A BEAMFORMING STUDY USING OUTPUTS FROM THE EXTENDED E3 SUBARRAY AT THE MONTANA LASA
Abstract
Short-period seismograms representing nine teleseismic earthquakes recorded by vertical component instruments were bandpass-filtered and beam- formed to determine the effect on average input signal-to-noise ratio, signal, and noise. Results of the study show that beamsteering all 25 outputs (prefiltered 0.4-3.0 cps) from the extended E3 subarray fails to improve the signal-to-noise by the square root of N, where N is the number of inputs to the beams. The analysis further indicates that beams consisting of 3, 6, and 7 input traces prefiltered 0.4-3.0 cps reduce rms noise levels at the subarray by approximately N to the 1/2 power at a minimum inter-sensor spacing equal to or greater than 6 kilometers. Finally, if the input data are prefiltered to the band 0.6-2.0 cps, the minimum spacing for N to the 1/2 power noise reduction is decreased to about 5 kilometers.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 11, 1967
- Accession Number
- AD0820291
Entities
People
- R. A. Hartenberger
- R. H. Shumway
Organizations
- Teledyne Technologies