利用多帶通信號欠采樣定理和數字變頻等技術，可以實現對多個帶通信號的同時直接采樣及提取處理。當采樣率低于信號最高頻率的2倍時，采樣后信號的信噪比將變差。該文討論采樣后信噪比與模數轉換器前的模擬濾波器以及采樣率之間的關系，所得結論對數字接收系統設計有指導意義。
關 鍵 詞 帶通信號; 均勻采樣; 混疊; 噪聲帶寬

Abstract Using sub-sampling theorem of multiple banpass signals and digital frequency converting techniques, multi-band-pass signals can be directly sampled and processed using no aliasing sampling rate. If sampling rate is lower than the two times of the maximum frequency of the signal, the signal-to-noise ratio will become worse. The relationships of signal-to-noise ratio of sampled signal, analog filter before analog-to-digital converter and sampling rate have been discussed, the results of the discussion have instructiveness for the design of digital receivers.
Key words band-pass signals; uniformly sampling; aliasing; bandwidth of noise