HOW TO INTRODUCE VOLTAGE SPIKE ON FREQUENCY SPECTRUM AT REGULAR INTERVALS

[AutomationUET]

Good Day everybody

Can you guide me how can I add the amplitude spikes of -200 dB magnitude at frequency intervals of 60,120,180,240,300 Hz in the frequency spectrum that I obtained using FFT Power spectrum. I have attched the graph in which I want to have addition of amplitude spikes.

Regards

Automata

[Charles_CLA]

Do you want to artificially set the value of each of your listed frequencies to -200dB or are you asking how to design your hardware to have notches in the response? Considering the second one isn't practically achievable, I'm guessing you just want to add artificial values to your graph display. The step size of an FFT is sampling frequency (Fs), divided by the number of samples (n) collected. The first point in the FFT array should be DC, the next point will be at frequency Fs/n. Suppose your Fs/n = 10, then 60Hz will be in the seventh bin (0, 10, 20, 30, 40, 50, 60). Simply replace index 6 with your desired value (-200dB). Let me know if I have completely misunderstood your question.

[crossrulz]

Instead of replacing, you might actually want to add to the value in that index.

[AutomationUET]

Dear Sir

You under stand my question. I want to add artificial values in graph. My Fs=25000S/sec and n=200000 so Fs/n=0.125. So for 60 hz my bin will at 480. Now how I replace index 480 with -200dB.

Attach is my block diagram.

Kind Regards

Automata

[Charles_CLA]

See attached.

[AutomationUET]

Dear Sir

I am using version8.2 of LabView. Can you send me the file after converting it into 8.2 version

Kind Regards

Automata

[Charles_CLA · Accepted solution]

Here it is in 8.2 Format.

[AutomationUET]

Dear Charles

Your attention and consideration is highly appreciated. Thank you

Best Regards

Automata