US 12,066,290 B2
Calibration of a magnetometer in a towed object telemetry unit based on turn data
Mattias Südow, Kista (SE)
Assigned to PGS Geophysical AS, Oslo (NO)
Filed by PGS Geophysical AS, Oslo (NO)
Filed on May 19, 2021, as Appl. No. 17/324,370.
Application 17/324,370 is a division of application No. 15/834,182, filed on Dec. 7, 2017, granted, now 11,041,720.
Claims priority of provisional application 62/433,370, filed on Dec. 13, 2016.
Prior Publication US 2021/0270607 A1, Sep. 2, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. G01C 17/38 (2006.01); G01C 17/28 (2006.01); G01V 3/15 (2006.01); G01V 13/00 (2006.01); G01V 1/20 (2006.01); G01V 1/38 (2006.01); G01V 3/12 (2006.01)
CPC G01C 17/38 (2013.01) [G01C 17/28 (2013.01); G01V 3/15 (2013.01); G01V 13/00 (2013.01); G01V 1/20 (2013.01); G01V 1/3817 (2013.01); G01V 3/12 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A system, comprising:
a first towed object telemetry unit including a first magnetometer, wherein the first towed object telemetry unit is coupled to a first section of a towed object;
a second towed object telemetry unit including a second magnetometer, wherein the second towed object telemetry unit is coupled to a second section of the towed object;
a first position control device coupled to the first section of the towed object;
a second position control device coupled to the second section of the towed object; and
a controller coupled to the towed object and configured to:
use the first position control device to roll the first section of the towed object and receive first roll data from the first towed object telemetry unit;
calibrate the first magnetometer based on the first roll data by adjusting bias and gain of the first magnetometer such that the first roll data fits a first sphere;
use the second position control device to roll the second section of the towed object and receive second roll data from the second towed object telemetry unit;
calibrate the second magnetometer based on the second roll data by adjusting bias and gain of the second magnetometer such that the second roll data fits a second sphere;
receive first turn data from the first towed object telemetry unit and second turn data from the second towed object telemetry unit as a result of a turn of the towed object from a first predetermined heading to a second predetermined heading different than the first predetermined heading;
further calibrate the first magnetometer based on the first turn data by adjusting bias and gain of the first magnetometer such that the first turn data scales to a first circle; and
further calibrate the second magnetometer based on the second turn data by adjusting bias and gain of the second magnetometer such that the second turn data scales to a second circle.