how to restore a filtered wave ?

[ppfishs]

I collect a vibration signal from a rotor,then will calculate the relative phase to a benchmark.
first I use the "windowed FIR Filter" to filter the signal to except the signal above work frequency
the use the filtered signal to calculate ,but the
filtered signal's wave is poor,I don't know hoe to
restore it in order to get the valid wave to crosscorelation.I post my VI.

[chutla]

Greetings:

Indeed, windowed functions are NOT fully recoverable...it's analogous to using a lossy compression code. If you've tried using all the inverse functions, and it still doesn't work, you might try capturing the data without a window, and using a frequency domain filter before any FFT conversions. YOur results won't have the "Brick Wall" that a window does, but still might be usable.

Just a suggestion

ERic