Design And Realization Of Embedded High Accuracy Synchronous Time Control And Signal Processing Circuit Board

With the development of the electronic technic, high accuracy synchronous time system has been more and more widespread used in many fields such as communications, deep-space exploration and national defence. We can easily use Global Positioning System(GPS) to make up high-precision and low-cost synchronization time system because it has high stability and precision atom standard and it's signal can wholly cover theearth at any time and at any weather.Firstly,the meaning of research, state-of-the-art and the applications of synchronous time equipment are summarized;then, the component and time service principle of the GPS system are introduced,the predominance of GPS in using for synchronous time system is analyzed.A embedded high accuracy synchronous time control and signal processing circuit board based on GPS and DSP is designed,which can be used for signal generating,data acquisition and data processing.The overrall design of the system and the realization of hardware platform are finished in this thesis .The development of some software is introduced, including the drivers of hardware in Win2000, the bootloader and application programs of DSP. Besides, the main control application program is developed in VC++6.0.The logical programing which realizes high accuracy synchronous time and high accuracy timekeeping is completed in Quartus II with VHDL language.The effect of the GPS signal's availability and stability on synchronous time precision is analyzed,and the correction methods are pionted out. This thesis presents a new method to measure the frequency of the crystal oscillator clock accurately, which is based on both the complement of the errors between GPS and crystal oscillator and statistics theory.The method has increased the synchronous time precision and timekeeping precision of the system availability. High accuracy synchronous time and timekeeping function of the synchronous time control and singal processing board have been realized.The board has been used in the correction system of a passive ranging sona successfully.