[41], [48] and we shall refer to the sequence set as a linear design. By proper intialization of the register contents, the generator of Figure 5.15 can be used to produce any of the N possible sequences {a(}}}, the component sequences {an} and {a'n}, and the all-ones sequence. The latter sequence, definitely not pseudorandom in nature, is simply avoided by not initializing both registers with all zeroes. A purely random non-zero ini- tialization of the registers is equally likely to produce any one of the sequences of interest. To load the registers for the production of {ants} for arbitrary initial shift 8 -s L'-1 -S L' fontol sequence select (cn+s) SECOND REGISTER INITIALIZER {an+a} {0n+8} -al-1 Figure 5.15. Fibonacci form of a linear generator structure for {a(}}} when both {bn} and {b'n} are over GF(p). Pseudonoise Generators Table 5.17 Initialization data for the liner generator structure of Figure 5.15. Register Initializations Output Size of Output Lower Upper Index Set Linear Span (pL - 1)(pL'-1) L + L' {b'n+i-1} pl' - 1 {bn+k-1} a particular j at a random shift, 8, one register of the sequence generator in Figure 5.15 may be initialized randomly with non-zero contents, and then the allowed choice(s) for the initial contents of the other register must be deter- mined mathematically. This calculation could be done off line, thereby com- plicating the use of the system by requiring that operators have tables of allowed register contents, or it could be mechanized in hardware, as sug- gested in Figure 5.15. If the second register initialization is mechanized in hardware and the computation can be carried out in a fraction of the registers' clock time with a unique answer, then the second register can be eliminated and the initial- izing hardware can be used to calculate the second register's output symbol for each successive contents of the first register. This calculating hardware, and the adder which combines the two component sequences, form an NLFFL function of the contents of the first register to prod