Pulse or digital communications – Multilevel
Patent
1996-02-23
1998-07-21
Chin, Stephen
Pulse or digital communications
Multilevel
375292, 341 56, H04L 2549
Patent
active
057844097
ABSTRACT:
Three-level (ternary) line codes are provided for use in transmitting binary data at high data rates (e.g. 100 Mbits/s) over twisted-pair cable, without producing excessive radiated emissions at frequencies above 30 MHz. A running digital sum (RDS) is computed for a stream of ternary symbols as it is encoded; if this RDS reaches a predetermined limit, the polarity of the next following non-zero symbol is determined so as to change the RDS towards zero. In addition, if the binary data stream and the RDS satisfy another predetermined criterion, such as the RDS having a particular polarity when two or more 0 symbols have occurred, then the next non-zero symbol is determined so as to have the opposite polarity; otherwise the next non-zero symbol has the opposite polarity to the preceding non-zero symbol. The RDS limit and the predetermined criterion can be selected to obtain a desired power spectral density for the ternary signal propagating over the twisted-pair cable.
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Electronics Letters, vol. 29, No. 12, 10 Jun. 1993 (pp. 1107-1109) Mobray, M. et al., "New 5B/6T Code for Data Transmission on Unshielded Twisted Pair Cable".
Electronic Letters, vol. 18, No. 24, 25 Nov. 1982, (pp. 1040-1041) Kim & Kim, "New runlength-limited and dc-free line code of minimum bandwidth".
Electronics Letters, vol. 30, No. 16, 4 Aug. 1994 (pp. 1284-1285) "Spectra of a class of run-length limited MLT3 Codes".
Chin Stephen
Hewlett--Packard Company
Kim Kevin
LandOfFree
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