Signal Design in the “Vibroseis”® Technique

Abstract

After more than twenty years of field practice, the most widely used signal in the Vibroseis technique remains the original so-called linear sweep. To many, it seems that substantial improvement should be expected from taking advantage of more sophisticated signal design techniques.The purpose of this paper is to present a tutorial survey of the basic concepts involved in signal design, tying together the known features of the linear sweep with those of the more general type.Several particular types of nonlinear sweeps are analyzed and the results of a field test seem to confirm the conclusions drawn from the conceptual analysis.After a brief consideration of still another type of nonlinear signals, a particular variety of pseudorandom sweeps, the author concludes by giving his views of what might be the role of nonlinear signal design in the future development of the Vibroseis technique.

Vibroseis deconvolution: a comparison of cross‐correlation and frequency‐domain sweep deconvolution

“…When the vibroseis technique was first implemented a linear sweep was the signal of choice. A sweep is an oscillating signal with time‐variant amplitude and a frequency that varies monotonically with time (Goupillaud 1976). A linear sweep is one that has an instantaneous frequency that is a linear function of time, where the autocorrelation is the Klauder wavelet.…”

High-resolution shear-wave seismic reflection as a tool to image near-surface subrosion structures – a case study in Bad Frankenhausen, Germany

“…6). Another advantage of the vibroseis technique is that, compared to impulse sources, the emitted highprecision frequency-modulated signal generates a repeatable and consistent wavelet (Klauder et al, 1960;Goupillaud, 1976;Nijhof et al, 1998;Drijkoningen, 2003).…”

The use of pseudorandom sweeps to reduce interference noise in simultaneous Vibroseis surveys

“…Pseudorandom sweeps, as originally described by Goupillaud (1976), were designed by grouping the sample values of a sweep into blocks with adjacent samples retaining a constant polarity. These blocks were then randomly concatenated keeping a sequence of positive and negative values (Goupillaud, 1976).…”

“…These blocks were then randomly concatenated keeping a sequence of positive and negative values (Goupillaud, 1976). The random nature of these sweeps resulted in the sweeps being substantially uncorrelated with each other enabling them to be acquired simultaneously without significant interference.…”