Re: Experiments that measure frequency domain
- From: Timo Nieminen <uqtniemi@xxxxxxxxxxxxxxxxx>
- Date: Tue, 11 Apr 2006 04:30:00 +1000
On Mon, 10 Apr 2006, Pete wrote:
I read there are experiments that measure the frequency response of a system
Y(w) and the researcher must use the inverse Fourier transform to get the
time response y(t). Unfortunately, it didn't give an example.
It seems odd that the researcher can't hook up his measuring device to the
apparatus and simply measure the time responses.
I'm curious -- what are some examples of experiments where Y(w) is more
easily measured than y(t)?
This can be the case when
(a) the time response happens so quickly that the resolution and response time of the instrument can't measure y(t). This tends to happen with very high frequencies eg in optics, where spectrometers are standard issue.
(b) the system has a very narrow resonance, so you get all the important information with a small number of frequency domain measurements. Narrow features in the frequency domain translate into very broad features in the time domain - think about how many samples in the time domain over what time are required to resolve a narrow resonance.
--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
.
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