04-01-2011 11:13 AM - edited 04-01-2011 11:15 AM
How to extract real and imaginary part from dynamic data? I tried it using integral vi, but i don't know how to multiply signal by sin and cos in correct phase?
this blue blocks are vi from microdaq lite
04-01-2011 11:29 AM
Which wire do you think contains complex data?
04-01-2011 12:31 PM
i dont know
04-01-2011 12:59 PM
OK, let's ask the question a little differently: What makes you think there's complex data? The Simulate Signal doesn't generate complex data, and the only other source of data is the microdaq VI, which generates a waveform. While a waveform could be complex, you cannot wire a waveform that has complex values to the Integral Express VI, so obviously that data is not complex.
04-01-2011 02:01 PM
I don't mean to separate real and imaginary part that is already in the data (if i understand you correctly), but i want to calculate it using this formula:
So i need to multiply signal from daq by sin but i don't know how
04-01-2011 03:35 PM
OK. Now that you have asked a specific question with enough details to understand what you are asking, the answer is easy.
First, extract from or convert the Dynamic Data to an array of Doubles. Create arrays of sin(wt) and cos(wt) which have the same length and the same sampling rate as the signal. Multiply using the standard function from the Numeric palette. It works fine with arrays.
Lynn
04-01-2011 04:34 PM
johnsold wrote:First, extract from or convert the Dynamic Data to an array of Doubles. Create arrays of sin(wt) and cos(wt) which have the same length and the same sampling rate as the signal. Multiply using the standard function from the Numeric palette. It works fine with arrays.
... or just do an FFT? 😄
04-02-2011 06:14 AM
I don't think thet FFT'll be usefull for nyquist plot.
04-02-2011 09:31 AM
FFT does the same integral as you posted except for scaling factors. The output of the FFT.vi is complex, meaning that it has both the sine and cosine terms. Look at the detailed help files. As altenbach said, this should get you the data you want. Try it.
Lynn