A New Class of Selected Ternary Pulse Transmission Plans for Digital Transmission Lines

Spectrum Shaping with Alphabetic Codes with Finite Autocorrelation Sequence

“…Let ... a(-1)a(o)a(1)u (2) ... denote the channel sequence, where a ( j ) E T . It is well-known [ 101 that the normalized power density spectrum $0 in the normalized frequency range [ O , 11 is given by a modified version of Bennett's formula:…”

“…The first code to be discussed is a (2,2,3) FAS code, which may be considered as an alternative to the bipolar code [ I ] . As is well known, the channel sequence produced by the bipolar encoder (with an unrestricted input sequence) may produce an arbitrarily long sequence of 0's which is unacceptable with respect to timing requirements.…”

“…As is well known, the channel sequence produced by the bipolar encoder (with an unrestricted input sequence) may produce an arbitrarily long sequence of 0's which is unacceptable with respect to timing requirements. Other codes which do not possess this undesirable property have been proposed; the best-known of these are the PST [2], HDBn and CHDBn [ 4 ] , and BnZS [ 131.…”

“…From the existence arguments of Section 2, it is easily seen that (2,2,3) codes exist with a= (1/4, 2/4, 1/4) only. The codebook which has the minimum value of A for these parameters is given in Table I.…”

“…This may be considered as a first approximation of a typical repeatered line as noted in [8]. The (2,2,3) code provides a fraction of a dB improvement over B3ZS for a cut-off frequency less than 4 X of the data rate. Another code we report has a spectrum superior in the lowfrequency range to that of the well-known MS43 code [ 3 1 .…”