The Development Of Digital Modulation Signal Generator

In the research and application domain of modern electronics technology, we often need signal generators, which have high precision and modulating frequency. Especially with the development of communications technology, there are more and more channels, which distribute densely, therefore, it becomes more and more important to have high precision and stabilization communications frequency. But it is difficult to generate those signals with traditional methods. So we introduce a signal generator, which has modulation function using DDS technology in the thesis.Direct Digital Synthesize technology is new era frequencies synthesize technology. It controls phase increment of the signal with digital. This method has many advantages, such as high distinguishing ratio of frequency, switching frequency rapidly, continuous phase while switching, low phase noise, full digital and easy to integrate. It is adopted widely because of these advantages.Basing on the theoretic analysis of DDS, a method is given to generate standard signals by frequency synthesize method in the thesis, which is based on phase accumulator. According to system attributes, Digital Mudulation Signal Generator, which has simple construction and good performance, is designed. The hardware and software of Digital Mudulation Signal Generator are discussed deeply. The hardware circuits of the system is designed by adopting TMS320F206 of Co. TI as its MCU, and AD9852 which is a chip of DDS produced by Co. AD as its core. We use advanced technology of electronic design automation during the hardware design. It simplifies the debug of the circuits, reduces the cycle of development, raises the performance and low the cost by using CPLD to carry out logical control. Not only can the signal generator generate Sin wave, FM wave, AM wave, PM wave, but also it can carry out 2FSK, 2ASK, 2PSK. It can give waves with frequency up to 40MHz and resolving power of 1Hz. Its frequency spread widely. The attribute of the signal generator attains advanced level in domestic corresponding domain.