Hi again... I'm using a IBOB-QUADC, the FPGA clock rate is 200MHz, and QUADC clock rate is 200 MHz. The size of PFB and FFT is 2^11 pnts, and that means that I have 1024 channels for each of the four inputs of the QUADC, is this correct?
My correlation block is called "xengine4", and within are 6 cross-correlations and 4 autocorrelations. That means that I have 16 BRAM in the correlator's design. For each BRAM I use a "vacc_32bit" block . If the design can handle four real independent streams, as we have discussed, Does this means that I should set each "vacc_32bit" block with 1024 channels? Best Regards Rolando Paz 2014-08-31 11:33 GMT-06:00 Dan Werthimer <[email protected]>: > > > i think the FFT biplex real 2x block > can compute real to complex FFT's on > 4, 8, 12, 16.... inputs, depending on how you set > the "Number simultaneous inputs" parameter. > > best wishes, > > dan > > > > > > > > On Sun, Aug 31, 2014 at 10:26 AM, Rolando Paz <[email protected]> wrote: > >> Hi Dan >> >> Now I understand :-) >> >> It's very different this: >> >> 4 time samples in parallel (fft_wideband_real) >> >> 4 real streams (fft_biplex_real_2x) >> >> Casper's website says ( >> https://casper.berkeley.edu/wiki/Fft_biplex_real_2x): >> >> ...Thus, a biplex core (which can do 2 complex FFTs) can transform 4 real >> streams. Twiddle factor, and other logic sharing, allows multiples of 4 >> input streams to be processed simultaneously with minimal resource >> increases... >> >> Does this mean that I only need a single block? >> >> Best Regards >> >> Rolando Paz >> >> >> 2014-08-31 11:06 GMT-06:00 Dan Werthimer <[email protected]>: >> >>> >>> >>> hi Rolando, >>> >>> the quad adc outputs one sample per FPGA clock, >>> so your correlator will need to use an FFT with real input, >>> complex output, 1 real input sample per clock. >>> >>> I think (but I'm not sure), the *fft_biplex_real_2x block does* >>> *two real to complex ffts, so you'll need* >>> *two of these blocks to compute four* >>> *fft's on four inputs.* >>> >>> *best wishes,* >>> >>> *dan* >>> >>> >>> On Sun, Aug 31, 2014 at 10:00 AM, Rolando Paz <[email protected]> wrote: >>> >>>> Could someone please explain why the QUADC designs use only the >>>> fft_bliplex_real_2x block? >>>> >>>> Why the fft_biplex_real_2x block uses more resources than the >>>> fft_wideband_real block? >>>> >>>> Best Regards >>>> >>>> Rolando Paz >>>> >>> >>> >> >
