The Design Of Three-phase Sinusoidal Signal Source Based On DDS

In domains such as electronics and communication technology, some signals are frequently employed as input signal or reference signal.The apparatus that produces these signals is generally referred to as signal generator or signal source or oscillator. It is widely applied in the fields of communication,electronic circuit, automatic control, teaching, scientific research, and experiment, etc. Due to the practical need in market, diverse signal sources are developed by researchers home and abroad, including pulse generator, sine wave source, synthetic signal source, arbitrary wave generator, etc., which are limited in the field of application, with little versatility/universal applicability. This thesis first elucidated the history of signal source both home and abroad, and the features of DDS technology, this is followed by a generalization of the features of current signal generator and its main manifestations, a new type of signal generator is designed by the employment of EDA technology, the design of the system is a layered one, which is realized by the adoption of DDS technology on the Quartus II software development platform.This study is oriented to the design of a signal source with multiple function, expansibility, and a strong updating ability. The main work involves the analysis of current signal source synthesis technology from the perspectives of technical scheme, hardware realization etc. Based on the generalization of existing technology, the programmability and reconfigurability of FPGA hardware and the DDS technology are utilized in constructing multifunctional, applicable and expandable signal source, additionally, the function of signal generator designed by the author is analyzed, thus revealing the fundamental structure of modular circuit, which determines the basic idea of software design. The main contents of this thesis are:1. A detailed comparison of the features of several commonest signal synthetic technology(such as PLL, DDS, etc.), which aims at the construction of technical route and scheme utilized in designing a new signal generator.2. A module division of the system of signal generator on the basis of FPGA(EPC20Q240C8,, which facilitates the modular design of the system.3. The realization of the output function of three-phase sinusoidal signal by adopting DDS technology, with frequency control word inputted through standard keyboard and frequency displayed in digital tube.4. The realization of two functions of signal generator: amplitude modulation(AM) and frequency modulation(FM) by employing DDS technology and an explanation the design method of Phase Modulation(PM).5. The design of ASK module, in which binary baseband sequence signals is generated through FPGA, these signals in turn undergo digital modulation in ASK module and produce a ASK signals, which are simultaneously demodulated, with the original digital sequence restored in this process.6. The analysis of the functional simulation of the system and its performance.To sum up, The signal generator designed in this study employs some merits of FPGA,such as programmability and reconfigurability,thus overcoming some deficiencies of DDS chip,for example,its lack of expandability and limited applicability.