Coherence as a criterion for multichannel combining low SNR communications in an upwelling environment

Louza, Fábio B.; Jesus, Sergio

http://hdl.handle.net/10400.1/17132

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Authors

Louza, Fábio B.

Jesus, Sergio

Abstract(s)

This paper presents a study on the impact of temporal (TCOH) and spatial (SCOH) coherence over low SNR communications in an environment with intense upwelling and demonstrates how to use coherence as a criterion to perform multichannel combining. Using low power signals collected in a shallow water experiment, from two independent and different geometry arrays with four hydrophones each, temporal coherence was estimated. Signals whose TCOH was above a threshold were averaged and SCOH between channels were estimated. Bit error rate results showed that SCOH can be used as a criterion to discard noisy and high multipath channels. Multichannel combination based on SCOH indicated that the use of the arrays can increase the processing gain, even if the sensors are just a few wavelengths from each other. Moreover, longer averaging times provided lower BER but reduced the effective bit rate.