基于Nios Ⅱ的宽频小信号等精度测频系统  

Wide-Band and Small-Signalequal Precision Frequency Measurement System Based on Nios Ⅱ

作　　者：郑志旺 李锦明 方帆 ZHENG Zhi-wang;LI Jin-ming;FANG Fan(School of Instrument and Electronics, North University of China, Taiyuan 030051, China;PLA Unit 32382, Beijing 100072, China)

机构地区：[1]中北大学仪器与电子学院,山西太原030051 [2]中国人民解放军32382部队,北京100072

出　　处：《中北大学学报（自然科学版）》2021年第3期275-281,共7页Journal of North University of China(Natural Science Edition)

摘　　要：为了实现等精度频率计对不同幅值的方波和正弦波信号频率的测量,简化硬件电路.采用Intel公司型号为EP4CE10的FPGA,基于Nios Ⅱ软核设计了宽频小信号等精度测频系统.待测信号首先经过自增益控制电路和高速比较器整形为兼容FPGA逻辑电平的3.3 V方波信号,然后由FPGA逻辑部分实现频率的测量并将结果写入FIFO,使用Nios Ⅱ软核控制LCD显示测量结果. Nios Ⅱ读取数值时,每次读取最近7次的计数值,舍去最大、最小值后对剩下的数据去平均值作为计算结果,以减小测量误差.测试结果表明,系统能够测量频率为10 Hz~50 MHz、幅值为10 mV~3.3 V的方波和正弦波信号的频率,测量精度在10-6范围内,并降低了硬件复杂性和软件开发难度,具有实际应用价值.To solve the problem of an equal precision frequency meter measuring the frequency of the square wave and sine wave signals with different amplitudes, the hardware circuit was simplified. The FPGA of EP4 CE10 produced by Intel company was used to design a broadband small-signal equal precision frequency measurement system based on Nios Ⅱ soft core. Firstly, the signal to be measured was shaped into a 3.3 V square wave signal compatible with the FPGA logic level by the self-gain control circuit and high-speed comparator. Then, the FPGA logic part realized the frequency measurement and wrote the result into FIFO, and used Nios Ⅱ soft core to control LCD to display the measurement result. When Nios Ⅱ read the value, it read the count value of the last seven times each time. After rounding off the maximum and minimum values, it averaged the remaining data as the calculation result to reduce the measurement error. The system can measure the frequency of the square wave and sine wave signals with the frequency from 10 Hz to 50 MHz and the amplitude from 10 mV to 3.3 V, and the measurement accuracy is in the range of 10-6, and the hardware complexity and software development difficulty are reduced. It has practical application value.

关 键 词：FPGA NiosⅡ 等精度 频率计 小信号 

分 类 号：TM935.13[电气工程—电力电子与电力传动]