system built by Matlab2018.a and Optisystem. Through the experimental analysis results, the reliability of the algorithm and the system in this paper is verified, and the design effect of immersive animation is effectively improved.

ОЦЕНКА ВЛИЯНИЯ КОЭФФИЦИЕНТА МАСШТАБИРОВАНИЯ БАЗОВОЙ ФУНКЦИИ ВЕЙВЛЕТ-ПРЕОБРАЗОВАНИЯ НА СТЕПЕНЬ ПРОЯВЛЕНИЯ ОСНОВНЫХ НЕИСПРАВНОСТЕЙ ЦЕНТРОБЕЖНЫХ НАСОСНЫХ АГРЕГАТОВ В ВЕЙВЛЕТ-КАРТИНАХ

Relevance Rotary-type machines, which include centrifugal pumping units, are widely used in the oil refining and petrochemical industries and represent an integral part of technological processes. Therefore, preventing their emergency failure is the most important task, which is solved using vibroacoustic diagnostics. Vibration diagnostic services of technical supervision departments process signals mainly using the spectral method of vibration signal analysis based on the Fourier transform. Along with the undeniable advantages, which include the simplicity of software implementation and the admissibility of optimization for the analysis of many functions of physical processes, this transformation has certain disadvantages. For example, due to the loss of information about the time factor, the idea of the dynamics of changes in the spectral composition of the signal is distorted, which does not allow for a comprehensive analysis of the vibration signal. In this regard, there is a need for additional methods of digital signal processing. In recent years, in the process of research carried out at the Ufa State Petroleum Technological University, it has been proven that a method based on wavelet transformation of vibration signals can be used to assess the technical condition of pumping and compressor equipment. This type of transformation is capable of recognizing not only periodic components of the signal, but also local ones, determining their time and frequency characteristics, and establishing the relationship between the levels of wavelet decomposition and the frequency ranges of wavelet filters. It has been determined that the level of decomposition during the wavelet transform of the signal can be taken as a criterion for clearing the vibration signal of the digital pump from the noise component in the presence of faults such as «imbalance» and «misalignment». Discrete wavelet transform of vibration signals makes it possible to determine amplitude modulation caused by the manifestation of faults of electromagnetic origin and inhomogeneity of the air flow in the gap between the rotor and stator of an electric motor, as well as to identify slowly developing (trend) signals associated with lubrication defects in the motor bearings of centrifugal pumping units. Wavelet patterns store complex information about the signal, however, when several types of faults or defects are combined, it is very difficult to identify the leading one and the degree of its development, especially in the early stages. In this case, the value of the scaling factor can serve as a characteristic of the degree of development of the fault, since it was found that wavelet patterns begin to differ comprehensively when setting the scaling factor of the wavelet transform of signals, starting from a value of 192, confirming the presence of an anomalous signal. Aim of research Increasing the accuracy of assessing the technical condition of centrifugal pumping units by selecting the scaling factor of the basic function of the wavelet transform of vibration signals. Research methods To practically solve the problems, methods and algorithms for digital processing of vibration signals based on the Fourier transform and wavelet transform were used. Results It has been established that for a more accurate assessment of the stage of development of the main faults of the digital pump using the continuous wavelet transform, it is necessary to use a scaling factor of the basic wavelet function equal to 512.

An Error Estimation System for Close-Range Photogrammetric Systems and Algorithms.

Close-range photogrammetry methods are widely used for non-contact and accurate measurements of surface shapes. These methods are based on calculating the three-dimensional coordinates of an object from two-dimensional images using special digital processing algorithms. Due to the relatively complex measurement principle, the accurate estimation of the photogrammetric measurement error is a non-trivial task. Typically, theoretical estimations or computer modelling are used to solve this problem. However, these approaches cannot provide an accurate estimate because it is impossible to consider all factors that influence the measurement results. To solve this problem, we propose the use of physical modelling. The measurement results from the photogrammetric system under test were compared with the results of a more accurate reference measurement method. This comparison allowed the error to be estimated under controlled conditions. The test object was a flexible surface whose shape could vary smoothly over a wide range. The estimation of the measurement accuracy for a large number of different surface shapes allows us to obtain new results that are difficult to obtain using standard approaches. To implement the proposed approach, a laboratory system for the error estimation of close-range photogrammetric measurements was developed. The paper contains a detailed description of the developed system and the proposed technique for a comparison of the measurement results. The error in the reference method, which was chosen to be phasogrammetry, was evaluated experimentally. Experimental testing of the stereo photogrammetric system was performed according to the proposed technique. The obtained results show that the proposed technique can reveal dependencies that may not be detected by standard approaches.

Measurement of Photoneutrons from Depleted Uranium and Comparison Study Using MCNPX-PoliMi

High-energy photon interrogation is a nondestructive technique that is used to detect special nuclear materials and characterize nuclear waste. The development of such systems is complex and requires Monte Carlo simulations to optimize system performance. Monte Carlo simulations rely on various scattering, absorption, and photonuclear cross-section data. While the scattering and absorption cross-section data have been extensively studied and validated with experiments, the results obtained from photonuclear simulations are often found to underpredict measured results, indicating uncertainties in the photonuclear cross sections themselves. Thus, there is a need for new measured results that can be used to quantify underpredictions in simulations using photonuclear cross-section data. In the present work, we interrogated depleted uranium with a 9-MV electron linac and detected photoneutrons with trans-stilbene organic scintillators. The measurement of photoneutrons with organic scintillators is challenging due to the presence of the intense photon flux, which causes issues such as pulse pile-up, detector saturation, and poor signal-to-background ratio. To mitigate these challenges, we used iron and polyethylene shielding of varying thicknesses around the depleted uranium target and a neural network–based digital pulse processing algorithm to recover neutron and photon information from piled-up events. Our goal was to compare the measured photoneutron count rate with the simulated rate obtained using the MCNPX-PoliMi transport code. For a light output window of 0.28 to 2.67 MeVee (1.66- to 6.85-MeV proton recoil energy), we found that the simulated count rate obtained using the ENDF/B-VII photonuclear cross-section library underpredicts the measured rate by 32.8% ± 3.2%. Additionally, we compared the simulated and measured photoneutron light output distributions. For the least thicknesses of shielding, the simulation was found to underpredict measurements in the 0.70- to 2.67-MeVee light output window. For the greatest thicknesses of shielding, the simulation was found to underpredict the measurement across the entire light output window of 0.28 to 2.67 MeVee.

DEVELOPMENT OF A COMPREHENSIVE APPROACH TO DIAGNOSING THE OVERHEAD LINE FAULTS LOCATION IN SINGLE-PHASE GROUND FAULTS BASED ON A DIGITAL SUBSTATION DATA PROCESSING ALGORITHM

Link for citation: Sushkov V.V., Sukhachev I.S., Sidorov S.V. Development of a comprehensive approach to diagnosing the overhead line faults location in single-phase ground faults based on a digital substation data processing algorithm. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 66-77. In Rus. Relevance. Emergency of electric complex of outgoing transmission lines is associated with the occurrence of damage to the line isolation and the resulting transients, marked by the presence of higher harmonic components of currents and voltage, which reduce the reliability and energy efficiency of electrical equipment of oil and gas companies: degrade the mechanical characteristics and efficiency of electric motors, accelerate aging of their isolation, disrupt the operation of control systems and emergency automatics, fault diagnostics systems. One of the reasons of high-level emergency situations, outages and emergency repairs in electric complexes of outgoing transmission lines of oil and gas companies is appearance of phase-to-ground faults. A large number of changing factors are known to influence the reliability of phase-to-ground fault location methods: parameters of transmission line operating mode, its structural and electrical parameters, fault type, transient resistance value, ground resistance and others. Inclusion in the transmission line fault location algorithms of averaged values of a number of the factors listed above independent of changes of humidity of soil and air, its temperature and other factors causes an error of methods of fault location up to 30 %. Accordingly, the research to develop a fault location method for overhead transmission lines with isolated neutral points during phase-to-ground faults based on a digital substation data processing algorithm, accounting for tower parameters and natural-climatic factors, is relevant. Objective: improving the reliability of power grids and providing consumers with power of the required standard by applying a digital fault location system to the outgoing transmission lines electrical complex. Methods: mathematical analysis of a power transmission line, taking into account its design features and natural-climatic factors on the basis of the method of mirror images; mathematical analysis of steady-state and transient modes of transmission line operation considering self and mutual parameters terms of wires; transmission line currents and voltages Fourier analysis; validation of developed method of phase-to-ground fault location in power grid of Tyumen region energy company. Results. The authors have developed the phase-to-ground faults location method for transmission lines in power grids with isolated neutral points, which differs in the following – first the faulty overhead line feeder branch is identified by correspondences between the negative sequence voltage values of the phase voltages at the transformer substation inputs, and then the distance to the location of the single-phase ground fault is determined along the branch line based on the resonant frequencies of the line taking into account its design features and natural and climatic factors.

Compact optical real-time imaging system for high-resolution SAR data based on autofocusing

Improved resolutions of synthetic aperture radar (SAR) have complicated real-time high-accuracy imaging. To reduce the time and power required by digital processing algorithms, we propose a novel idea of photoelectric combination and design a SAR optical imaging system. Range matched filtering is realized in the digital domain, whereas azimuth autofocusing is realized through free propagation in the optical domain, with range cell migration correction at the speed of light. To adapt to changeable SAR parameters, a compound lens is formed by combining spatial light modulators. The system is simple, compact, efficient, and adaptable, with nano-second processing delays.

Design and Analysis of Multiplexer based Approximate Adder for Low Power Applications

Low power consumption is crucial for error-acceptable multimedia devices, with picture compression approaches leveraging various digital processing architectures and algorithms. Humans can assemble useful information from partially inaccurate outputs in many multimedia applications. As a result, producing exact outputs is not required. The demand for an exact outcome is fading because new innovative systems are forgiving of faults. In the domain where error-tolerance is accepted, approximate computing is a new paradigm that relaxes the requirement for an accurate modeling while offering power, time, and delay benefits. Adders are an essential arithmetic module for regulating power and memory usage in digital systems. The recent implementation and use of approximate adders have been supported by trade-off characteristics such as delay, lower power consumption. This study examines the delay and power consumption of conventional and approximate adders. Also, a simple, fast, and power-efficient multiplexer-based approximate adder is proposed, and its performance outperforms the adders compared with existing adders. The proposed adder can be utilized in error-tolerant and various digital signal processing applications where exact results are not required. The proposed and existing adders are designed using EDA software for the performance calculations. With a delay of 81 pS, the proposed adder circuit reduces power consumption compared to the exact one. The experiment shows that the designed approximate adder can be used to implement circuits for image processing systems because it has a smaller delay and uses less energy.

Upgraded algorithm for implementing the electronic counting frequency meter method for measuring frequency deviation

The ways of reducing the error of measurement methods of frequency deviation and expanding the measurement ranges of frequency deviation are considered. The possibilities of reducing the error of the electronic counting frequency meter method using digital signal processing algorithms are investigated. Digital signal processing algorithms are implemented in the software developed by the authors of a modern spectrum analyzer. The algorithm of digital signal processing of the spectrum analyzer is described. Using a mathematical model embedded in the calculation algorithm of the developed software, the measurement error of frequency deviation is estimated. The possibility of using the electronic counting frequency meter method with the help of digital signal processing algorithms of the spectrum analyzer has been experimentally investigated. The sources of error of the classical method of electronic counting frequency meter and possible ways of their elimination are considered. Comparisons of the proposed implementation of the electronic counting frequency meter method with the classical method, which is implemented in the State Primary Standard of the unit of frequency deviation GET 166-2020, are carried out. The proposed implementation of the method has expanded the measurement range of frequency deviation towards small values in comparison with the classical method of electronic counting frequency meter. Limitations and prospects of application of the investigated method in reference means of measuring frequency deviation based on analog-to-digital converters are considered.

ЗАСТОСУВАННЯ ДРОНІВ У ТРАНСПОРТНІЙ ІНФРАСТРУКТУРІ

Background. The article is devoted to the real possibilities and prospects of creating and using unmanned aerial vehicles in road and railway infrastructures. As part of the conducted experiment, the task of creating a drone was set using the simplest means of development in laboratory conditions. Methods. To assess the viability of the proposed solutions, the method of the natural experiment has been used. Results. The drone created as a result of the experiment is able to automatically stabilize its position, and a receiver board can be installed on it, which will enable remote control. In the future, additional modules can be installed on the quadro copter using the deep learning mechanism. And the use of an intelligent pattern detection and recognition system based on effective digital data processing algorithms will allow to significantly reduce the time for data processing, obtain more accurate results and ensure access to information in the shortest possible time, which will be another factor contributing to the active implementation of unmanned technologies. Сonclusions. Thanks to the ability to obtain various data, unmanned aerial vehicles will be able to significantly reduce the costs of solving various tasks in the near future and become indispensable assistants in the transport infrastructure sector.

The Effect of Gamma Values in Detection of Internal Root Resorption in CBCT Images: An In Vitro Study

Background: Accurate and early diagnosis of internal root resorption is essential for determining the outcome of treatment and prognosis. Several digital processing algorithms have been introduced for the diagnosis of internal root resorption. The aim of the present study was to evaluate the effect of gamma values in the detection of internal root resorption in cone-beam computed tomography (CBCT) images. Methods: A total of 45 healthy extracted single-rooted teeth were selected for the study. The teeth were mesiodistally sectioned at the central groove of their occlusal surface using a diamond disc (0.1 mm diameter). Internal root resorption was simulated at the cervical, middle, and apical regions of a root canal. CBCT images were prepared by gamma values (low, medium, and high modes). Data were analyzed using McNemar tests, Cohen’s kappa coefficient, and the receiver operating characteristic curve. A P value less than 0.05 (typically≤0.05) was considered statistically significant. Results: Sensitivity and overall accuracy of CBCT images with all gamma modes (low, medium, and high) were high, and they were slightly higher in the high gamma mode (Sensitivity: 94% and overall accuracy: 100%) than in two gamma modes (low and medium). The sensitivity and specificity of high and medium gamma modes in three regions of the root canal (cervical, middle, and apical) were at optimal thresholds compared to the low gamma mode. Conclusions: Gamma modes, particularly the high gamma mode, in CBCT imaging can be adopted as a promising processing filter for the detection of internal root resorption.

Analysis of the Influence of Software and Hardware Noise on the Results of Digital Signal Processing

The achievement of a higher quality signal processing occurs, among other things, due to the complication of its processing algorithms, i. e., an increase in the amount of calculations. This processing must be carried out in real time. One of the ways to overcome this problem is to split a complex algorithm into several simpler parts that must be executed in parallel and then combined. For this purpose, digital computing platforms are used, which are built on the basis of various discrete elements, such as programmable logic integrated circuits, microcontrollers or multi-core digital signal processors. Based on the results of the research, a mathematical expression was obtained that shows that the final signal-to-noise ratio significantly depends on the processing frequency. This ratio also depends on the element base on the basis of which digital processing algorithms are implemented. Using the characteristics of individual chips as an example, it is shown that the use of certain chip types is preferable in some cases because it allows the processing to be implemented in a wider clock frequency range.

Automation of mine interferometric analyzer of methane and carbon digestion concentration in air

The lack of automatic control is a drawback of mine interferometric analyzers of methane and carbon digestion concentration in air. We present the results of developing an algorithm for automating the process of measuring the concentration of methane and carbon dioxide in air with a mine interferometric analyzer. An automatic determination of the shift of the interference pattern by the gas under study is proposed using an opto-electronic device. The main automated functions, i.e., control of the radiation source and electric pump, measurement channels and movement of the movable gas-air chamber along with processing of digital images of interferograms are implemented in a device with the metrological characteristics corresponding to the parameters of the mine interferometer SHI-11. The algorithm for digital processing of the interference pattern (interferogram) is implemented in the MATLAB package. The result of using the developed algorithm for measuring methane concentration showed the effectiveness and required accuracy of the procedure. Automation of carbon dioxide measurements provided for the appropriate calibration of the scale by loading the calibration coefficients into the memory of the microcontroller. The results obtained can be used to automate the determination of the gas concentration in air at the enterprises of oil and gas, chemical and mining industries.

A Method for the Design of Bicomplex Orthogonal DSP Algorithms for Applications in Intelligent Radio Access Networks

In this paper, a new method for designing orthogonal bicomplex digital signal processing (DSP) algorithms is developed. In contrast to those previously reported on, the method proposed is universal, since it is not affected by the order or the type of the real digital processing algorithm employed as a prototype. The method is based on a transformation starting with either real or complex orthogonal DSP algorithms represented in the z-domain, and transforming them into orthogonal bicomplex algorithms. The proposed new method is applied in the design of bilinear orthogonal bicomplex DSP systems with a canonical number of elements, the main advantage of which is that the order of the digital system is reduced by a factor of four. As well as being canonical, the orthogonal bicomplex digital systems are also symmetrical structures, as a result of which they offer parallelism and subsequent unification. It is experimentally shown that bicomplex orthogonal DSP algorithms acquire the properties of the initial algorithm prototype, irrespective of whether it is real or complex. Since the new design method is universally applicable, it can be used to develop bicomplex orthogonal digital algorithms of any order and type. Being simple, canonical, and symmetrical—and, thus, leading to lower equipment cost, reduced complexity, and higher energy efficiency—these structures may well be appropriate for the enhancement of the implementation of intelligent algorithms in next-generation radio access networks.

A Novel Method for Intelligibility Assessment of Nonlinearly Processed Speech in Spaces Characterized by Long Reverberation Times.

Objective assessment of speech intelligibility is a complex task that requires taking into account a number of factors such as different perception of each speech sub-bands by the human hearing sense or different physical properties of each frequency band of a speech signal. Currently, the state-of-the-art method used for assessing the quality of speech transmission is the speech transmission index (STI). It is a standardized way of objectively measuring the quality of, e.g., an acoustical adaptation of conference rooms or public address systems. The wide use of this measure and implementation of this method on numerous measurement devices make STI a popular choice when the speech-related quality of rooms has to be estimated. However, the STI measure has a significant drawback which excludes it from some particular use cases. For instance, if one would like to enhance speech intelligibility by employing a nonlinear digital processing algorithm, the STI method is not suitable to measure the impact of such an algorithm, as it requires that the measurement signal should not be altered in a nonlinear way. Consequently, if a nonlinear speech enhancing algorithm has to be tested, the STI—a standard way of estimating speech transmission cannot be used. In this work, we would like to propose a method based on the STI method but modified in such a way that it makes it possible to employ it for the estimation of the performance of the nonlinear speech intelligibility enhancement method. The proposed approach is based upon a broadband comparison of cumulated energy of the transmitted envelope modulation and the received modulation, so we called it broadband STI (bSTI). Its credibility with regard to signals altered by the environment or nonlinear speech changed by a DSP algorithm is checked by performing a comparative analysis of ten selected impulse responses for which a baseline value of STI was known.

Algorithms for optimal digital information processing in information-measuring systems

Algorithms for optimal digital information processing in information-measuring systems

ДВУХСТУПЕНЧАТЫЙ АЛГОРИТМ СОГЛАСОВАННОЙ ФИЛЬТРАЦИИ СИГНАЛОВ

Introduction. Introduction. To combat inter-symbol interference resulting from multipath signal propagation, spreading of the signal frequency spectrum, channel equalizing, OFDM-multiplexing with orthogonal frequency division of channels is used. To reduce the influence of non-linear signal distortions, methods of pre-distortion, diversity reception, as well as special algorithms for digital processing of the demodulator output signal are used. The effect of additive noise is reduced by using a filter matched to the signal. Objective. It is advisable to develop a matched filtering algorithm that allows one to simultaneously reduce the influence of additive noise, non-linear signal distortions and its multipath propagation on the correct message reception. The idea of selecting the orthogonality weight can also be used to achieve the goal. Result. To reduce the influence of non-linear distortions on the correct reception of a message under conditions of multipath signal propagation and additive interference, it is proposed to use two stages of signal processing. The first step is to minimize the noise dispersion caused by intersymbol interference and non-linear signal distortions. The specified dispersion is minimized by determining the orthogonality weight of the basis-functions that make up the signal. The second step is to use a classic matched filter. The proposed two-stage matched filtering algorithm makes it possible to simultaneously reduce the influence of non-linear distortions, intersymbol interference resulting from multipath propagation, and additive interference on the correct signal reception. Signals distorted and delayed in time relative to the main signal are proposed to be considered as additive interference.

Widely Linear Filtering for Multiimpairment Compensation in Dispersion Managed mQAM Modulated Optical Systems

We propose a blind joint equalization algorithm for M-QAM signals based on a widely linear filtering approach. The proposed scheme jointly compensates for receiver IQ imbalance, receiver IQ skew, polarization mixing, carrier recovery, followed by transmitter IQ imbalance and skew. We first investigate the proposed scheme&#x2019;s tolerance to each of these impairments through numerical simulations for 32 GBd PM-16QAM and PM-64QAM signals and compare its performance with the conventional digital processing algorithms with and without IQ imbalance compensation. The proposed joint transceiver equalizer outperforms the conventional algorithms with a <i>Q²</i> improvement of greater than 1 dB, and with improved tolerance to IQ imbalance. Further, with the proposed algorithm, we experimentally demonstrate the improvement in <i>Q²</i> value with respect to conventional DSP for both PM-16QAM and PM-64QAM signals. We also show that the MSE convergence of the proposed joint equalizer is much faster than conventional DSP algorithms.