Re: Analysis Support files
In LV 7.1, lvanlys.dll and other DLLs it needs are included in the Rum-Time Engine of LabVIEW. So you don't need to add any files in the application builder.
Re: what does different filter order, signal processing specialist please help
The peak in the signal may introduce high frequency components ( 2000Hz in your case). So when you apply a lowpass filter, it will be affected. The disstortion when the order is high is because of your signal is of finite length (You do not have all the history data of the signal). A less than 10 order should work for most of cases. If you like, you may attach your signal and VI so that I can look at it in more details.
Re: Power Spectrum vi
I am not sure which VI you were using exactly. Is Power Spectrum.vi on the palette FunctionAnalyzeSIgnal ProcessingFrequency Domain? I have tried this VI and do not have the problem you mentioned. Would you attach some testing VIs?
Re: convolution.vi isn't working properly
Can you send the lvanlys.dll used in your application? Thanks.
Re: How do I create a Gaussian filter in LabVIEW?
You may use a lowpass filter and set the passband of the filter a bit higher than the frequency of the square wave.
Re: what does different filter order, signal processing specialist please help
Hi, An ideal lowpass filter will let all the frequencies under the cutoff frequency (2KHz in your case) pass without any change and filt out those greater than the cutoff frequency totally. Theoretically, when the order is infinte, you'll get an ideal lowpass filter. However, infinte order is not practical. Firstly, you do not have all the history data of the signal (since minor infinte). Secondly, the computing is impossible for infinte filter length. So when the order is a finite value, the lowpass filter is an approximation to the ideal filter. That means the frequencies under cutoff frequency are not passed exactly and the frequencies greater than the cutoff frequency are not really removed totally. The greater the order, the more the filter close to the ideal one and the more computations. This is the reason why you got different result when using different order. But it is not necessary to have filter with so high order you tried. Typically an order less than 10 will work well.
Re: convolution.vi isn't working properly
The lvanlys.dll with size of 516 is the one shipped with LabVIEW 7.0. Those small ones are out of date. You may delete them to fix the problems. To know which dll is using by your example VI, try to delete each lvanlys.dll. The one you can NOT delete is that used.
Re: Phase unwrapping algorithm
Unwrap Phase.vi makes the jumps between every two adjacent points of the input sequence less than pi. x[n] = x[n-1] + floor((x[n] - x[n-1])/2pi+0.5)*2pi
Re: Quantify noise in freq. domain
I am not sure I understand your question. Is it possible you wire the output (complex) of FFT to the input of RMS.vi directly? If yes, the RMS.vi only compute the RMS of the real part. You may need to instert an absolute value operation. Good luck
Re: How do i use the peak detection vi in labview when designing...
What do you mean real time? Does the data come point by point. If yes, you may call Peak Detector PtByPt.vi from the palette FunctionsAnalyzePoint By PointTime Domain PtByPt.
