Improved alternate transmission of different codes in M-sequence pulse compression using phase-shifted complex M-sequences

摘要

The alternate transmission of two different codes in M-sequence pulse compression has been proposed to achieve an extension in the measurable distance from one-code transmission without degradation of the temporal resolution of distance measurement. In the proposed method, the received signal is correlated with each transmitted M-sequence. Distances are then alternately measured from two cross-correlation functions. However, the truncation noise and truncated interference noise are generated in both cross-correlation functions. In this study, the alternate transmission of phase-shifted complex M-sequences is proposed to suppress the truncation and truncated interference noises. The amplitudes of these noises vary with the combination of M-sequences and the phase differences between M-sequences. Therefore, noise amplitudes in various combinations and phase differences are investigated. Consequently, noise amplitudes are found to be lower than in the previous study of integer M-sequences when the phase difference of the optimum combination is approximately 90 degrees or 270 degrees.