If you try to use a PFB FIR or FFT block with a large number of taps ( > 4K maybe), it doesn't work because you end up with long arays of coefficients which the drawing script tries to stuff in the field of a RAM/ROM block to initialize it. The fields have a finite maximum length, so you end up with an array that looks like [1 2 3 4 with no closing ]. Apparently it can cause Matlab to crash, but I've never had that experience. I tried to make a single input complex FFT last night w/ 2^13 channels and found that the initialization vector in the map ROM in the reorder block in the unscrambler was truncated. Glenn
On 5/6/08, John Ford <[email protected]> wrote: > > We are going to put that fix in the ported version of the library > > (it's not in the current green blocks). Right now you need to change > > those values to a variable and keep the backpopulate_mask script from > > removing that variable to get around the problem. > > -Terry > > > > > > On May 5, 2008, at 6:51 PM, G Jones wrote: > > > >> Hello, > >> Was a work around ever found for using the green blocks for long > >> FFTs/PFBs? I am running into the problem where the initial value > >> vector in a block ram is too long so it gets truncated. > > > Can someone expound on this? What is a "long" pfb/fft? Are there any > notes on this anywhere? > > John > > > > >> > >> Thanks, > >> Glenn > >> > > > > > > >
