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Coherent averaging of the passive fathometer response using short correlation time
1Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, California 92093-0238, USA. jtraer@ucsd.edu
The Journal of the Acoustical Society of America
|January 10, 2012
Summary
This study improved the passive fathometer algorithm using data from Mediterranean experiments. Advanced methods enhanced signal-to-noise ratio, overcoming wave-induced array motion for clearer oceanographic data.
Area of Science:
- Oceanography
- Acoustics
- Signal Processing
Background:
- The passive fathometer algorithm is used for underwater acoustic measurements.
- Drifting array experiments provide valuable oceanographic data.
- Wave-induced motion can degrade signal quality in array measurements.
Purpose of the Study:
- To apply and refine the passive fathometer algorithm using Mediterranean experimental data.
- To investigate the impact of array motion on signal-to-noise ratio (SNR).
- To develop methods for improving SNR and data coherence.
Main Methods:
- Application of the passive fathometer algorithm with varying correlation times (0.34 to 90 s).
- Comparison of observed SNR with a 1D ideal waveguide model.
- Implementation of a peak-tracking algorithm to correct for array depth variations.
- Utilizing multirate adaptive beamforming with long correlation times on short data snapshots.
Main Results:
- Observed SNR matched the 1D model for short correlation times (< 2 s).
- Wave-driven periodic array motion (1 m amplitude, 7 s period) caused destructive interference, limiting SNR growth.
- The peak-tracking algorithm successfully removed motion-induced interference.
- Multirate adaptive beamforming significantly increased the SNR of the passive fathometer response.
Conclusions:
- The passive fathometer algorithm can be effectively applied to experimental data.
- Array motion is a significant factor affecting SNR, but can be mitigated.
- Advanced signal processing techniques like peak-tracking and adaptive beamforming enhance passive acoustic measurements.
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