Thank you very much again! On Sun, Sep 30, 2012 at 6:22 PM, Josh Blum <j...@ettus.com> wrote:
> > > On 09/29/2012 09:46 AM, Anisha Gorur wrote: > > Thanks Josh, that helps quite a bit! Our sampling frequency is not > > particularly fast, it will only be around 5 MS/S. Right now the send and > > receive frame size are still the defaults, 1472 for receive and 1444 for > > send. In the notes, it says "to improve receive latency, configure the > > transport for a smaller frame size", will this work for send latency as > > well? Also is there an equation I can use to determine what the best > frame > > sizes would be, or should I just go with trial and error and use > > latency_test.cpp to determine if it has shifted? If you change the frame > > size, how much improvement in latency do you usually see? > > Again, thank you so much. > > -Anisha > > > > The reason that shrinking the receive frame size reduces latency is that > the RX DSP chain produces samples at a fixed rate. Therefore, the device > cannot release a packet until samples_per_packet / sample_rate. The > first sample is a packet is delayed by the time it takes to produce the > last sample. > > However, in the case of transmission/send there is no such issue. > Essentially your application is the pacer and producer of samples. So > you have total control. > > -Josh > > > On Fri, Sep 28, 2012 at 6:57 PM, Josh Blum <j...@ettus.com> wrote: > > > >> > >> > >> On 09/28/2012 02:46 PM, Anisha Gorur wrote: > >>> Thanks Matt! > >>> Do you have any idea for what kind of latency we would expect? Also > would > >> > >> The dominating factor in latency here is the gigabit ethernet, this > >> tends to be around 100us. Here are a few notes about that: > >> > >> > >> > http://files.ettus.com/uhd_docs/manual/html/transport.html#latency-optimization > >> > >>> the data be routed through the host? My Radio, We only have a couple > >> months > >> > >> Normally the samples would all go to the host computer that configured > >> the USRP. It is possible to configure the USRP with one machine but send > >> the samples to an arbitrary network location: > >> > >> > >> > http://files.ettus.com/uhd_docs/manual/html/usrp2.html#alternative-stream-destination > >> > >> For that matter, there is nothing wrong with splitting up the USRP > >> configuration among several computers. It all depends how you plan on > >> using the data. > >> > >>> to do this, but we have tried to synchronize USRPs before, so we are > >> aware > >>> of some of the problems. > >> > >> Anything in particular that I could help to clarify? > >> > >> -josh > >> > >>> Thanks, > >>> Anisha > >>> > >>> On Wed, Sep 26, 2012 at 3:51 PM, My Radio <myradioplatf...@gmail.com> > >> wrote: > >>> > >>>> One should remember the extremes involved in syncing all USRP'S which > >> will > >>>> lead to developing a new driver for USRP2. > >>>> > >>>> What about the your APP development time?. Are you interested in > >>>> developing new driver or app ? > >>>> > >>>> > >>>> On Thu, Sep 27, 2012 at 12:04 AM, Matt Ettus <m...@ettus.com> wrote: > >>>> > >>>>> You can use a gigabit ethernet switch and put all the USRPs on there. > >>>>> You should be able to make USRPs send data to each other. You will > of > >>>>> course need to do work to get your algorithms into the FPGA. > >>>>> > >>>>> Matt > >>>>> > >>>>> On Wed, Sep 26, 2012 at 12:38 PM, Anisha Gorur <at...@virginia.edu> > >>>>> wrote: > >>>>>> I have a quick theoretical question. Is there any way to construct > an > >>>>>> 8-channel receiver using 4 USRPS without data going through the host > >>>>>> computer? Basically some kind of way to daisy chain mimo cables > >> (though > >>>>> I > >>>>>> know this is not possible), or at least get the same benefits you > >> would > >>>>>> receive from daisy chaining mimo cables, without using a switch or > >>>>> network > >>>>>> connections. > >>>>>> > >>>>>> Thank you, > >>>>>> Anisha > >>>>>> > >>>>>> > >>>>>> _______________________________________________ > >>>>>> Discuss-gnuradio mailing list > >>>>>> Discuss-gnuradio@gnu.org > >>>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >>>>>> > >>>>> > >>>>> _______________________________________________ > >>>>> Discuss-gnuradio mailing list > >>>>> Discuss-gnuradio@gnu.org > >>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >>>>> > >>>> > >>>> > >>>> > >>>> _______________________________________________ > >>>> Discuss-gnuradio mailing list > >>>> Discuss-gnuradio@gnu.org > >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >>>> > >>>> > >>> > >>> > >>> > >>> > >>> _______________________________________________ > >>> Discuss-gnuradio mailing list > >>> Discuss-gnuradio@gnu.org > >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >>> > >> > >> _______________________________________________ > >> Discuss-gnuradio mailing list > >> Discuss-gnuradio@gnu.org > >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >> > > > > > > > -- Anisha Gorur Class of 2012 Electrical Engineering
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