Transmission and reception of duobinary multilevel pulse-amplitude-modulated optical signals using finite-state machine-based encoder
US6424444B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 2001 |
| Grant date | Jul 23, 2002 |
| Priority date | — |
| Expiry date | Feb 24, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/4917
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Methods and apparatus to transmit and receive information bits encoded in duobinary, multilevel pulse-amplitude-modulated (PAM) optical signals are described. The transmitted optical signal has a narrow optical spectrum and a low symbol rate. Information bits are encoded in a M-ary PAM symbol sequence, where M≧2. The PAM symbol sequence is input to a finite-state machine, which yields an encoded sequence that changes sign between two symbol intervals when the encoded sequence takes on a nominally zero value during an odd number of intervening symbol intervals. The encoded sequence is lowpass filtered and modulated onto an optical electric field. The receiver processes a received optical electric field to obtain an electrical signal proportional to the received optical intensity, and performs M-ary symbol-by-symbol decisions to recover the transmitted information bits, without potential error propagation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.