Texas Instruments Corporation

Toby R Trevino

John James Sallas

Cameron B Wason

Haroon I Alvi

John S Shoffner

A vibrator seismic source has a sweep generator for providing a pilot signal and sensors for generating a feedback signal representative of the force imparted to the ground by the vibrator pad. Circuitry is incorporated for separating the fundamental signal from the feedback signal and for separating the distortion from the feedback signal. Means are provided for generating a control signal for controlling the action of the vibrator means. Included are means for reducing the amplitude of the pilot signal a designated amount, determined by the distortion, and means for algebraically summing the reduced amplitude pilot signal and the fundamental signal to provide an error signal. The error signal is input to a loop filter to perform real time correction of the control signal. The reduced amplitude pilot signal is input to means for adjusting the control signal for trends in the distortion. Additionally, the control system employs a phase detector circuit that outputs any phase difference between the feedback and pilot signals. The phase difference is applied to the control signal to shift the feedback signal phase to correspond to the pilot signal.

Vibrator seismic source having adaptive distortion limiting control

A vibrator seismic source has a sweep generator for providing a pilot signal and sensors for generating a feedback signal representative of the force imparted to the ground by the vibrator pad. Circuitry is incorporated for separating the fundamental signal from the feedback signal and for separating the distortion from the feedback signal. Means are provided for generating a control signal for controlling the action of the vibrator, the control signal being reduced or increased by the difference between the pilot signal and the fundamental signal, and further reduced by the distortion, if any. A threshold circuit is employed to ignore distortion below the threshold level and a threshold circuit is provided to ignore differences in amplitude between the pilot and fundamental signals when the difference is below the threshold. Additionally, the control system employs a phase detector circuit that outputs any phase difference between the feedback and pilot signals. The phase difference is applied to the control signal to shift the feedback signal phase to correspond to the pilot signal.

Growing community of inventors

Garland, TX, United States of America

Toby R Trevino