On Mon, 29 Mar 2010 00:16:39 -0700 (PDT), Andor
<andor.bariska@gmail.com> wrote:

>On 28 Mrz., 14:18, Rick Lyons <R.Lyons@_BOGUS_ieee.org> wrote:
>> On Mon, 22 Mar 2010 07:14:08 -0700, Tim Wescott <t...@seemywebsite.now>
>> wrote:
>>
>>
>>
>>
>>
>> >Rune Allnor wrote:
>> >> On 22 Mar, 14:35, "blackhermi" <dheeraj.iitm@n_o_s_p_a_m.gmail.com>
>> >> wrote:
>> >>> Hi
>>
>> >>> I need to find out the frequencies present in the variation of a physical
>> >>> quantity from a discretely sampled data of finite length. Which window (if
>> >>> any) should I use?
>>
>> >> It depends entirely on the data and what you attempt to do.
>> >> If the SNR is large and the sinusoidals are well separated,
>> >> then don't use any. If the SNR is low and you need to
>> >> suppress side lobes, choose a window that can be tuned to
>> >> your particular needs (the Kaiser window is just about the
>> >> only one that fits that bill). Or avoid controversy by using
>> >> the most popular window that everybody else use. I don't have
>> >> any statistics, but the Hanning / Hann / von Hann window ought
>> >> to end up among the top 3 in the popularity polls.
>>
>> >Understanding the properties of the FFT would help, too -- that will let
>> >you understand why you want to window the data, which in turn will help
>> >you understand what window (if any) you want and why.
>>
>> >While I could stand in front of a room of fellow engineers and defend a
>> >choice of window by "it's popular _and_ it doesn't matter much anyway",
>> >defending it with "'cause it's popular" would quite deservedly get me
>> >laughed out of the room.
>>
>> Hi Tim,
>> &#4294967295; If someone asks me, "Why did you use the
>> Hanning window in this application?",
>> I typically answer with either, (1) "Because that's
>> the way God wanted it to be.", or (2) "Because that's
>> what the voices told me to use."
>
>Hi Rick
>
>My knee-jerk answer would be: "The guy's name was von Hann!"
>
>Regards,
>Andor
Hi Andor,
   You are exactly correct.

Regards,
[-Rick-]

On 28 Mrz., 14:18, Rick Lyons <R.Lyons@_BOGUS_ieee.org> wrote:
> On Mon, 22 Mar 2010 07:14:08 -0700, Tim Wescott <t...@seemywebsite.now>
> wrote:
>
>
>
>
>
> >Rune Allnor wrote:
> >> On 22 Mar, 14:35, "blackhermi" <dheeraj.iitm@n_o_s_p_a_m.gmail.com>
> >> wrote:
> >>> Hi
>
> >>> I need to find out the frequencies present in the variation of a physical
> >>> quantity from a discretely sampled data of finite length. Which window (if
> >>> any) should I use?
>
> >> It depends entirely on the data and what you attempt to do.
> >> If the SNR is large and the sinusoidals are well separated,
> >> then don't use any. If the SNR is low and you need to
> >> suppress side lobes, choose a window that can be tuned to
> >> your particular needs (the Kaiser window is just about the
> >> only one that fits that bill). Or avoid controversy by using
> >> the most popular window that everybody else use. I don't have
> >> any statistics, but the Hanning / Hann / von Hann window ought
> >> to end up among the top 3 in the popularity polls.
>
> >Understanding the properties of the FFT would help, too -- that will let
> >you understand why you want to window the data, which in turn will help
> >you understand what window (if any) you want and why.
>
> >While I could stand in front of a room of fellow engineers and defend a
> >choice of window by "it's popular _and_ it doesn't matter much anyway",
> >defending it with "'cause it's popular" would quite deservedly get me
> >laughed out of the room.
>
> Hi Tim,
> &#4294967295; If someone asks me, "Why did you use the
> Hanning window in this application?",
> I typically answer with either, (1) "Because that's
> the way God wanted it to be.", or (2) "Because that's
> what the voices told me to use."

Hi Rick

My knee-jerk answer would be: "The guy's name was von Hann!"

Regards,
Andor

On Mon, 22 Mar 2010 07:14:08 -0700, Tim Wescott <tim@seemywebsite.now>
wrote:

>Rune Allnor wrote:
>> On 22 Mar, 14:35, "blackhermi" <dheeraj.iitm@n_o_s_p_a_m.gmail.com>
>> wrote:
>>> Hi
>>>
>>> I need to find out the frequencies present in the variation of a physical
>>> quantity from a discretely sampled data of finite length. Which window (if
>>> any) should I use?
>> 
>> It depends entirely on the data and what you attempt to do.
>> If the SNR is large and the sinusoidals are well separated,
>> then don't use any. If the SNR is low and you need to
>> suppress side lobes, choose a window that can be tuned to
>> your particular needs (the Kaiser window is just about the
>> only one that fits that bill). Or avoid controversy by using
>> the most popular window that everybody else use. I don't have
>> any statistics, but the Hanning / Hann / von Hann window ought
>> to end up among the top 3 in the popularity polls.
>
>Understanding the properties of the FFT would help, too -- that will let 
>you understand why you want to window the data, which in turn will help 
>you understand what window (if any) you want and why.
>
>While I could stand in front of a room of fellow engineers and defend a 
>choice of window by "it's popular _and_ it doesn't matter much anyway", 
>defending it with "'cause it's popular" would quite deservedly get me 
>laughed out of the room.

Hi Tim,
  If someone asks me, "Why did you use the 
Hanning window in this application?", 
I typically answer with either, (1) "Because that's 
the way God wanted it to be.", or (2) "Because that's 
what the voices told me to use."

See Ya',
[Rick-]

On 23 Mar, 02:17, "steveu" <steveu@n_o_s_p_a_m.coppice.org> wrote:
> >Rune Allnor wrote:
>
> >> On 22 Mar, 15:25, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
>
> >>>Rune Allnor wrote:
>
> >>>>On 22 Mar, 15:14, Tim Wescott <t...@seemywebsite.now> wrote:
>
> >>>>>Rune Allnor wrote:
>
> >>>>"Why did you use the Gavrilovich-Cheng window? What properties
> >>>>does that window offer that a regular window like, say, a Hann
> >>>>window, does not?"
>
> >>>Good idea. Nobody knows wtf is Gavrilovich-Cheng window, so everybody
> >>>will will shut up so not to look as an idiot.
>
> >> I wouldn't play on human stupidity quite like that - there
> >> is the chance that someone like Jerry or myself is in the
> >> audiendce. In that case, the presenter will look like the
> >> idiot. I know. I did ask that question, once upon a time
> >> many years ago. Made a total fool - unintentionally! - of
> >> the presenter when she had no answer to why she had made
> >> some choise she had commented on during the presentation.
>
> >Dr. Rune, did anybody (besides you and your vis-a-vis) realized what was
> >it all about? Perhaps they were just annoyed that you woke them up from
> >deep sleep.
>
> >> If you want to play an insult, hide it in plain sight: Make
> >> the obvious choise, but without justification. Or keep
> >> quiet about the key trick while exanding on some triviality.
>
> >Whether it was intended to be insult or not, I have no slightest idea
> >about Gavrilovich-Cheng window. But I found Lanczos window in Wikipedia
> >(how to spell Lanczos ?). They say it is absolutely the very best window
> >and you must use it for all cases.
>
> I thought Windows 7 was the very best window you must use in all cases.

I certainly need to change to a better window soon - water has
been seeping in when weather was at its weatest this winter.

Rune

>
>
>Rune Allnor wrote:
>
>> On 22 Mar, 15:25, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
>> 
>>>Rune Allnor wrote:
>>>
>>>>On 22 Mar, 15:14, Tim Wescott <t...@seemywebsite.now> wrote:
>>>
>>>>>Rune Allnor wrote:
>>>
>>>>"Why did you use the Gavrilovich-Cheng window? What properties
>>>>does that window offer that a regular window like, say, a Hann
>>>>window, does not?"
>>>
>>>Good idea. Nobody knows wtf is Gavrilovich-Cheng window, so everybody
>>>will will shut up so not to look as an idiot.
>> 
>> I wouldn't play on human stupidity quite like that - there
>> is the chance that someone like Jerry or myself is in the
>> audiendce. In that case, the presenter will look like the
>> idiot. I know. I did ask that question, once upon a time
>> many years ago. Made a total fool - unintentionally! - of
>> the presenter when she had no answer to why she had made
>> some choise she had commented on during the presentation.
>
>Dr. Rune, did anybody (besides you and your vis-a-vis) realized what was 
>it all about? Perhaps they were just annoyed that you woke them up from 
>deep sleep.
>
>> If you want to play an insult, hide it in plain sight: Make
>> the obvious choise, but without justification. Or keep
>> quiet about the key trick while exanding on some triviality.
>
>Whether it was intended to be insult or not, I have no slightest idea 
>about Gavrilovich-Cheng window. But I found Lanczos window in Wikipedia 
>(how to spell Lanczos ?). They say it is absolutely the very best window 
>and you must use it for all cases.

I thought Windows 7 was the very best window you must use in all cases.

Steve

Rune Allnor wrote:

> On 22 Mar, 15:25, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> 
>>Rune Allnor wrote:
>>
>>>On 22 Mar, 15:14, Tim Wescott <t...@seemywebsite.now> wrote:
>>
>>>>Rune Allnor wrote:
>>
>>>"Why did you use the Gavrilovich-Cheng window? What properties
>>>does that window offer that a regular window like, say, a Hann
>>>window, does not?"
>>
>>Good idea. Nobody knows wtf is Gavrilovich-Cheng window, so everybody
>>will will shut up so not to look as an idiot.
> 
> I wouldn't play on human stupidity quite like that - there
> is the chance that someone like Jerry or myself is in the
> audiendce. In that case, the presenter will look like the
> idiot. I know. I did ask that question, once upon a time
> many years ago. Made a total fool - unintentionally! - of
> the presenter when she had no answer to why she had made
> some choise she had commented on during the presentation.

Dr. Rune, did anybody (besides you and your vis-a-vis) realized what was 
it all about? Perhaps they were just annoyed that you woke them up from 
deep sleep.

> If you want to play an insult, hide it in plain sight: Make
> the obvious choise, but without justification. Or keep
> quiet about the key trick while exanding on some triviality.

Whether it was intended to be insult or not, I have no slightest idea 
about Gavrilovich-Cheng window. But I found Lanczos window in Wikipedia 
(how to spell Lanczos ?). They say it is absolutely the very best window 
and you must use it for all cases.

VLV

On Mar 22, 9:35&#4294967295;am, "blackhermi" <dheeraj.iitm@n_o_s_p_a_m.gmail.com>
wrote:
> Hi
>
> I need to find out the frequencies present in the variation of a physical
> quantity from a discretely sampled data of finite length. Which window (if
> any) should I use? I think doing an fftn in MATLAB uses a rectangular
> function by default. Please correct me if I am wrong.
>
> Also, is there a way to create a 2D version of a given window?
>
> Thanks and Regards

Do you know apriori how many frequencies are in the data? I.e., do you
have a physical reason for there being n frequnecies in the data? Are
the frequencies constant in time?

Clay

Jerry Avins wrote:
> Vladimir Vassilevsky wrote:
> 
>   ...
> 
>> Good idea. Nobody knows wtf is Gavrilovich-Cheng window, so everybody 
>> will will shut up so not to look as an idiot.
> 
> I'm the sort who, smelling something new to learn, would ask all sorts 
> of (possibly embarrassing) questions.

I make a point of asking about things that are new to me -- I either 
learn something useful, or I expose a poseur.  Since either of these are 
good things, there's no reason not to ask.

(Note: even if one _thinks_ one is exposing a poseur, one should always 
ask with full humility -- if it turns out that the speaker is 
Gavrilovich's niece, and learned her DSP on her uncle's knee, it reduces 
the embarrassment.  And if you _are_ exposing a poseur, then you can 
retain your status as the little kid in "The Emperor's New Cloths".)

-- 
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Tim Wescott wrote:


> But using a technique just because all your friends use it* -- that's 
> just crying out for some corrective action.

That's #1 point in the future book "How to quit being an idiot and start 
living": Have a purpose. Don't do anything just because many other 
people do that.

VLV

On 22 Mar, 15:25, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> Rune Allnor wrote:
> > On 22 Mar, 15:14, Tim Wescott <t...@seemywebsite.now> wrote:
>
> >>Rune Allnor wrote:
>
> >>>On 22 Mar, 14:35, "blackhermi" <dheeraj.iitm@n_o_s_p_a_m.gmail.com>
> >>>wrote:
>
> >>>>Hi
>
> >>>>I need to find out the frequencies present in the variation of a physical
> >>>>quantity from a discretely sampled data of finite length. Which window (if
> >>>>any) should I use?
>
> >>>It depends entirely on the data and what you attempt to do.
> >>>If the SNR is large and the sinusoidals are well separated,
> >>>then don't use any. If the SNR is low and you need to
> >>>suppress side lobes, choose a window that can be tuned to
> >>>your particular needs (the Kaiser window is just about the
> >>>only one that fits that bill). Or avoid controversy by using
> >>>the most popular window that everybody else use. I don't have
> >>>any statistics, but the Hanning / Hann / von Hann window ought
> >>>to end up among the top 3 in the popularity polls.
>
> >>Understanding the properties of the FFT would help, too -- that will let
> >>you understand why you want to window the data, which in turn will help
> >>you understand what window (if any) you want and why.
>
> >>While I could stand in front of a room of fellow engineers and defend a
> >>choice of window by "it's popular _and_ it doesn't matter much anyway",
> >>defending it with "'cause it's popular" would quite deservedly get me
> >>laughed out of the room.
>
> > The alternative is to stand on the podium and defend why one uses
> > some obscure window:
>
> > "Why did you use the Gavrilovich-Cheng window? What properties
> > does that window offer that a regular window like, say, a Hann
> > window, does not?"
>
> > You'd better have a clear answer to that one, or avoid the
> > question being asked at all.
>
> Good idea. Nobody knows wtf is Gavrilovich-Cheng window, so everybody
> will will shut up so not to look as an idiot.

I wouldn't play on human stupidity quite like that - there
is the chance that someone like Jerry or myself is in the
audiendce. In that case, the presenter will look like the
idiot. I know. I did ask that question, once upon a time
many years ago. Made a total fool - unintentionally! - of
the presenter when she had no answer to why she had made
some choise she had commented on during the presentation.

If you want to play an insult, hide it in plain sight: Make
the obvious choise, but without justification. Or keep
quiet about the key trick while exanding on some triviality.

The Danes and the English are masters at that game: One basks
in the glory of some comment for hours or days, until the
intended meaning all of a sudden dawns upon you.

Sir Humphrey Appleby of "Yes (Prime) Minister" is the
seminal example:

http://en.wikipedia.org/wiki/Yes_Minister

Rune