AN EXPERIMENT ON ACOUSTIC REFLECTION FROM THE SEA SURFACE.
Abstract
An experiment on underwater acoustic relfection from the ocean's surface was conducted in a water depth of 32 m by utilizing an omnidirectional, 3.5-kHz fixed source at a submerged depth of 16 m. Two-cycle pulses at a repetition rate of 10 pulses per second were received on a hydrophone suspended at a depth of 10.7 m from a small boat. Underwater grazing angles ranged from 15 to 40 degrees. Surface reflection loss was observed to vary over a range of approximately 20 dB with periods closely associated with the predominant water wave periods. Surface reflection gains of up to 5 dB occurred frequently. The average loss ranged from 1 dB at a grazing angle of 15 degrees to 4 dB at an angle of 40 degrees, with only a slight dependence on direction of propagation relative to the direction of the sea. Signals propagated via the surface-reflected path, when correlated with signals propagated via the direct path, exhibited an average peak value of normalized cross correlation of 0.95. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 28, 1970
- Accession Number
- AD0708684
Entities
People
- Raymond H. Ferris
- William A. Kuperman
Organizations
- United States Naval Research Laboratory