How about this: Send me a copy of the model and I'll do a sanity check :-)
On 03/18/2013 08:04 AM, Nimish Sane 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 <ryan.m.mon...@gmail.com
<mailto:ryan.m.mon...@gmail.com>> 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 <tel:%28973%29%20642%204958>
Fax: (973) 596 3617 <tel:%28973%29%20596%203617>
nimish.s...@njit.edu <mailto:nimish.s...@njit.edu>
