Patent ID: 8176786

Claim:
A method for autonomous baseline-free diagnosis of a structure, comprising: generating a first acoustic signal from a first location on the structure, wherein the first acoustic signal has a main frequency and a bandwidth, and wherein the bandwidth is not more than ten percent of the main frequency; receiving the first acoustic signal at a second location on the structure, wherein the first location and the second location are different; generating a second acoustic signal from the second location on the structure, wherein the second acoustic signal has a main frequency and a bandwidth, and wherein the bandwidth is not more than ten percent of the main frequency; receiving the second acoustic signal at the first location on the structure; measuring the S 0 modes and A 0 modes of the first acoustic signal received at the second location; measuring the S 0 modes and A 0 modes of the second acoustic signal received at the first location; and identifying differences in the S 0 modes and A 0 modes of the first and second acoustic signals received at the second and first locations, respectively.