A non-coherent digital receiver of a spread spectrum communication system for baseband synchronizing of a reference pseudo-noise sequence with a received pseudo-noise sequence modulated in a received spread spectrum signal. The digital receiver includes a receiving unit for translating the spread spectrum signal into an in-phase signal and a quadrature-phase signal; a pseudo-noise code generator for generating a reference pseudo-noise code sequence comprising a pseudo-noise early code, a pseudo-noise punctual code, and a pseudo-noise late code; a correlator unit for correlating the in-phase signal and the quadrature-phase signal with the reference pseudo-noise code sequence to produce early, punctual, and late correlation signals comprising in-phase and quadrature-phase components; an adaptive threshold control unit for adaptively generating a variable threshold in response to the pseudo-noise punctual code and the in-phase and quadrature-phase signals; a synchronization detecting and tracking unit for detecting initial synchronization and phase difference between the received pseudo-noise code sequence modulated in the spread spectrum signal and the reference pseudo-noise code sequence for controlling generation of the reference pseudo-noise code sequence and synchronization between the received pseudo-noise code sequence and the reference pseudo-noise code sequence; and a demodulator for demodulating the spread spectrum signal into a baseband signal.
Non-coherent digital receiver of a spread spectrum communication system