[USRP-users] RFNoC timing clarification

Jonathon Pendlum jonathon.pendlum at ettus.com
Wed Jul 12 12:58:30 EDT 2017


Hey Jason,

The timestamp of each packet describes the time the first sample in the
packet was received. The timestamp is based on a counter in
noc_block_radio_core (timekeeper.v.) that increments at the sample rate
(i.e. radio_clk). The time is relative to that counter's placement in the
processing chain. We do not do anything to back out the delays from
elements in front of the counter, such as the delay through the front end
filters, ADC, digital I/Q correction, etc.

Jonathon

On Wed, Jul 12, 2017 at 9:20 AM, Jason Matusiak via USRP-users <
usrp-users at lists.ettus.com> wrote:

> I have a timing question that has me going in circles, I don't understand
> how the USRP timestamps work when using RFNoC.
>
> In a normal system, packets have timestamps with them (or at least the
> first one does) and you can compute the time of any samples based on the
> timestamp, sample rate, and number of samples since the timestamp, right?
>
> Now, if I am using RFNoC, the timestamps aren't attached to the samples,
> right?  Where does that timestamp get associated:  Further down the stream?
>
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