(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2012-09)
Gieleghem, Ryan T.
Signal detection and synchronization in the time varying ocean environment is a difficult endeavor. The current common methods include using a linear frequency modulated chirped pulse or maximal length sequence as a detection pulse, then match filtering to that signal. In higher signal to noise ratio (SNR) environments (~0 dB
and higher) this has been a suitable solution. As the SNR drops lower however, this
solution no longer provides an acceptable probability of detection for a given tolerable
probability of false alarm. The issue derives from the inherent coherence issues in
the ocean environment which limit the useful matched filter length. This thesis proposes
an alternative method of detection based on a recursive least squares linearly
adaptive equalizer which we term the Adaptive Linear Equalizer Detector (ALED).
This detectors performance has demonstrated reliable probability of detection with
minimal interfering false alarms with SNR as low as -20 dB. Additionally this thesis
puts forth a computationally feasible method for implementing the detector.
