Abstract :
Properly designed low detectability, discrete sequence, spread spectrum waveforms approximate the attributes of thermal noise. Use of a complex, pseudorandom, encoding sequence, with a uniform phase and arbitrary amplitude distribution removes all chip rate lines from non-linear (zero memory) processing at harmonics of the carrier. Non-linear processing cannot determine features at harmonics of the carrier such as the chip rate, or collapse the waveform to identify the carrier. Baseband (about DC) terms can produce chip rate harmonics, but rectangular chips do not suffer this difficulty. Further, Gaussian encoding approximates a Gaussian noise process considerably better than a constant amplitude waveform.
