AnsweredAssumed Answered

vrf Viewing Data Acquired by DAQ in Frequency Domain

Question asked by VRFuser on Jun 4, 2006

Hi all,


I am using a data acquisition card (DAQ)’s analog input to connect to a vibration sensor in order I am able to measure the vibration of a motor. I am using different frequency to drive the motor in order to measure its response at different frequencies. So I would like to view its response in frequency domain continuously. How can I do that?


The function of the DAQ card is basically sampling and then I will send commands to read the data back into VEE. The data in this case will be referenced to be in time domain. How can I change it to be in frequency domain?


I have tried the following methods.


1) I tried FFT formula but the frequency information does not seem to be correct. If I were to use a chart (without FFT done on the data) and I use the chart with the data going through FFT, the amplitude shows the same for Y axis. For x-axis, the former chart will be reference to time, while the latter chart will always have the peak at the beginning of the data.


2) I do not seem to quite get it when I use the “Build Waveform† function and then the “Spectrum Graph†. There is no inbuilt FFT function for this DAQ.


Any ideas how I can achieve my aim?




Eng Chye, Neo (æ¢ è £è´¢)



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