Optical health monitoring for aircraft overheat and fire detection systems

A method of detecting thermal conditions for an aircraft, the method comprising:

• emitting, by a first local controller, a first optical signal to a first zone fiber optic cable, wherein the first zone fiber optic cable is routed through each of a first plurality of zones of the aircraft;
• receiving, by the first local controller, a response signal from the first zone fiber optic cable based upon the first optical signal;
• wherein the first zone fiber optic cable includes fiber Bragg gratings, and wherein emitting, by the first local controller, the first optical signal comprises emitting the first optical signal using a broadband laser;
• determining, using the first local controller, at least one temperature for each of the first plurality of zones based on the response signal;
• wherein determining, using the first local controller, the at least one temperature of each of the first plurality of zones comprises determining the at least one temperature based on time division multiplexing (TDM);
• indicating a first condition for a respective one of the first plurality of zones if the at least one temperature for the respective one of the first plurality of zones is greater than a threshold;
• wherein emitting, by the first local controller, the first optical signal comprises emitting laser pulses having a constant amplitude using a step frequency methodology;
• and
• wherein determining, using the first local controller, the at least one temperature of each of the first plurality of zones comprises determining the at least one temperature based on optical frequency domain reflectometry (IOFDR).