The matched-phase coherent multi-frequency matched-field processor

Coherent multi-frequency matched-field processing is investigated using a m atched-phase coherent matched-field processor. Its main difference from pre vious coherent processors is that the relative phases of the Fourier compon ents contained within the recorded signal are not assumed to be known a pri ori. Rather they are considered free parameters that can be determined usin g a global functional minimization algorithm. Additionally, this processor uses only the cross-frequency terms, making it less susceptible to the detr imental effects of ambient noise; in one example, this processor shows a fi ve decibel improvement over a similar coherent processor. Along with its in creased sensitivity with respect to the broadcast source levels, this coher ent processor exhibits superior range resolution as compared with multi-fre quency incoherent processors, due to the cross-frequency interference of th e vertical eigenmodes. Within this work we explore the efficacy of the algo rithms used to determine the relative phases along with the performance of the matched-phase coherent processor itself, performed within the context o f data collected during an event from the SWellEx-96 experiment. Performanc e comparisons between this processor, an incoherent processor, and another coherent processor are demonstrated using this data set. [S0001-4966(00)027 05-3].