Engineering aspects of multichannel processing based on measured noise correlations

The problem of separating seismic signals from noise on a multichannel basis, by making use of the spatial organization of the noise, is discussed. A brief description of the method used to synthesize the multi-channel system on a computer is presented. Results obtained by multichannel processing the outputs from a 19-seismometer array, including signal response, noise response, and signal-to-noise ratio improvement are shown. These results are compared with those obtained by performing a simple summation of the array outputs, and are also compared with those which would be expected from simple summation if the noise were not organized in space. A practical method of applying analog multichannel processing in the field is presented. Finally, examples of teleseismic signals which have been extracted on a multichannel basis are shown.