Chirp technique approach for objects' identification

Identification of inhomogeneities is of importance in the areas of tissue characterization, nondestructive evaluation and underwater acoustics. Such identification could help to differentiate tumors from surrounding tissue in ultrasonic scans, and tumors might be characterized as being benign or malignant. This paper presents a specific approach to the identification of inhomogeneities by using a pulsed swept frequency technique (chirping). The unique feature of this technique allows frequency domain data to be determined directly from time domain data without a need to use a Fourier transform algorithm and vice versa. The combined information contained in the time and frequency domain allows such parameters as size, shape, position, and structure of the object to be determined. The theoretical principles of the pulsed swept frequency technique are briefly outlined and the results of the experimental measurements of time and frequency domain scattering characteristics from objects of simple geometry are presented. Preliminary experimental data taken in the range of ka=100-900 indicate that the chirping approach can be successfully used in identification of differently shaped objects in water as well as objects embedded in tissue.