Abstract
Many quality control (QC) methods are used to monitor the output force from seismic vibrators. These QC tools usually provide the vibrator output force in three aspects — fundamental force, phase, and harmonic distortion — to measure the quality of the ground force compared with the predetermined sweep. As the vibrator works on challenging earth surfaces, such as unconsolidated ground surfaces, the peak harmonic distortion, a key vibrator QC parameter, always exceeds its QC threshold. This necessitates a vibrator reshoot and thereby a degradation of productivity. The purpose of this paper is to demonstrate that in unconsolidated ground surface areas a new setting of the harmonic cutoff frequency on a vibrator controller is recommended. This new setting reduces the unnecessary harmonics around 200 Hz so that the peak harmonic distortion is controlled in the required QC range. Therefore, unnecessary vibrator reshoots can be avoided, leading to improved productivity.