Accurate Navigation

Accurate Navigation

For most tasks, a geo-reference of the data collected is of outmost importance. SeaCat is designed to support the IHO S-44 standard. It features an iXBlue Phins III strapdown-aided inertial navigation system of high accuracy. The Phins III processes the data of three fiber-optic gyros, three accelerometers and the following additional aiding sensors:

  • RDI Explorer DVL, 600 kHz with phased array transducer. The Doppler Velocity Log measures as well the speed with reference to the bottom and water mass layer as the altitude above seafloor.
  • Sensortechnics KTE6100A digital pressure sensor for depth measurement,
  • Valeport MiniSVS 50 mm, accuracy ±0.019 m/s (sound velocity sensor enhances the accuracy of the acoustic DVL)
  • Garmin GPS 15 or Ashtech MB 100 GPS receiver. Differential RTK options and military p-code can be integrated (not ATLAS delivery).

All data are fused in a state-of the-art non-linear Kalman filter which computes a very precise position.

Feature Specification
Position accuracy < 0.3% distance travelled, CEP*
Heading accuracy 0.05° (heading x secant latitude)
Roll, pitch accuracy 0.01°
Heave, surge, sway 5 cm or 5% (whatever is higher)
Heading, roll, pitch resolution 0.001°
Acceleration resolution 1 mg
Rotation rate resolution 1.25cm, all frequencies

*) Performance assumes GPS aiding whilst aligning at surface and Sonar/Doppler

aiding whilst under water.


For specific operations, the navigation accuracy can be further enhanced

by means of the following strategies:

  • Acoustic aiding
  • Geo-referenced aiding