scholarly journals Design and Implementation of a Long Range Indoor VLC System using PWM

2019 ◽  
Vol 3 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Majed Basha ◽  
Martin J. Sibley ◽  
Peter J. Mather
Keyword(s):  
High Speed ◽  
Pulse Width Modulation ◽  
Low Cost ◽  
Transmission Range ◽  
Band Pass Filter ◽  
Ambient Light ◽  
Visible Light Communications ◽  
Pass Filter ◽  
Light Interference ◽  
Front End

Visible Light Communications (VLC) is currently considered one of the most promising Optical Wireless Communications (OWC) for commercial applications, due to the widespread deployment of Light Emitting Diodes (LEDs) for energy efficiency, durability and low cost. With the ability to provide several THz of bandwidth, VLC is expected to co-exist with legacy and future Radio Frequency (RF) media as a reliable solution to the rapid demand of high-speed wireless communication. VLC is challenged by two main drawbacks: ambient light interference and the transmission range. To overcome these drawbacks, we propose a tuned VLC Analog Front-End (AFE) using simple and low-cost electronic circuity. The proposed VLC receiver architecture consists of a transimpedance amplifier, a fourth order Multiple Feed Back (MFB) band pass filter and a comparator. Experimental results demonstrated that by employing the proposed front-end the VLC transmission range could be extended up to 4.7 m by using Pulse Width Modulation (PWM). Moreover, the proposed system showed robustness against ambient light interference under the indoor scenario.

A Experiment Study of De-Noising to Reduce the Effect of Artificial Light Interferences for Visible Light Communications Using White-LEDs

2013 ◽  
Vol 694-697 ◽  
pp. 1465-1468
Author(s):  
Rong Cheng ◽  
Xiao Ming Yan
Keyword(s):  
Visible Light ◽  
Optical Power ◽  
Artificial Light ◽  
Band Pass Filter ◽  
Visible Light Communications ◽  
Pass Filter ◽  
White Leds ◽  
Voice Transmission ◽  
Light Interference ◽  
Band Pass

The optical power penalty (OPP) due to the artificial light interference (ALI) can influence the performance of the Visible Light Communications (VLC) system significantly. In this paper, a de-noising scheme based on band-pass filter is achieved in a voice-transmission VLC experiment system and it was proved a effective scheme to improve the quality of the transmission significantly

scholarly journals Preparation of Nickel Nanoparticles by Direct Current Arc Discharge Method and Their Catalytic Application in Hybrid Na-Air Battery

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 684 ◽  
Author(s):  
Fengmei Su ◽  
Xuechao Qiu ◽  
Feng Liang ◽  
Manabu Tanaka ◽  
Tao Qu ◽  
...  
Keyword(s):  
Direct Current ◽  
Composite Structures ◽  
High Speed ◽  
Large Scale ◽  
Nickel Nanoparticles ◽  
Arc Discharge ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Air Battery ◽  
Discharge Method

Nickel nanoparticles were prepared by the arc discharge method. Argon and argon/hydrogen mixtures were used as plasma gas; the evaporation of anode material chiefly resulted in the formation of different arc-anode attachments at different hydrogen concentrations. The concentration of hydrogen was fixed at 0, 30, and 50 vol% in argon arc, corresponding to diffuse, multiple, and constricted arc-anode attachments, respectively, which were observed by using a high-speed camera. The images of the cathode and anode jets were observed with a suitable band-pass filter. The relationship between the area change of the cathode/anode jet and the synchronous voltage/current waveform was studied. By investigating diverse arc-anode attachments, the effect of hydrogen concentration on the features of nickel nanoparticles were investigated, finding that 50 vol% H2 concentration has high productivity, fine crystallinity, and appropriate size distribution. The synthesized nickel nanoparticles were then used as catalysts in a hybrid sodium–air battery. Compared with commercial a silver nanoparticle catalyst and carbon black, nickel nanoparticles have better electrocatalytic performance. The promising electrocatalytic activity of nickel nanoparticles can be ascribed to their good crystallinity, effective activation sites, and Ni/NiO composite structures. Nickel nanoparticles prepared by the direct current (DC) arc discharge method have the potential to be applied as catalysts on a large scale.

scholarly journals A Low-Cost, High-Precision Method for Ripple Voltage Measurement Using a DAC and Comparators

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 586
Author(s):  
Jincheng Liu ◽  
Jiguang Yue ◽  
Li Wang ◽  
Chenhao Wu ◽  
Feng Lyu
Keyword(s):  
High Precision ◽  
High Speed ◽  
Low Cost ◽  
Estimation Method ◽  
Electronic System ◽  
Voltage Measurement ◽  
Pass Filter ◽  
Switched Mode Power Supply ◽  
Dc Component ◽  
Microcontroller Unit

As the core of electronic system, the switched-mode power supply (SMPS) will lead to serious accidents and catastrophes if it suddenly fails. According to the related research, the monitoring of ripple can acquire the health degree of SMPS indirectly. To realize low-cost, high-precision, and automatic ripple measurement, this paper proposes a new ripple voltage (peak-to-peak value) measuring scheme, utilizing a DAC and two high-speed comparators. Within this scheme, the DC component of SMPS output is blocked by a high-pass filter (HPF). Then, the filtered signal and the reference voltage from a DAC together compose the input of a high-speed comparator. Finally, output pulses of the comparator are captured by a microcontroller unit (MCU), which readjusts the output of the DAC by calculation, and this process is repeated until the DAC output is exactly equal to the peak (or valley) value of ripple. Moreover, in order to accelerate the measurement process, a peak estimation method is specially designed to calculate the output ripple peak (or valley) value of buck topology through merely two measurements. Then the binary search method is utilized to obtain a more exact value on the basis of estimative results. Additionally, an analysis of the measurement error of this ripple measurement system is executed, which shows that the theoretical error is less than 0.5% where the ripple value is larger than 500 mV. Furthermore, appropriate components are selected, and a prototype is manufactured to verify the validity of the proposed theory.

scholarly journals Antiresonant Reflecting Guidance and Mach-Zender Interference in Cascaded Hollow-Core Fibers for Multi-Parameter Sensing

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4140
Author(s):  
Maoxiang Hou ◽  
Jun He ◽  
Xizhen Xu ◽  
Ziliang Li ◽  
Zhe Zhang ◽  
...  
Keyword(s):  
Transmission Loss ◽  
Low Cost ◽  
Gas Pressure ◽  
Band Pass Filter ◽  
Hollow Core ◽  
Pass Filter ◽  
Multiple Parameters ◽  
Linear Relationships ◽  
Band Pass ◽  
Spectral Ranges

We propose and demonstrate a cascaded hollow-core fiber (HCF) device for multi-parameter sensing based on the combination of antiresonant reflecting guidance (ARRG) and Mach-Zender interference (MZI). The device was fabricated by splicing two sections of HCF together. Two sets of fringes, which have different free spectral ranges, were generated from ARRG and MZI, respectively, and were aliasing in the transmission spectrum. The two sets of fringes were then separated using a band pass filter and a Gaussian fitting technique. The wavelengths at two transmission loss dips formed by ARRG and MZI exhibit a temperature sensitivity of 14.1 and 28.5 pm/°C, and a strain sensitivity of 0.4 and −0.8 pm/με, respectively. By using a crossing matrix with differences sensitivities, the cross-sensitivity between temperature and strain can be solved. The gas pressure response of the cascaded HCF device was also tested up to 300 °C, and linear relationships between the gas pressure sensitivities and temperature were found, which can be used in gas pressure application in various temperatures. Moreover, the proposed cascaded HCF sensor is compact, low cost, and simple for fabrication, and hence offers a promising way for the simultaneous measurement of multiple parameters, such as temperature, strain, and gas pressure.

scholarly journals A Low-Voltage Multi-Band ZigBee Transceiver

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1474
Author(s):  
Zhiqun Li ◽  
Yan Yao ◽  
Zengqi Wang ◽  
Guoxiao Cheng ◽  
Lei Luo
Keyword(s):  
Frequency Synthesizer ◽  
Low Voltage ◽  
Supply Voltage ◽  
Maximum Output Power ◽  
Cmos Technology ◽  
Maximum Output ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Front End ◽  
Band Pass

This paper presents a low-voltage ZigBee transceiver covering a unique frequency band of 780/868/915/2400 MHz in 180 nm CMOS technology. The design consists of a receiver with a wideband variable-gain front end and a complex band-pass filter (CBPF) based on poles construction, a transmitter employing the two-point direct-modulation structure, a Ʃ-Δ fractional-N frequency synthesizer with two VCOs and some auxiliary circuits. The measured results show that under 1 V supply voltage, the receiver reaches −93.8 dBm and −102 dBm sensitivity for 2.4 GHz and sub-GHz band, respectively, and dissipates only 1.42 mW power. The frequency synthesizer achieves −106.8 dBc/Hz and −116.7 dBc/Hz phase noise at 1 MHz frequency offset along with 4.2 mW and 3.5 mW power consumption for 2.4 GHz and sub-GHz band, respectively. The transmitter features 2.67 dBm and 12.65 dBm maximum output power at the expense of 21.2 mW and 69.5 mW power for 2.4 GHz and sub-GHz band, respectively.

scholarly journals Carrierless amplitude and phase modulation in wireless visible light communication systems

2020 ◽  
Vol 378 (2169) ◽  
pp. 20190181 ◽  
Author(s):  
N. Bamiedakis ◽  
R. V. Penty ◽  
I. H. White
Keyword(s):  
Visible Light ◽  
Communication Systems ◽  
High Speed ◽  
Low Cost ◽  
Visible Light Communication ◽  
Practical Implementation ◽  
Visible Light Communications ◽  
Modulation Formats ◽  
Spectrally Efficient ◽  
Basic Features

Visible light communications (VLCs) have attracted considerable interest in recent years owing to the potential to simultaneously achieve data transmission and illumination using low-cost light-emitting diodes (LEDs). However, the high-speed capability of such links is typically limited by the low bandwidth of LEDs. As a result, spectrally efficient advanced modulation formats have been considered for use in VLC links in order to mitigate this issue and enable higher data rates. Carrierless amplitude and phase (CAP) modulation is one such spectrally efficient scheme that has attracted significant interest in recent years owing to its good potential and practical implementation. In this paper, we introduce the basic features of CAP modulation and review its use in the context of indoor VLC systems. We describe some of its attributes and inherent limitations, present related advances aiming to improve its performance and potential and report on recent experimental demonstrations of LED-based VLC links employing CAP modulation. This article is part of the theme issue ‘Optical wireless communication’.

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