Remote-Optically Powered And Controlled Sensor Platform

This thesis presents a remote-optically powered and controlled sensor platform, and it also discusses and analyses most of designs in the system. This system is designed in the Institute of High-frequency and Quantum-electronics (IHQ) of University of Karlsruhe. Due to time limit, the system has not been completed. The unfinished work will be finished by my colleague who will take over this project. However, we have proposed the first multi-functional bidirectional transmission system based on power over fiber technology, and this structure has attracted some famous companies such as BMW, Areva and so on.This system is made up of base station, fiber link and remote unit. The base station powers and controls the remote unit over fiber by modulating high power laser diode, and the remote unit sends all sensor data and video data back to the base station by modulating VCSEL diode.The system has a LCD & Joystick interface. A friendly graphical control menu for MSP430 and Nokia 6610 LCD has been developed for users to control the remote unit by joystick. An adjustable laser driver has also been developed, which can emit from 100 mA to 4 A CW current and from 100 mA to 600 mA modulated current. The output current can be modulated up to 400 MHz. A cheap high power laser diode is used to power and control the remote unit via 810 nm wavelength. The control signal is transmitted as an AC component imposed on power signal, which realizes the bidirectional transmission. In the remote unit, a multi-segment photovoltaic cell is used for optical to electrical conversion instead of a single-segment photovoltaic cell. A special circuit is designed to separate the AC-component from the electrical power and stabilize the DC-component after the AC-component separation. The DC-component is used for powering the remote unit and the separated AC-component is for controlling the remote unit. The MSP430 microcontroller in remote unit takes charge of data-acquisition, processing and transmission. The sensor data and video data acquired and processed on the remote unit are directly modulated by the microcontroller, and then they are sent to a simple VCSEL driver circuit. Finally, the VCSEL driver circuit drives the VCSEL diode to transmit the data. A photodiode and a trans-impendence amplifier (TLA) are used to receive the optical signal from remote unit. After data processing, the data acquired will be shown on the Nokia 6610 LCD display.