FPGA高精度测量频率研究

Study on FPGA high-precision frequency measurement

广播载波频率的精确测量是检测载波频率是否稳定的重要手段。由于常规测量频率的方法存在频率测量前后沿不确定性的问题,使测量结果存在1个字的测量误差。提出了全同步测频法测频,实现了被测信号、标准信号和闸门信号三者同步,从而消除了标准信号的1个字的量化误差。用VHDL语言编写了测频程序,在FPGA(现场可编程门阵列)上实现计数和控制,将测量数据通过串行线送到ARM微处理器上计算并显示出来,实现了四路中波载波的频率精确测量。

The precise measurement of radio carrier frequency is an important measure to detect carrier frequency. The conventional method of measuring frequency exists the uncertainty problem which will make an inaccuracy error of one word. This paper presented synchronous frequency measuring method which could realize the three synchronous between measured signal,standard signal and the gate signal. Compared with conventional method, the inaccuracy error of one word was eliminated. VHDL language was used to write the frequency measurement procedures through FPGA to realize the count and control. The tested data was carried by a serial line to ARM microprocessor to calculator and display. The precise frequency measurement of four medium wave carriers was realized.