孔径抖动对中频采样系统信噪比影响的研究

孔径抖动对中频(或射频)带通采样系统信噪比的影响非常严重.理论上,尽管相同带宽的中频信号和基带信号可以用相同的频率进行采样,但中频采样受孔径抖动等因素的影响更大,其采样技术要求也更高.如果在中频采样系统中解决不好孔径抖动问题,很可能根本采集不到正确的信号.本文通过分析孔径抖动产生的原因,孔径抖动与ADC (模数转换器)的信噪比以及与被采样信号上限频率之间的关系,找出了由孔径抖动决定的被采样信号的上限频率与ADC模拟带宽之间存在差距的原因,并发现了过采样率与处理增益及孔径抖动之间的关系.最后,介绍了几项减小孔径抖动的具体措施.

A Research for the Effect on the SNR of IF Sampling System Due to Aperture Jitter

Aperture jitter heavily affects the performance of an intermediate frequency or radio frequency bandpass sampling system.In theory,although the IF signal and baseband signal with the same bandwidth can be sampled using the same frequency,sampling an IF signal is effected by jitter more badly,and its sampling techniques are more difficult.If the aperture jitter issues of IF sampling system can not be well solved,it will be very possible to miss the right digital signal.The paper analyzes the causation of inducing aperture jitter,and the relationships between aperture jitter,SNR of ADC and the highest frequency of sampled signal.It presents the reasons of introducing the error between the highest frequency of sampled signal and analog bandwidth of ADC,and finds out the relationship of over-sampling ratio and gain processing and aperture jitter among IF sampling system.At last,it introduces several actual methods to reduce the aperture jitter.