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what is zoom fft
3

what is zoom fft

what is zoom fft

(OP)
Does anyone know zoom fft?
Could anyone give me some URL about "zoom fft"?
thanks

RE: what is zoom fft

What were the symptoms when your search engine broke?

TTFN

RE: what is zoom fft

On the analyzer I am used to, it simply means that the frequency range being fft'd lies in a user specified range, instead of it being from 0 to the maximum capability of the analyzer. You can see more detail that way.

RE: what is zoom fft

IRstuff :

Am I off topic or are you ?

By the way, standbychen, not all analyzers have that capability.

RE: what is zoom fft

(OP)
What I found are too simple.
I want to know this algorithm in detail.

RE: what is zoom fft

There appear to be several methods you can use to accomplish this. I have a book in front of me called "Modal Testing" by D.J. Ewins where he goes into these in some detail - too much to trot out here, but perhaps not enough to easily write an algorithm immediately - depends on how good you are at converting broad math concepts into computer code. I'm sure there are even more detailed descriptions out there.  

RE: what is zoom fft

Bruel and Kjaer Technical Review 2-1980 had an article about zoom FFT, but it's not available for download.

TTFN

RE: what is zoom fft

2
I have posted a zoom FFT paper and software program at:

http://www.vibrationdata.com/signal.htm

The paper is from Bruel & Kjaer.

Please send me an Email if you would like the paper.

Tom Irvine

RE: what is zoom fft

(OP)
Tomirvine,
  I really want this paper.
  Would you please sent this paper to
  standbychen@sohu.com
  Thanks!

RE: what is zoom fft

Tomirvine,
  I want this paper too.
  Would you please sent this paper to
  phyhust@sina.com
  Thanks!

RE: what is zoom fft

Tomirvine,
  I want this paper too.
  Would you please sent this paper to
  gaia1030@hanwha.co.kr
  Thanks!

RE: what is zoom fft

So far I have not come across any URL on Zoom FFT. The main different from a conventional FFT is the frequency resolution. I have implemented the B&K Zoom FFT using Fortran almost 10 years ago while at Strathclyde University. The method of Zoom are wide and varied depending on the zoom factor and the algorithm, some have to be radix of 2 while the B&K zoom FFT uses a phase cancellation to get rid of the alias component. The beauty about B&K zoom is that it perform the zoom using the same sampling rate as the conventional FFT. I have used this zoom to successfully detect a defective gear tooth in a vehicle gearbox.

You may be able to find some algorithm under IEEE DSP transactions or any DSP book. I may still have afew copy of the paper lying somewhere in my study.

RE: what is zoom fft

Tomirvine,

I would like this paper too. Would you please send this paper to paul@buzzmac.com

Many thanks!

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