4 October 1994 Optical cavity resonance in a fly-by-light flight control system
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Abstract
Optical pulse reflections in the signal paths of a fly-by-light flight control system employing time division multiplexing can interfere with data returning date to the receiver. To determine how reflections of the interrogation pulse may interfere with optical data signals returning from an optical transducer to the flight control computer. Fresnel reflection theory and geometric optics are used to predict the intensity and return times of the pulse reflections at the receiver. A channel with multiple connectors and a 12-bit position transducer is considered as an example of a typical channel in a fly-by-light flight control system. The optical power and return times of the pulse reflections in the example channel are predicted and are compared with the optical power and return time window of the returning data signal. To check the analytical prediction, a dynamic simulation of the example optical channel is used to model the signal behavior. Although the analysis shows that the reflections from the connector interfaces can interfere with the transducer data by arriving at the same time as the data, these spurious signals can be rejected if the optical receiver is designed properly. It is recommended that the Fresnel reflection intensity, the number of disconnects in the interconnect cable and the relative insertion loss of the interconnect cable compared to that of the transducer must be minimized to warrant reliable operation and simpler receiver design.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Simon Turner, Simon Turner, Fernando Dones, Fernando Dones, Deepak Varshneya, Deepak Varshneya, } "Optical cavity resonance in a fly-by-light flight control system", Proc. SPIE 2295, Fly-by-Light, (4 October 1994); doi: 10.1117/12.188843; https://doi.org/10.1117/12.188843
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