bharat pathak wrote:> Hi, > > We can very well represent brickwall filter in FFT domain.No. You can't represent a transition band narrower than one bin width.> Also we know that IFFT of brickwall will look like > sin(x)/x function extending towards +/- infinity.Again no. The continuous inverse Fourier transform of a continuous brick-wall response is a sinc. Your filter is discrete and so is an FFT.> How to derive this using IFFT equation??You can't derive what isn't so. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
how to derive IFFT of boxcar filter
Started by ●February 22, 2008
Reply by ●February 22, 20082008-02-22
Reply by ●February 22, 20082008-02-22
Hi Bharat, The reason you are getting a wide variety of answers is that you are playing fast and loose with some of the terms. Specifically, there are several members of the Fourier Transform family. http://www.dspguide.com/ch8/1.htm In the member simply called the "Fourier Transform", both domains are continuous and run from negative to positive infinity. A "brick wall" in one domain corresponds with a sinc function in the other domain. Another member is called the Discrete Fourier Transform (DFT), in which both domains are discrete and periodic. As mentioned by the other posts, this periodic nature distorts the "brick wall - sinc" relationship. Lastly, the Fast Fourier Transform (FFT) isn't one of the members-- it is one of many algorithms for computing the DFT. So, when you start out talking about the "brick wall -- sinc", and then ask about the IFFT, it isn't clear what question you really have. Everyone is trying to be helpful and read between the lines. If the responses so far haven't helped you, I'd suggest you rephrase the question with more detail. Regards, Steve
Reply by ●February 22, 20082008-02-22
Thanks Steve and All for helping me out on this. I think the crux lies in understanding the family of fourier transforms as Steve mentioned. Regards Bharat
Reply by ●February 23, 20082008-02-23
On Fri, 22 Feb 2008 09:42:32 -0600, "bharat pathak" <bharat@arithos.com> wrote:> >> >>Hi Bharat, >> If I remember correctly, you have copy of >>the 2nd edition of my DSP book. Perhaps the >>discussion on page 107 will be of some help to you. >> >>Regards, >>[-Rick-] > >Hi Rick, > > On page 107 i have 3.12.1 Processing Gain of single DFT > > Can u tell me what section num and heading r u referring to? > >Thanks and Regards >BharatHello Bharat, I have an E-mail record (from July 2007) of sending you the errata for the 2nd edition of my book, so my post should have made sense. The section I was referring to is Section 3.13.6. Now maybe you have some Indian or Chinese version of my book, in which case I have no idea on what page is Section 3.13.6 ("The Inverse DFT of a General Rectangular Function"). [-Rick-]
Reply by ●February 23, 20082008-02-23
> I have an E-mail record (from July 2007) of sending >you the errata for the 2nd edition of my book, so my >post should have made sense. The section I was referring >to is Section 3.13.6. > >Now maybe you have some Indian or Chinese version of >my book, in which case I have no idea on what >page is Section 3.13.6 ("The Inverse DFT of a General >Rectangular Function").Hello Rick, I got it. Also when I changed the company, I lost the soft copy of the errata list.Can you please resend? bharat-at-arithos-dot-com Thanks for your help. Regards Bharat
Reply by ●February 24, 20082008-02-24
On Sat, 23 Feb 2008 19:52:42 -0600, "bharat pathak" <bharat@arithos.com> wrote:> >> I have an E-mail record (from July 2007) of sending >>you the errata for the 2nd edition of my book, so my >>post should have made sense. The section I was referring >>to is Section 3.13.6. >> >>Now maybe you have some Indian or Chinese version of >>my book, in which case I have no idea on what >>page is Section 3.13.6 ("The Inverse DFT of a General >>Rectangular Function"). > >Hello Rick, > > I got it. Also when I changed the company, I lost > the soft copy of the errata list.Can you please > resend? > > bharat-at-arithos-dot-com > > Thanks for your help. > >Regards >BharatHi, You must have a somewhat "oddball" version of my book, so I just now sent you the errata for the First Printing. [-Rick-]
Reply by ●February 24, 20082008-02-24
Reply by ●February 29, 20082008-02-29
DSPGURU wrote: > On Feb 22, 1:04 am, "bharat pathak" <bha...@arithos.com> wrote: ... > Kamar Ruptan > DSP Guru Hi Kamar, With all due respect, may I ask that you not use the term "DSPGURU" as a handle in this group? You see, I created the dspGuru website, at http:\\www.dspguru.com, several years ago with the help of some of the regular posters to this newsgroup, many of which are still regular contributors. Although I'm sure this isn't your intention, I'm concerned that your use of that name might suggest to others in this group that you are somehow associated with the site, even though you are not. Not only is "dspguru" the central part of the domain name, it is a trademark owned by my little company, Iowegian International Corporation. (See http:\\www.iowegian.com.) Please understand that I do not doubt your DSP knowledge or your good intentions. However, trademark law requires that a trademark be defended from confusing uses in order for the trademark owner to retain the mark. In that vein, please consider this a friendly request for a favor from someone who you may never have heard of before, but who has contributed to this newsgroup in the past. In fact, I once even shared a certain blacklist with such comp.dsp luminaries as Rick Lyons, Robert Bristow-Johnson, Jerry Avins, and Peter K. -- not to brag. ;-) :-) =g2 _____________________________________________________________________ Grant R. Griffin Publisher of dspGuru http://www.dspguru.com Iowegian International Corporation http://www.iowegian.com See http://www.iowegian.com/img/contact.gif for e-mail address
Reply by ●February 29, 20082008-02-29
DSPGURU wrote: > On Feb 22, 1:04 am, "bharat pathak" <bha...@arithos.com> wrote: ... > Kamar Ruptan > DSP Guru Hi Kamar, With all due respect, may I ask that you not use the term "DSPGURU" as a handle in this group? You see, I created the dspGuru website, at http:\\www.dspguru.com, several years ago with the help of some of the regular posters to this newsgroup, many of which are still regular contributors. Although I'm sure this isn't your intention, I'm concerned that your use of that name might suggest to others in this group that you are somehow associated with the site, even though you are not. Not only is "dspguru" the central part of the domain name, it is a trademark owned by my little company, Iowegian International Corporation. (See http:\\www.iowegian.com.) Please understand that I do not doubt your DSP knowledge or your good intentions. However, trademark law requires that a trademark be defended from confusing uses in order for the trademark owner to retain the mark. In that vein, please consider this a friendly request for a favor from someone who you may never have heard of before, but who has contributed to this newsgroup in the past. In fact, I once even shared a certain blacklist with such comp.dsp luminaries as Rick Lyons, Robert Bristow-Johnson, Jerry Avins, and Peter K. -- not to brag. ;-) :-) =g2 _____________________________________________________________________ Grant R. Griffin Publisher of dspGuru http://www.dspguru.com Iowegian International Corporation http://www.iowegian.com See http://www.iowegian.com/img/contact.gif for e-mail address
Reply by ●February 29, 20082008-02-29
DSPGURU wrote: > On Feb 22, 1:04 am, "bharat pathak" <bha...@arithos.com> wrote: ... > Kamar Ruptan > DSP Guru Hi Kamar, With all due respect, may I ask that you not use the term "DSPGURU" as a handle in this group? You see, I created the dspGuru website, at http:\\www.dspguru.com, several years ago with the help of some of the regular posters to this newsgroup, many of which are still regular contributors. Although I'm sure this isn't your intention, I'm concerned that your use of that name might suggest to others in this group that you are somehow associated with the site, even though you are not. Not only is "dspguru" the central part of the domain name, it is a trademark owned by my little company, Iowegian International Corporation. (See http:\\www.iowegian.com.) Please understand that I do not doubt your DSP knowledge or your good intentions. However, trademark law requires that a trademark be defended from confusing uses in order for the trademark owner to retain the mark. In that vein, please consider this a friendly request for a favor from someone who you may never have heard of before, but who has contributed to this newsgroup in the past. In fact, I once even shared a certain blacklist with such comp.dsp luminaries as Rick Lyons, Robert Bristow-Johnson, Jerry Avins, and Peter K. -- not to brag. ;-) :-) =g2 _____________________________________________________________________ Grant R. Griffin Publisher of dspGuru http://www.dspguru.com Iowegian International Corporation http://www.iowegian.com See http://www.iowegian.com/img/contact.gif for e-mail address
