Spatial interfrequency correlation effects in a surface‐scatter channel

The effect of spatial separation on the cross correlation between the system response functions for a two‐receiver surface‐scatter channel is investigated. The system response at the two receivers is determined for all possible pairs of frequencies. The analysis assumes relatively close separation of receivers and uses the Fresnel‐corrected model for surface scatter in the specular direction. The surface is assumed to be Gaussian, with typical size of boundary deformations small compared to typical Fresnel zones.The analysis shows that the correlation is approximately maximum for zero‐frequency separation and drops off at a rate determined by the reverberation time. For small reverberation times and small grazing angles correlation may extend over fairly large values of frequency difference. The effect of spatial separation is generally a reduction in correlation and a more rapid decrease of correlation with frequency, but this can be compensated to some extent by time shift between the two system responses. Experimental evidence is included to support the theoretical predictions presented.Subject Classification: [43]30.20; [43]20.15; [43]60.20.