Hi Marcus,

> > I'm working on synchronising two USRPs (connected via a MIMO) and have
> > calibrated the time-offset which occurs between them for a given set
> > of signal generator's frequency, USRPs frequency and the sampling rate.
> >
> > My next step is to do a phase-compensation for one of the USRPs so
> > that both are aligned in the time-domain. I read from this
> > <http://www.ettus.com/content/files/kb/mimo_and_sync_with_usrp.pdf>
> > document that for Phase-shifting, we need to use MRC algorithm or
> > Periodic Calibration. Also I saw that a "Phase Shift" block has been
> > used in that document which I guess was developed by the author who
> > wrote it, as I could not find it in the GRC.
> >
> > I'm willing to develop one such simple phase-shift block. Can anyone
> > suggest me how to approach in implementing it i.e in terms of any
> > algorithm's reference that you can suggest to achieve this purpose?
> >
> > Note: I want my Phase-Shift block to work in real time i.e it should
> > be able to adjust the phase-offset of one of the signals so that that
> > signal gets aligned with the other in the time-domain.
>
> The attached demonstrates phase-shifting using a simple complex multiply
> block.
>
> If you want to do coarser phase shifts (large multiples of 180deg), you
> can use a delay block.
>
>
Presently I'm calculating the delay between two synchronised signals coming
out of the USRP source (connected to a signal generator) by recording their
samples and finding the offset between their first peak or zero-crossing.

Now if we want to time-align them in real-time, how can we implement a
delay block that calculates the delay each time the grc flow is run and set
the delay_value in the block accordingly so that they are time-aligned? i.e
I don't want to record the samples rather I'd like to know how to find the
delay and shift any of the two signals so that they get aligned?

Best,
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