On Sun, Aug 31, 2014 at 3:40 PM, Rolando Paz <[email protected]> wrote:
> 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? > > yes, that's correct: 2048 real points in and out of the PFB FIR, as well as into the FFT. 1024 complex points out of the FFT. > 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? > yes. > > 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 >>>>> >>>> >>>> >>> >> >
