The use of pseudorandom sweeps for vibroseis acquisition

The use of pseudorandom sweeps (rather than the more conventional sweeps whose instantaneous frequency changes linearly) has received periodic attention over the past 45 years. In a previous article (Dean, 2014) I summarised the work published in this area including the different motivations for their use as well as different methods for generating a variety of different sweeps. At the time, I attributed their lack of use to the difficulty in transmitting them and their relatively low energy levels when compared with conventional, linear, sweeps. In this article I summarise recent work (i.e. not covered in Dean (2014)) involving pseudorandom sweeps before describing some of our own test results. I then discuss the implications of this recent work on the future of the method.