discretize...

[John Ragle]

Try using google:

    "Results 1 - 10 of about 2,180,000 for numerical discretization."

There are lots of words that are not in common lay usage but which
nevertheless exist and are functional parts of the English language.

Come on, guys, get a life!

John Ragle -- W1ZI
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[David Christ]

With so many words in the English language I wonder why some of the
new ones are coined.  I am not an expert on FFT and higher math, but
would someone please explain to me what discretize signifies that is
not covered by quantize.  Some definitions of quantize follow.

Quantize - approximate (a signal varying continuously in amplitude)
by one whose amplitude is restricted to a prescribed set of discrete
values

Quantization - In digital signal processing, quantization is the
process of approximating ("mapping") a continuous range of values (or
a very large set of possible discrete values) by a relatively small
("finite") set of ("values which can still take on continuous range")
discrete symbols or integer values. ...

Just an old vacuum tube guy trying to understand the new world better

David K0LUM



At 9:04 PM -0400 3/27/10, John Ragle wrote:

>Try using google:
>
>     "Results 1 - 10 of about 2,180,000 for numerical discretization."
>
>There are lots of words that are not in common lay usage but which
>nevertheless exist and are functional parts of the English language.
>
>Come on, guys, get a life!
>
>John Ragle -- W1ZI
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html

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[Kok Chen]

On Mar 27, 2010, at 7:13 PM, David Christ wrote:

> I am not an expert on FFT and higher math, but
> would someone please explain to me what discretize signifies that is
> not covered by quantize.

The word "discrete" in DFT refers to discrete "time" samples, and not to the quantization of the samples into finite amplitude levels.  I.e., unlike the Fourier Transform, the input of a DFT is not a continuous function but defined only at discrete points, 0, T, 2T, ...(n-1)T.

Although it often is used that way, the input to a forward DFT does not have to be in the time domain -- the DFT is useful for other things than just estimating the spectrum of a time series.  A common example is the use of DFT to compute the discrete cepstrum of a signal.

References:

http://en.wikipedia.org/wiki/Discrete_Fourier_transform
http://en.wikipedia.org/wiki/Cepstrum 

73
Chen, W7AY

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