??? Re: Lock-in Amplifier and DAQmx

[huangyao]

hi,Travis W,I am a freshman to the LIA.
I also have some problems when using the example" MultiChannelLockIn-DAQmx" you provided.
Running the VI,I get no results,the frequency is always 1.00,and the Y,X,R,Theto are all zero.I have check my connectors,and the input and reference signals both work on my Scope.
My card is PCI 6221(Can the card be used for the lockin amplifier?),and the software is labview 8.20.
 
Thanks,
Huangyao (my email box is <a href="mailto:yhua...@163.com" target="_blank">yhua...@163.com</a>)
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[huangyao]

Hi,Neal M,thanks for you help.It is really very nice of you.
Now,I have another problem.I am doing a test about the vibration,and I want to test the frequency of the vibration (supposing&nbsp;there is only a single frequency in the test),but as we know, the lock-in amplifier's output is usually a DC value,can it be used for&nbsp;my vibration test.If yes,how to make it or how to set the parameters?I know the setting is very important.
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I have used the example"MultiChannel LockIn - DAQmx" to have a try ,but it seemed to not work quite well.
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Your reply will be greatly appreciated!
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Thanks,
HuangYao.

[Neal M]

Hello again Huang Yao,

I am not quite sure what you are trying to do.&nbsp; The lock in amplifier
is all in software, so it is not outputting a DC value.&nbsp; Do you mean a
number for the frequency?&nbsp; If you want to turn this into an AC
waveform, then you want to use a VI such as the Sine Waveform.vi (in
the functions palette under Programming»Waveform»Analog
Waveform»Generation).

Perhaps some screenshots of what you are seeing vs what you want to see would help.

[preston johnson]

For vibration test, you will want to use a FFT and assorted other scaling and filtering tools.&nbsp; If you have standards you want to test to, you will want to consider the sound and vibration&nbsp;measurement suite, <a href="http://www.ni.com/soundandvibration" target="_blank">www.ni.com/soundandvibration</a>
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