多帶通信號(hào)采樣的信噪比分析

利用多帶通信號(hào)欠采樣定理和數(shù)字變頻等技術(shù)，可以實(shí)現(xiàn)對(duì)多個(gè)帶通信號(hào)的同時(shí)直接采樣及提取處理。當(dāng)采樣率低于信號(hào)最高頻率的2倍時(shí)，采樣后信號(hào)的信噪比將變差。該文討論采樣后信噪比與模數(shù)轉(zhuǎn)換器前的模擬濾波器以及采樣率之間的關(guān)系，所得結(jié)論對(duì)數(shù)字接收系統(tǒng)設(shè)計(jì)有指導(dǎo)意義。
關(guān) 鍵 詞 帶通信號(hào); 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