Adaptive Cancellation of Magnetic Noise Generated by Ocean Surface Waves
Abstract
A method of suppressing ocean surface wave-generated magnetic noise from near surface-mounted total field magnetometer signals is presented. This technique uses reference data furnished by a measurement of the ocean surface displacement at a single point in the vicinity of the magnetometer to cancel adaptively the magnetic noise generated by the surface wave field. A transfer function is derived which relates the ocean surface displacement measurement to the associated magnetic noise field. Experimental data obtained from a total field magnetometer mounted 7 meters above the ocean surface in approximately 18 meters of water display good correlation with an ocean surface displacement measurement made with a sub-surface-mounted pressure gauge. The transfer function which relates these measurements shows good agreement with the theoretically derived transfer function. When the surface displacement time series is used as the reference input to an adaptive noise canceller, the surface wave-generated magnetic noise is suppressed by approximately 20 dB at the main swell frequency of 0.08 Hz. Within the frequency band between 0.05 Hz and 0.3 Hz, the degree of cancellation varies between 10 dB and 20dB. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 15, 1980
- Accession Number
- ADA085127
Entities
People
- G. A. Garcia