scholarly journals Generating and Detecting Solvable Chaos at Radio Frequencies with Consideration to Multi-User Ranging

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 774 ◽  
Author(s):  
Aubrey N. Beal ◽  
Seth D. Cohen ◽  
Tamseel M. Syed
Keyword(s):  
Matched Filter ◽  
Low Cost ◽  
Digital Signal ◽  
Present Theory ◽  
Noise Sources ◽  
Multiple Systems ◽  
High Entropy ◽  
Detection Techniques ◽  
Close Proximity ◽  
Correlation Properties

High entropy waveforms exhibit desirable correlation properties in radar and sonar applications when multiple systems are used in close proximity. Unfortunately, the information content of these signals can impose high sampling requirements for digital detection techniques. Solvable chaotic oscillators have been proposed to address such issues due to their simple, matched filters, where hardware has been demonstrated with a bandwidth of 10–20 kHz. To extend applications of these systems, we present theory, design, and experimental verification of solvable chaos at 1 MHz using simple off-the-shelf components. The waveforms produced by this system were propagated over a 2.45 GHz RF link and detected with an RLC-based, purely analog matched filter. Further, we show that properties of this special class of chaotic systems can be exploited to yield RF noise sources that are generally advantageous for multi-user ranging applications when compared to conventional techniques. The result is a simple, low-cost, and potentially low-power RF ranging system that requires very little digital signal processing.

scholarly journals Cloud Detection Based on High Resolution Stereo Pairs of the Geostationary Meteosat Images

2020 ◽  
Vol 12 (3) ◽  
pp. 371 ◽  
Author(s):  
Sahar Dehnavi ◽  
Yasser Maghsoudi ◽  
Klemen Zakšek ◽  
Mohammad Javad Valadan Zoej ◽  
Gunther Seckmeyer ◽  
...  
Keyword(s):  
High Resolution ◽  
Matched Filter ◽  
Stereo Pair ◽  
Cloud Detection ◽  
Operating Characteristics ◽  
Detection Techniques ◽  
Infrared Imager ◽  
Detection Approach ◽  
Considerable Impact ◽  
Image Pairs

Due to the considerable impact of clouds on the energy balance in the atmosphere and on the earth surface, they are of great importance for various applications in meteorology or remote sensing. An important aspect of the cloud research studies is the detection of cloudy pixels from the processing of satellite images. In this research, we investigated a stereographic method on a new set of Meteosat images, namely the combination of the high resolution visible (HRV) channel of the Meteosat-8 Indian Ocean Data Coverage (IODC) as a stereo pair with the HRV channel of the Meteosat Second Generation (MSG) Meteosat-10 image at 0° E. In addition, an approach based on the outputs from stereo analysis was proposed to detect cloudy pixels. This approach is introduced with a 2D-scatterplot based on the parallax value and the minimum intersection distance. The mentioned scatterplot was applied to determine/detect cloudy pixels in various image subsets with different amounts of cloud cover. Apart from the general advantage of the applied stereography method, which only depends on geometric relationships, the cloud detection results are also improved because: (1) The stereo pair is the HRV bands of the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) sensor, with the highest spatial resolution available from the Meteosat geostationary platform; and (2) the time difference between the image pairs is nearly 5 s, which improves the matching results and also decreases the effect of cloud movements. In order to prove this improvement, the results of this stereo-based approach were compared with three different reflectance-based target detection techniques, including the adaptive coherent estimator (ACE), constrained energy minimization (CEM), and matched filter (MF). The comparison of the receiver operating characteristics (ROC) detection curves and the area under these curves (AUC) showed better detection results with the proposed method. The AUC value was 0.79, 0.90, 0.90, and 0.93 respectively for ACE, CEM, MF, and the proposed stereo-based detection approach. The results of this research shall enable a more realistic modelling of down-welling solar irradiance in the future.

scholarly journals A 40 Mb/s VLC System Reusing an Existing Large LED Panel in an Indoor Office Environment

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1697
Author(s):  
Xicong Li ◽  
Zabih Ghassemlooy ◽  
Stanislav Zvánovec ◽  
Paul Anthony Haigh
Keyword(s):  
Modulation Depth ◽  
Light Emitting Diode ◽  
Low Cost ◽  
Data Communication ◽  
Experimental System ◽  
Digital Signal ◽  
Visible Light Communication ◽  
Cost Driver ◽  
Limiting Factors ◽  
Light Sources

With advances in solid-state lighting, visible light communication (VLC) has emerged as a promising technology to enhance existing light-emitting diode (LED)-based lighting infrastructure by adding data communication capabilities to the illumination functionality. The last decade has witnessed the evolution of the VLC concept through global standardisation and product launches. Deploying VLC systems typically requires replacing existing light sources with new luminaires that are equipped with data communication functionality. To save the investment, it is clearly desirable to make the most of the existing illumination systems. This paper investigates the feasibility of adding data communication functionality to the existing lighting infrastructure. We do this by designing an experimental system in an indoor environment based on an off-the-shelf LED panel typically used in office environments, with the dimensions of 60 × 60 cm2. With minor modifications, the VLC function is implemented, and all of the modules of the LED panel are fully reused. A data rate of 40 Mb/s is supported at a distance of up to 2 m while using the multi-band carrierless amplitude and phase (CAP) modulation. Two main limiting factors for achieving higher data rates are observed. The first factor is the limited bandwidth of the LED string inside the panel. The second is the flicker due to the residual ripple of the bias current that is generated by the panel’s driver. Flicker is introduced by the low-cost driver, which provides bias currents that fluctuate in the low frequency range (less than several kilohertz). This significantly reduces the transmitter’s modulation depth. Concurrently, the driver can also introduce an effect that is similar to baseline wander at the receiver if the flicker is not completely filtered out. We also proposed a solution based on digital signal processing (DSP) to mitigate the flicker issue at the receiver side and its effectiveness has been confirmed.

A dsPIC Microcontroller Based System Identification of Positive Output Buck Boost Converter for Module Mismatch Application

2015 ◽  
Vol 785 ◽  
pp. 106-110
Author(s):  
M.N.M. Hussain ◽  
Ahmad Maliki Omar ◽  
Intan Rahayu Ibrahim ◽  
Kamarulazhar Daud
Keyword(s):  
Direct Method ◽  
Low Cost ◽  
Digital Signal ◽  
Solar Irradiation ◽  
Identification System ◽  
Pv System ◽  
Partial Shading ◽  
Single Output ◽  
Pv Module ◽  
Power Point

An identification system of multiple-input single-output (MISO) model is developed in controlling dsPIC microcontroller of positive output buck-boost (POBB) converters for module mismatch condition of photovoltaic (PV) system. In particular, the possibility of the scheme is to resolve the mismatch losses from the PV module either during shading or mismatch module occurrences. The MPPT algorithm is simplified by identification approach of indirect incorporated with a simple incremental direct method to form a combined direct and indirect (CoDId) algorithms. Irregular consumption of solar irradiation on a PV module shall step-up or step down the voltage regarding to the desired DC output voltage of POBB converter. This optimized algorithm will ensure that the PV module to kept at maximum power point (MPP), preventing power loss during module mismatch incident in PV module especially during partial shading condition. The simulation and laboratory results for PV module of polycrystalline Mitsubishi PV-AE125MF5N indicate that the proposed model and development of PV system architecture performs well, while the efficiency up to 97.7% at critical of low solar irradiance level. The controlling signal is based on low-cost embedded microcontroller of dsPIC30F Digital Signal Control (DSC).

scholarly journals On the Clouds: A New Way of Computing

2010 ◽  
Vol 29 (2) ◽  
pp. 87 ◽  
Author(s):  
Yan Han
Keyword(s):  
Cloud Computing ◽  
Low Cost ◽  
Content Management ◽  
Management Systems ◽  
Multiple Systems ◽  
Computing Services ◽  
It Project ◽  
Cloud Computing Services ◽  
Repository Software ◽  
Content Management Systems

This article introduces cloud computing and discusses the author’s experience “on the clouds.” The author reviews cloud computing services and providers, then presents his experience of running multiple systems (e.g., integrated library systems, content management systems, and repository software). He evaluates costs, discusses advantages, and addresses some issues about cloud computing. Cloud computing fundamentally changes the ways institutions and companies manage their computing needs. Libraries can take advantage of cloud computing to start an IT project with low cost, to manage computing resources cost-effectively, and to explore new computing possibilities.

scholarly journals A Review of Self-Coherent Optical Transceivers: Fundamental Issues, Recent Advances, and Research Directions

2021 ◽  
Vol 11 (16) ◽  
pp. 7554
Author(s):  
Isiaka Alimi ◽  
Romil Patel ◽  
Nuno Silva ◽  
Chuanbowen Sun ◽  
Honglin Ji ◽  
...  
Keyword(s):  
High Speed ◽  
High Performance ◽  
Low Cost ◽  
Dynamic Environment ◽  
Digital Signal ◽  
Research Directions ◽  
Recent Advances ◽  
Heterogeneous Nature ◽  
Signal Processing Algorithms ◽  
Processing Algorithms

This paper reviews recent progress on different high-speed optical short- and medium-reach transmission systems. Furthermore, a comprehensive tutorial on high-performance, low-cost, and advanced optical transceiver (TRx) paradigms is presented. In this context, recent advances in high-performance digital signal processing algorithms and innovative optoelectronic components are extensively discussed. Moreover, based on the growing increase in the dynamic environment and the heterogeneous nature of different applications and services to be supported by the systems, we discuss the reconfigurable and sliceable TRxs that can be employed. The associated technical challenges of various system algorithms are reviewed, and we proffer viable solutions to address them.

scholarly journals Review on the Millimeter-Wave Generation Techniques Based on Photon Assisted for the RoF Network System

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jiangnan Xiao ◽  
Chuang Zhao ◽  
Xingxing Feng ◽  
Xu Dong ◽  
Jiangli Zuo ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Cost ◽  
Electronic Devices ◽  
Low Frequency ◽  
Digital Signal ◽  
Development Trend ◽  
Wave Generation ◽  
Communication Link ◽  
Network System ◽  
High Frequency Microwave

With the development trend of wireless and broadband in the communication link and even the whole information industry, the demand of high-frequency microwave bandwidth has been increasing. The RoF network system solves the problem of spectrum congestion in low-frequency band by providing an effective technology for the distribution of high-frequency microwave signals over optical fiber links. However, the traditional mm-wave generation technique is limited by the bandwidth of electronic devices. It is difficult to generate high-frequency and low-phase noise mm-wave signals with pure electrical components. The mm-wave communication technology based on photon assisted can overcome the bandwidth bottleneck of electronic devices and provide the potential for developing the low-cost infrastructure demand of broadband mobile services. This paper will briefly explain the characteristics of the RoF network system and the advantages of high-frequency mm-wave. Then we, respectively, introduce the modulation schemes of RoF mm-wave generation based on photon assisted including directly modulated laser (DML), external modulation, and optical heterodyne. The review mainly focuses on a variety of different mm-wave generation technologies including multifrequency vector mm-wave. Furthermore, we list several approaches to realize the large capacity data transmission techniques and describe the digital signal processing (DSP) algorithm flow in the receiver. In the end, we summarize the RoF network system and look forward to the future.

scholarly journals A reconfigurable software defined ultra-wideband impulse radio transceiver

2010 ◽  
Vol 8 ◽  
pp. 67-73 ◽  
Author(s):  
M. D. Blech ◽  
A. T. Ott ◽  
P. Neumeier ◽  
M. Möller ◽  
T. F. Eibert
Keyword(s):  
Software Defined Radio ◽  
Matched Filter ◽  
Digital Signal ◽  
Impulse Radio ◽  
Ultra Wideband ◽  
Modulation Scheme ◽  
Digital To Analog Converter ◽  
Shift Keying ◽  
Reconfigurable Software ◽  
Radio Transceiver

Abstract. An ultra-wideband (UWB) software defined radio (SDR) implementation is presented. The developed impulse radio (IR) transceiver employs first order bandpass (BP) sampling at a conversion frequency which is four times the channel bandwidth. The subsampling architecture directly provides the RF signal avoiding any non-ideal mixer stages and reduces the requirements of digital signal processing implemented in a field programmable gate array (FPGA). The transmitter consists basically of a multi-Nyquist digital to analog converter (DAC), whereas the implemented matched filter (MF) receiver prototype employs a standard digitizing oscilloscope. This design can be adaptively reconfigured in terms of modulation, data rate, and channel equalization. The reconfigurable design is used for an extensive performance analysis of the quadrature phase shift keying (QPSK) modulation scheme investigating the influence of different antennas, amplifiers, narrowband interferers as well as different equalizer lengths. Even for distances up to 7 m in a multipath environment robust communication was achieved.

An Improved Passive Anti-Islanding Technique for Distributed-Generation Photovoltaic Systems

2013 ◽  
Vol 433-435 ◽  
pp. 995-999
Author(s):  
Shao Ru Zhang ◽  
Shao Yuan Li
Keyword(s):  
High Reliability ◽  
Low Cost ◽  
Phase Variation ◽  
Operating Mode ◽  
Detection Zone ◽  
Electrical Grid ◽  
Detection Techniques ◽  
Frequency Detection ◽  
Grid Connected Inverter ◽  
Passive Techniques

Islanding detection techniques for DGPV are employed in order to determine the status of the electrical grid. In fact, the grid-connected inverter must be stopped once the islanding operating mode is detected according to standards and grid-code limits. Passive anti-islanding techniques monitor grid parameters to detect islanding. One advantage of passive techniques is a lower THD injected into the grid by active techniques. Thus, passive techniques were studied and an improved passive detection technique was proposed in this paper. The ratio of phase variation and the voltage variation at the point of common coupling (PCC) was adopted to detect islanding. In addition, this method combined with the under/over voltage detection and the under/over frequency detection. Then, the proposed technique not only has the merit of low cost and easy to operate, but also has multiple judgment and high reliability. The simulation results under Matlab/Simulink show that the proposed technique is very effective in reducing the non-detection zone and that the islanding operation can be detected more rapidly and effectively than traditional passive techniques, and that it can not misjudge when the load reduce suddenly.

DESIGN AND PERFORMANCE SIMULATION OF STRUCTURED MICROWAVE ABSORBER BASED ON CONDUCTIVE ABS 3D PRINTING FILAMENT

2021 ◽  
Vol 4 (4) ◽  
pp. 425-431
Author(s):  
M. B. Abdullahi ◽  
M. H. Ali
Keyword(s):  
3D Printing ◽  
Absorption Rate ◽  
Low Cost ◽  
Normal Incidence ◽  
Transverse Magnetic ◽  
Microwave Absorber ◽  
Shielding Effectiveness ◽  
Geometrical Structures ◽  
Detection Techniques ◽  
Absorption Characteristics

Electromagnetic absorbing materials with broadband, lightweight, wide-angle, and polarization-insensitive characteristics attracts extensive research interest recently, due to rapid advancement in radar detection techniques and communication devices. Three-dimensional printing is being employed to realize cost-effective structured electromagnetic absorbers that has lately become a common practice of improving radar stealth performance and shielding effectiveness. Structured absorbers permit realization of desired absorption characteristics by careful design of their geometrical structures. In this study, a two-layer structured microwave absorber using conductive ABS polymer is simulated. COMSOL Multiphysics environment is used to investigate the absorption characteristics of the designed structure. Under normal incidence, simulation results revealed at least 90% of absorption from 7.2 GHz to 18.0 GHz for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations. Oblique incidence results for TE polarization indicate that the absorption rate is more than 90% in the whole range of 7.2–18 GHz frequency band up to 450 while the absorption rate is more than 80% for 600 incident waves. The absorption rate is more than 90% in the 7.2-18 GHz range for oblique incidences of up to 300 only for TM polarization, but greater than 70% at 450 incident angles. Additionally, the designed absorber is independent of the polarization of the incident wave. As a result of the exhibited favourable absorption characteristics, the studied absorber provides great potentials for its experimentation and practicability using the low-cost 3D printing manufacturing process

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