Some alternate vibrator signals

The linear swept‐frequency sine wave has been the only seismic vibrator drive signal seriously used in almost two decades of operational vibrator activity. However, there are other drive signals and alterations of this commonly accepted signal which offer improved peak‐to‐side lobe ratios on signal autocorrelations, as well as significant savings in field data acquisition and subsequent data processing times. In fact, one class of input signals allows vibrator signal recordings to have the same time duration as equivalent dynamite signal recordings. Another class provides effective discrimination against periodic interferences such as 60-Hz power‐line interference. Fortunately, these characteristics can be combined in the same input signal. The theory which suggests these improvements is outlined, and experimental seismic data which support the theory are shown. Data recorded at identical locations while using one conventional and three alternate input signals of equal bandwidths and energies are compared...