基于多周期同步测量的频率计设计

Design of frequency meter based on multi-periods synchronization measurement

针对工程实践中发现的频率计存在1字节误差以及待测信号幅度过大的问题。基于多周期同步测量计数理论,提出了一种以C8051F020与FPGA为最小系统的频率计制作方案,实现对待测信号频率及脉宽的精确测量。系统主要包括3部分:信号整形部分、频率计算部分、液晶显示部分。待测信号经过信号处理后和标准信号一同输入FPGA内部,单片机协同FPGA对信号进行频率测量并读取测频数据,然后将读取到的数据经过运算处理后显示。经实验验证,该系统测频范围可达0.1Hz^10 MHz,有效消除了1个字节的误差且具有一定的抗干扰能力。

According to the engineering practice,the problem of 1bytes error of the frequency meter and lower amplitude of the signal are found.This paper presents a method of making a frequency meter with the minimum system of C8051F020 and FPGA based on the theory of multi-periods synchronization measurement,and realizes the measurement of frequency and pulse width of the measured signal.The system mainly consists of the signal shaping module,the frequency calculation module,the LCD module.After amplification and rectification,the signal to be measured and the standard signal are input into FPGA.Two signals are counted in FPGA,and MCU calculates and processes the receiving data.Finally,the result of measurement is shown in the LCD.The test show that the system can measure the frequency up to 0.1Hz^10MHz,effectively eliminate the error of 1byte and certain anti interference ability.