Accession Number : ADA308086

Title :   Experimental Investigation of a High Resolution Sonar.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Huat, Lim C.

PDF Url : ADA308086

Report Date : MAR 1996

Pagination or Media Count : 91

Abstract : This thesis investigated a laboratory synthetic aperture sonar designed to test the algorithms and techniques needed to detect, classify and identify minelike objects. Previous synthetic aperture sonar work at NPS achieved 5 cm range resolution and 1 cm azimuth resolution. This thesis developed a pulsed, frequency modulated, synthetic aperture sonar that achieved range and azimuth resolutions of about 1 cm. The processed images clearly reveal targets with a high degree of certainty. However, the ability to classify and identify mines and rocks is less certain because of speckle and glint effects. The high resolution algorithms improved the detection and overall image quality of targets, and achieved a signal to noise ratio of 35 dB. The 2:1 frequency spread of the FM chirp increased the signal to noise ratio by 20 dB compared to an unfocused synthetic aperture system. However, a significant finding is that resolution alone is not sufficient to classify and identify minelike targets in complex backgrounds. Resolution of this problem will require a different approach such as utilizing adaptive acoustic daylight to avoid the speckle and glint problems inherent with coherent illumination. To achieve a classification and identification capability, a completely different approach to acoustic illumination and signal processing is needed.

Descriptors :   *MINE DETECTION, *SONAR SOUND ANALYZERS, *SONAR TARGETS, *SYNTHETIC APERTURE SONAR, ALGORITHMS, SIGNAL PROCESSING, SIGNAL TO NOISE RATIO, COHERENCE, THESES, ILLUMINATION, HIGH RESOLUTION, IDENTIFICATION, QUALITY, ADAPTIVE SYSTEMS, GLINT, PULSE COMPRESSION, UNDERWATER TARGETS, UNDERWATER MINES, SONAR IMAGES, SONAR PULSES.

Subject Categories : Acoustic Detection and Detectors
      Undersea and Antisubmarine Warfare

Distribution Statement : APPROVED FOR PUBLIC RELEASE