Pulse or digital communications – Repeaters – Testing
Patent
1986-10-02
1989-05-16
Safourek, Benedict V.
Pulse or digital communications
Repeaters
Testing
375 37, 371 56, H04L 2534
Patent
active
048316350
ABSTRACT:
In a data transmission system using a predetermined trellis code, the output signal points are selected from a predetermined alphabet representing (k+n)-bit input words by using the values of n bits of each input word, and bits from previous input words, to identify a particular one of 2.sup.m subsets of the signaling alphabet m>n. The other k bits of the input word identify a pair of signal points of the identified subset. The sum of the components of one point of each pair is no less than zero and the sum of the components of the other point of that pair is no greater than zero. A running sum of the components of the signal points previously generated is maintained. If at any point in time the running sum is greater than zero, the signal point of the identified pair whose component sum is no greater than zero is generated, and vice versa. This scheme provides a channel-coded signal having a spectral null at dc.
REFERENCES:
patent: 3521274 (1970-07-01), Sawai
patent: 4528550 (1985-07-01), Graves et al.
patent: 4562426 (1985-12-01), Forney, Jr.
patent: 4581601 (1986-04-01), Calderbank et al.
Calderbank Arthur R.
Lee, deceased Ting-Ann
American Telephone and Telegraph Company
AT&T Bell Laboratories
AT&T Information Systems Inc.
Huseman Marianne
Safourek Benedict V.
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