FFT spectrum (mag-phase).vi for plotting a array of complex data.

[Chaks]

I have used the FFT spectrum (mag-phase).vi for plotting a array of complex data. The data corresponds to a signal of 40MHz & sampling rate is 184.32 MHz. But the plot shows the signal only near 0.2 Hz. I have attached the vi and the file that contains the complex data. Please note the complex data in the file is in the format of I & Q samples alternatively. So in the VI they have been seggregated and arranged as x+iy format and given to the fft function. In the FFT spectrum (mag-phase).vi, I could not see any input for sampling rate. So can anyone guide the right way to get the display at 40 Mhz.

Message Edited by Chaks on 02-26-2008 08:11 AM

[rpursley8]

The FFT Spectrum function is expecting waveform data as the input.  Waveform data contains the data points, a starting time, and a step time (dt).  Since you are inputting just the data points, your dt defaults to 1.  Convert your double array into waveform data and include the correct value of dt (1/186.32 MHz), you will get what you are expecting.


Message Edited by rpursley8 on 02-26-2008 09:50 AM

[Chaks]

Thank you very much Randall Pursley. It is working.

Chaks.