Each of the nodes, or channels, in the digital vertical cable is made up of a hydrophone and a 24 bit Delta-Sigma A/D converter electronics module. Nodes are inter-changeable and designed to be easily replaced in the field. An acoustic position system is integrated into each node. The spacing between nodes and overall cable length is determined by the user. Power consumption by each node has been minimized to facilitate power transmission down the cable from an autonomous buoy battery pack.

Applications:

Vertical Array System
• The total system consists of a vertical two conductor hydrophone cable anchored to the sea floor and connected by an S-tether to the autonomous recording buoy. The recording buoy communicates with the shipboard interface via radio telemetry.

Towed Array System
• The total system consists of a horizontal hydrophone cable which is a coaxial neutrally buoyant cable with a maximum operating depth of 6000 meters. The array may include heading and depth sensor modules. Data is integrated in the sub-surface towfish electronics. Data from ancillary sensors are multiplexed with the acoustic data by the towfish electronics and transmitted to the surface.

System Specifications:

Hydrophones
Sensitivity	-194 dB re: 1V/µPa
Self-Noise	0.07 µBar RMS
Dynamic Range	117 dB
Frequency Response	2 Hz - 3000 Hz
Directivity	Omni-directional to 2 kHz
Operating Depth	10,000 feet

Emphasis On:
• Systems approach
• Light weight mooring system
• 1 to 96 channels configurable
• 24-bit Delta Sigma A/D converter at each hydrophone channel
• Identical node modules
• Motion-insensitive hydrophones
• Downlink telemetry to nodes
• Optional GPS time synchronization