eements will be tems, 2nd edn. Peter Peregrinus. registered, with the seventh bit overlapping into the data region. For Byrne, C.J., Karafin, B.J. and Robinson, D.R. (1963) Systematic random data this last bit will register an agreement or disagreement Jitter in a Chain of Digital Regenerators, Bell System Technical with equal probability, thus overall, the mean number of agreements Journal, 42, pp. 2679-2714. for a window position error of 1-bit will be 3.5. Repeating this Carlson, A.B. (1986) Communication Systems, McGraw-Hill, 3rd calculation for other window positions generates the plot of Figure 28.22. This confirms that the sequence 0011011 is a good FAW in Catchpole, R.J. (1975) Efficient Ternary Transmission Codes, Elec- that it produces a strong correlation spike when in alignment with tronic Letters, 11, pp. 482-484, (October) relatively low sidelobes associated with the out of alignment win- Cattermole, K.W. (1983) Principles of Digital Line Coding, Inter- dow positions. In this respect we note that the correlation values for national Journal of Electronics, 55, pp. 3-33. alignment errors of 1 or 2 bits are especially low, that is, it is a good CCIR (1986) Report 967-1, Digital Television: Transmission Im- word to use for well behaved systems which rarely experience more pairments and Methods of Protection. than 1 or 2 bit slips. Under such circumstances the pattern is thus CCITT (1988a) Recommendation G.821, Error Performance of an seen to be reasonably immune to unfavourable data bit combina- International Digital Connection Forming Part of an Integrated tions and/or isolated transmission errors, both of which could in- Services Digital Network, Blue Books, Geneva. crease the apparent number of agreements but are unlikely to CCITT (1988b) Recommendation M.550. Performance Limits for achieve the in alignment peak value. Bringing into Service and Maintenance of Digital Paths, Sec- The choice of FAW for a particular system will depend upon many tions and Line Sections, Blue Books, Geneva. factors. For e