Direct spread spectrum and its power spectrum

The results on power density spectrum are depicted. This shows that for long sequence, its characteristic approaches that of a synchronous random telegraph signal. Interestingly for short sequence there is a depletion of power spectral density at DC. This principally arises out of the small but finite negative autocorrelation terms. For both long and short sequences, the nominal spectral bandwidth remains the chip rate. It has not been broadened at all by the multiplication process.