Fiber-Optic Link Design Considerations for Applications in Noisy Industrial Environments

Industrial system considerations suggest the need for fiberoptic data links that have the ability to reduce susceptibility to noise from EMI or RFI, to isolate a system from high voltages and transmit reliable data. This paper deals with the design aspects of a fiber-optic system link, suitable for industrial process applications, and addresses process environments with slowly changing parameters such as: pressure, temperature, position (both rotary and linear), etc., available at the output of system interfacing sensors in the form of voltages, where less attention has been paid thus far. The approach used involves a voltage-pulse frequencyvoltage conversion technique with a VCO in the modulator and a PLL circuit in the demodulator. By changing a few components, the system can be converted into a simplex intercommunication optical link.