DETERMINATION OF SEISMIC SYSTEM DISTORTION AND ITS COMPENSATION USING DIGITAL FILTERS

Geophysics ◽  
1968 ◽  
Vol 33 (2) ◽  
pp. 285-301 ◽  
Author(s):  
Russell L. Gray ◽  
J. Hans Leitinger ◽  
John C. Hollister
Keyword(s):  
Digital Filters ◽  
Signal To Noise Ratio ◽  
Recording System ◽  
Computational Technique ◽  
Seismic Recording ◽  
Exploration Tool ◽  
Velocity Impulse ◽  
Complete Amplitude ◽  
Amplitude Compensation ◽  
Seismic System

Distortion is inherent in recording seismic data. Although some distortion serves a useful purpose, distortion of desirable seismic events decreases resolution thereby reducing the effectiveness of the seismograph as an exploration tool. This paper describes an experimental‐computational technique to determine the distortion introduced by a seismic recording system. The technique utilizes a piezoelectric shaketable to obtain suitable input‐output pairs from which the velocity impulse response of the system is computed. Distortion introduced by the system is compensated by digital filters that are designed in the frequency domain. Nearly complete phase compensation is achieved by designing filters with phase characteristics that closely approximate the negative phase characteristics of the seismic system. Complete amplitude compensation is intentionally averted because of practical considerations. The degree of amplitude compensation deemed feasible is controlled by the relative frequency content of signal and noise. Synthetic examples which simulate field data indicate that approximate compensation filters are effective in removing much of the signal distortion introduced by the seismic recording system without decreasing the signal‐to‐noise ratio.

A digital seismic recording system

1972 ◽  
Vol 62 (6) ◽  
pp. 1641-1647
Author(s):  
D. F. Allsopp ◽  
M. D. Burke ◽  
G. L. Cumming
Keyword(s):  
Seismic Reflection ◽  
Dynamic Range ◽  
Low Noise ◽  
Recording System ◽  
Low Noise Amplifiers ◽  
Deep Crust ◽  
Seismic Recording ◽  
Band Pass ◽  
Quality Recording ◽  
Seismic System

abstract A multi-channel seismic system which records directly on a nine-track synchronous digital tape is described. Low-noise amplifiers with a band-pass of 0.1 to 50 Hz coupled with a 14-bit A to D converter provide the wide-frequency response and dynamic range necessary for high-quality recording of seismic reflection signals from the deep crust.

Sign‐bit amplitude recovery with applications to seismic data

Geophysics ◽  
1982 ◽  
Vol 47 (11) ◽  
pp. 1527-1539 ◽  
Author(s):  
J. T. O’Brien ◽  
W. P. Kamp ◽  
G. M. Hoover
Keyword(s):  
Seismic Data ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Recovery Process ◽  
Signal To Noise ◽  
Common Depth Point ◽  
Seismic Recording ◽  
Noise Ratio ◽  
Correct Application ◽  
Complete Amplitude

Sign‐bit digital recording means that only the sign of the analog signal is recorded with one bit. In conventional seismic recording, 16 to 20 binary bits are acquired per sample point. The economic advantages of sign‐bit acquisition are immediately obvious. Complete amplitude recovery, comparable to full‐gain recording, can be achieved by correct application of sign‐bit techniques. We describe the amplitude recovery process in a semiintuitive manner to promote the understanding necessary for proper application of the technique. The dynamic range requirements in seismic applications are discussed. Sign‐bit digitization is a completely viable technique for recording seismic data, provided that two conditions are fulfilled. First, in real time, the coherent‐signal‐to‐randomnoise‐ratio must be ⩽1.0. Second, the data must be recorded with sufficient redundancy. Redundancy is achieved by source repetition, sweep correlation, and high‐fold common‐depth‐point stacking, usually in combination. Failure to abide by these two restrictions results in (1) incomplete amplitude recovery, i.e., clipped data, and (2) insufficient dynamic range in the recovered signal. We derive the requirement that the signal‐to‐noise ratio be less than one; we also discuss the consequences of violating that requirement, namely clipping, at various points in the processing sequence. The amount of information lost is proportional to the degree of clipping; a small amount can be tolerated. Calculated expectation values show that (subject to the requirement that the signal‐to‐noise ratio be less than 1.0) an unbiased estimator can be chosen. The variance of these estimators is approximately the same as that for full‐gain seismic techniques. With sufficient redundancy, the variance can be made as small as necessary to achieve the required dynamic range. With proper attention to these findings, sign‐bit digitized data are found to be a totally viable tool.

Development on Seismic Recording System

2013 ◽  
Author(s):  
Jian Guo ◽  
Shanhui Xu ◽  
Guangding Liu
Keyword(s):  
Recording System ◽  
Seismic Recording

Head Instability Detection for Testing Process in Perpendicular Magnetic Recording System

2013 ◽  
Vol 770 ◽  
pp. 319-322 ◽  
Author(s):  
Piya Kovintavewat ◽  
Santi Koonkarnkhai ◽  
Aimamorn Suvichakorn
Keyword(s):  
Magnetic Recording ◽  
Signal To Noise Ratio ◽  
Disk Drive ◽  
Detection Algorithm ◽  
Recording System ◽  
High Signal ◽  
Signal To Noise ◽  
Perpendicular Magnetic Recording ◽  
Read Head ◽  
Pass Through

During hard disk drive (HDD) testing process, the magneto-resistive read (MR) head is analyzed and checked if the head is defective or not. Baseline popping (BLP) is one of the crucial problems caused by head instability, whose effect can distort the readback signal to the extent of causing possible sector read failure. Without BLP detection algorithm, the defective read head might pass through HDD assembling process, thus producing an unreliable HDD. This situation must be prevented so as to retain customer satisfaction. This paper proposes a simple (but efficient) BLP detection algorithm for perpendicular magnetic recording systems. Results show that the proposed algorithm outperforms the conventional one in terms of both the percentage of detection and the percentage of false alarm, when operating at high signal-to-noise ratio.

Enhancing signal-to-noise ratio and resolution in low-field NMR relaxation measurements using post-acquisition digital filters

2018 ◽  
Vol 57 (9) ◽  
pp. 616-625 ◽  
Author(s):  
Tatiana Monaretto ◽  
Andre Souza ◽  
Tiago Bueno Moraes ◽  
Victor Bertucci-Neto ◽  
Corinne Rondeau-Mouro ◽  
...  
Keyword(s):  
Digital Filters ◽  
Signal To Noise Ratio ◽  
Nmr Relaxation ◽  
Signal To Noise ◽  
Low Field ◽  
Relaxation Measurements ◽  
Low Field Nmr ◽  
Noise Ratio

scholarly journals Some Remarks about Entropy of Digital Filtered Signals

Entropy ◽  
2020 ◽  
Vol 22 (3) ◽  
pp. 365
Author(s):  
Vinícius S. Borges ◽  
Erivelton G. Nepomuceno ◽  
Carlos A. Duque ◽  
Denis N. Butusov
Keyword(s):  
Additional Condition ◽  
Word Length ◽  
Digital Filters ◽  
Significant Positive Correlation ◽  
Signal To Noise Ratio ◽  
Number Representation ◽  
Signal To Noise ◽  
Finite Precision ◽  
Elliptic Filter ◽  
Numerical Resolution

The finite numerical resolution of digital number representation has an impact on the properties of filters. Much effort has been done to develop efficient digital filters investigating the effects in the frequency response. However, it seems that there is less attention to the influence in the entropy by digital filtered signals due to the finite precision. To contribute in such a direction, this manuscript presents some remarks about the entropy of filtered signals. Three types of filters are investigated: Butterworth, Chebyshev, and elliptic. Using a boundary technique, the parameters of the filters are evaluated according to the word length of 16 or 32 bits. It has been shown that filtered signals have their entropy increased even if the filters are linear. A significant positive correlation (p < 0.05) was observed between order and Shannon entropy of the filtered signal using the elliptic filter. Comparing to signal-to-noise ratio, entropy seems more efficient at detecting the increasing of noise in a filtered signal. Such knowledge can be used as an additional condition for designing digital filters.

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