Search

A prototype of bispectral passive imaging system designed for the diagnosis of machine systems from their noises is presented. The principle is generalized aiming machine‐system diagnosis and the concrete construction of scanner of a microphone and the details of the signal processings as well as the obtained images are shown. Typical characteristics of the system are as follows: (a) images to be reconstructed, spatial distribution of the degree of interference among three frequency components or spatial distribution of intensity of noises emitted from the object; (b) maximum resolution, 15/f cm where f is the used frequency (f=0.5∠10 kHz); (c) time required to obtain one image, from 30 to 90 min depending on the number of sampling points; (d) display of result, print out on a typewriter or colored display on a TV monitor.