Synchronous Detection Research Articles

Time Synchronization and Signal Detection in Non-Orthogonal Unicast and Broadcast Networks

The next generation digital TV (DTV) broadcast, namely Advanced Television System Committee (ATSC) 3.0, relies on substantial single frequency networks (SFN), each of which requires a studio to transmitter link (STL) to transmit data from the broadcast gateway (BG), leading to significant construction costs. Therefore, the wireless in-band distribution link (IDL) technology is proposed, which uses layered-division multiplexing (LDM) to transmit the STL data via wireless links from the BG to the SFN transmitters within the same spectrum as the broadcast services. In this paper, we propose the time synchronization and signal detection algorithm for wireless IDL systems with both unicast and broadcast signals. We introduce two multiplexing schemes, N-LDM and 3-LDM, and demonstrate their superiority over traditional frequency division multiplexing (FDM). To overcome the challenge of multi-access interference and synchronization errors caused by multipath, we develop a unique word (UW) design algorithm for transmitted signals and a double threshold correlation detection algorithm (DTCDA) that outperforms traditional ones. We employ a second threshold to enhance detection performance at low signal-to-noise ratios, and utilizes successive interference cancellation (SIC) to mitigate multiple-access interference. More importantly, our approach requires no knowledge of the unicast user number or channel state information. Simulation results validate the effectiveness of the proposed scheme.

Dual-phase digital lock-in implementation based on Nyquist rate and sampling subtraction.

Lock-in amplifiers (LIA) are widely used in laboratory environments to detect low-amplitude signals buried in noise as well as real and imaginary parts of a complex quantity. They are based on the technique of synchronous detection, where the signal of interest is modulated into a desired frequency, sent to the medium or device to be analyzed, and captured by a detector. The detector scheme relies on the concept of phase-sensitive detection, generally resulting in two components: in-phase and quadrature. This article shows a very simple and low computational-cost way to implement a dual-phase LIA, using readily available microcontrollers, running a simple and fast algorithm. Three examples of signal detection are presented (sound wave signal, impedance meter, and weak signal recovery) to point out the flexibility and capabilities of the proposed methodology.

Analysis and Design of a Cost-Effective Single-Input and Regulatable Multioutput WPT System

In this letter, a single-input and regulatable multi-output (SIRMO) wireless power transfer (WPT) system is presented. In particular, the system uses positive and negative half-wave rectifiers and a synchronous rectifier to realize multiple output channels. Each output channel is controllable, providing a flexible wireless charger to meet various charging requirements. Moreover, this system utilizes the inherent half-wave-rectifier channels (#B and #C) to detect synchronous signals for the rectifiers rather than using additional synchronous detection circuits, thereby leading to a cost-effective system. Finally, a 300W laboratory prototype is contrasted with three voltage levels, i.e., 48V, 30V, and 24 V. With the help of the control logic, this system shows excellent robustness against different occasions such as load variations, input disturbance and misalignment. The overall efficiency ranges from 86.7% to 90.6%.

A novel hybrid piezo-triboelectric sensor (PTS) based on the surface modification for monitoring the operating status of the moving component

Nowadays, industrial sensors based on piezo-triboelectric effects have been successfully applied for the detection of sophisticated devices. The current study proposes a novel hybrid piezo-triboelectric sensor (PTS) to detect the operating states of the moving component (MC) in the machine. Firstly, the PTS is designed as a hierarchical structure to achieve synchronous detection of two motion states of MCs. Secondly, the surface frosting and nanoparticle doping adds the friction coefficient of the sensor to improve charge transfer efficiency, so the voltage signals of the PTS are more than 39.05% higher than that of the sensor with smooth surfaces under 0.5 kPa ∼ 1.5 kPa pressure. In addition, the frosted surface reduces the impact of surface damage caused by impurities on the voltage signals compared with a smooth surface. Moreover, the direction sensing part within PTS contains 4 perceptual units to generate direction sensing signals that are correlated with state sensing signals to reflect the definite operating information of the MC. Meanwhile, the sensing properties of the PTS effectively demonstrate relative motion between the adjacent element and the MC in the actuator. With excellent performance, this work provides a new paradigm shift for the application of hybrid sensors in equipment detection.

Experimental development of a gated UV-induced spectroscopic lidar for the daytime study of plant ecology and photosynthesis: multi-modal measurement of fluorescence of trees growing in a field and Mie-Raman-fluorescence of the surrounding atmosphere.

A gated UV-induced spectroscopic lidar operational during daylight was developed to better understand the plant growth status in real time and the influence from the surrounding atmosphere chemical environment. Initial indoor experiments and short-range (100m) field measurements were very positive. The lidar worked as a vegetation fluorescence lidar, as well as an atmospheric Mie-Raman-fluorescence lidar. A UV (355nm) laser was effective to induce fluorescence and Raman scattering, and a synchronous detection technique made it possible to detect weak signals, even in daytime. Tree spectra containing chlorophyll fluorescence of tree leaves offered information about the growth status of trees. Atmospheric spectra containing aerosol Mie scattering, N 2, O 2, H 2 O Raman scattering, and pollutant fluorescence helped us to learn about atmospheric circumstances surrounding trees. The multi-modal information is useful for comprehensive understanding of plant ecology.

A Synchronous and Accurate Detection Method for Gas Pipeline Leakage Position and Flow Rate Based on Double Fiber Bragg Gratings

Fast and accurate detection of pipeline leaks plays an important role in reducing economic losses and ensuring the safety of personnel. However, for the two important indicators of gas pipeline detection, how to effectively detect the leakage location and leakage rate simultaneously is a serious challenge. In this paper, we present an innovative optical fiber detection method based on double fiber Bragg gratings (FBGs) string to solve this problem. Combined with the theory of material mechanics and fluid mechanics, the binary equations are derived as the demodulation formula. In the detection, the corresponding physical quantities can be calculated by substituting the center wavelength of the two FBGs after drift. The experiments demonstrate that this sensor’s gas flow rate sensitivity in different positions can be up to 466.67 pm∙s/m. Meanwhile, at the same flow rate and different leakage positions, the sensor has sensitive symmetrical performance. The error results manifest that the velocity error is not more than 0.13 m/s, and the relative position detection error is not more than 0.167%. Overall, besides the extended measurement range and excellent linearity, our method also has the advantages of low production cost, simple structure and ease of production, which is more suitable for gas pipeline health monitoring in the future.

A SERS bioassay based on vancomycin-modified PEI-interlayered nanocomposite and aptamer-functionalized SERS tags for synchronous detection of Acinetobacter baumannii and Klebsiella pneumoniae

Klebsiella pneumoniae (KP) and Acinetobacter baumannii (AB) are two important gram-negative bacteria that cause pneumonia and have been recently known to be associated with food. The rapid detection of these pathogens in food is important to minimize their colonization of the gut and stop new threats of the disease from spreading across the food chain. Herein, a double-edged sword aptasensor was developed for the synchronous detection of KP and AB in food and clinical samples. A highly sensitive, selective, specific, and synchronous detection of the target bacteria was achieved, and the limit of detection (LOD) was 10 cells/mL with a liner range of 50 to 105 cells/mL. The total assay time was 1.5 h. This study does not only provide a new tool for the detection of the target bacteria, but also serves as a promising tool for food safety and pneumonia diagnosis.

Design and Implementation of Three-Channel Drainage Pipeline Ground Penetrating Radar Device.

In order to solve the current problems that conventional video inspection can only detect, as an internal pipeline defect and drainage pipeline radar inspection device detects in a single direction and at radar frequency in water pipeline defect detection, a three-channel drainage pipeline ground penetrating radar (GPR) inspection device was designed and developed, the assembly and commissioning of the device prototype were completed, and an actual engineering test application was carried out. Focusing on the problem that the detection direction and depth of the single-channel detection device are limited, a three-channel drainage pipeline GPR inspection device is designed to realize the synchronous detection of the inside of the pipeline, the pipeline body, and the external environment of the pipeline, improving the detection depth and efficiency. According to the design scheme of the three-channel drainage pipeline GPR inspection device, the assembly of the device prototype was completed. The device contains three radar channels, the top of the main frequency of the antenna is 1.4 GHz, the two sides are 750 MHz, the video camera has a pixel count of 4 million, and the positioning accuracy is less than 1 mm, the waterproof grade is IP68, the detection accuracy of pipe deformation (slope) is 0.1°, the detection depth outside the pipe is 1.2 m, and the detection accuracy of corrosion thickness is 15 mm. In a practical application of the device, the Jianguomenqiao sewage pipeline in Beijing, China, was tested, resulting in the discovery of 87 defects, including 39 loose soil areas at the bottom of the pipe exterior, 40 void areas, and 8 cavities.

Application of a Quality by Design-based approach in development and validation of an RP-HPLC method for simultaneous estimation of methotrexate and mangiferin in dual drug-loaded liposomes.

The present study delineates the development of a novel rugged and sensitive stability-indicating risk-based HPLC method for the concurrent estimation of methotrexate and mangiferin in dual drug-loaded nanopharmaceuticals based on an analytical QbD approach. Preliminary screening trials along with systemic risk analysis were performed, endeavouring to explicate the critical method attributes, namely pH, percentage orthophosphoric acid content and percentage methanol content, that influence critical quality attributes. Box-Behnken design was utilized for the optimization of the tailing factor as response for methotrexate and mangiferin in short run time. The chromatographic conditions were optimized by performing 17 experimental runs acquired from Design-Expert software. The chromatographic conditions after the analysis of an optimized zone within the confines of the design space were chosen as mobile phase water-methanol adjusted to pH3.0 with 0.05% orthophosphoric acid (65:35, v/v) and flow rate 1.0ml/min using a C18 analytical column at an isosbestic wavelength of 265 nm. Furthermore, the validation of the optimized method was done in accordance with International Conference on Harmonization guidelines and were reckoned to be in the prescribed limits. The developed RP-HPLC method has a high degree of practical utility for synchronous detection of methotrexate and mangiferin in pharmaceutical nano-dosage forms such as protein-based-nanoparticles, nanocrystals, polymeric nanoparticles and metallic nanoparticles in in vivo and in vitro studies.

Ultrasensitive and rapid detection for multiple dopings in saliva and urine using surface-enhanced Raman spectroscopy

Abuse of dopings is one of the serious issues affecting competitive sports globally. Traditional means of analysis for doping detection face the challenges of costly, bulky, and complicated pretreatment, as well as long detection times. Therefore, it is critical to achieve on-site and rapid detection for dopings. Herein, we proposed a strategy for ultrasensitive and quick detection of multiple dopings using a combination of liquid phase extraction and surface-enhanced Raman spectroscopy. The clenbuterol, methadone, oxycodone, and chlordiazepoxide were four dopings, which could be detected conveniently in human saliva and urine using the above approach. The limit of detection for clenbuterol, methadone, oxycodone, and chlordiazepoxide in saliva were 25, 10, 50, and 25 ng/mL, respectively, and in urine, 25, 5, 50, and 25 ng/mL. Finally, in about a minute, four dopings at concentration of 100 ng/mL in saliva and urine can be detected accurately and synchronously. This synchronous detection strategy further demonstrates the enormous advantages of SERS in on-site and rapid detection of multiple drugs.

Study on Acoustic Sensing Characteristics of a Novel Grooved SiO2 Waveguide Resonator

Photoacoustic sensor has become a research hotspot in the field of acoustic sensing in recent years due to its high sensitivity and anti-electromagnetic interference. A novel high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> grooved silica waveguide acoustic sensor (GSWAS) is proposed, which is etched and filled the Polydimethylsiloxane (PDMS) above the waveguide coupling region. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> factor of the sensor is of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.82\times 10^{{6}}$ </tex-math></inline-formula> . In order to detect the sound signal easily and intuitively, an acoustic sensing system was built by using Pound–Drever–Hall (PDH) frequency locking technology, and the weak sound signal was demodulated by using the method of synchronous demodulation of high frequency modulation. Experimental results show that the designed sensor has a flat response in the frequency range of 0.4–15 kHz and can accurately detect the acoustic signal, with a high sensitivity of 1143 mV/Pa and a signal-to-noise ratio (SNR) of up to 45.19 dB under the action of acoustic signal of 8 kHz. This article explores a new method of frequency bandwidth and high sensitivity sound detection, laying a foundation in the field of acoustic signal detection such as aeroacoustics, photoacoustic imaging, and all that.

Application of QbD-based approach to the development and validation of an RP-HPLC method for simultaneous estimation of pregabalin and naringin in dual-drug loaded liposomes.

The current work delineates the development of a novel, rugged and sensitive stability-indicating risk-based HPLC method based on an analytical quality-by-design (QbD) approach for the concurrent estimation of naringin and pregabalin in dual-drug-loaded nanopharmaceuticals. Preliminary screening trials were conducted, along with systemic risk analysis, in order to identify the critical method attributes, namely injection volume, pH and acetonitrile content, that influence critical quality attributes. The Box-Behnken design was used to optimize the tailing factor as a response to pregabalin and naringin in a short run time. The chromatographic conditions were improved by running 17 experimental runs generated by design expert software. After analysing the optimized zone within the confines of the design space, the following chromatographic conditions were chosen: mobile phase water-acetonitrile adjusted to pH6.9 with phosphate buffer (80:20, %v/v), at flow rate of 1.0ml/min using a C18 analytical column at an isobestic wavelength of 212 nm. Furthermore, the optimized method was validated in accordance with International Conference on Harmonization guidelines and was found to be within the prescribed limits. The developed RP-HPLC method has a high degree of practical utility in in vivo and in vitro studies for the synchronous detection of pregabalin and naringin in pharmaceutical nanodosage forms such as protein-based nanoparticles, nanocrystals, polymeric nanoparticles and metallic nanoparticles.

Simultaneous Determination of Zearalenone and Aflatoxin B1 in Maize by High Performance Liquid Chromatography

This experiment established a method for the simultaneous detection of Zearalenone (ZEN) and Aflatoxin B1 (AFB1) in corn using High-Performance Liquid Chromatography with fluorescence detector. The sample was extracted with acetonitrile: 0.2% formic acid water (volume ratio: 80:20) and passed through a Prime HLB 3cc purification column. Liquid phase detection conditions: The chromatographic column is Agilent C18 (150mm×4.6mm,5μm) The mobile phase is acetonitrile: water (volume ratio: 80:20). The retention time is qualitative and the external standard method is quantitative. The results showed that the correlation coefficients for ZEN 20～1000ng/mL and AFB1 1～50ng/mL were 0.9989 and 0.9976, respectively, and the detection limits were 5μg/kg and 0.8 μg/kg, with an average spiked recovery of 92.7% to 106.2%. This study combines the detection methods in the current two national standards into one, which can simultaneously achieve rapid and synchronous detection of ZEN and AFB1 in corn. The required extraction and detection time is reduced from 60 minutes to 30 minutes, which is 50% less than the original time. The detection results have high accuracy and good stability.

Integrated Filter Design for Analog Field Mill Sensor Interface

The design process of an integrated bandpass filter targeted for the noise filtering stage of the synchronous demodulation unit of an electric field mill sensor interface is presented. The purpose of this study of filter integration techniques is to avoid the challenging and, in some cases, impossible passive element integration process and to incorporate the final filter design in an entirely integrated field mill sensing system with superior performance and an optimized silicon-to-cost ratio. Four different CMOS filter implementations in the 0.18 μm process of XFAB, using OTA (Operational Transconductance Amplifier)-based configurations for passive element replacement in cascaded filter topologies and leapfrog techniques, are compared in terms of noise performance, total harmonic distortion, dynamic range, and power consumption, as well as in terms of integrability, silicon area, and performance degradation at process corners/mismatches. The optimum filter design performance-wise and process-wise is included in the final design of the integrated analog readout of a field mill sensor, and post-layout simulation results of the total circuit are presented.

IRT and DIC Synchronous Detection of Stress Intensity Factors and Plastic Zone Ranges

To achieve non-contact in situ detection of stress intensity factors (SIF), this paper innovatively adopts the advanced IRT and DIC synchronous detecting system to measure SIFs as using plastic zone range to assist in determining the state of stress fields. Though this synchronous detecting method has been applied to analyze thermomechanical coupling effects of materials, it has never been used to detect SIFs, which requires a high accuracy of point stress state detection. Thus, to testify its feasibility and accuracy in SIF detection, three engineering materials were subjected to various loading conditions to provide sufficient verification. Firstly, the coefficients of volumetric strain and temperature change of different materials were calibrated by thermocouple and infrared thermography. Then, the compact tensile specimens were subjected to high-speed loading, of which the SIFs and plastic zone ranges were computed by taking several measurement points on infrared and deformation images. Compared with the theoretical values, the errors of the SIF and K-dominated range measured by this experimental method are all within 5%. It demonstrates that the synchronous detecting method has a wide application prospect in high-accurate crack tip strain field and crack development analysis.

Multi-feature detection of in-field grain lodging for adaptive low-loss control of combine harvesters

The phenomenon of grain lodging significantly affects the low-loss harvesting performance of automatic drive harvesters, and it has become an objective trend to simultaneously detect multi-feature grain lodging information with machines in the field. In order to solve the problem of high harvest loss in grain lodging areas, we propose a new method for synchronous detection of grain lodging multi-feature information based on 3D point cloud data of a depth camera, in order to realize adaptive regulation of unmanned and low-loss harvesting. The multi-feature information of lodging grain is composed of lodging position, degree and direction, which can provide effective support information for the adaptive regulation of automatic driving harvesters. For the scene of grain harvesting operation with low contrast characteristics, we make full use of the environmental characteristics of the lodging areas that are located in the non-lodged area, and construct a synchronous airborne extraction strategy for grain lodging multi-feature information. The test results show that the maximum detection error of the lodging degree is less than 9.0 cm, and the minimum detection error is better than 1.0 cm; the maximum detection error of the lodging direction is not more than 9.0°, the minimum detection error is less than 1.0°, the maximum harvesting height error is less than 5.0 cm, and the minimum harvesting height error is less than 5.0 cm. Better than 2.0 cm. Our method provides an effective solution for synchronous airborne detection of multi-feature grain lodging information, which can significantly reduce harvest loss in grain lodging areas, and is expected to accelerate the development of truly unmanned harvesting operations.

Si-based mid-infrared photodetector with dynamic Schottky barrier height modulation applicable for synchronous detection

We have proposed an electrical shutter operation of a nano-antenna infrared photodetector using Schottky barrier height (SBH) modulation, where the SBH is modulated by a reverse bias voltage V b applied to the detector. The inhomogeneity of the Schottky junction may be dominant in the mechanism of barrier height reduction. Compared to the photocurrent i ph obtained by modulating the frequency of on–off of the incident light, the proposed method yields almost the same value. Therefore, it can be concluded that the proposed method is capable of synchronous detection measurement. In addition, since the proposed method does not require a mechanical shutter, it is a compact system that can be used in very small electrical equipment.

Channel-Aided Transmission Parameter Signalling Detection for DTMB-A

For reliable synchronization and transmission parameter signalling (TPS) detection, the preamble based on distance detection (PBDD) is adopted in the digital terrestrial television multimedia broadcasting - advanced (DTMB-A) standard. However, the conventional signalling detection methods do not take the channel information into consideration and will undergo severe performance loss over frequency-selective channels, especially those with strong and long delay echos. In this paper, a novel two-stage TPS detection method is proposed based on the preamble for DTMB-A system, which utilizes the channel information to enhance the detection accuracy. After coarse distance evaluation, the equalization will be performed on the possible candidate subcarriers to reconstruct the OFDM signalling block, hence a more reliable correlation statistic can be obtained to achieve more accurate signalling detection. As demonstrated in the simulations, the detection accuracy can be improved remarkably by compensating the impact of the transmission channel compared with the traditional detection schemes, while the increment of the computational complexity is acceptable.

Wideband Synchronous Measurement-Based Detection and Location of High Impedance Fault for Resonant Distribution Systems With Integration of DERs

The increasing integration of distributed energy resources (DERs) into the distribution system has caused interference with the signals stimulated by high impedance faults (HIFs). Many existing HIF detection or location methods that are only based on the superficial nonlinearity features of signals rather than the deep laws, will become invalid. This paper proposes a detection and location scheme for HIFs by theoretically analyzing the relationships between signals and systems. By establishing the equivalent circuit of a resonant distribution system, an online method to calculate the kernel system parameters is proposed, based on which an adaptive criterion for HIF detection is provided. In this way, the ability to detect HIF is adequately exploited and independent of DER influences. The method is able to detect HIF over 8.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}{\Omega }$ </tex-math></inline-formula> under common operating conditions. Furthermore, the nonlinearity of HIF is analyzed by deriving laws about how wideband signals distribute in the system. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3^{\mathrm{ rd}}$ </tex-math></inline-formula> harmonic component of zero-sequence signals is proved to be superior in HIF location in terms of signal content and discrimination, which is also demonstrated to be valid under the influence of DER harmonic injection. On this basis, a HIF location method utilizing the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3^{\mathrm{ rd}}$ </tex-math></inline-formula> harmonic zero-sequence signals is proposed. The effectiveness of the method and its robustness to the DER interference are validated by simulated and field HIFs in 10kV systems.

Adaptive synchronous demodulation transform with application to analyzing multicomponent signals for machinery fault diagnostics

The combination of the complex structure and the nonstationary operating pattern makes the measured signal of the machinery a multi-component one with a complex time-varying spectral structure, challenging most time–frequency analysis methods in resolution, adaptability, and objectivity. As such, we propose a novel time–frequency analysis method, namely, the adaptive synchronous demodulation transform (ASDT), by adaptively designing a demodulation term according to the spectral structures of the target signals. The proposed demodulation term can make each component of the windowed signal stationary simultaneously without any prior knowledge, such as the number of components and the corresponding estimated instantaneous frequencies. ASDT possesses three main advantages: it can be used to analyze signals with nonlinear instantaneous frequencies; it can obtain the optimum frequency resolution when window width is set; and the demodulation term is flexible, implying that it can be specifically designed according to the frequency structures of different types of signals. Furthermore, ASDT allows for signal recovery. To testify the superiority of the proposed ASDT, two synthetic signals with parallel and proportional IFs structures were built, and several real-life signals, vibration signals collected from a planetary gearbox test rig and water turbine, and an echo signal collected from a brown bat were used. A comparison of the analysis results of ASDT with those of STFT, continuous wavelet transform, and Wigner–Ville distribution demonstrated the superiority of ASDT over conventional methods.