FIR windowed filter?

[yanhuaguang for china]

I use the FIR windowed filter.vi to filter the noise from the signal,and then do fft caculation,and the result value is not the true value,so we must correct it, but I don't kown how to correct it.
i have post the VI.
THANK YOU!

[ColinAE]

Hello.

I took your program and set the following parameters:
1. Set the Frequency of the base wave to 100
2. Set the Sampling Frequency to 1000
3. Set the number of samples to 1000
4. Set the cutoff frequency to 200 (will filter out all signals above 200Hz)

After running with these settings the 300 Hz sine wave that is generated is filtered out. I am not sure what might have been going wrong but ensure that the inputs on the FIR vi are what you expect.

Try running with these settings and if you still have questions, please try some of the FIR filter examples that ship with LabVIEW.

Regards,
Colin C
Applications Engineer