Re: [Discuss-gnuradio] Predictable latency?

[Thomas Schmid]

This is correct. Your samples go through buffers, and therefore it is
hard to predict the latency each and every sample will have to get
from software to the USRP. I did a study on this a while back. If you
are interested, you can find the paper here:
http://nesl.ee.ucla.edu/document/show/242

What you can do though is calculate the minimum and the maximum
latency that the samples will have. Also, I am not sure how far the
mblock and GNU Radio is in regards to timestamping outgoing samples (I
didn't follow the GNU Radio development lately) is, but if you can
tell the USRP when to send out which sample, then you could easily
predict the latency itself.

Cheers,
Thomas

On Tue, Aug 19, 2008 at 8:14 AM, Chris Stankevitz <address@hidden> wrote:
>
>
> Geib, Jeffrey (Civilian) wrote:
>>
>> I have an application where I don't necessarily care what the latency
>> is, but I need it to be predictable and/or constant.  Is there a way to
>> achieve this with the USRP hardware?
>
> USRP supplies data via USB.  I believe the delay of USB data through the
> operating system and into your application is not predictable or constant.
>
> Chris
>
>
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-- 
"Don't complain; Just work harder" - Randy Pausch

Thomas Schmid, Ph.D. Candidate
Networked & Embedded Systems Laboratory (NESL)
University of California, Los Angeles (UCLA)

http://gresci.blogspot.com/ - Science articles on green technology