Accession Number:

AD0829164

Title:

HYPERFINE BEAMSTEERING USING A SIGNAL CROSSCORRELATION TECHNIQUE

Descriptive Note:

Seismic data laboratory rept.

Corporate Author:

TELEDYNE INDUSTRIES INC ALEXANDRIA VA EARTH SCIENCES DIV

Personal Author(s):

• McCowan, D. W.
• Flinn, E. A.

Report Date:

1968-03-01

Pagination or Media Count:

26.0

Abstract:

A method is developed to eliminate automatically the loss in signal amplitude of LASA phased sums with travel-time anomaly corrections due to small mis-alignments in the signal arrivals. This method is a hyper-fine or vernier adjustment of the trace alignments, making use of a least-squares estimate of the misalignments made from the time lags of all possible crosscorrelations between the signals. A mathematical description of the procedure and its errors is given. Three events with different signal-to-noise ratios recorded by 11 LASA subarrays were chosen as examples of the method. The results show improvements ranging from 0.0 to 0.5 db in the phased sum of the subarray sums. The results seem to depend on the signal-to-noise ratio of the event, the method performing best when that ratio is high.

Descriptors:

• *SEISMOLOGICAL STATIONS
• CORRELATION TECHNIQUES
• DETECTION
• EARTHQUAKES
• EPICENTERS
• LEAST SQUARES METHOD
• MONTANA
• NOISE
• PHASE SHIFT CIRCUITS
• PHASED ARRAYS
• SEISMIC WAVES
• SIGNAL TO NOISE RATIO
• SPECTRUM SIGNATURES
• VELOCITY

Subject Categories:

• Seismology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE