frequency domain in dsp module with speedy-33 target

[rcarr]

Hi,

I am using the speedy-33 to generate a sine wave, square wave, sawtooth wave, and a ramp wave. I am doing an FFT analysis on them to display the signals in the frequency domain. However the x-axis displays the sample number for both the time domain and frequency domain. Is there a way to moake it so the x-axis is displaying either the time in the time domain or frequency in the frequency domain.

Thanks for your help.

[rcarr]

P.S. here is a screen shot of my code and the display I'm getting. How do I get the x-axis of the display to read the frequency values and the time values for their respective domains?

[Sappster]

Hi Rcarr,

I'm a little confused as to what time data you expect to see? The signal you are generating is just and array of numerics, but there is sampling information used to create that signal. Do you want to have the signal start at 0 and display the time that has elapsed?

In short, you can't do this within a VI running on the Speedy-33. However if you pass data to a host VI then you can manipulate the graph. You can do this by calculating a multiplier for the x-scale of your graph based on the dx of you sampling. There is a property node for the graph where you can set this multiplier but you can only use it on a host VI not running on the Speedy-33.

If you use the Simulate Signal Express VI you will have to create a constant that is the same value as the property you specify within the properties. You might consider using the EMB sine wave.VI that has an input for sampling rate and number of samples. You can then take the reciprocal of the sampling frequency and run that to the multiplier input by passing it to your host VI.

Let me know if I can help any further or if you have any questions.

[rcarr]

Thanks, but I figured it out. It had something to do with the scaling factor I was using.