基于DDS的数字式频率特性测试仪的软件设计

A Design of DDS- based Digital Frequency Characteristics Tester

设计并制作了一台基于 DDS 的数字式频率特性测试仪。该测试仪利用 DDS 芯片和自主设计的增益补偿电路产生扫频范围为1～40MHz 正交正弦信号，用模拟乘法器、LPF 和 AD 变换器获得被测网络的幅频特性和相频特性的原始数据，通过理论分析与计算，设计出频率特性的坐标变换算法，并通过单片机系统将被测网络的幅频特性和相频特性曲线显示在 LCD 显示屏上。本测试仪还使用μC ／GUI 技术设计显示界面，使用红外遥控技术实现遥控操作功能，使仪器具有良好的用户体验。

A DDS -based digital frequency characteristics tester has been manufactured.The machine uses DDS chips and self -designed gain compensation circuit to generate orthogonal sinusoidal signal with sweep fre-quency ranging from 1 MHz to 40MHz;and it utilizes analog multiplier,LPF and AD converter to acquire raw data of amplitude -frequency characteristic and phase -frequency characteristic of the circuit under test.Through theo-retical analysis and calculation,the tester designs coordinate transformation algorithm for frequency response,and displays the amplitude -frequency characteristic and phase -frequency characteristic diagram of the circuit under test on a liquid crystal display.In addition,the tester employs μC /GUI as well as infrared remote control technolo-gy,which helps to provide good user experiences.Test results show that the tester achieves the expected design goal,and has a certain degree of practical value.