Patent ID: 7266260

Claim:
A method of interrogating a plurality of sensor units each containing one or more FBG sensors, comprising: (a) switching on and off a gain modulated device at a repetition rate predetermined for a sensor unit under interrogation out of said plurality of sensor units, said gain modulated device receiving an input at an input end and producing an output at an output end, said input end and output end being separate ends; (b) splitting said output from said output end of said gain modulated device into at least a first portion and a second portion; (c) sending said first portion to said plurality of sensor units each of which generates a reflection; (d) feeding said reflection by each of said sensor units as an input to said input end of said modulated device which is configured to be switched on when said reflection by said sensor unit under interrogation arrives and switched off when said reflection by another of said sensor units arrives; (e) repeating steps (b)-(d) for a number of times until said output from said gain modulated device in step (a) is sufficient for wavelength measurement; (f) changing said repetition rate of step (a) to a predetermined rate for interrogating another of said plurality of sensor units.