Digital Output Signal Research Articles

Investigation on the randomly-coupled unit grouping multi-core fibers with different unit arrangement

Randomly-coupled unit grouping multi-core fiber (RC-UG-MCF) is a new fiber structure that combines weakly and strongly coupled multi-core fiber technologies. Compared to the weakly-coupled MCF with a large cladding size, the RC-UG-MCF can shrink the cladding size by grouping the cores. On the other hand, the RC-UG-MCF only maintains a few cores in the strongly-coupled condition, which can reduce the multiple-input multiple- output digital signal processing (MIMO-DSP) complexity compared to the coupled MCFs with full MIMO-DSP for all the cores. In this paper, we intro- duce three types of randomly-coupled unit grouping 12-core fiber, which are randomly-coupled 2-core unit grouping MCF (RC-2CUG-MCF), RC-3CUG- MCF and RC-4CUG-MCF. Subsequently, we compare these three RC-UG- MCFs in terms of group delay spread, inter-unit crosstalk (XT), and cladding size. To achieve an inter-unit XT of −40 dB/100 km, RC-3CUG-MCF can provide a solution to maintain MIMO-DSP scale at the level of 6 × 6 with 180-µm cladding radius. However, the RC-2CUG-MCF has worse inter-unit XT, and the RC-4CUG-MCF has larger MIMO complexity. Based on the analysis, there is a trade-off relationship between the MIMO-DSP scale and the fiber cladding size, assuming that the target inter-unit XT is fixed.

Implementation of a high-resolution micro-grating accelerometer using a subdivision interpolation technique

This paper proposes a subdivision interpolation technique for an optical accelerometer based on diffraction grating interferometry. The diffraction light intensity curve presents a sine shape with the increase of the acceleration. To address the issues of linearization signal processing across the entire range, a subdivision interpolation circuit is employed, in conjunction with a 90° phase shift and high-precision DC bias-voltage techniques, converting an analog signal with sinusoidal characteristics from the photodetector into standard incremental digital signals that vary linearly over the full range. The novel methodology, to the best of our knowledge, ensures that its performance is least affected by the phase imbalance, offset error, and amplitude mismatch induced by fabrication and alignment errors of the grating, achieving high-resolution digital signal output. The experiment results reveal that the optical accelerometer based on grating interferometry achieved a sensitivity of 85.2 V/g, a resolution of 137.6 µg, as well as a subdivision interpolation factor of 45. This work provides a significant guide for the development of high-resolution MOEMS accelerometers in practical applications.

Anomaly Detection in Binary Time Series Data: An unsupervised Machine Learning Approach for Condition Monitoring

A key element of smart manufacturing is condition monitoring and heath controlling of production machines. In today's rapidly evolving landscape of industrial machinery and equipment, optimizing the operation of production lines is critical to ensure high productivity and product quality. Timely detection and prevention of faults in the production process plays a crucial role in minimizing downtime, reducing costs, and ensuring optimal performance. The scientific challenge here is that the increasing number of sensors and actuators with digital input and output signals in the production machines creates different patterns, which are difficult to evaluate using conventional statistical methods. Another difficulty is identifying the cause of the failure to be able to intervene rapidly and in a focused manner in the event of irregularities. For this reason, this research study presented a comprehensive analysis of anomaly detection in binary time series data using various machine learning models. The study included preprocessing of the dataset, normalizing the data, and evaluation of the anomaly detection performance of the different models. The accuracy, detection rate, and F1-score are used as evaluation measures. The execution time of each model is also analyzed. In addition, the identification of sensors that cause anomalies is investigated and the impact of false detections is discussed. Experimental results show the strengths and weaknesses of each model and provide valuable insights for selecting the appropriate anomaly detection approach. The Isolation Forest, Local Outlier Factor, DBSCAN, and kMeans models show high precision and detection, while the Autoencoder and Variational Autoencoder models show high precision but lower detection. The one-class Support Vector Machine model achieves balanced performance. AutoML shows excellent results in recognition rate but is not real-time capable. The results highlight the trade-offs between performance and computational efficiency and point to further research potential in real-time implementation.

Smart Home with Voice Control Lights Using Arduino Uno R3

The development of science and technology has positively impacted human life, which has now reached the age of electric voice commands. An intelligent home management system allows humans to operate their house's electrical gadgets, such as lighting, using simple voice commands, eliminating the need to move around to switch on or off equipment. When users of indoor lighting use sound waves to operate the system or turn on the lights, the sound sensor sends an input signal to the microcontroller, which is then processed with the microcontroller's output in the form of a voltage to turn on the load. The system will function when the FC-04 sound sensor receives sound input (sound code). The FC-04 sound sensor can only provide a digital output signal with a value of 1 and 0 in the form of a clap, which is then accumulated on Arduino with a value above 400 million by the program uploaded to be used as a 5-volt output to turn on/off the lights. This is because when turning on the lights from a certain distance, several factors can affect it, including setting the sound sensor's sensitivity and noise levels in the surrounding area.

Application-Specific Integrated Circuit of an Inter-IC Sound Digital Filter for Audio Systems

In digital audio systems, filters and equalizers are essential modules for audio improvement at the input and output stages. Due to their computational complexity, most audio tasks are processed with digital signal processors. Due to the fact that latency in audio systems is a critical specification and audio trends require higher sample rates, noise canceling, and bigger data sizes, having an independent high-resolution equalizer would reduce the computational power needed for audio systems. This research had the goal of designing and implementing a hardware architecture for a configurable filter bank based on finite impulse response (FIR) filters and a noise-cancellation stage with an inter-integrated circuit (I2C) communication interface, which allows the filter configuration. The system was implemented as a standalone integrated circuit (IC) for which its inputs were the inter-IC sound (I2S) bus control signals. The digital audio system was optimized to perform one-cycle convolutional operations by implementing a vector–vector arithmetic logic unit. Furthermore, this applied research provides the register transfer level description and the functional verification of the digital design, the system-on-chip (SoC) implementation in TSMC 180 nm technology, and the post-silicon validation with a printed circuit board for testing the output digital signals of the system.

Test Automation of Motor Over Temperature Protection Extension Module of Drive

In industries, for releasing any product into the market, various stages of testing procedure must be done on the product to test its functionality and reliability. The testing procedure has to be frequent and accurate enough to enable early defect detection. Manual testing procedures are time-consuming, need more human resources at the place of testing, have no concept of documentation, and have more chances of human errors. To overcome the variously described limitations of manual testing, test automation is a key tool for providing prompt feedback, tracking of developed firmware versions time-to-time and reducing the tester’s efforts to perform tests task repetitively. The main goal is to speed up test execution cycles and improve the accuracy as well as the performance of the module for end-user customer satisfaction. The proposed system works based on replacing the potentiometer with a relay configuration controlled by the digital output signal of the Programmable Logical Controller and Automated Test Framework. The study describes the transition from manual testing of modules with complex setup environments to automatic testing of modules with implemented hardware changes.

Single-line multi-voltage threshold method for scintillation detectors

The multiple thresholds used in multi-voltage threshold (MVT) method provide more detailed information about the pulse amplitude of the input analog pulses than the simple time-over-threshold (TOT) method, thus allowing for better energy estimation and pulse reconstruction capabilities. However, as the number of thresholds increases, the number of comparators and digital signal readout channels required for MVT also increases. This requirement owing to the increased number of thresholds is the main disadvantage of MVT implementation using field-programmable gate array (FPGA)-based time-to-digital converters (TDCs) because the FPGA resources required for TDC implementation are substantial and FPGAs have a limited number of input/output ports. Therefore, we propose a new single-line MVT method to improve the integrity of the FPGA-only data acquisition system without analog-to-digital converters by reducing the FPGA input channels required for the MVT method. The proposed method, which applies three different levels of thresholding, reduces the digital output signal line in the MVT by employing a 3-input XOR logic gate. The XOR gate integrates the output signals from the comparators and generates 1-bit line digital pulse train. We evaluated the energy performance of the proposed single-line MVT method using three different energy estimators. The energy estimates were compared with the ground truth energy calculated using domino-ring-sampler 4 (DRS4)-sampled analog pulses. The proposed method showed virtually equivalent energy resolution to that of DRS4-based pulse digitization method and better energy linearity than the conventional TOT method. Among the energy estimation methods used in single-line MVT, the crossing-point triangular sum method showed the best energy linearity. The proposed single-line MVT method will be useful when data acquisition systems without ADCs are implemented using FPGA-based TDCs. This is because the proposed method alleviates the problem of limited input ports and the numerous resources required for TDCs in FPGAs.

Integrated three-dimensional Hall switch sensor based on independent optimized Hall devices

This paper presents an integrated 3D Hall switch sensor with a 100 kHz signal bandwidth, which can detect three-dimensional (3D) magnetic field and output digital signals. 3D magnetic field detection relies on the integration of the horizontal Hall devices (HHD) and vertical Hall devices (VHD), and usually requires the performance of HHD and VHD to match each other. Therefore, an independent optimization method is applied to 3D Hall sensor to realize the matching between HHD and VHD. This method allows the doping concentration and doping profiles of VHD can be designed different from HHD. The simulation results show that the optimized HHD can achieve a voltage sensitivity SV of about 20mV/VT and a residual offset of 20 μV at a 3.3 V supply voltage, while VHD are optimized independently for SV up to 20mV/VT, and the residual offset is less than 100 μV after applying offset cancellation technology. In addition, in order to reduce the power consumption and area of the Hall sensor, the Hall signal processing circuit adopts the time-division multiplexing method to realize the detection of the 3D magnetic field in one working period. During the working period, the circuit uses logic control timing circuit to realize wake-up and sleep mode, which further effectively reduces the overall power consumption of the sensor. The Hall sensor chip has been fabricated in 0.18 μm CMOS technology with an area of 1.46 mm2. The measured results show the power consumption of the chip in the Z-axis direction is about 11.88 mW in the wake-up mode and only 49 μW in the sleep mode, at a 3.3 V supply voltage.

Тhe error of a standard air flow velocity measurement procedure in wind tunnels of low subsonic speeds

The standard air flow velocity measurement procedure has been developed in order to unify and standardize the measuring instruments used and data processing algorithms, reduce the development time and certify such standard methods. Sources of error in indirect measurements of air flow velocity in the range 3–105 m/s are investigated. The sources of instrumental error of indirect measurements are analyzed – pressure sensors with digital and analog output signals, pitot tube, temperature and relative air humidity sensors, atmospheric pressure sensors. It is shown that the greatest contribution to the instrumental error is made by measuring the pressure difference and atmospheric pressure. The errors of method, which depends on the measurement model, is considered. A new mathematical model of measurements is proposed, which includes optimal expressions for determining the density of moist air and corrections for compressibility and allows to reduce the methodological error, and requirements for the metrological characteristics of the measuring instruments used are developed, ensuring that the total error of indirect measurements of the flow velocity complies with the allowable limits of ±0,2 m/s. Recommendations are given on the use of measuring instruments and algorithms for processing measurement results, which make it possible to reduce the measurement error by 39 % and develop a standard air flow velocity measurement procedure. The standard procedure is relevant for aviation industry enterprises, where the air flow rate is measured by the pneumometric method.

Markov Chain: A Novel Tool for Electronic Ripple Analysis

Objective: To delineate a novel surrogate approach to analyse the ripple component by constructing a complex network using the Markov model. Methods: Adjacency matrices (A) are constructed from the digital storage oscilloscope output signal of the Full-Wave (FWR) and Half-Wave Rectifiers (HWR) without and with a filter. The centrality measures - indegree, outdegree, in closeness, out closeness, Weighted Network Clustering Coefficient (WNCC) – are also computed for the Markov chain. Findings: With the increase of filter capacitance, more elements in the adjacency matrix become zero. Finally, only one matrix element corresponding to A10;10 remains nonzero for FWR and A20;20 for HWR, indicating the total rectification of the signal at 10 volts. The Markov chain analysis shows that as the ripple component decreases, the number of unconnected nodes increases and the self-loop of the last node increases. For the rectifier output without filtering, it is found that all the nodes are interconnected through edges. The greater the filtering efficiency, the greater the indegree and outdegree, and the lesser the incloseness, outcloseness and WNCC measures. Keywords: Complex network; Markov chain; Rectifier; Time series; Ripple

Overall Design and Hardware Realization of Space Stargazing Camera

In order to improve the accuracy of satellite attitude, a complete stargazing camera was designed using KAC-06040 CMOS digital image sensor. An optical system with a focal length of 1220mm, an F-number of 6.71, and a field of view of 0.84 degrees was designed. The electronics system uses FPGA as the core control device to control CMOS to output digital signals, and transmit the signals back to the satellite data transmission system through TLK2711. The star camera has two working modes of imaging and transmitting the threshold and coordinate information of the star point. Through the field imaging experiment, it can be known that the camera has fine imaging quality, strong transplantability and high reliability. Within the field of view, about 1.2 stars can be photographed, and stars of magnitude 9 can be observed at the same time, which can effectively assist the star sensor to work.

Theoretical Foundations of Construction of the Electronic System for Spatial Measuring of Air Signals Aircraft Plane’s with One Fixed Receiver of Incoming Air Flow

It is noted that it is necessary to obtain reliable information about air signals that determine the spatial movement of aircraft plane (AP), including small-sized, unmanned and manned, to ensure flight safety in the surface disturbed layer of the atmosphere. It is shown that traditional air data systems of AP implementing aerodynamic and wind cock methods for measuring the parameters of incoming air flow using air pressure receivers installed on the right and left side and distributed over the fuselage, braking temperature receiver and wind cock sensors of aerodynamic angles of incidence and gliding have a complex design, considerable weight and cost, which limits their use on small-sized, unmanned and other aircraft classes. It is noted that the developed air data system with one fixed receiver of incoming air flow, built on the basis of the vortex method for measuring the parameters of incoming air flow, can significantly simplify the design and reduce the mass of system, but provides measurement only in the azimuthal or vertical plane in a limited range of measurement of the aerodynamic angle. The air data system being developed, which implements an ion-mark method for measuring the parameters of incoming air flow, allows for panoramic measurement of the aerodynamic angle, but also only in one plane with increasing complexity of the design and increasing requirements for the identity of the channels of the multichannel measuring circuit, which also limits their use on small-sized aircraft. The known capabilities and advantages of the ultrasonic method for measuring the parameters of gas flows and a panoramic sensor of the aerodynamic angle and true airspeed with a fixed receiver of the incoming air flow have determined the possibility of using the ultrasonic method for spatial measurement of air signals. The functional scheme of the electronic system for spatial measuring air signals of aircraft plane with one (integrated) fixed receiver of incoming air flow and ultrasonic instrumentation channels connected to the input of the computer is revealed. To expand the functionality, a static pressure receiver-hole is installed on the external streamlined surface of the system’s receiving board, connected by a pneumatic channel to the input of an absolute pressure sensor with a frequency output, which is also connected to the input of a computer, at the output of which digital output signals of the air data system of aircraft plane are generated. Analytical models of informative signals and algorithms for spatial determination of air signals in instrumentation channels of the electronic system with one fixed receiver of incoming air flow are obtained. The essential advantages of the considered electronic system are revealed, which increase the competitiveness and efficiency of the system application on small-sized and other classes of aircraft planes to improve flight safety and the efficiency of solving flight tasks.

CMOS SPAD sensor chip for the readout of scintillating fibers

The detection of light from optical fibers is required in a variety of particle detector types like fiber trackers or sampling calorimeters. Instead of using classical photo sensors like PMTs or SiPMs and associated readout electronics, we propose to combine Single Photon Sensitive Avalanche Diodes (SPADs) and CMOS readout electronics on the same silicon die. We have developed, fabricated and initially characterized such a ‘Digital SiPM’ solution. In order to provide a high flexibility in fiber diameters and positions, our architecture allows for assigning the individual SPADs to programmable ‘groups’ which are routed to chip pins. The purely digital output signals provide the timing by the rising edge and an amplitude information by the pulse width. The first available chip has been successfully used to detect light of individual fibers from a fiber bundle. The proposed concept could significantly reduce the mechanical and electronic complexity as well as the cost of fiber readouts and possibly improve their performance.

DEVELOPMENT OF SOLAR HEAT CONCENTRATION BOX DRYER AND LM 35 SENSOR AS TEMPERATURE MEASURING DEVICE

The solar heat concentration box is a system which convert the solar energy to heat energy in a closed system for farmers to dry their farm produce. The system uses solar collector to harness energy from the Sun and concentrate it on a drying chamber to remove moisture from plantain, tomatoes, yam and pepper harvested from the farm. The system have three compartments system. Firstly, heat chamber. The heat chamber is made up of a solar glass collector, reflector foil and a rectangular wooden box. This chamber converts the Sun energy to heat energy. It is mounted at angle of 60o to the drying chamber. Secondly, the drying chamber. The drying chamber comprises of a cuboids, tray and isolating material. This is the chamber where the farm produce is laid and removal of moisture takes place. Thirdly, an electronic system which is made up of LM 35 sensor is used to convert the heat distribution inside the drying chamber to temperature. The LM 35 is interface with an Ardiuno UNO microcontroller. The microcontroller converts the analog signal output generated from the sensor to a digital output signal which is been display on visual system. The electronic device will enable farmers measure the temperature of the drying chamber at a particular time or period of the day. The system will enable farmers to dry perishable farm produce which is seasonal. This will reduce food shortage and increase in the cost of such seasonal and perishable farm produce during harvest and off-season.

Analysis of Public Mental Health Status and Exploration of Social Anxiety in the Context of Epidemic

To explore the mental health and social anxiety of the public in the context of the epidemic, this article combines intelligent analysis methods to explore social anxiety. In this article, the digital voltage signal output by the processor chip interface is converted into an analog voltage signal. Moreover, this article changes the changing law of duty cycle with the program designed to achieve the purpose of outputting a variety of mental health waveforms that is composed of the sine wave, triangular wave, and square wave. In addition, this article constructs an intelligent hardware system. The research shows that the system proposed in this article can play an important role in the analysis of mental health and social anxiety in the context of the epidemic and has a certain supporting role in the psychological counseling of the social masses in the context of the epidemic.

Lys-AuNPs@MoS2 Nanocomposite Self-Assembled Microfluidic Immunoassay Biochip for Ultrasensitive Detection of Multiplex Biomarkers for Cardiovascular Diseases.

The progression of cardiovascular diseases is accompanied by myocardial injury and necrosis, heart failure, and inflammatory response. Accordingly, ultrasensitive and rapid detection of multiple biomarkers plays a vital role in clinical diagnosis and timely treatment. Here, we developed a novel Lys-AuNPs@MoS2 nanocomposite self-assembled microfluidic immunoassay biochip with digital signal output and applied it to the simultaneous detection of multiple serum biomarkers including inflammatory factors and cardiovascular biomarkers, PCT, CRP, IL6, cTnI, cTnT, and NT-BNP, with high throughput and sensitivity. The digital output signal was collected in the solid phase on the chip surface with two-dimensional distribution of targets. Lys-AuNPs@MoS2 nanocomposites self-assembled biochips could simultaneously detect all six biomarkers in 60 samples in 40 min with detection limit of a few to tens of pg/mL for all serum biomarkers. The microfluidic biochip based on Lys-AuNPs@MoS2 nanocomposites provides a promising method in applications for clinical diagnosis.

3-Layer stacked pixel-parallel CMOS image sensors using hybrid bonding of SOI wafers

We report 3-layer stacked pixel-parallel CMOS image sensors developed for the first time. The hybrid bonding of silicon-on-insulator wafers through damascened Au electrodes in a SiO2 insulator on the front and backside realizes both face-to-face and face-to-back bonding, developing a multi-layer stacked device. A 3-layered pixel circuit is developed to confirm the linear response of 16-bit digital signal output. A prototype sensor with 160 × 120 pixels successfully captures video images, demonstrating the feasibility of multi-layered sensors of high performance as well as multi-functions including signal processing, memory, and computing for applications such as high-quality video cameras, measurements, recognition, robots, and various IoT devices.

Магнитоизмерительный преобразователь на основе осциллисторного эффекта

Magnetic testing is one of the most widespread types of the NDT. When carrying out magnetic testing various analog magnetic measuring sensors are used: ferroprobe, based on Gauss and Hall effects, etc. A perspective direction of research in the field of nondestructive testing and technical diagnostics is the development of measuring transducers with a digital output signal, or a signal easily convertible into a code. The paper considers magnetic transducer based on the oscillistor effect, which has a threshold nature and involves the appearance of electric current oscillations, flowing through a semiconductor sample, placed in the longitudinal electric and magnetic fields. The results of experimental studies of the dependence of the threshold electric field strength on the magnetic field strength are presented. The scheme of the converter of magnetic field induction into the impulses of electric voltage, and diagrams of its work are given. The sensitivity of the converter depends on the frequency of the sample frequency generator and the conversion coefficient of the ramp generator.

Analysis and Suppression of the Frequency-Aliasing Phenomenon Related to the Sorting-Algorithm-Based Voltage-Balance Strategy in an MMC System

The frequency-aliasing phenomenon, which can distort high-frequency harmonics in the analog input signal into low-frequency harmonics in the output digital signal, is widespread in the process of analog to digital conversions. The sorting-algorithm-based voltage-balance strategy is also such a conversion process. This strategy converts the analog-continuous-sinusoidal fundamental wave into the digital-discrete inserted-submodule number, deciding how many submodules are required to operate in modular multilevel converters (MMC). Thus, the frequency-aliasing phenomenon can occur in this strategy and deteriorate the performance of MMC as well. This article first proposes the mechanism of the frequency-aliasing phenomenon in the sorting-algorithm-based voltage-balance strategy. A quantitative analysis is then presented to indicate the root cause of the frequency-aliasing phenomenon in the voltage-balance strategy. This analysis also intuitively describes the frequency-aliasing phenomenon's effect, such as harmonic redistributions in the large-signal model, the phase delay in the small-signal model, and the associated deteriorations including the system stability's decrease and the power quality's reduction. Based on the above analysis, an optimal value design method is proposed to suppress the frequency-aliasing phenomenon by determining an appropriate voltage-balance frequency. A code restructuration method is further implemented to adapt the voltage-balance strategy to the optimal frequency and to avoid extra switching actions at the same time. The deteriorations caused by the frequency-aliasing phenomenon and the effectiveness of proposed methods are finally demonstrated via simulations experiments.

Analysis and optimization of few-mode fibers with low differential mode group delay by variational method

Mode-division multiplexing (MDM) technology based on few-mode fibers (FMFs) is the current research hotspot of optical fiber communication system because of its ability to increase the transmission capacity several times. When the number of multiplexed modes is large, the crosstalk between modes can be removed by multiple input multiple output digital signal processing algorithm at the receiving end. The larger the differential mode group delay (DMGD, <inline-formula><tex-math id="Z-20220504070336-1">\begin{document}$ \tau_{\rm DMGD} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20212198_Z-20220504070336-1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20212198_Z-20220504070336-1.png"/></alternatives></inline-formula>), the more complex the algorithm is. Therefore, in order to reduce the complexity of the receiver, it is necessary to use FMFs with low DMGD. The variational method is proposed to analyze any FMFs with higher refractive index of core than that of cladding. The analytical formula of the fundamental mode size, the normalized propagation constant for each of all guided modes, and DMGD relative to the fundamental mode are derived. Moreover, their relationship with the normalized frequency and other fiber manufacturing parameters are given. On this basis, the graded-index FMFs are studied, and the fiber parameters are optimized. The optimization parameters are the difference between the maximum core refractive index and cladding refractive index <i>n</i><sub>1</sub> – <i>n</i><sub>2</sub> = 0.01, the core radius <i>a </i>= 14 μm, and the paramenter of refractive index distribution <i>α </i>= 1.975. In the optimized FMF, 6 LP modes can be guided and |<inline-formula><tex-math id="Z-20220504070445-1">\begin{document}$ \tau_{\rm DMGD} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20212198_Z-20220504070445-1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20212198_Z-20220504070445-1.png"/></alternatives></inline-formula>| is less than 15 ps/km within the C band and L band. In the end, the effects of the fiber manufacturing errors on DMGD are discussed.