Inverse synthetic aperture imaging using 140 kHz ultrasonic laboratory sonar

Abstract

A sonar system operating at 40 kHz in air has been developed to allow the capture of acoustic data in a laboratory environment. The system can serve as a teaching tool for students in seismology, sonar and radar, as well as a useful tool for the development and testing of signal and image processing algorithms. The system can be used for monostatic or bistatic modes of imaging. Range compression is achieved by deconvolution filtering which compensates for the linear system effects of the transducers and other components. A deconvolution filter is generated via a calibration technique in which the system response is measured by pointing the transmitting transducer directly at the receiving transducer. Results are presented which demonstrate the capability of the system for range profiling and 2-D imaging, using the inverse synthetic aperture technique whereby the scene to be imaged is moved across the beam of the sensor. The focused image is obtained by synthetic aperture azimuth focusing / migration techniques. The range and azimuth resolutions achieved with system are discussed.