Method to find Correlation for a random variable and thereby power spectral density of random signal
The correlation for greater than 1 is 0 because each bit in the chain is independent of the last bit.  For example were the current bit a 1, the probability of the next bit being a 1 is just 50/50.  Were the current bit a -1, the probability of the next bit being a 1 is still 50/50.