On 5/12/05, Olin Lathrop wrote: > > Curious about one thing though -- anyone have a correlation or > > calculation to compare software proportional filtering to an RC filter? > > I use my FILTBITS program followed by CSVPLOT to show the step response of a > filter. You type in the bit shift amount for each filter pole, and it makes > a plot. For example, the attached plot is of a 3 pole filter with 4 bits of > shift (FF = 1/16 in my filter equation, FF may be what you intended K to be) > per pole. When you say poles here, do you actually cascade the simple IIR under discussion or do you use an "unrolled" equation? I hadn't realized that it would be useful to cascade this filter. Do you have your FILTBITS program available somewhere? I couldn't find it on Embedinc. Also what is your mnemonic for FF? I would normally use K and can only think of feed-forward or fast Fourier for FF... > My MPASM preprocessor also has built in functions for computing filter > fraction values given the iteration frequency and either the -3dB rolloff > frequency or the 1/2 step response time. See the FFTC2 and FFFREQ built in > functions. The preprocessor, PREPIC, is described at > http://www.embedinc.com/pic. You have a man page, but do you release the source code for PREPIC? Thanks Bradley -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist