Hi Dave,
I haven't been following all of this discussion, but bear with me:
I saw a problem similar to what you're experiencing in the past. I
designed a block (my "optimized" PFB), which was designed to only ever
output one sync pulse (the sync_delay's were designed to never respond
to later pulses). I later discovered that for some obscure reason, this
caused the downstream system to randomly shift channel 0. Sound familiar?
You can't easily tell if the PFB output is correct, except by running an
FFT on PFB'ed data and considering the output. That would at least,
tell you that the PFB is doing its job, but won't easily diagnose the
problem. You could also put in a slow sine wave (one that's not in the
middle of a FFT channel) and look at the PFB output. I would expect
that there would be no discontinuities in the time domain (or they
should be very small). If you see a big one, that's probably the end of
your PFB frame, and would indicate a botched sync timing.
That help?
--Ryan Monroe
On 11/26/2012 12:20 PM, Ricardo Finger wrote:
Hello Dave,
The zero channel jumps to a different place every time I run the bof,
but when running is stable.
I am not using and external sync pulse.
On simulations the pulse period looks ok, but I don't know if is
synchronized with the data. Actually, I don't know how to check this.
For example: if I use for simulation a band limited white noise; how
can I know when the first channel is going out of the pfb or fft? I
guess with a big DC offset I could "mark" channel 0, but anyway I
wouldn't know how this should look at the pfb output...
Cheers,
r
On 26-11-2012 14:04, David MacMahon wrote:
Hi, Ricardo,
On Nov 23, 2012, at 8:55 AM, Ricardo Finger wrote:
The zero channel jumps around every time I run the bof (It can be
anywhere).
Is the zero channel different but stable each separate time you run
the bof or does it jump around while the design is running?
On simulations the pulse looks ok for both cases.
What are you using for the external sync pulse? Are you sure that
the design is syncing up to it at startup? What happens if you run
the design without the external sync pulse?
Just some ideas,
Dave
