length of hanning window

[vedran]

Hi,

i have pci-6014 daq card and i want to apply FFT and CrossCorrelation functions on my input signals. what i need is to set LENGTH of hanning window for crosspower. how should i do that?

i'm also matlab user and there is a nice "power spectral" function:
"PSD(input, length of window or NFFT, sample rate, WINDOW) that is doing what i need.

thanx

Vedran Divkovic
RUB
Germany

[Sastry V.]

Hello Vedran,

There are two ways to look at it. Number one is what you are saying. That is truncate the signal according to the length of the window and apply the window. But in LabVIEW, you already have finite samples, so the only thing you are applying is the windowing function whose length is now the same as the number of samples. In the function that you are talking about, "length of window or NFFT" is exactly what I am talking about. In the case o LabVIEW you are using NFFT that is, the number of sample points.

So it boils down to the following :

1. Use window length and windowing function to be applied on a signal

or

2. If the number of samples is already finite, the truncation part is already done. hence only thing left to be done is the
application of windowing function.

Please do let me know if you have any questions.

Sincerely,
Sastry V
Applications Engineer
National Instruments

[vedran]

hello Sastry,

yes, solution 2 sounds fine. i'm working with signals which number of samples is already finite (about 30s at 1000kHz).

thanx again

Vedran Divkovic
RUB
Germany