频谱分析仪的数字中频设计方案

Design Methods of Spectrum Analyzers with Digital IF Technology

为了提高频谱分析仪的频率分辨率,同时降低模拟中频、视频电路组件的生产难度,现代频谱分析仪大多采用数字中频技术,利用模数转换器把模拟中频信号转换为数字信号,经过数字下变频、数字滤波、数字检波或快速傅里叶变换运算后得到射频信号的幅度和频率信息,再经过视频滤波处理后得到清晰的信号频谱。文中论述的信号处理方案实现了频谱的数字分析,在实际应用中验证了其指标的稳定。

Today, most spectrum analyzers （SA） are designed with digital IF technology to increase frequency resolution and de- crease the manufacture difficulty of analog IF and video circuits. SA converts analog signal to digital by ADC（ analog to digital con- verter） ,and processes the digital signal by digital down converter, digital filter, digital detector and FFT. So that the SA can get the amplitude and frequency information of input radio signal, and finally get a clear spectrum trace by video filter. The methods introduced in this article have been proved in our products. Using this methods, the SA we developed has excellent, steady and re- liable performance.