Data telemetered in harsh environments are traditionally compressed, filtered, and processed before being transmitted, if telemetered at all. The user then has limited information about the status of monitored systems; however, the user's knowledge can be improved by real-time raw information transmission.
In harsh environments, data are traditionally transmitted over dedicated lines, through variations in a power source, or wirelessly. These methods suffer from signal attenuation and dispersion over long lengths, leading to lower data rates. Optical fiber systems, however, have low attenuation, little dispersion, and can use a variety of communication schemes, such as varying signal amplitudes, phases, or wavelengths. In particular, quadrature amplitude modulation (QAM) or pulse amplitude modulation (PAM) methods common for fiber telemetry backhauls can achieve greater bandwidths in harsh environments to realize real-time data retrieval without the need for processing.
This paper reviews the current state-of-the-art fiber-optic telemetry systems for harsh environments and discusses a proof-of-principle demonstration using higher-order optical modulation techniques to obtain data rates that are orders of magnitude greater than those achieved by electrical telemetry equivalent systems. The demonstration consisted of optical and electrical components that operated at temperatures up to 200°C and transmitted data along 18 km of fiber with over 10 dB of optical margin. The current state of the project and its application to a wide variety of possible field uses are explored.
Additionally, the use of fiber communications is reviewed to help improve data delivery to users in the energy industry, a topic of growing interest. It also highlights the innovative approaches for developing real-time, high-data-rate, bidirectional optical fiber telemetry for harsh environments.