Re: [Discuss-gnuradio] Predictable latency?

[Eric Blossom]

On Tue, Aug 19, 2008 at 02:01:40PM -0400, Geib, Jeffrey (Civilian) wrote:
> On Tue, Aug 19, 2008 at 10:27:15AM -0400, 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?  
> > 
> > Thanks!
> 
> Latency measured relative to what?
> Rx only, Tx only or Tx/Rx?
> 
> Eric
> 
> I am looking for fixed latency from Rx to Tx.  I want to take a
> continuous stream of input data, process it, and transmit it back out.
> The processing needs to know what the precise latency is between the
> samples at the DAC and ADC.
> 
> >From the previous replies and Thomas Schmid's analysis, it appears that
> this isn't feasible with the current interface.   It appears this could
> be done with the mblock and inband signaling additions, where then I
> could schedule each packet to be output at a known timestamp. 

Yes.  As soon as George and company get the timestamp issue sorted
out, this should work fine.

Eric