FIBER OPTICS SYSTEM WITH SELF TEST CAPABILITY

摘要

FIBER OPTICS SYSTEM WITH SELF TEST CAPABILITYABSTRACT OF THE DISCLOSUREA fire detection system incorporating fiber opticsand having a selectively energizable light source forapplying light pulses to a fiber optics path and a one-way light transmitting element, such as a dichroicmirror, at the remote end of the fiber optics path forreflecting the pulses back to the detection portion ofthe system, thus providing a Built In Test Equipment(BITE) test capability in the system. Instead of adichroic mirror, a bandpass filter may be used as thelight transmitting member. The bandpass filter isselected to transmit light with wavelengths in therange from about 1.3 to 1.5 microns, in which case thelight source is a light emitting diode (LED) emittinglight at a wavelength of approximately 0.9 microns.The fiber optics path includes a branch which is coupledto the light source. This branch may comprise onefiber of a multi-fiber bundle or it may be an auxiliaryfiber of a commercially available fiber optics combiner.An overall system incorporates a plurality ofthese individual fire detection arrangements inconjunction with a BITE control stage and associatedfire alarm. Any detected fire activates the fire alarm.However, the same fire detection signal, when the systemis operated in the BITE test mode, is used by the BITEapparatus to detect failures in the system and identifythe portion of the system experiencing the failure.