How can I store recorded Data in an array? (C#)

[okeih]

Hello everybody, I´m a freshman in programming, so it's probably an easy answer for you guys. I'm using Microsoft Visual Studio 2005 and C# together with the Measurement Studio 2008. My Hardware: NI 6036E I would like to have an analog output and the opportunity to measure a signal simultaneously. I used the wizard and it works pretty fine. I was also able to add some code in order to get my desired signal type. Now my problem: I am also able to record a signal via the wizard, but I just see it on the waveformgraph. I would like to store this signal in an array in order to conduct an FFT. How can a store this signal? Thanks for your help! I appreciate it! Heiko

[Adri_K.]

Heiko,

You can create an array of type AnalogWaveform<double>[]. You can then save the acquired data to this value.

-Adri

[okeih]

Thanks for the hint! It seems to work. But now I have trouble with the FFT. I’m using the following code:

AnalogWaveform<double>[] wf=e.GetData();

waveformGraphInputSignal.PlotWaveforms(wf);

ComplexDouble[] fftOutput= NationalInstruments.Analysis.Dsp.Transforms.RealFft(wf); 

When I do it like this, I'll get the following error message: “Cannot convert from ‘NationalInstruments.AnalogWaveform<double>[] to ‘double[]’” I understand the error message but how can I solve the problem? Thanks again!  

[okeih · Accepted solution]

I found it out myself:-)

AnalogWaveform<double>[] wf=e.GetData(); 

waveformGraphInputSignal.PlotWaveforms(wf);

double[] recordedData = wf[0].GetRawData();

ComplexDouble[] fftOutput = NationalInstruments.Analysis.Dsp.Transforms.RealFft(recordedData); 

double[] magoutput = new double[fftOutput.Length]; for (int i = 0; i < fftOutput.Length; i++)

{

magoutput[i] = fftOutput[i].Magnitude;

}

waveformGraph2.Plots[0].PlotY(magoutput, 100, 1);

[okeih]

Hi again,

as I mentioned before, I was able to conduct the FFT with   “Analysis.Dsp.Transforms.RealFft”. But actually I would like to have the result onesided.

So I tried to use “SpectralMeasurements.Measurements.AmplitudePhaseSpectrum”. But I have trouble with the parameters.

I found a descriprtion for the parameters, but that doesn’t help much. Do you have any example how to use the method? 

Thanks Heiko

[Adri_K.]

Heiko,

There is example code that is documented in the Measurement Studio Help for the Measurements.ApmlitudePhaseSpectrum Method. A trick for pulling up the help for a particular method is to place your cursor in the method name and hit F1.

-Adri