Hi, I have a GnuRadio modem I've developed and I'd like to reduce latency. It does IP encapsulation and for testing, I use two USRPs to implement an OTA connection between the modems.
I've reduced latency so far by 1) adding fill frames/bytes only at the very last block before the USRP sink and 2) increasing the sample rate to the device. This has gotten my slightly under 100 ms latency, which is good compared to what I started with, but I think we can do better. My assumption is that there is still some latency in the last buffer between the last block and the USRP sink and perhaps some in the USRP USB transport itself. I am using B200s in this case, BTW. I suspect that what I really must do is now tweak the usrp buffer params from here: https://files.ettus.com/manual/page_transport.html But, I have no idea what they are set to by default (any way to tell)? And some naive manipulation of them hasn't improved anything. I also tried tweaking the mx output buffer size on the last block before the USRP sink without any improvement. Any advice from Ettus folks would be appreciated :) I am giving a talk at GRCon that addresses the latency reduction work so far, so if we can get any more, I'll throw that in as well. - Dan -- Very Respectfully, Dan CaJacob
_______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
