A Method of Digitized FM with Controllable Modulation Index Based on FPGA
Yan Deng · Modern Electronics Technique · 2006
The digitized FM system is actually a Direct Digital Synthesis(DDS) system that the frequency of the output is controllable.The modulated signal which is converted into digital signal by A/D converter,and the frequency word of DDS is controlled by this digital signal,so the frequency of the output is determined by this modulated signal and realizes the FM.(Also,)we could change the FM index by adding zero behind the result of A/D converter.The system is realized by FPGA.The(result) of simulation is made by MAX+PLUSⅡ and the actual wave form of system both show that FM index can be changed in large scale.