Hi all: This issue has been resolved. There was a bug in my design in a downstream block that creates packets.
Thanks a lot for you help, Nimish On Mon, Mar 18, 2013 at 8:04 AM, Nimish Sane <[email protected]> wrote: > @Dan: > We apply sync pulse only once. From the memo you have mentioned, this is > an acceptable mode. We do not apply resync pulses, and can also confirm > that there is just one sync pulse. > > @Dave: > We have never seen such behavior in simulations. I am double checking > though. > > @Ryan: > Your observations are correct, but I do not understand what you mean by > hooking up all outputs correctly. That seems to be fine. We are using the > block's outputs correctly. > > FWIW, we run the design on two different FPGA clocks (150 MHz and 200 MHz) > and see similar behavior. > > Thanks, > > Nimish > > > On Fri, Mar 15, 2013 at 2:14 PM, Ryan Monroe <[email protected]>wrote: > >> Comments: >> >> -The FFT is probably fine. If it was broken, it would probably be 100% >> broken. At least this looks like a spectrum >> -It appears to me as if the broken section is exactly 1/8th of the >> spectrum. Did you hook up all of your outputs correctly? >> -What's up with the spikes in the spectrum? If they were interleave >> artifacts, I'd expect to see the one which is at channel ~1800 closer to >> 2048. Maybe they are some other tone though >> >> >> >> On 03/15/2013 12:14 PM, Nimish Sane wrote: >> >> Hi all: >> >> I am attaching a plot for Power of two inputs vs frequency channels. As >> can be seen, we have this persistent problem where some channels at the end >> just do not make any sense. We suspect that there is something going wrong >> in the FFT block. Has anybody seen such behavior before or can think of >> what may be going wrong? >> >> Following are some specifications that may be useful: >> Hardware: ROACH2 with KATADC. >> ADC Clock: 800 MHz, >> FPGA clock: 200 MHz >> Toolflow: XSG 11.5 with Matlab 2009b with RHEL5.8 >> Libraries: SKA >> FFT green block: fft_wideband_real >> FFT size: 2^13 (4096 Output channels) >> >> Thanks, >> >> Nimish >> -- >> Nimish Sane >> >> Center for Solar-Terrestrial Research >> New Jersey Institute of Technology >> University Heights >> >> Newark, NJ 07102-1982 USA >> >> Tel: (973) 642 4958 >> >> Fax: (973) 596 3617 >> [email protected] >> >> >> >
