I found there are two method to do FIR. A. find the coefficient from fourier series. B. Window method. My thinking about A. 1. Use fourier series to contribute a desire filter curv(ac response) 2. find fourier series 3. convolution signal with series 4. Get the FIR. I am correct? Thank you very much. Best regards, Boki.
The way to do FIR filter.
Started by ●June 4, 2004
Reply by ●June 4, 20042004-06-04
boki wrote:> I found there are two method to do FIR. > > A. find the coefficient from fourier series. > B. Window method. > > My thinking about A. > > 1. Use fourier series to contribute a desire filter curv(ac response) > 2. find fourier series > 3. convolution signal with series > 4. Get the FIR. > > > I am correct? > > Thank you very much. > > Best regards, > > Boki.A and B are two steps of the same method. A second method uses a program that iteratively calculates coefficients that are optimum according to some criterion. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 5, 20042004-06-05
Jerry Avins <jya@ieee.org> wrote in message news:<40c11f5a$0$2922$61fed72c@news.rcn.com>...> boki wrote: > > > I found there are two method to do FIR. > > > > A. find the coefficient from fourier series. > > B. Window method. > > > > My thinking about A. > > > > 1. Use fourier series to contribute a desire filter curv(ac response) > > 2. find fourier series > > 3. convolution signal with series > > 4. Get the FIR. > > > > > > I am correct? > > > > Thank you very much. > > > > Best regards, > > > > Boki. > > A and B are two steps of the same method. A second method uses a program > that iteratively calculates coefficients that are optimum according to > some criterion. > > JerryGoogle for DSPlay by prof Roger Cattin. It is a teaching tool and it generates good simple filters. Once you graduated from that one, get SciLab from Inria in France - it comes with excellent DSP documentation in PDF form - both of these tools are free. Cheers, Herman http://www.AerospaceSoftware.com
Reply by ●June 9, 20042004-06-09
Thanks for information. Best regards, Boki. HermanZA8@netscape.net (Herman Oosthuysen) wrote in message news:<25c456ac.0406051256.5844fd94@posting.google.com>...> Jerry Avins <jya@ieee.org> wrote in message news:<40c11f5a$0$2922$61fed72c@news.rcn.com>... > > boki wrote: > > > > > I found there are two method to do FIR. > > > > > > A. find the coefficient from fourier series. > > > B. Window method. > > > > > > My thinking about A. > > > > > > 1. Use fourier series to contribute a desire filter curv(ac response) > > > 2. find fourier series > > > 3. convolution signal with series > > > 4. Get the FIR. > > > > > > > > > I am correct? > > > > > > Thank you very much. > > > > > > Best regards, > > > > > > Boki. > > > > A and B are two steps of the same method. A second method uses a program > > that iteratively calculates coefficients that are optimum according to > > some criterion. > > > > Jerry > > Google for DSPlay by prof Roger Cattin. It is a teaching tool and it > generates good simple filters. Once you graduated from that one, get > SciLab from Inria in France - it comes with excellent DSP > documentation in PDF form - both of these tools are free. > > Cheers, > > Herman > http://www.AerospaceSoftware.com
Reply by ●June 9, 20042004-06-09
I think window method has its different coefficient between window method and fourier method, am I wrong? @@ Boki. Jerry Avins <jya@ieee.org> wrote in message news:<40c11f5a$0$2922$61fed72c@news.rcn.com>...> boki wrote: > > > I found there are two method to do FIR. > > > > A. find the coefficient from fourier series. > > B. Window method. > > > > My thinking about A. > > > > 1. Use fourier series to contribute a desire filter curv(ac response) > > 2. find fourier series > > 3. convolution signal with series > > 4. Get the FIR. > > > > > > I am correct? > > > > Thank you very much. > > > > Best regards, > > > > Boki. > > A and B are two steps of the same method. A second method uses a program > that iteratively calculates coefficients that are optimum according to > some criterion. > > Jerry
Reply by ●June 9, 20042004-06-09
boki wrote:> I think window method has its different coefficient between window > method and fourier method, am I wrong? @@ > > Boki. > > > > Jerry Avins <jya@ieee.org> wrote in message news:<40c11f5a$0$2922$61fed72c@news.rcn.com>... > >>boki wrote: >> >> >>>I found there are two method to do FIR. >>> >>>A. find the coefficient from fourier series. >>>B. Window method. >>> >>>My thinking about A. >>> >>>1. Use fourier series to contribute a desire filter curv(ac response) >>>2. find fourier series >>>3. convolution signal with series >>>4. Get the FIR. >>> >>> >>>I am correct? >>> >>>Thank you very much. >>> >>>Best regards, >>> >>>Boki. >> >>A and B are two steps of the same method. A second method uses a program >>that iteratively calculates coefficients that are optimum according to >>some criterion. >> >>JerryThe coefficients derived by transforming the frequency response to the time domain, when used to filter, display ringing related to the "Gibbs phenomenon" [Google for that]. Windowing changes those coefficients to reduce the ringing at the price of broadening the filter's transitions. With filters, the transition sharpness can be restored by making the filter longer. When the same window is applied to to real data to reduce the effects of its not being a complete period of a periodic series, there is no way to retrieve lost resolution. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
