数据采集系统信号混叠的研究

Discussion on the Signal Aliasing Phenomenon in Data Acquisition System.

在数据采集系统中 ,对带宽为fa 的模拟信号 ,采样率必须满足fs>2fa 的要求 ,否则将产生混叠 (Alias ing)现象。在采样前的去混叠滤波器必须满足频带及动态两方面的要求 ,当系统的动态范围很大时 ,已很难再使用模拟滤波器。由于近来数字信号处理器 (DSP)技术的进步 ,一种将过采样及抽取的概念引入数据采集系统的设计已取得成功。

In data acquisition system,the sampling rate fs should be more than double bandwidth fa for acquired analog signal,otherwise there will be signal aliasing phenomenon after sampling.Therefore,the antialiasing filter must satisfy the requirements of both bandwidth and dynamics range before sampling.It is difficult to adpot analog antialiasing filter when the dynamics range very large.Recently years,with DSP techniques further developing,it has made successes to introduce the oversampling and decimation techniques into data acquisition system.The paper expounds the application of DSP technique in seismic crosswell multirate system by a exemple.