| Abstract: | A coded seismic technique is developed that can result in a higher signal-to-noise ratio than a conventional single-pulse method does. The technique is cost-effective and time-efficient and therefore well suited for shallow-reflection surveys where high resolution and cost-effectiveness are critical. A low-power impact source transmits a few to several hundred high-frequency broad-band seismic pulses during several seconds of recording time according to a deterministic coding scheme. The coding scheme consists of a time-encoded impact sequence in which the rate of impact (cycles/s) changes linearly with time providing a broad range of impact rates. Impact times used during the decoding process are recorded on one channel of the seismograph. The coding concept combines the vibroseis swept-frequency and the Mini-Sosie random impact concepts. The swept-frequency concept greatly improves the suppression of correlation noise with much fewer impacts than normally used in the Mini-Sosie technique. The impact concept makes the technique simple and efficient in generating high-resolution seismic data especially in the presence of noise. The transfer function of the impact sequence simulates a low-cut filter with the cutoff frequency the same as the lowest impact rate. This property can be used to attenuate low-frequency ground-roll noise without using an analog low-cut filter or a spatial source (or receiver) array as is necessary with a conventional single-pulse method. Because of the discontinuous coding scheme, the decoding process is accomplished by a "shift-and-stacking" method that is much simpler and quicker than cross-correlation. The simplicity of the coding allows the mechanical design of the source to remain simple. Several different types of mechanical systems could be adapted to generate a linear impact sweep. In addition, the simplicity of the coding also allows the technique to be used with conventional acquisition systems, with only minor modifications. |
| Genre: | Article |
| ProdID: | 70018105 |
| Citation Author: | Park, C. B.; Miller, R. D.; Steeples, D. W.; Black, R. A. |
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| Citation End Page: | 1803 |
| Citation Issue: | 6 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geophysics |
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| Citation Number Of Pages: | 15 |
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| Citation Search Results Text: | Swept Impact Seismic Technique (SIST); 1996; Article; Journal; Geophysics; Park, C. B.; Miller, R. D.; Steeples, D. W.; Black, R. A. |
| Citation Start Page: | 1789 |
| Citation Volume: | 61 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | Swept Impact Seismic Technique (SIST); 1996; Article; Journal; Geophysics; Park, C. B.; Miller, R. D.; Steeples, D. W.; Black, R. A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1996 00:00 -0600 |
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