Underwater Acoustic Communication and Positioning State of the Art and New Uses

Transcription

1 Underwater Acoustic Communication and Positioning State of the Art and New Uses

2 Radio signals Work only on very short distances Salty water particularly problematic No underwater GPS Cables Too heavy, bulky, for longer distances and depths Impractical for small AUV and ROV applications Can be broken by passing ship Acoustic communication Worked only under ideal conditions Prone to interferances from noise High energy consumption Environmental concerns

3 Signal arrives as a multitude of overlapping echoes at the receiver Highly dynamic situation, changes can occur within seconds Caused by reflections in the surface sea-floor, density and temperature variations

4 Advantages S2C: Ultrawide band signals with continous frequency changes Multipath echoes can be separated with S2C s signal compression High signal gain at the receiver end More available bandwidth Energy efficient Environmentally friendy (very low energy content per frequency cell) High precision measurements simultaneously (range and speed)

5 Fast and Self adapting Signal parameters optimized with each transmission Achieve the best transmission at given conditions without sacrificing reliability Advanced data management for efficient acoustic communication Optional to have multiple channels Transparent link to the end-user: Automatic error correction Maintain packet order Extended functionality Use the same signals for accurate positioning with an integrated ultra-short baseline (USBL) antenna or long-baseline (LBL) antenna Basis for new sonar development Networking options: Relaying for longer distances Broadcasting Special protocols to take the transmission delays into consideration Meshes with automatic re-routing and increased reliability

6 Combined data transmission and positioning Acoustic communications and positioning emulator Communication networks Technological evolution towards reduction in size and power consumption Researcher and developer tools (Sandbox, digital/analog Wet-End) Continuous improvements for reliability

7 Developer tools White Line Science Edition Sandbox included, with up to 64GB space for own development TCL/Expect, GCC Toolchain NS2 Framework SUNRISE Driver Ideal for protocol development and testing Wet-End Digital or analog input Testbed for signal modulation scheme testing

8 S2C acoustic modem EMULATOR PC Sensor Software Modem PC Sensor Software Modem Emulator PC ROV/AUV Software Software Modem

9 S2C acoustic modem emulator structure: data-link layer emulator Linux kernel module that controls the data exchange between the data-link layer and the physical layer physical layer simulator acoustic channel simulator What is simulated? signal propagation delays data packet collision detection packet synchronization errors time difference of arrivals on the USBL grid elements movement of the virtual modems (in development)

10

11 Baikal Deep Underwater Neutrino Telescope (BDUNT) at a depth of 1200 m in the Baikal lake Requires careful Calibration of the Sensor positions 2010 by using S2C Technology: Accuracy achieved: 5 mm

12 Facility AREVA, pool test

13 1.5 Z, m X, m Y, m Position estimations accuracy: 0,07% of the slant range (Drms), or angular deviation: 0,04 from the correct attitude

14 RS Maria S. Merian, Atlantic ocean, 6000 m DNS project, Germany

15 UBLS positioning results short range (near to bottom) long range (open water) Position estimations precisions: short range (200 m): 0,085 % of the slant range (Drms), long range (2 km): 0,117 % of the slant range (Drms),

16 Conclusions: 1. The accuracy (Drms) of the combined USBL positioning and communication system stays about 0.1 % of the slant range. At a distance of 100 m between the USBL transceiver and the transponder the positioning error stays under 10 cm. 2. Data exchange with bitrates of 10 kbps along with positioning provides additional control opportunities, Vehicle navigation in real-time mode (acoustic commands) etc.

17 UW Networks Multi-Sensors Multi-Channel - Systems S2C R-Series LBL / USBL Positioning S2C Sonar-Technique Mechanic Control Acoustic Releasers etc. Data-Logger / Monitoring Systems Modular ICT Systems

18