Hi Li Jian I am including the casper list in the reply in case others find this useful.
> When I use dec_fir to design a bandpass filter I had meet many > questions. > I don't know how to configure dec_fir's coefficients.I could not get > more information about dec_fir from CASPER's webpage. > the result (spectrum) is wrong. > can you show me detailed how to configure the coefficients. > I have always used the dec_fir as a low pass filter. To make it a band-pass I would mix the band of interest down to base-band and then use the dec_fir as a low-pass filter to extract this band (basically a digital down converter). The problem with using it as a band-pass filter is that it decimates the result (i.e it is not a standard FIR but a FIR followed by decimation, that is why its name is dec_fir). Unless your band of interest is located to take this into account, this decimation will cause aliasing that may mess up your data. The way I normally get the coefficients for the low pass filter I am designing is to use fdatool to design the filter, then export the coefficients to the Workspace as a variable, and use this variable to get the coefficients into the mask. Hope this helps. Regards Andrew
