Identify the PN sequence length of a PN sequence generator w

Identify the PN sequence length of a PN sequence generator with each of the following: Four shift registers Nine shift registers Twenty-three shift registers

Solution

Relation between length of PN sequence(p) and number of shift registers(n) is given as p = (2^n)-1.

So for 4 shift registers p = 15

for 9 shift registers p = (2^9)-1.

for 4 shift registers p = (2^23)-1.