Comunicação de dados por luz visível através de LEDs usados na iluminação de ambientes

<p class="Normal1">Este trabalho propõe um sistema de Comunicação por Luz Visível (<em>Visible Light Communication</em>, VLC), de baixo custo e fácil implementação para aplicações, por exemplo, em Internet das Coisas <em>(Internet of Things</em>, IoT). São apresentados resultados de simulações, ressaltando os pontos fortes e fracos da arquitetura proposta. Os resultados obtidos são baseados no uso de Diodos Emissores de Luz (<em>Light Emitting Diodes</em>, LED) para a iluminação residencial e na modulação ASK (<em>Amplitude Shift Keying</em>). O sistema possui a capacidade de transmissão simplex de informações multimídia de maneira eficiente, de acordo com a técnica de modulação e o protocolo de comunicação empregados, utilizando um <em>clock</em> óptico de 4 MHz e alcançando uma taxa de transmissão efetiva de 3,2 Mbits/s.</p>

An internally-controlled memristor-based amplitude shift keying modulator

Purpose The purpose of this paper is to design and construct an amplitude shift keying (ASK) modulator, which, using the digital binary modulating signal, controls a floating memristor emulator (MR) internally without the need for additional control circuits to achieve the ASK modulated wave. Design/methodology/approach A binary digital unipolar signal to be modulated is converted by a pre-processor circuit into a suitable bipolar modulating direct current (DC) signal for the control of the MR state, using current conveyors the carrier signal’s amplitude is varied with the change in the memristance of the floating MR. A high pass filter is then used to remove the DC control signal (modulating signal) leaving only the modulated carrier signal. Findings The results from the experiment and simulation are in agreement showed that the MR can be switched between two states and that a change in the carrier signals amplitude can be achieved by using an MR. Thus, showing that the circuit behavior is in line with the proposed theory and validating the said theory. Originality/value In this paper, the binary signal to be modulated is modified into a suitable control signal for the MR, thus the MR relies on the internal operation of the modulator circuit for the control of its memristance. An ASK modulation can then be achieved using a floating memristor without the need for additional circuits or signals to control its memristance.