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Optical Fiber Driver and Receiver Using a Three-Level Flux Mode Encoded by a Simplified Bipolar Differential Biphase Bichannel Code

IP.com Disclosure Number: IPCOM000043609D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Vachee, P: AUTHOR

Abstract

This idea allows an improvement by a factor of two the data rate of an optical fiber used in a three-level coded flux mode (no DC component). The invention uses a simplified version of the Bipolar Differential Biphase Bichannel (BDBB) code described in U.S. Patent 4,283,789. This code allows the multiplexing of data on local telephone lines, built with twisted pairs, without phase ambiguity and a DC component. Transmission on optical fibers does not need differential encoding (to avoid phase ambiguity) because an optical fiber is not polarized, so the encoding and decoding mechanism can be highly simplified. As shown in Fig.

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Optical Fiber Driver and Receiver Using a Three-Level Flux Mode Encoded by a Simplified Bipolar Differential Biphase Bichannel Code

This idea allows an improvement by a factor of two the data rate of an optical fiber used in a three-level coded flux mode (no DC component). The invention uses a simplified version of the Bipolar Differential Biphase Bichannel (BDBB) code described in U.S. Patent 4,283,789. This code allows the multiplexing of data on local telephone lines, built with twisted pairs, without phase ambiguity and a DC component. Transmission on optical fibers does not need differential encoding (to avoid phase ambiguity) because an optical fiber is not polarized, so the encoding and decoding mechanism can be highly simplified. As shown in Fig. 1, the two data (Data 1 and Data
2) to be sent at the same time on the optical fiber are encoded by the simplified BDBB encoder, then sent to the three-level flux optical driver which transmits the multiplexed Data (1 and 2) on the optical fiber. At the receiving end, a three-level flux optical receiver sends the received multiplexed data (1 and 2) to the simplified BDBB decoder, which demultiplexes the data and converts it into their original Data 1 and Data 2 form. At the optical fiber site, data are encoded into a three-level code, so no difference is encountered with a normal data stream; however, at the BDBB decoder output the data rate has been doubled. The simplified BDBB encoder logic circuit is shown in...