The Study And Implementation Of Multi-channel Data Acquisition And Storage Technology With Variable Sampling Rate

In modern engineering practice and scientific research, people have placed greaterdemands on data acquisition and storage system to obtain abundant target information.Although a variety of new data acquisition and storage systems are emerging, most of themhave single sampling rate, so they can not meet the needs of measuring signals which arebecoming more diverse. Therefore, this paper introduces a multi-channel data acquisition andstorage card with variable sampling rate.This data acquisition and storage card has16channels, and the whole test system canmount at least6this card. Two multi-channel ADCs sample and convert independently underthe control of FPGA. In this way, the sampling rate of two ADCs may different from eachother, each ADC’s sampling rate parameter together with the card address is issued by theinteractive interface. When sampling different signals and different sampling rates have beenchosen for them, the cut-off frequency of anti-aliasing filter must be adjusted accordingly. Inthis paper, the cut-off frequencies of the filters can automatically adjust by the help ofswitched-capacitor filters whose cut-off frequencies are adjustable. After A/D conversion hasfinished, the data not only upload to the computer, but store in the onboard Flash memory. Inthis paper, operations of Flash including invalid block recognizing, block-by-block erasing,page-by-page reading and page-by-page writing are accomplishes. The test results show thatthe sampling rate of each ADC can be chosen in the range of50ksps,25ksps,10ksps,5kspsand1ksps; the cut-off frequency of anti-aliasing filter can automatically match the variablesampling rate; the other functional modules perform well and can achieve the basic functions.In the end, the paper summarizes the work has been done and the results have achievedat the present stage, unfinished work and future research directions are also mentioned.