Data Acquisition System for Monitoring the Slow Movement of Solid

In the research of monitoring the slow movement of solid object by using the laser Doppler measurement technology,the data acquisition system is required to have some major features,e.g.precise measurement of small current,relatively wide measurement range and high response speed.To meet the requirements,we design a set of data acquisition system of direct weak current digitization,which consists of main control chip DSP,CPLD that is used to implement logic control,and USB2.0 interface that aims to upload and download data in a high speed.The experiments indicate that the measurement range of unipolar current and bipolar current are 0 ～6.45 and-3.25 ～3.23 respectively,the measure precision of charge is about 0.05pC,and the sampling rate is 12.9KHz.The system has great practicability,which is very appropriate for detecting both weak current and voltage.