ALOHA Cabled Observatory

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Aloha Proof of Concept Module

Prior to installation of the Aloha Cabled Observatory package which will service many experiments, we need to cut the HAW-4 cable, move the cable to approximately 12 km to Station ALOHA , and terminate it with a hybrid electro-optical wet-mate connector (Link to ODI web site).  This operation will be accomplished using the U.S. Navy Cable Repair ship, USNS Zeus . We expect to be ready to install by February 12, 2007, and hope to have the Aloha Observatory deployed by 2008.

Rather than just install the bare connector, we will also install a Proof of Concept Module (Proof Module) to demonstrate the capabilities of the infrastructure. The Proof Module consists of a power supply, communications module, and two sensors, a high-rate hydrophone and a pressure sensor. The hydrophone will be sampled at over 80 KHz, yielding data from 0.01 Hz to 40 KHz with about 20-bit resolution. The pressure sensor will complete the pressure spectrum from DC to 0.1 Hz. The Proof Module will be suspended above the cable termination for ease of installation and recovery (see diagram). The Proof Module will detect tides, tsunami, earthquakes, wave activity, ships, whales and acoustic devices operating at Station ALOHA, hopefully exciting the community into utilizing the potential of the ALOHA Observatory and similar systems.

The ALOHA Proof Module communications module consists of a fiber-optic regenerator or repeater, Muldex (multiplexer/demultiplexer) (Link to SSC06 Paper), microprocessor module, hydrophone, and Digiquartz ^® pressure sensor. The Muldex, as designed by Mark Tremblay, is data transmission rate and protocol- independent. It is designed for use on any SL-280 or SL-560 fiber-optic cable system (the first two generations of fiber telecommunications systems).

• The Muldex converts the digital data from the hydrophone and microprocessor module to an optical signal that is transmitted through the fiber.

• The microprocessor module monitors temperature and internal pressure of the pressure vessel. It also handles data from the externally mounted pressure sensor.

Rev: 08/10/2007