Software Modems for
Underwater Sensor Networks
Raja Jurdak, Pedro M. Q. Aguiar, Pierre Baldi and Cristina
Videira Lopes
Abstract
The
prohibitive monetary cost and high power consumption of existing acoustic
hardware represent an obstacle for underwater sensor network deployment
efforts. To address this issue, we propose underwater networks that rely on
widely available speakers and microphones in electronic devices, coupled
with
software modems, to establish acoustic communication links. In this paper, we analytically
and empirically explore the potential of this acoustic communication system for
the underwater environment with a generic PC microphone as a receiver and with
the Tmote Invent sensor module speaker as
a
transmitter. After waterproofing the components with elastic membranes that
provide suitable coupling with the water, our experiments profile the hardware
communication capability in a controlled aquatic environment. The medium
profiling results expose the favorable frequencies of operation for the
hardware, enabling us to design a software FSK modem. The experiments to
evaluate the data transfer capability of our 8-frequency FSK software modem in
the underwater channel yield an error-free channel capacity of 24 bps, and they
also demonstrate that the system supports data rates up to at least 48 bps
within a transmission range of 17 m.
In proceedings of
IEEE/OES Oceans’07.