Improved Two-Valued and Three-Valued Integrand Codes for Real-Valued Self-Orthogonal Finite-Length Sequence

A real-valued self-orthogonal finite-length sequence has a zero-sidelobe autocorrelation function except at both shift ends. Two-valued and three-valued integrand codes for the sequence are effective for a practical application. This paper presents the improved two-valued and three-valued integrand codes. The allocation of code values in every time chip is optimized so that the Fourier spectrum of the equivalent multivalued pulse-width-modulation (PWM) code waveform at every chip may resemble each other. The codes are smoothed through Gaussian low pass filter. The sidelobes of the autocorrelation outputs are improved to be about 10-dB lower than those for the not-optimized codes.