Patent ID: 8396360

Claim:
A communication method comprising: transmitting non-coherent optical test signals onto an optical waveguide having substantially uniformly distributed inhomogeneities and a plurality of spaced-apart locations at which information is introduced, components of the transmitted test signals being caused by the waveguide to return in a distributed backscattering manner resulting from the uniformly distributed inhomogeneities as the test signals travel along the waveguide; receiving first component signals backscattered by the distributed inhomogeneities located along the waveguide beyond a first location at which information is introduced; receiving second component signals backscattered by the distributed waveguide inhomogeneities beyond a second location at which information is introduced, the second component signals being returned through the first location; and, performing a subtraction operation involving the second component signals and the first component signals, the operation distinguishing information introduced at the second location from information introduced at the first location, wherein the test signals are formed as pairs of signal copies, the signal copies of each pair being transmitted onto the waveguide with a temporal offset relative to one another, wherein the non-coherent optical test signals are generated by an optical signal source having a coherence time less than the temporal offset.