Source Of Synchronous Digital PLL Frequency GPS Second Pulses

With the rapid development of electronic technology and communication technology, the using of the synchronous clock signal is more and more widely, and the precision of synchronous clock signal becomes higher and higher. In this paper, synchronous broadcasting technology as the research background, designing a high precision frequency source system based on the1pps signal of the GPS.The principle and development background of the frequency synthesis technology and the development background of the GPS were firstly analyzed in the thesis, and finally decided using the AD9548chip which can directly lock the lpps signal from the GPS as the core of the system, combined with the GPS OEM board to complete the synthesis of synchronous signal, and using the FPGA as the control chip to finish the function configuration of the AD9548chip. The system mainly consists of FPGA control chip, AD9548chip, GPS OEM board, the serial communication module, filter circuit and so on.The SPI data transmission based on FPGA can configure the AD9548chip accurately the GPS OEM board transmit the1pps signal that abstract from the data that acquired from GPS through GPS antenna to AD9548as the reference input signal. The AD9548generated the synchronous output signal by locking the frequent and phase of the1pps signal.The using of the UART serial communication between FPGA and upper PC machine can complete the hot switching of the output signal frequency of AD9548chip, and amplified the output signal of the AD9648by the amplifying circuit, providing high stability and high-precision frequency source signal for the equipment that need synchronous frequency signal.