Hi Rolando, My first suggestion would just be to carefully look at your design and follow the sync and data paths looking for issues. Otherwise you can simulate a signal in a particular FFT bin and check with a scope to make sure it stays where it should relative to the sync pulse. For these kinds of simulations, sometimes I just make the simulation input a constant (i.e., a DC signal). This should result in a spike in FFT channel 0, which occurs the clock after the sync pulse.
Cheers Jack On Sat, 10 Mar 2018 at 17:42 Rolando Paz <[email protected]> wrote: > Very interesting. Thanks Jack. > > Is there any way to find the place and value of the latency that I must > remove or add, to the synchronization pulse inside my design? > > Regards > > Rolando > > > 2018-03-10 18:47 GMT-06:00 Jack Hickish <[email protected]>: > >> Hi Rolando, >> >> This sort of channel number offset issue usually indicates a misalignment >> between the sync pulse in the design and data where your data goes through >> an operation that has some latency, and this latency isn't compensated for >> in the sync signal. >> One clue is that there is usually a spike in FFT bin 0 (i.e., the DC >> bin). In your plots this spike appears at the end of the spectrum for the >> per-antenna plots, and seemingly at bin ~2 in the beamformer plot. >> >> You should fix this in your simulink design, by adding or removing >> latency in the sync or data signals to keep them aligned. You could just >> shift your spectra in software, but that's a bit of a hack -- really you >> should just fix the hardware bug. >> >> Cheers >> Jack >> >> >> On Sat, 10 Mar 2018 at 15:54 Rolando Paz <[email protected]> wrote: >> >>> Hi Jack >>> >>> I did some tests with my beamformer design (4 inputs). >>> >>> Currently I only have a 70MHz test tone at the A and B inputs. I do not >>> have anything connected at C and D inputs . >>> >>> The tone at A and B inputs is slightly offset to the left with respect >>> to the 70MHz signal. >>> >>> In the C and D inputs appear some signals that I do not know why they >>> appear. >>> >>> Do you know why the spectrum can move? >>> >>> In the case of the beamformer signal, it appears displaced to the right >>> of the 70MHz tone. Why does this happen? >>> >>> Is this corrected in the spectrometer design (matlab design) or is it >>> corrected with python? >>> >>> Best Regards >>> >>> Rolando Paz >>> >> > -- You received this message because you are subscribed to the Google Groups "[email protected]" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected].
