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From: Vladimir Malakhov on 20 Apr 2008 15:44
Dear all!
JustAnAngel has informed about impressive and revolutionary technology
of spectral transform.
I'm afraid this technology was well known and well forgotten.
In the 30 years old good book of Tietze & Schenk there was paragraph
about frequency detector. For the frequency W(t) which needs to be
detected, each subsequent samle of signal A(t) is multiplied by
Sin(Wt)
and Cos(Wt). Each result of A(t)*Sin(Wt) multiplication comes to the
input of first low-pass filter, and each result of A(t)*Cos(Wt)
multiplication comes to the input of second low-pass filter. Both
filters are identical. For the cut-off frequency F of filters, 1/F = T
is a window of detector. Then, one takes outputs of filters Out(Sin)
and Out(Cos) and calculates the magnitude as Sqrt(Out(Sin)**2 +
Out(Cos)**2). One may take frequencies W1, W2 ... Wn, then may perform
the abowe calculations for each frequency and have the spectral
transform as a result.
Yours sinfull engineer,
V. Malakhov.
From: Jerry Avins on 21 Apr 2008 11:24
Vladimir Malakhov wrote:
> Dear all!
> JustAnAngel has informed about impressive and revolutionary technology
> of spectral transform.
> I'm afraid this technology was well known and well forgotten.
> In the 30 years old good book of Tietze & Schenk there was paragraph
> about frequency detector. For the frequency W(t) which needs to be
> detected, each subsequent samle of signal A(t) is multiplied by
> Sin(Wt)
> and Cos(Wt). Each result of A(t)*Sin(Wt) multiplication comes to the
> input of first low-pass filter, and each result of A(t)*Cos(Wt)
> multiplication comes to the input of second low-pass filter. Both
> filters are identical. For the cut-off frequency F of filters, 1/F = T
> is a window of detector. Then, one takes outputs of filters Out(Sin)
> and Out(Cos) and calculates the magnitude as Sqrt(Out(Sin)**2 +
> Out(Cos)**2). One may take frequencies W1, W2 ... Wn, then may perform
> the abowe calculations for each frequency and have the spectral
> transform as a result.
> Yours sinfull engineer,
> V. Malakhov.

If I understand what you wrote, that's the old "by hand" way to do a
Fourier transform.

Jerry
--
Engineering is the art of making what you want from things you can get.
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From: dbell on 21 Apr 2008 18:50
On Apr 20, 3:44 pm, Vladimir Malakhov <schnei...(a)yandex.ru> wrote:
> Dear all!
> JustAnAngel has informed about impressive and revolutionary technology
> of spectral transform.
> I'm afraid this technology was well known and well forgotten.
> In the 30 years old good book of Tietze & Schenk there was paragraph
> about frequency detector. For the frequency W(t) which needs to be
> detected, each subsequent samle of signal A(t) is multiplied by
> Sin(Wt)
> and Cos(Wt). Each result of A(t)*Sin(Wt) multiplication comes to the
> input of first low-pass filter, and each result of A(t)*Cos(Wt)
> multiplication comes to the input of second low-pass filter. Both
> filters are identical. For the cut-off frequency F of filters, 1/F = T
> is a window of detector. Then, one takes outputs of filters Out(Sin)
> and Out(Cos) and calculates the magnitude as Sqrt(Out(Sin)**2 +
> Out(Cos)**2). One may take frequencies W1, W2 ... Wn, then may perform
> the abowe calculations for each frequency and have the spectral
> transform as a result.
> Yours sinfull engineer,
> V. Malakhov.

How did you determine that this is what their "Revolutionary"
technology is?

Dirk
From: Vladimir Malakhov on 22 Apr 2008 13:46
On 21 ÁÐÒ, 19:24, Jerry Avins <j...(a)ieee.org> wrote:
> If I understand what you wrote, that's the old "by hand" way to do a
> Fourier transform.

Oh, yes.
That's the old agorithm of Fourier transform with "moving" (or
"sliding") window.
Vladimir.
From: Vladimir Malakhov on 22 Apr 2008 14:08
On 22 ÁÐÒ, 02:50, dbell <bellda2...(a)cox.net> wrote:
> How did you determine that this is what their "Revolutionary"
> technology is?
>
Sorry, I wrote "I'm afraid", not "I'm sure".
JustAnAngel noticed some features (looking like key advantages) of
this "Revolutionary" technology.
All same things are available with the old method of spectral
(Fourier) transform.
Vladimir.
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