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Burst communication – a solution for the underwater information management

100%

Nissen I.

Hydroacoustics

2015

tom Vol. 18

113-126

The performance of collaborating information systems in the hydrosphere is based on the robustness and tolerance of the wireless communication task. It is strongly intertwined with the cooperation and coordination reliability under water for sharing resources and common purposes. Key technology and bottleneck is the physical layer communication in the underwater ''chameleon'' acoustic channel environment and the challenges of non trivial channel effects like the multipath propagation - which is rapidly varying over time and space. In this contribution we introduce the burst communication as one possible solution. These transmissions are supposed to be of a very short duration. The purpose is to occupy the acoustical channel in the underwater column only for a short time window, like in impulse and click communication (similar to the use by marine mammal, Khoisan and wugbe languages), e.g. to reduce the probability of transmission collisions and allows an efficient EMission CONtrol (EMCON).

Stationary underwater channel experiment: Acoustic measurements and characteristics in the Bornholm area for model validations

63%

Nissen I. , Kochańska I.

tom Vol. 19

285--296

The underwater acoustical channel is time-variant, and even on small time scales there is often existing no ‘acoustical frozen ocean’. Popular is the use of WSSUS-channel transmission modeling (Wide-Sense Stationary Uncorrelated Scattering) for the stochastic description of bandpass signals in GSM mobile phones with moving participants; since this results in a halved number of model parameters. For underwater sound applications such as detection, navigation and communication this approach provides limited a-priori-knowledge for adaptive algorithms with moving cooperative participants. The FWG of the WTD71 is collecting phase-accurate channel measurements from different sea areas in different time and application scenarios, with moving and stationary communication nodes since 2001. This paper presents a SIMO experiment from 2010, with a high precision continuous observation period of eleven hours using two stationary bottom nodes, mostly uncoupled from the influence of surface waves and from the sea floor. Transmitter and receiver node with a distance of two nautical miles between them were stationary installed on the bottom in shallow watersin the Bornholm Basin of the Baltic Sea. The sound speed has been measured continuously in the water column with a moving measurement chain. The question for this experiment was: Is the WSSUS-property fulfilled in water, when participants communicate motionless with negligible current, bottom influence and movements of the surface? The answer is: No, not in this experiment.

Data compression and clustering of one-third-octave spectra by acoustical colors

51%

Józwiak R. , Nissen I. , Listewnik K.

2017

tom Vol. 20

85--92

This article presents a new approach for the data compression and clustering of one-third octave spectrum by using "acoustical colours". Using in-situ measurements by the IGLOO – sensor nodes it can show that this approach allows a clustering of the colors for a quick look classification. This is helpful using wireless acoustical transmissions with restricted transfer volume in underwater sensor networks without jamming their own measurements.