10 January 1997 Code-division multiplexing of fiber optic sensors with LED sources
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Abstract
Code division multiplexing can be used to increase the number of senors operated on one light emitting diode (LED) and thereby reduce the unit sensor cost of the complete sensor system. We have successfully designed a system to multiplex 32 sensors on one LED with output power of approximately 0.4 mW, at 850 nm wavelength. The LED is modulated with a pseudo-random pulse sequence and distributed through a 2 by 32 coupler to 32 reflective sensors. Sensor response is measured by computing the cross correlation of the transmitted code and the sensor reflection. The response is separated in time by varying the length of the sensor fiber. Sensor noise is reduced by averaging and cross correlation of the sensor response with the transmitted code sequence. All processing is done by microcomputer and a digital oscilloscope. The system was demonstrated with multimode fiber connected to 2 Fabry-Perot sensors and 1 amplitude sensor. Noise values on each sensor imply that more than 32 sensors can be monitored with code division multiplexing technology.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Henry K. Whitesel, John K. Overby, Antal A. Sarkady, Carl P. Jacobson, "Code-division multiplexing of fiber optic sensors with LED sources", Proc. SPIE 3000, Laser Diode and LED Applications III, (10 January 1997); doi: 10.1117/12.263488; https://doi.org/10.1117/12.263488
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