The HabCam2 vehicle is towed on a Rochester Dataline 0.688” single mode optical fiber cable with three, 10 AWG copper conductors and three counter helically wound steel layers of armor providing torque balancing. A Focal Technologies single optical pass slip ring is used at the winch. The cable terminates at the vehicle into a oil filled j-box providing access to power (120 VAC) and optical communications. Subsea, sensors and camera signals are packetized into a gigabit Ethernet signal and transmitted to the surface. A bi-directional Ethernet LAN is established using a Optolink optical transceiver over a single fiber using two wavelengths, 1280 and 1350 um. A single 12-bit machine vision color camera with cameralink interface is coupled to A Pleora Gigabit Ethernet frame grabber sending images to the surface at a rate up to 20 images per second. The frame grabber also triggers the four strobes and controls the camera exposure time. The use of these open standard interfaces (Camera Link and Gigabit Ethernet) means that future replacement of the camera with a different sensor becomes straight forward. A 12mm Nikon 1” C-mount lens completes the optical system. The 120 VAC is rectified, filleted and converted to 12 and 48 VDC at 300 W each. All additional sensors are based on a serial RS-232 interface to 2, 4 port serial to Ethernet converters (MOXA Nport 5410). Each sensor is supplied with an independent IP address thereby simplifying logging and control. We wrote custom Windows software for displaying and logging data from all of the sensors on HabCam I. Topside network transmissions are used to route data between various pieces of software that need access to it. For example, data from the CTD and the vessel-mounted fathometer are transmitted to a “flying” display, allowing a winch operator to prevent the system from striking the seafloor.
Sensors and Equipment
HabCam I uses four 20 Watt-Second Machine Vision strobes (Perkin Elmer MVS-5000) mounted in underwater housings placed radially around the camera at a distance of about 50 cm. The strobe beams are focused and collimated with fresnel lenses to provide a rectangular beam pattern approximately 1 m2 at an altitude of 3 m off the bottom.