Spatial characteristics of the NORESS noise field and implications for array detection processing

Abstract The spatial characteristics of the NORESS noise field have been studied by computing cross-correlations as functions of intersensor separation for various frequency bands. The correlation curves exhibit distinct negative minima. The sensor separations for which these minima are attained are found to vary systematically with frequency. These observations suggest that waves propagating at Rayleigh wave velocities are a major contributor to the NORESS noise field. In order to assess the capabilities of NORESS to suppress noise and hence provide useful beam-forming gains, noise suppression spectra were computed hourly for various NORESS sub-configurations over a one-year period. The negative minima of the noise correlation functions find a counterpart in these computations. For several NORESS sub-geometries there is a frequency range for which the noise suppression spectrum exceeds the N 1 2 level. This feature is shown to be stable over time, and furthermore shows no strong dependency on the actual noise level.