Diversity-based acoustic communication with a glider in deep water

Abstract

The primary use of underwater gliders is to collect oceanographic data within the water column and periodically relay the data at the surface via a satellite connection. In summer 2006, a Seaglider equipped with an acoustic recording system received transmissions from a broadband acoustic source centered at 75 Hz deployed on the bottom off Kauai, Hawaii, while moving away from the source at ranges up to ∼200 km in deep water and diving up to 1000-m depth. The transmitted signal was an m-sequence that can be treated as a binary-phase shift-keying communication signal. In this letter multiple receptions are exploited (i.e., diversity combining) to demonstrate the feasibility of using the glider as a mobile communication gateway.

Experimental demonstration of single carrier underwater acoustic communication using a vector sensor

“…While data from satellites and airplanes can provide with some useful information, it does not present information far below the ocean surface [1]. Variable undersea observation equipments such as autonomous underwater vehicles (AUVs) have emerged over the last decade to further understand the internal changes of ocean.…”

Single Carrier with Frequency Domain Equalization for Synthetic Aperture Underwater Acoustic Communications

“…Several approaches to achieve phase coherent UWA communication with a single receiver have been developed in recent years [ 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. In synthetic aperture communications, only one or a few hydrophones are employed on the underwater platforms.…”

“…They provided an effective data rate of 30/M kbits/s (M is the transmission number) with 8-phase shift keying (PSK) modulations at about a 3.5 km range in shallow water. A glider with a single hydrophone is used for long-range acoustic communication in deep water [ 18 ]. This system improved the performance even when individual receptions had low signal-to-noise ratios (SNR).…”

Array design considerations for exploitation of stable weakly dispersive modal pulses in the deep ocean

“…The underwater acoustic channel is a challenging communications media due to the constantly fluctuating ocean environment and due to multipath propagation which results in large channel delay spread [9]. In a deep ocean long-range acoustic communication system, a signal consisting of a sequence of symbols experiences significant ISI (up to several seconds or hundreds of transmitted symbols [10]), which precludes achieving reliable high-speed data transmissions. A common solution is to design a receiver that compensates for the ISI and employs a decision feedback equalizer (DFE) [9].…”