The Nautile uses 2 different systems permanently operational: in-vehicle navigation and surface navigation.
- Anschutz gyrocompass, standard 20, 110-222 type
- RDI doppler log, 300 kHz,
- The distancemeter for all acoustic data acquisition of distances to beacons and digital filtering.
3 modes of navigation :
Three softwares are used to obtain the navigation curves:
- Long baseline navigation in bottom-track mode using the distancemeter data regardless of the log data
- Dead reckoning navigation using the gyrocompass data and the log and heading data ; it requires regular manual adjustment
- Hybrid navigation using all the available sensor data
Performance for in-vehicle navigation:
Long base navigations in hybrid or bottom-track mode are reliable,
Navigation in bottom-track mode can be checked immediately after diving due to the high user-friendliness of navigation tools and VEMO+ software (navigation route graphic design)
A ± 2-m accuracy was calculated on an area spotted between 3 beacons without acoustic masking. This precision is not related to immersion.
Surface calculator: Poséidon
The calculator software is translated in a current language. It is used to:
- Calibrate the beacons area: beacons absolute positioning,
- Position the ship, the Nautile and an elevator in the beacons area,
- Supply the surface navigation results and configuration parameters on Ethernet.
The scientific station provides real-time monitoring of the long baseline surface navigation on the VEMO+ screen,
The user-friendly Man Machine Interface makes it simpler to implement the system,
The long baseline system accuracy is related to immersion and so less reliable than navigation in bottom-track mode. However it is used redundantly for navigation results.