There are a plethora of tools, both commercial and free, which I have found online for designing filters. The ones I have tried (so far) prompt for frequency response, number of steps (for FIR), then generate coefficients and a frequency response plot.
Question: are there any particular sites or programs, which allow you to input or modify the coefficients? Free would be preferable, but (especially for an FIR with a large number of taps) commercial will do in a pinch.
(Matlab is too expensive for me, but I've heard of freeware Octave: if anyone recommends it for filter design I'd be willing to try it out)