Short: FIR Filter Designer V2.3 Author: harald.zottmann@t-online.de Uploader: harald zottmann t-online de Type: misc/sci Version: 2.3 Replaces: misc/sci/FIRDesign2* Architecture: m68k-amigaos FIR Filter Designer =================== The Amiga FIR Filter Designer designs optimized Finite Impulse Response Filters. Amiga OS 3.x is required. The program requires a minimum Workbench screen size of 640x400. The FIR Filters designed by the program FIR Filter Designer V2.3 can be loaded by the program AudioLab16 from Maurizio Ciccione. AudioLab16 can be found on the Aminet in the directory /mus/edit. The problem of designing finite impulse response (FIR) digital filters experienced great activity in the early 1970`s. Most of this work was directed at the problem of optimal filter design, in the weighted Chebyshev sense. The algorithm for this program, by McClellan, Parks and Rabiner, will design the optimal Chebyshev approximation for linear phase filters. The Chebyshev optimization is done very efficiently by means of the Remez exchange algorithm, and this particular FIR filter design program has found wide use. The window method filter design process is based upon Fourier series. It is possible to represent a frequency function as a Fourier series, whose coefficients represent the coefficients of the filter. To form a casual filter, the Fourier series is truncated and shifted. Truncating the Fourier series causes a phenomenon called the "Gibbs effect" - a spike occurs wherever there is a discontinuity in the desired magnitude of the filter. To counteract this, the filter coefficients are convolved in the frequency domain with the spectrum of a window function, thus smoothing the edge transitions at any discontinuity. This convolution in the frequency domain is equivalent to multiplying the filter coefficients with the window coefficients in the time domain. History ======= Date Version Type Comments ---- ------- ---- -------- 06/08/98 V2.30 Release - Automatic refresh for Prism window - Selectable bitwidth for filter taps - Some minor bugfixes 08/03/98 V2.20 Release - Updated GUI to fit for larger fonts - Changed registration address 06/02/98 V2.10 Release - Fixed a serious bug with big font sizes - New ToolType for FONTNAME and FONTSIZE 20/01/98 V2.00 Release - Window method filter design - Requires OS3.x now - Improved GUI - Progress bar - Extended documentation - Recompiled with SAS/C V6.58 20/07/96 V1.20 Release - ToolType support - Filterlength now up to 512 taps - Internal improvements - Displays floating point errors - View log file with external viewer - Displays also the corrected phase 01/05/96 V1.10 Release - Versions for: MC 68000 MC 68020 MC 68040 - Updated the installer script - Now compatible with AudioLab16 - Grids in the Prism window - Some redesigns and optimizations - Fixed Bug with too small workbench 29/11/95 V1.01 Release - Fixed several Enforcer Hits - Fixed Bug with not updating gadgets - Recompiled with SAS/C V6.56 - Less Shareware Requesters - Installer Script - Added Pattern in Filerequester - More Examples 21/07/95 V1.00 Release First AMINET Release