METHOD OF MEASURING DISTANCE TO MONITORED FACILITY Russian patent published in 2012 - IPC G01S15/08 

FIELD: physics.

SUBSTANCE: periodic pulsed acoustic signal is generated and emitted at the monitored facility by a vertically aligned four-module antenna mounted on the seabed. Antenna emission is synchronised with zero time at the reception point on the monitored facility. The signal is received at the monitored facility by two receivers. One of the receivers lies directly on the ground and is a vector receiver at whose output the vertical and horizontal components of the oscillating velocity vector are measured. The second receiver is a non-directional acoustic pressure receiver. Group lag time is determined from the measured parameters while preliminarily determining time intervals. The unknown distance to the monitored facility is calculated using invariant velocity which is equal to the velocity of the bottom wave, the group time and preliminarily measured density and sound velocity in the bottom water layer, density and velocity of bottom waves in the ground.

EFFECT: reduced measurement error.