Abstract:

We propose a novel class of M-ary spread spectrum based on the quasi-Orthogonal multi-PN code. A hybrid matrix based on the Golay complementary sequence is deduced and used for the M-ary spread spectrum, which greatly enhances the band efficiency and robustness, and compared with the spread spectrum technique, it provides a larger spread gain and a stonger anti-intercept capture capability. In order to overcome the difficulties incurred by a long PN code spread spectrum system such as high computational complexity of synchronization and complicated hardware realization, a novel fast acquisition algorithm based on the 2-stage FFT is presented whose complexity is largely reduced compared with the conventional PMF-FFT algorithm. The receiver can effectively eliminate distortion caused by phase offset of the carrier using quadrature subchannel information for intersect data dispreading.

Key words: M-ary spread spectrum, quasi-orthogonal multi-PN code, code acquisition, frequency offset correction