关注北斗导航的新调制方案 刚看到一篇宣传八股文:http://mil.news.sina.com.cn/2013-06-17/0856728272.html,对其中的技术内容非常感兴趣,比如“探索出一套创新的信号调制理论”,“信号体制与主动抗干扰相结合的方案”,于是仔细搜索了一番。 原来,所谓的创新的信号调制理论是DualQPSK,根据项目组的介绍,http://csnc4.beidou.gov.cn/Item/Show.asp?m=1&d=1848,DualQPSK看起来是在北斗1代升级过程中,为了向下兼容而研发的一种候选技术方案。 在一篇论文中找到如下摘要:http://cpfd.cnki.com.cn/Article/CPFDTOTAL-WXDH201205002002.htm :Future GNSS systems introduce the requirement to multiplex several binary spreading codes into a constant envelope on the same carrier. This paper studies the 4-code multiplexing model and presents a novel DualQPSK modulation that multiplexes four codes as two QPSK signals at the same center frequency. The analytical expression of DualQPSK is derived from the constellation of Alternative-BOC modulation. Then the proposed DualQPSK modulation is compared with the theoretical lower bound and conventional multiplexing techniques as Interplex and Majority Vote. The result shows that DualQPSK has the optimum efficiency and is actually an implementation that achieves the theoretical lower bound. The baseline of COMPASS B3 band contains a BOC(15,2.5) signal and a QPSK(10) signal. The special constraint is that the backward compatible QPSK(10) signal must be maintained, which makes the traditional techniques inapplicable. The BOC(15,2.5) and QPSK(10) signals modulated by DualQPSK are investigated in aspects of combining efficiency, power spectrum and inter-modulation interference. It is proven that optimum transmission efficiency and complete receiver compatibility is obtained by DualQPSK. The DualQPSK modulation is demonstrated as an attractive solution for COMPASS B3 signals. [此贴子已经被作者于2013-6-17 10:02:31编辑过] |