Reducing scintillation effects for optical free-space transmission
US6868519B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 2001 |
| Grant date | Mar 15, 2005 |
| Priority date | — |
| Expiry date | Jan 11, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/0071
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A process and apparatus is described for recovering from optical transmission degradation due to scintillation effects in optical free space. A payload bit stream is encoded into Reed-Solomon codewords. These are fragmented and distributed as interleaved segments over a cell matrix of a SDRAM buffer store which is made large enough to correct a burst error occurring over 20 million consecutive bits. The rate imbalance between conventional read vs. write operations for SDRAM devices, which would otherwise obviate their use in this application by preventing real time operation, is overcome by an address remapping that avoids having to changing page addresses each time SDRAM memory is referenced. The remapping facilitates a more nearly equal allocation of READ overhead and WRITE overhead. An optical communications system employs at both the transmit and receive ends, substantially equivalent SDRAM buffer with address remapping capability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.