There is a lot of confusion regarding spread spectrum communications in the underwater communications field,...
DSPComm recently delivered several Aquacomm underwater acoustic wireless modems and Aquatrans high-performance oil-filled transducers to the Seaformatics Group in Canada. The Seaformatics Group is a research arm of the Memorial University of Newfoundland and Labrador (MUN), Canada, carrying out cutting-edge research into empowering the Seafloor. In this particular project, the group is developing seabed instrumentation and underwater wireless networking mounted on self-powered autonomous pods. These pods, known as SEAFormatics Pods, are designed to monitor the subsea and seabed environment. The applications include geological imaging, earthquake detection, marine science and applications in the subsea oil and gas industry, as well as defence applications.
One particular innovation is that these pods can be self-powered for extended periods of time underwater without human intervention. This is achieved through a patent-pending custom-designed horizontal axis turbine that uses sea currents to generate and store electric energy, thus allowing indefinite operation in the subsea environment. As it is well-known in this industry, the sole use of batteries to provide energy is a severe limiting factor. Further, the pods have a plug-and-play capability where the sensor modules can be changed depending on the goals of the deployment.
DSPComm’s Aqauacomm modems and Transducers power the wireless connectivity of the pods. Acoustic wireless communications are critical for the system, as the health of the pods can be monitored remotely, as well as data reticulation between the pods and the surface. The networking system is designed so that up to 100 pods can be networked in one area. The range between pods is up to two kilometres in distance, so that with 100 pods a massive subsea area can be covered and networked.
Unlike in terrestrial RF communications and networking, underwater networking is unique due to the relatively large propagation time, as well as a limited availability of bandwidth in the acoustics channel. Due to this fact, research has shown that the traditional methods of time and/or frequency multiplexing methods do not work so well. DSPComm modems come into their own in the underwater networking area, as the modems are spread spectrum CDMA modems, which provides a viable method for successful underwater networking due to the fact that the same frequency and time-space is used, and the multiplexing is carried out by different spreading codes. Previous research in underwater ad-hoc networking has been undertaken by a well-known Australian research institute (CSIRO) using DSPComm modems and shown to work successfully.
The SEAFormatics team carried out extensive research and trialed modems from several leading manufacturers, and chose DSPComm modems as the most reliable modem to operate in highly reflective shallow waters typical of coastal areas. The modem was also the best fit for other important criteria of the pod, such as small footprint, low power consumption, straightforward API and highly configurable operational parameters.
In this second phase of the deployment, the system will be tested for an extensive period of time and DSPComm supplied further sets of modems and transducers for this phase. DSPComm has supported and worked closely with the group to ensure a successful outcome.