Signal Processing Module Research Articles

Automatic control strategy of electronic and electrical engineering based on FPGA

Field Programmable Gate Array (FPGA) have demonstrated significant potential in the field of automation control due to their flexibility, programmability, and high performance. This study designs an FPGA-based automation control strategy for motor control systems, encompassing four core modules: signal acquisition, signal processing, control algorithm, and output drive. The signal acquisition module employs the AD9280 high-speed, high-precision ADC chip to achieve rapid and accurate signal acquisition. The signal processing module utilizes digital filtering and FFT analysis within the FPGA to extract key information such as motor speed. The control algorithm module adopts an adaptive fuzzy control strategy that fine-tunes control rules in real-time to ensure precise control. The output drive module generates PWM signals via the FPGA to drive the motor, guaranteeing efficient and stable operation. Experimental results indicate that the FPGA-based control strategy significantly outperforms traditional methods in terms of response speed and stability, capable of meeting the high-performance requirements of modern industrial motor control systems. This research provides new technical insights and practical references for the field of automation control in electrical and electronic engineering.

SiPM-based LiDAR with multipulse sequence modulation and multithreshold signal processing.

A light detection and range technology (LiDAR) system that enables rapid ranging under extremely low signal-to-noise ratios (SNRs) during daylight conditions based on a SiPM (silicon photomultiplier) detector is proposed. The system emits a sequence of modulated laser pulses by controlling the semiconductor laser and then processes the SiPM response signals using dynamic multithreshold. The experimental result shows that, under extremely low SNR of daylight, the system achieves a 100% success rate in continuous ranging of a low reflectivity target at 125 m, with a ranging precision of less than 20 cm and a ranging time of less than 10 µs. Our system provides a significant reference value for achieving high-speed, noise-resistant, miniaturized, practical, and low-cost LiDAR based on a SiPM.

Design and DSP implementation of signal processing module for underwater acoustic transponder

Design and DSP implementation of signal processing module for underwater acoustic transponder

An electronic energy compensation method for flattening the energy response of SiPM-GGAG:Ce,B based gamma detector

Abstract The energy response of gross gamma dose rate monitors needs to be flat in order to prevent overestimation of dose at low gamma energies. In this paper, a discriminator threshold modulation based electronic energy compensation algorithm has been proposed for SiPM-scintillator based gamma detectors. Theoretical simulation studies were carried out in order to optimize the parameters of the periodic ramp voltage used for modulation of the discriminator threshold of a SiPM-GGAG:Ce,B based gamma dose rate monitor. A customized threshold modulation circuit and signal processing electronics were developed for this gamma detector. For experimentally optimizing the parameters, the energy response studies of the detector, with and without the discriminator threshold modulation, were carried out. With the optimized parameters for a periodic ramp threshold, the count rates for 241Am (60 keV) and 60Co (1173 and 1332 keV) were observed to be within ±30% of the count rate obtained for 137Cs (662 keV). Using the electronic energy compensation techniques presented in this paper, a flat energy response of the SiPM-scintillator gamma detector for the energy range of 60 keV to 1.5 MeV could be achieved.

Bio‐Inspired Hybrid Laser Direct Writing of Interfacial Adhesion for Universal Functional Coatings

AbstractEnhancing interfacial adhesion between functional coatings and target surfaces facilitates long‐term stable service by mitigating interferences of mechanical mismatches. Design of mechanical interlocks affords an effective strategy to strengthen the interfacial bonding with durability and compatibility, but the in‐depth investigations are still lacked. Herein, a gecko‐inspired hierarchical strategy realized by hybrid laser direct writing is proposed, which incorporates an armored frame scale for surface protection and a riveted anchor scale for interlocks. Such dual‐scale configurations endow the functional coatings with the stronger adhesion to the targets than the pristine and mono‐scale cases, resulting in 2 orders of magnitude enhancement resistant to tape peeling tests. Utilizing this scheme, a laser‐induced integrated deicing system is in situ manufactured on thermoplastics, primarily comprising superhydrophobic structures, carbon‐based sensors as well as adhesive copper (Cu) interconnects and heaters, where Cu‐based devices exhibit superior resistance to water impacts and stress fatigue. Interfacing with signal processing modules, such an all‐in‐one system demonstrates real‐time temperature monitoring and high efficiency in deicing (4.24 folds faster than the control group). The facile route for intensified adhesion holds promise in the interfaces within advanced equipment and under harsh scenarios.

Data-Driven Channel Modeling for End-to-End Visible Light DCO-OFDM Communication System Based on Experimental Data

End-to-end systems have been introduced to address the issue of independent signal processing module design in traditional communication systems, which prevents achieving global system optimization. However, research on indoor end-to-end Visible Light Communication (VLC) systems remains limited, especially regarding the channel modeling of high-speed, high-capacity Direct Current-biased Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) systems. This paper proposes three channel modeling methods for end-to-end DCO-OFDM VLC systems. The accuracy of the proposed methods is demonstrated through R-Square model fitting performance and data distribution analysis. The effectiveness of the proposed channel modeling methods is further validated by comparing the bit error rate (BER) performance of traditional receivers and existing deep learning (DL)-based receivers. The results show that the proposed methods can effectively mitigate both linear and nonlinear distortions. By employing these channel modeling methods, communication systems can reduce the spectral occupancy of pilot signals, thereby significantly lowering the complexity of traditional channel estimation methods. Thus, these methods are suitable for use in end-to-end VLC communication systems.

A chip-integrated homodyne detection system with enhanced bandwidth performance for quantum applications

The rapid development of quantum technology has driven the need for high-performance quantum signal processing modules. Balanced homodyne detector (BHD) is one of the most promising options for practical quantum state measurement, providing substantial advantages of cost-effectiveness, no cooling requirement, and system compactness. However, due to the stringent requirements in BHD design, it typically suffers from a relatively small operating bandwidth which limits the overall speed of a quantum system. In this study, we propose comprehensive modelling for the BHD in quantum applications and enhance the performance of BHDs based on our modelling. Specifically, we utilise a photonic chip approach and optimise the electronic design to create the integrated BHD, which significantly boosts the 3 dB bandwidth to 4.75 GHz and achieves a shot-noise-limited bandwidth of 23 GHz. We demonstrate the capability of this setup to generate quantum random numbers at a rate of 240 Gbit s−1, highlighting its potential for ultra-high-speed quantum communication and quantum cryptography applications.

Design of Digital Lock-in Amplifier based on FPGA

Abstract In order to achieve high-precision measurement of strong noise background signal, a digital lock-in amplifier based on field programmable gate array (FPGA) is designed. The core of the lock-in amplifier consists of a signal processing module, an acquisition and quantisation module and a digital demodulation module. The signal processing module completes the amplification and gain adjustment of the input signal and modulates the signal to be measured into a specific frequency band, which is digitally quantised by the analog to digital converter (ADC) after anti-aliasing filtering and transmitted to the FPGA, and the signal to be measured is extracted by phase-sensitive detection through the mutual-correlation digital demodulation method, thus realising the detection of the weak signal. The performance of the lock-in amplifier is evaluated with a signal generator as the input source, and the results show that the signal-to-noise improvement ratio is 35dB and the relative measurement error of voltage is less than 0.03% after the digital lock-in amplifier is processed, which accurately restores the direct current (DC) signals in the noisy background, and provides an effective technical way for the accurate measurement of weak signals.

Entertainment robot based on IoT and VR interaction for motion training posture monitoring

With the development of artificial intelligence technology, the role of social robots in sports activities has gradually become prominent. Robots can help with intelligent control of sports venues, assist in motion guidance, and engage in emotional communication with users, helping athletes adjust their emotions. This article studies the motion training posture monitoring of entertainment robots based on the interaction between the Internet of Things and VR. A new high-intensity motion attitude monitoring system based on quantum dot photodetectors has been developed to improve monitoring accuracy and stability. Entertainment robots can simulate and analyze motion training postures, and provide relevant technical guidance. The quantum dot photodetectors were integrated into the sensor components, and the collected data was transmitted to the data acquisition and processing unit through signal transmission and processing modules. The collected data was processed and analyzed to achieve real-time monitoring and tracking of the target object’s attitude. Multiple experiments were conducted on the entire system, simulating various high-intensity exercise environments, and evaluating the performance parameters of the system. Through continuous optimization and improvement, the stability and accuracy of the system were ultimately ensured.

Development of an in-service NDT system for storage tanks

The large storage tank is one of the major infrastructures. Once a leak occurs, it often causes environmental pollution and even catastrophic accidents. In the early years, the method of emptying tanks and cutting plates for defects inspection was adopted to avoid leakage. However, there exist some deficiencies such as large blindness, long downtime and high cost. Since there are many problems in the traditional testing, inspection without emptying the tank and without stopping production is an indispensable technical means to ensure the safe operation of the tank. An in-service non-destructive testing (NDT) system for storage tanks without emptying is developed in this paper, which mainly includes sensors, the signal processing module, the testing crawler, the winding and releasing mechanism and control module et. al. The sensors, signal processing module and testing crawler need to be placed into the tank from the roof man-hole by the crane, while the control module is located outside the tank. The sensor can realize the combined inspection of magnetic field leakage (MFL) and electromagnetic acoustic transducer (EMAT). The laboratory experiments indicate that the system can realize in-service inspection of the corrosion defects on the bottom and works well in water. The new testing system will overcome the shortage of off-line service inspection methods that emptying and cleaning tanks are needed before inspection and environmental risks are involved. These research works guarantee the safe operation of storage tanks and provide an alternative NDT system for storages related industrial projects.

A Gas Sensors Detection System for Real-Time Monitoring of Changes in Volatile Organic Compounds during Oolong Tea Processing.

The oxidation step in Oolong tea processing significantly influences its final flavor and aroma. In this study, a gas sensors detection system based on 13 metal oxide semiconductors with strong stability and sensitivity to the aroma during the Oolong tea oxidation production is proposed. The gas sensors detection system consists of a gas path, a signal acquisition module, and a signal processing module. The characteristic response signals of the sensor exhibit rapid release of volatile organic compounds (VOCs) such as aldehydes, alcohols, and olefins during oxidative production. Furthermore, principal component analysis (PCA) is used to extract the features of the collected signals. Then, three classical recognition models and two convolutional neural network (CNN) deep learning models were established, including linear discriminant analysis (LDA), k-nearest neighbors (KNN), back-propagation neural network (BP-ANN), LeNet5, and AlexNet. The results indicate that the BP-ANN model achieved optimal recognition performance with a 3-4-1 topology at pc = 3 with accuracy rates for the calibration and prediction of 94.16% and 94.11%, respectively. Therefore, the proposed gas sensors detection system can effectively differentiate between the distinct stages of the Oolong tea oxidation process. This work can improve the stability of Oolong tea products and facilitate the automation of the oxidation process. The detection system is capable of long-term online real-time monitoring of the processing process.

A GNU radio-based design for GPS software simulation source

GPS (Global Positioning System) plays a crucial role in modern navigation and positioning applications. Traditional research and development of GPS signals require expensive hardware equipment, limiting the flexibility and scalability of the system. In this paper, an open-source software called GNU Radio is utilized to construct a GPS signal simulation system, leveraging its rich modules and signal processing libraries. The GPS baseband signals are generated using signal processing modules provided by GNU Radio. Appropriate noise and interference are added to simulate the signal characteristics in real-world environments. Both single-channel and multi-channel signal models are presented. By comparing the generated GPS signals with those from hardware-based simulators, the results demonstrate that the GPS software simulator based on GNU Radio can produce high-quality GPS signals with excellent flexibility and adjustability.

Photoacoustic trace gas detection of OCS using a 2.45 mL Helmholtz resonator and a 4823.3 nm ICL light source

A miniaturized photoacoustic spectroscopy-based gas sensor is proposed for the purpose of detecting sub-ppm-level carbonyl sulfide (OCS) using a tunable mid-infrared interband cascade laser (ICL) and a Helmholtz photoacoustic cell. The tuning characteristics of the tunable ICL with a center wavelength of 4823.3 nm were investigated to achieve the optimal driving parameters. A Helmholtz photoacoustic cell with a volume of ∼2.45 mL was designed and optimized to miniaturize the measurement system. By optimizing the modulation parameters and signal processing, the system was verified to have a good linear response to OCS concentration. With a lock-in amplifier integration time of 10 s, the 1σ noise standard deviation in differential mode was 0.84 mV and a minimum detection limit (MDL) of 409.2 ppbV was achieved at atmospheric pressure and room temperature.

Label- and Reagent-Free Optical Sensor for Absorption-Based Detection of Urea Concentration in Water Solutions.

Contactless and label-free detection of urea content in aqueous solutions is of great interest in chemical, biomedical, industrial, and automotive applications. In this work, we demonstrate a compact and low-cost instrumental configuration for label-free, reagent-free, and contactless detection of urea dissolved in water, which exploits the absorption properties of urea in the near-infrared wavelength region. The intensity of the radiation transmitted through the fluid under test, contained in a rectangle hollow glass tubing with an optical pathlength of 1 mm, is detected in two spectral bands. Two low-cost, low-power LEDs with emission spectra centered at λ = 1450 nm and λ = 2350 nm are used as readout sources. The photodetector is positioned on the other side of the tubing, in front of the LEDs. The detection performances of a photodiode and of a thermal optical power detector have been compared, exploiting different approaches for LED driving current modulation and photodetected signal processing. The implemented detection system has been tested on urea-water solutions with urea concentrations from 0 up to 525 mg/mL as well as on two samples of commercial diesel exhaust fluid ("AdBlue™"). Considering the transmitted intensity in presence of the urea-water solution, at λ = 1450 nm and λ = 2350 nm, normalized to the transmitted intensity in presence of water, we demonstrate that their ratio is linearly related to urea concentration on a wide range and with good sensitivity.

A near-zero quiescent power breeze wake-up anemometer based on a rolling-bearing triboelectric nanogenerator

AbstractWind sensors have always played an irreplaceable role in environmental information monitoring and are expected to operate with lower power consumption to extend service lifetime. Here, we propose a breeze wake-up anemometer (B-WA) based on a rolling-bearing triboelectric nanogenerator (RB-TENG) with extremely low static power. The B-WA consists of two RB-TENGs, a self-waking-up module (SWM), a signal processing module (SPM), and a wireless transmission unit. The two RB-TENGs are employed for system activation and wind-speed sensing. Once the ambient wind-speed exceeds 2 m/s, the wake TENG (W-TENG) and the SWM can wake up the system within 0.96 s. At the same time, the SPM starts to calculate the signal frequency from the measured TENG (M-TENG) to monitor the wind speed with a sensitivity of 9.45 Hz/(m/s). After the wind stops, the SWM can switch off the B-WA within 0.52 s to decrease the system energy loss. In quiescent on-duty mode, the operating power of the B-WA is less than 30 nW, which can greatly extend the service lifetime of the B-WA. By integrating triboelectric devices and rolling bearings, this work has realized an ultralow quiescent power and self-waked-up wireless wind-speed monitoring system, which has foreseeable applications in remote weather monitoring, IoT nodes, and so on.

The Ammunition Projectile Test and Evaluation Used Polymer Flexible Film Sensors System Design and Application

Background. The mainly lethal ability of ammunition fragments on creatures is achieved by hitting the effective organs or key parts of the biological body with high-speed projectiles. How to efficiently and accurately obtain the projectile speed and hitting position coordinates when the fragment hits the creature after the ammunition blast is the key to the scientific evaluation of ammunition power. Materials and Methods. For the measurement of fragment velocity and hitting coordinates, a series of flexible film circuit sensors can be generated by printing comb-like circuits on polyethylene terephthalate substrates using silver paste printing technology. These sensors are cheap, flexible, and easy to fold and can be printed into different shapes according to the characteristics of the test target to simulate the biological key organs or lethal parts. At the same time, the software and hardware design of the high-speed data signal reading and processing module can realize the data rapidly recording and processing and quickly give the ammunition fragment parameter test results. Results. The test accuracy of the fragment velocity of the laser light screen target and the flexible circuit sensor is compared through the live-fire test. It is proved that the test accuracy of the flexible sensor based on the polymer substrate can meet the accuracy requirements. The flexible sensor based on the organ simulation can quickly give the accurate hit position of the fragment. Conclusion. The newly polymer substrate printed circuit sensor system is a new type of sensor used to replace the laser screen target, and the copper comb printed circuit in the ammunition power test, which can improve the parameter test accuracy, reduce the test consumption, and improve the test quality.

Rapid Photoacoustic Exhaust Gas Analyzer for Simultaneous Measurement of Nitrogen Dioxide and Sulfur Dioxide.

A rapid photoacoustic (PA) exhaust gas analyzer is presented for simultaneous measurements of nitrogen dioxide (NO2) and sulfur dioxide (SO2). A laser diode (LD) emitting at 450 nm and a light-emitting diode (LED) with a peak wavelength of 275 nm operated simultaneously, producing PA signals of NO2 and SO2, respectively. The LD and LED were modulated at different frequencies of 2568 and 2570 Hz, and their emission light beams were transmitted through two resonant tubes in a differential PA cell (DPAC), respectively. A self-made dual-channel digital lock-in amplifier was used to realize the simultaneous detection of dual-frequency PA signals. Cross interference between the PA signals at the two different frequencies was reduced to 0.02% by using a lock-in amplifier. In order to achieve a rapid dynamic measurement, gas sampling was accelerated by an air pump. The use of mufflers and the differential PA detection technique significantly reduced the gas sampling noise. When the gas flow rate was 1000 sccm, the response time of the PA dual-gas analyzer was 8 and 17 s for NO2 and SO2, respectively. The minimum detection limits of NO2 and SO2 were 1.7 and 26.1 ppb when the averaging time of the system was 10 s, respectively. Due to the wide spectral bandwidth of the LED, NO2 produced an interference to the detection of SO2. The interference was reduced by the precise detection of NO2. Since the radiations of the LD and LED passed through two different PA tubes, the impact of NO2 photochemical dissociation caused by UV LED luminescence on NO2 gas detection was negligible. The sharing of the PA cell, the gas lines, and the signal processing modules significantly reduced the size and cost of the PA dual-gas analyzer.

Optimized pilot structure for PS-PDM ultrahigh-order QAM coherent optical transmission

We proposed and experimentally demonstrated a general pilot structure for probabilistic shaped (PS)-polarization division multiplexing (PDM) M-ary quadrature amplitude modulation (MQAM) coherent optical transmission, where a portion of PS-MQAM symbols is exploited as the pilot symbols with the same information entropy as the transmitted signal. The pilot symbols are simultaneously used in the entire digital signal processing (DSP) modules for polarization de-multiplexing, frequency offset estimation, carrier phase recovery, nonlinear equalization, and linear equalization. Compared to the conventional quadrature phase shift keying (QPSK) pilot structure, the proposed MQAM pilot structure can yield the nonlinear properties of the overall signal so that nonlinear equalization can effectively improve the performance of the normalized generalized mutual information. The remarkable performance has been achieved at the shaping parameters of 3.25 and 4.35 for 1024QAM and 4096QAM signals based on the proposed pilot scheme, which corresponds to the raw spectral efficiency of 16.190 and 20.381 bit/s/Hz, respectively. The pilot ratio is optimized to 5% for higher achievable information rates (AIRs).

Correlation Between Volume and Pressure of Intracranial Space With Craniectomy Surface Area and Brain Herniation: A Phantom-Based Study.

There are proponents of decompressive craniectomy (DC) and its various modifications who claim reasonable clinical outcomes for each of them. Clinical outcome in cases of traumatic brain injury, managed conservatively or aided by different surgical techniques, depends on multiple factors, which vary widely among patients and have complex interplay, making it difficult to compare one case with another in absolute terms. This forms the basis of the perceived necessity to have a standard model to study, compare, and strategize in this field. We designed a phantom-based model and present the findings of the study aimed at establishing a correlation of the volume of intracranial space and changes in intracranial pressure (ICP) with surface area of the craniectomy defect created during DC and brain herniation volume. A roughly hemispherical radio-opaque container was scanned on a 128-slice computed tomography scanner. Craniectomies of different sizes and shapes were marked on the walls of the phantom. Two spherical sacs of stretchable materials were subsequently placed inside the phantom, fixed to three-way connectors, filled with water, and connected with transducers. The terminals of the transducer cables were coupled with the display monitor through a signal amplifier and processor module. Parts of the wall of the phantom were removed to let portions of the sac herniate through the defect, simulating a DC. Volume measurements using AW volume share 7® software were done. Resection of a 12.7 × 11.5 cm part of the wall resulted in a 10-cm-diameter defect in the wall. Volume differential of 35 mL created a midline shift of 5 mm to the side with lesser volume. When measuring pressure in two stretchable sacs contained inside the phantom, there always remained a pressure differential ranging from 1 to 2 mm Hg in different recordings, even with sacs on both sides containing an equal volume of fluids. Creating a circular wall defect of 10 cm in diameter with an intracavitary pressure of 35 mm Hg on the ipsilateral sac and 33 mm on the contralateral sac recorded with intact walls, resulted in a true volume expansion of 48.411 cm3. The herniation resulted in a reduction of pressure in both sacs, with the pressure recorded as 25 mm in the ipsilateral sac and 24 mm in the contralateral sac. The findings closely matched those of the other model-based studies. Refinement of the materials used is likely to provide a valid platform to study cranial volume, ICP, craniectomy size, and brain prolapse volume in real time. The model will help in pre-operatively choosing the most appropriate technique between a classical DC, a hinge craniotomy, and an expansive cranioplasty technique in cases of refractory raised ICP.

Emotion recognition with EEG-based brain-computer interfaces: a systematic literature review

Electroencephalography (EEG)-based Brain-Computer Interface (BCI) systems for emotion recognition have the potential to assist the enrichment of human–computer interaction with implicit information since they can enable understanding of the cognitive and emotional activities of humans. Therefore, these systems have become an important research topic today. This study aims to present trends and gaps on this topic by performing a systematic literature review based on the 216 published scientific literature gathered from various databases including ACM, IEEE Xplore, PubMed, Science Direct, and Web of Science from 2016 to 2020. This review gives an overview of all the components of EEG based BCI system from the signal stimulus module which includes the employed device, signal stimuli, and data processing modality, to the signal processing module which includes signal acquisition, pre-processing, feature extraction, feature selection, classification algorithms, and performance evaluation. Thus, this study provides an overview of all components of an EEG-based BCI system for emotion recognition and examines the available evidence in a clear, concise, and systematic way. In addition, the findings are aimed to inform researchers about the issues on what are research trends and the gaps in this field and guide them in their research directions.