deconvolution problem
in [DSP]
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From: Andor on 24 Sep 2009 04:45 On 24 Sep., 09:49, "sofiyya" <karimae...(a)gmail.com> wrote: > >On Sep 23, 7:25 am, "sofiyya" <karimae...(a)gmail.com> wrote: > > This is the result I get when I don't truncate w: > > ans = > > Columns 1 through 9 > > -0.0903 -0.2708 -0.5417 -0.9028 -0.7292 -0.5208 -0.2778 > -0.0000 0.2778 > > Columns 10 through 16 > > 1.4583 2.7292 4.0903 5.5417 0.8333 0.5903 0.3125 > > which is also wrong! Your method is flawed alltogehter. In general, w will have infinite length. Any truncation to use the FFT won't produce the expected results. w can be found through long division of v2 by v1. This is very simple to do with pencil and paper, the first couple of values in w are w = [1 0 0 0 -5 4 ...] Regards, Andor
From: Andor on 24 Sep 2009 05:00 On 24 Sep., 10:45, Andor <andor.bari...(a)gmail.com> wrote: > On 24 Sep., 09:49, "sofiyya" <karimae...(a)gmail.com> wrote: > > > > > > > >On Sep 23, 7:25 am, "sofiyya" <karimae...(a)gmail.com> wrote: > > > This is the result I get when I don't truncate w: > > > ans = > > > Columns 1 through 9 > > > -0.0903 -0.2708 -0.5417 -0.9028 -0.7292 -0.5208 -0.2778 > > -0.0000 0.2778 > > > Columns 10 through 16 > > > 1.4583 2.7292 4.0903 5.5417 0.8333 0.5903 0.3125 > > > which is also wrong! > > Your method is flawed alltogehter. In general, w will have infinite > length. Any truncation to use the FFT won't produce the expected > results. w can be found through long division of v2 by v1. This is > very simple to do with pencil and paper, the first couple of values in > w are > > w = [1 0 0 0 -5 4 ...] If you add 5 more terms yourself, I'll reveal the matlab one-liner that calculates w to arbitrary length :-).
From: sofiyya on 24 Sep 2009 07:31 >On 24 Sep, 09:49, "sofiyya" <karimae...(a)gmail.com> wrote: >> >On Sep 23, 7:25 am, "sofiyya" <karimae...(a)gmail.com> wrote: >> >> This is the result I get when I don't truncate w: >> >> ans =3D >> >> =A0 Columns 1 through 9 >> >> =A0 =A0-0.0903 =A0 -0.2708 =A0 -0.5417 =A0 -0.9028 =A0 -0.7292 =A0 -0.520= >8 =A0 -0.2778 =A0 >> -0.0000 =A0 =A00.2778 >> >> =A0 Columns 10 through 16 >> >> =A0 =A0 1.4583 =A0 =A02.7292 =A0 =A04.0903 =A0 =A05.5417 =A0 =A00.8333 = >=A0 =A00.5903 =A0 =A00.3125 >> >> which is also wrong! > >Once again: Are you sure the problem as stated has a solution? > >Rune > No, I'm not sure! But I didn't find explication for this! Maybe the deconvolution is not a stable solution...
From: sofiyya on 24 Sep 2009 08:27 Thank you for your response, Yes, with pencil and paper we can calculate w but it will be difficult for a long vector, that's why I look for a methods to do it with matlab.. Maybe it's impossible or maybe this depends on the coefficients of vect1 or vect2.. I guess that we can't always find w / conv(w,vect1)=vect2; >On 24 Sep., 10:45, Andor <andor.bari...(a)gmail.com> wrote: >> On 24 Sep., 09:49, "sofiyya" <karimae...(a)gmail.com> wrote: >> >> >> >> >> >> > >On Sep 23, 7:25 am, "sofiyya" <karimae...(a)gmail.com> wrote: >> >> > This is the result I get when I don't truncate w: >> >> > ans =3D >> >> > =A0 Columns 1 through 9 >> >> > =A0 =A0-0.0903 =A0 -0.2708 =A0 -0.5417 =A0 -0.9028 =A0 -0.7292 =A0 -0.5= >208 =A0 -0.2778 =A0 >> > -0.0000 =A0 =A00.2778 >> >> > =A0 Columns 10 through 16 >> >> > =A0 =A0 1.4583 =A0 =A02.7292 =A0 =A04.0903 =A0 =A05.5417 =A0 =A00.8333 = >=A0 =A00.5903 =A0 =A00.3125 >> >> > which is also wrong! >> >> Your method is flawed alltogehter. In general, w will have infinite >> length. Any truncation to use the FFT won't produce the expected >> results. w can be found through long division of v2 by v1. This is >> very simple to do with pencil and paper, the first couple of values in >> w are >> >> w =3D [1 0 0 0 -5 4 ...] > >If you add 5 more terms yourself, I'll reveal the matlab one-liner >that calculates w to arbitrary length :-). >
From: Andor on 24 Sep 2009 09:04 As I said, if you calculate 5 more terms in the w that I started below, I will tell you how to calculate w (given v1 and v2) in Matlab with one single command that has only 28 characters (challenge: who can do it in less?). :-) On 24 Sep., 14:27, "sofiyya" <karimae...(a)gmail.com> wrote: > Thank you for your response, > > Yes, with pencil and paper we can calculate w but it will be difficult for > a long vector, that's why I look for a methods to do it with matlab.. Maybe > it's impossible or maybe this depends on the coefficients of vect1 or > vect2.. I guess that we can't always find w / conv(w,vect1)=vect2; > > > > > > >On 24 Sep., 10:45, Andor <andor.bari...(a)gmail.com> wrote: > >> On 24 Sep., 09:49, "sofiyya" <karimae...(a)gmail.com> wrote: > > >> > >On Sep 23, 7:25 am, "sofiyya" <karimae...(a)gmail.com> wrote: > > >> > This is the result I get when I don't truncate w: > > >> > ans =3D > > >> > =A0 Columns 1 through 9 > > >> > =A0 =A0-0.0903 =A0 -0.2708 =A0 -0.5417 =A0 -0.9028 =A0 -0.7292 =A0 > -0.5= > >208 =A0 -0.2778 =A0 > >> > -0.0000 =A0 =A00.2778 > > >> > =A0 Columns 10 through 16 > > >> > =A0 =A0 1.4583 =A0 =A02.7292 =A0 =A04.0903 =A0 =A05.5417 =A0 > =A00.8333 = > >=A0 =A00.5903 =A0 =A00.3125 > > >> > which is also wrong! > > >> Your method is flawed alltogehter. In general, w will have infinite > >> length. Any truncation to use the FFT won't produce the expected > >> results. w can be found through long division of v2 by v1. This is > >> very simple to do with pencil and paper, the first couple of values in > >> w are > > >> w =3D [1 0 0 0 -5 4 ...] > > >If you add 5 more terms yourself, I'll reveal the matlab one-liner > >that calculates w to arbitrary length :-).- Zitierten Text ausblenden - > > - Zitierten Text anzeigen -
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