US Patent 9594174 Computing rotation data using a gradient of translational data

Translational data in a first direction is measured by particle motion sensors contained in an elongated housing of a sensor device provided at an earth surface. The particle motion sensors are spaced apart along a second, different direction along a longitudinal axis of the elongated housing. Rotation data around a third direction is computed based at least in part on computing a gradient of the translational data with respect to the second direction.