Re: B2xx round trip delay

[Ali G. Dezfuli]

By the way, if instead of time, we concentrate on the phase change on the correlation peaks, 

can we get to a better measure to relate it to RTD? For instance, we can send two sequences

of the same type and track the correlation peaks phase change and relate it to the RTD?

Thank you!

On Sun, Aug 13, 2023 at 8:15 AM Marcus D. Leech <patchvonbraun@gmail.com> wrote:

On 13/08/2023 00:36, Ali G. Dezfuli wrote:
> Hi all,
> I'd like to measure the round-trip delay (RTD) between two B200 USRPs.
> For that, I send a raised-cosined-filtered, BPSK modulated
> PN-sequence, and as soon as
> I get this signal at the receiver, send back the same sequence from
> the Rx to the Tx, and by correlation, I find the RTD.
> The question is that the measured RTD is not fixed. I wonder how can I
> make it fixed when the distance between the two USRPs is fixed.
> After that (A -> B -> A) I want to do that in reverse order (B -> A ->
> B) and expect to have the same RTD.
> Thanks
In your scenario, the latency will necessarily be variable--after all
your samples are entering a computer program where those
   samples are processed and then sent back in the other direction.
Since computer software on a general-purpose operating
   system cannot have fixed latency at fine-grained levels, this is
completely expected.

This document may help:

https://kb.ettus.com/Synchronizing_USRP_Events_Using_Timed_Commands_in_UHD