# Accession Number:

## AD0639435

# Title:

## COLLECTION AND ANALYSIS OF SEISMIC WAVE PROPAGATION DATA. SUPPLEMENT 2: AN ERROR ANALYSIS OF DIGITAL EQUALIZING FILTERS.

# Descriptive Note:

# Corporate Author:

## MICHIGAN UNIV ANN ARBOR INST OF SCIENCE AND TECHNOLOGY

# Personal Author(s):

# Report Date:

## 1966-08-01

# Pagination or Media Count:

## 25.0

# Abstract:

Present day computer systems allow computation of an approximate Wiener operator for the time-domain filtering and smoothing of signals of finite and short length. However, the memory capacity of a particular computer storage introduces a constraint on the length of the operator and signal. To produce the least mean-square-error, it was helpful to know the extent to which the length of the operator should be compromised by including additional informationsample points of the signal. If N is the number of samples of the signal to be equalized and T is the number of points in the optimum digital operator then the system imposes the constraint that KN T2 M where M is the free capacity of the computer memory and K is the number of multiples of signal length required for the correlations. To find out whether an optimum relation between T and N exists, a program to determine the digital operator and to compute the mean-square-error between the filtered result and the desired signal was written for an IBM 7090 computer. The computed errors for some typical seismic signals are presented as a function of operator length, signal length, signal-to-noise ratio, and the number of records used to determine averages. The results suggest that equalization occurs both as a process of signal shaping and of noise reduction, but not necessarily simultaneously. The optimal parameters for optimum equalization depend on the nature of the signal and noise, and may require new determination under novel conditions. Author

# Descriptors:

# Subject Categories:

- Seismology
- Non-Radio Communications