Based On The Development Of Dds And Pll Digital Fm Source

Frequency synthesizer is the hardcore of a electronic system. With the rapid development of telecommunication, radar, electronic spy and antagonizing technology, the system has higher demands to its performance indexes. The key capabilities of carrier wave frequency synthesis are frequency stability and phase noise. In case the parameter index of phase wobble of frequency source does not match the requested target, the system performance will decline and result in an actual loss of SNR.The thesis analysized the basic operating principle and specialities of digital direct frequency synthesizer, and phase locked loop frequency synthesizer. It also analysized the possibities and specialities of digital modulation with apply DDS. Then, comparing and studying the methods of DDS + PLL, it discussed stray and relative noise. To aim at difficult control of DDS's stray, the thesis provided a couple of ways to improve it and had made an identical result.In the consideration of the actual complexity, and apply commonality and flexibility, the thesis adopted DDS with PLL scheme, and got the S wave band frequency source with high-frequent stability, low phase noise, low stray, thin step size, and FSK modulation. This will be the correct source of some kind of remote control survey system.