A Gavia base vehicle consists of the following modules:

• Nosecone Module
• Battery Module
• Control and Communication Module
• Propulsion and Servo Module

• Doppler Velocity Log (DVL) Module
• Acoustic Communication and Positioning Module
• Vehicle Safety Module: Navigation Sonar and Drop Weight
• Aided Inertial Navigation System (AINS) Module
• Side Scan Sonar Module
• Digital Camera Module
• Strobe Light Module
• CTD Module
• Standard Payload Modules

For the Gavia modules we have selected only precision instrumentation from leading manufactures. We add continuously to our instrumentation module offerings, and in addition we make custom modules to meet specialized instrumentation needs.

GAVIA BASE VEHICLE MODULES

NOSECONE PAYLOAD MODULE

A selection of sensors can be mounted in the NOSECONE PAYLOAD MODULE, including digital stills and video cameras. The module can be rotated to adjust the orientation of a transverse looking transducer such as down or side looking cameras.

CONTROL AND COMMUNICATION MODULE

This module holds the control and communication electronics. These include a PC computer for high-level mission control and a real-time microprocessor for time critical autopilot functions. The unit also contains a high quality magneto-inductive 3-axis compass and two-axis tilt sensor for vehicle attitude measurement, as well as the Wireless LAN and the satellite communication electronics.

The CONNING TOWER houses the GPS receiver antenna and the surface communication antennas for the RF and satellite links. It also contains a strobe beacon to aid the visual localization of the vehicle.

ACTUATOR AND PROPULSION MODULE

The ACTUATOR AND PROPULSION MODULE accommodates the micro controller, servomotors, magnetic couplings and actuators controlling the vehicle attitude. The actuators are independent, enabling active roll control.

The ACTUATOR AND PROPULSION MODULE also contains the propulsion motor and propeller. The motor shaft is brought out through a magnetic coupling, eliminating the need for dynamic seals.

BATTERY MODULE

This module contains batteries, chargers, and the power management unit. A vehicle can contain more than one power module for extended duration of operation.

OPTIONAL VEHICLE MODULES

DOPPLER VELOCITY LOG MODULE

This module houses a Doppler velocity log (DVL), that provides velocity information for geodetic positioning under water. The DVL measures the true velocity of the vehicle with respect to water and with respect to the bottom when the vehicle is in bottom tracking mode. The DVL also provides vehicle altitude.

ACOUSTIC COMMUNICATION AND POSITIONING MODULE

This module houses an acoustic communication transducer, used for through water communication. The same transducer can be used for vehicle positioning in conjunction with an external LBL transponder buoys or a USBL system. The transducer comes as standard with an accurate ranging function based on round-trip timing. This means that a submerged stationary vehicle can be located from the surface by measuring the range to the vehicle from different locations whilst cruising on the surface.

VEHICLE SAFETY MODULE: NAVIGATION SONAR AND DROP WEIGHT

The vehicle safety module houses the 360¡ scanning navigation sonar providing advance information for close range bottom tracking and obstacle avoidance. This module also holds a drop weight for fast emergency ascent.

AIDED INERTIAL NAVIGATION SYSTEM MODULE

The aided inertial navigation system (AINS), comprises of ring laser gyros and linear accelerometers for precise positioning and navigation underwater. The system works in conjunction with the DOPPLER VELOCITY LOG MODULE.

SIDE SCAN SONAR MODULE

The side scan sonar is available in several frequencies ranging from 150 kHz to 2400 kHz. This is a low power design that is based on the principle that less power emitted generates less unwanted noise in the received signal. Images are very sharp and resolution is high. The side scan sonar transducers are externally mounted either side of Gavia's hull. A sample image taken by Gavia is shown. This is an image from the left hand transducer at 600 kHz.

STROBE LIGHT MODULE

A hull mounted strobe light for stills photography. The STROBE LIGHT MODULE can be used with a transverse looking camera mounted in the NOSE CONE PAYLOAD MODULE. The strobe light will give optimum illumination of the seabed at an altitude of 1 - 2 meters.

CTD MODULE

A precision CTD (conductivity, temperature and depth) recorder is mounted in the CTD module for continuous profile measurements of salinity and temperature. The CTD module is carried on top of Gavia's pressure housing behind the conning tower for easy removal and calibration.

STANDARD PAYLOAD MODULES

Further equipment can be accommodated in standard payload transducer modules or internal payload modules.

18 July 2003 - Specifications may change without prior notice.