How to enhance frequency resolution of fft spectrum on x-axis

Dear Sir
I get the frequency spectrum of my real time signal. Frequency span that I want to analyze is 0~500hz. I get that span by setting the sampling rate. But the frequency resolution coming on graph is of 100hz (as shown in attachment). My requirement is to have frequency resolution of 10hz with same frequency span. Please guide me how can I achieve this.
I shall be thankful to you
Kind Regards
Muhammad Irfan
Student
UTP Malaysia
0060149087570
Solved!
Go to Solution.
Attachments:
fft graph1.JPG ‏40 KB

I set the dt value to 0.002. For this I set sampling rate 2000hz and no.of samples 1000000. In this way I achieve frequency span of 250hz. But resolution is still 100hz (as shown in attach 1). My question is how can I set resolution to 10hz? I increase the number of samples but from doing this only the frequency span changes and resolution remain same as 100hz. Resolution become 10hz only when I set total frequency span to 50 hz (but My frequency span of intrest is 0~500hz or 0~250hz not below thos).
I am attaching the gaph in attachment 2 from where you can undersatnd what type of resolution and frequency span I want.
Attachments:
fft graph2.JPG ‏39 KB
desired values for scales.JPG ‏35 KB

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Hi How81,
   I won't comment on your code, I'm unable to see it (I have LV 71.1). So I'll discuss a little bit the DSP.
   If you want such a low frequency resolution, you have to sample a little longer. If your top-frequency is 25 Hz, I don't see the need for sampling at 1 kS/s, that gives a Nyquist freq. of 500 Hz!!! You'll only have a large amount of data, not of your interest!
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LabVIEW 6281-50.vi ‏61 KB

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