Communication system for underwater use
US7006407B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 28, 2002 |
| Grant date | Feb 28, 2006 |
| Priority date | — |
| Expiry date | Mar 28, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/0057
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
For digital underwater transmission an information sequence (17) of digital bits is partitioned into a succession of symbols each comprising n bits where n is equal to or greater than one (2n potential symbols), each symbol (19) is replaced (20) a corresponding base code sequence of length m bits and the result (21) is passed to an acoustic transducer after bi-phase modulation (22) on a carrier. The code has good correlation properties, e.g. a pseudo-random maixmal length sequence, a Gold code or a Kasami code, and the value of m/n is at least (32). Preferably the base sequence is cyclically extended at one or both ends prior to modulation, and Solomon Reed redundancy coding (18) is initially applied to the information sequence. The output (23) of modulator (22) may be prefaced (26) by a pair of chirp waveforms (24). Provision is made for Doppler and multi-path correction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.