Patent ID: 6459478
Filing Date: 2002-10-01
Classification: G01M

Abstract:
A method for determining a return loss of a device under test DUT in a system comprising a fiber coupler for receiving an optical input power (Ps) at a first input, coupling out a stimulus signal at a first output derived from the optical input power (Ps), receiving a response signal on the applied stimulus signal, and for providing a returning optical power (P) at a third output derived from the received response signal; the method comprising:coupling a reference cable with a reflectivity Rref to the first output of the fiber coupler, and measuring a first value Pref of the returning optical power; exchanging the reference cable for a customer cable, whereby an end of the customer cable is provided in a way that no, or substantially no, reflection occurs, and measuring a first value Ppara of the returning optical power; coupling the customer cable between the first output of the fiber coupler and the DUT, whereby an end of the DUT is provided in a way that no, or substantially no, reflection occurs, and measuring a value PDUT of the returning optical power; and determining the return loss of the DUT by using value Rref first value Pref, first value Ppara, and PDUT.