LEI Zhi-yuan^1,2,3, GUO Ji¹, LU Xiao-chun^1,3

(1. National Time Service Center, Chinese Academy of Sciences, Xi′an 710600, China;

2. Key Laboratory for Precision Navigation and Timing Technology, National Time Service Center,

Chinese Academy of Sciences, Xi′an 710600, China;

3. Graduate University of Chinese Academy of Sciences, Beijing 100039, China)

Abstract: In order to understand the constant envelope AltBOC(alternate binary offset carrier) modulation easily, we first derived 2-codes AltBOC starting with BOC signal and combining with the directly perceived signal phase diagram, then derived 4-codes AltBOC, and at last the expression of constant envelope AltBOC signal was derived as well as some numerical characteristics concerned were given.