An Introduction to Chirp Sonar and It's Applications
Wei-Zhi Liao
Abstract
Chirp sonar is a calibrated wide-band digital FM sonar that provides quantitative, high-resolution, low-noise sub-bottom data. Chirp sonar system includes a linearly swept FM pulse(frequency isn't fixed, ranging in 2-12 kHz), receiver, and a computer system which records and shows data immediately. The best resolution of chirp-sonar profile is about 10 cm, and the deepest penetration is about 100 m under sea-floor.
Koreans used the chirp sonar system to investigate their seas around Korean Peninsula. High-resolution chirp-sonar profiles show many characteristics corresponding to different sediments. They combined high-resolution profiles, sediment cores, and some other data (e.g.,seismic data). Using these data, they divided chirp-sonar reflections into many types and interpreted the sedimentary processes that have occurred since the last glacial period (i.e., about 22000 year B.P.).
Chirp sonar data contains information on physical properties of sediments (e.g., sound speed, rigidity, porosity, and bulk density). By compering measured physical sediment properties on cores to physical parameters contained in chirp-sonar data, one may predict sediment properties from chirp-sonar data alone.
Reference
LeBlanc, L.R., Mayer, L., Rufino, M., Schock, S.G. and King, J. (1992). Marine sediment classification using the chirp sonar, J. Acoust. Soc. Am., 91(1), 107-115.
Lee, S.H., Bahk, J.J., Chough, S.K., Back, G.G. and Yoo H.S. (2004). Late Quaternary sedimentation in the Ulleung Interplain Gap, East Sea (Korea). Marine Geology,206, 225-248.