Zoom FFT vs FFT Amplitude Accuracy

[LV_COder]

Is there any accuracy issue with Zoom FFT when analyzing signals with low input power, assuming the same RBW is used? If speed is not a concern, what is the advantage of using Zoom FFT?

[altenbach]

This seems like a general signal processing questions, independent of programming language.

Zoom FFT is not stock LabVIEW, but part of the sound and vibration toolkit. What is your definition of vague terms like "accuracy" or "low input power"?

Obviously, the analysis involves quite a bit of processing (modulation, filtering, decimation, transforms, etc.) and these are all things that can influence the exact result. 

Can you attach a small simulation that demonstrates what you are trying to show?

[dsb@NI]

Zoom FFT and Baseband FFT return frequency- and amplitude-accurate results, and you can prove this to yourself by creating a test VI that computes a signal with known frequency components and comparing the Zoom FFT and Baseband FFT to expected results.

The major advantage of the Zoom FFT is that it decouples the input block size from the FFT size which can dramatically decrease the size of the transform when the zoom factor is high. Zoom FFT does not change the immutable relationship that frequency resolution is inversely proportional to the period of the measurement (i.e. df = 1/T). When enough samples have been processed, the Zoom FFT VI computes the zoom frequency spectrum and updates the average.

Reference this example:
examples\Sound and Vibration\Frequency Analysis\Multifunction FFT (Simulated).vi