摘要：
在传统的FSK调制方式中，两个载波频率转换期间，已调信号存在相位和频率突变，造成系统频带利用率不高和信号频谱衰减太慢。用DDS进行标准FSK调制，可使其相位连续，但由于存在频率瞬间突变，在已调信号相位路径中将产生拐点，这仍使得信号频谱衰减过慢。本文提出的DDS与FPGA相结合的Ramped FSK调制方式中，通过DDS线性扫频使得频率瞬间突变转换成频率渐变，消除了已调信号相位路径中的拐点，使频谱主瓣以外衰减加快，进而满足通信系统对减小邻道辐射干扰的要求。
熊卓列,张深基. 基于DDS与FPGA相结合的Ramped FSK调制方式的实现[J]. 电信科学, 2006, 22(6): 53-56.
Zhuolie Xiong,Shenji Zhang. Realization of Modulation Mode Based on Combination with DDS and FPGA Abstract The paper comes up with a point of view: the inflexion can be eliminated,the attenuation of the outside of main lobe of frequency spectrum can be quickened, and the need of decreasing radiated interference from the near channel in the communication system can be satisfied by the means that frequency abrupt change is converted into frequency gradual change in the ramped FSK modulation mode combined with DDS and FPGA.[J]. Telecommunications Science, 2006, 22(6): 53-56.
