You'll probably want to make a block to do the padding, or mux in zeros. Matt
On Thu, Oct 16, 2014 at 3:00 PM, David Halls <david.ha...@toshiba-trel.com> wrote: > Thanks Matt. is this likely to be the cause of the Us at the beginning? > How can I pad simply in GNU radio? can i add padding to every burst? if so > that seems straightforward. I can just mux some zeros in. > > Also should the padding be included in the burst length? > > > -------- Original message -------- > From: Matt Ettus > Date:2014/10/16 22:54 (GMT+00:00) > To: David Halls > Cc: John Malsbury ,GNURadio > Subject: Re: [Discuss-gnuradio] Source Block - Flow Control > > > On TX, if you need your first sample to be valid and everything settled in > the radio, you should zero pad ahead of it. If you need your last sample > to go out clean, you should zero pad after it. In both cases, a few > microseconds worth is usually fine. This flushes buffers and filters, but > also gives physical devices like antenna switches to settle. > > Matt > > On Thu, Oct 16, 2014 at 2:46 PM, David Halls <david.ha...@toshiba-trel.com > > wrote: > >> >> >> -------- Original message -------- >> From: Matt Ettus >> Date:2014/10/16 22:42 (GMT+00:00) >> To: John Malsbury >> Cc: David Halls ,GNURadio >> Subject: Re: [Discuss-gnuradio] Source Block - Flow Control >> >> >> >> On Thu, Oct 16, 2014 at 8:40 AM, John Malsbury < >> jmalsbury.perso...@gmail.com> wrote: >> >>> I'm happy this is working for you, David. So do I understand >>> correctly, that the adding tx_time finally made the MIMO case work? >>> >>> I'd never done burst transmission with multiple USRP outputs. I'm not >>> totally surprised but I wasn't sure what would happen. >>> >>> Maybe someone from Ettus can comment on this? Since UHD is trying to do >>> time alignment in the multi_usrp class, what happens to time alignemt in >>> the non-continuous-streaming case if you *don't* include a tx_time tag? >>> >> >> >> Noncontinuous streaming means there is some amount of down time. If >> you don't include tx_time tags, the device doesn't know when to start back >> up again, so each antenna is going to start at a different time. >> >> Matt >> >> >> That seemed exactly the kind of behaviour I saw where sync between the >> two streams was lost. Matt, can you comment on whether I need to put dummy >> padding items before the first burst? to flush buffers and is there a >> delicate way to do this? >> >> >> ------------------------------ >> >> NOTE: The information in this email and any attachments may be >> confidential and/or legally privileged. This message may be read, copied >> and used only by the intended recipient. If you are not the intended >> recipient, please destroy this message, delete any copies held on your >> system and notify the sender immediately. >> >> Toshiba Research Europe Limited, registered in England and Wales >> (2519556). Registered Office 208 Cambridge Science Park, Milton Road, >> Cambridge CB4 0GZ, England. Web: www.toshiba.eu/research/trl >> >> >> >> ------------------------------ >> This email has been scanned for email related threats and delivered >> safely by Mimecast. >> For more information please visit http://www.mimecast.com >> ------------------------------ >> > > > ------------------------------ > > NOTE: The information in this email and any attachments may be > confidential and/or legally privileged. This message may be read, copied > and used only by the intended recipient. If you are not the intended > recipient, please destroy this message, delete any copies held on your > system and notify the sender immediately. > > Toshiba Research Europe Limited, registered in England and Wales > (2519556). Registered Office 208 Cambridge Science Park, Milton Road, > Cambridge CB4 0GZ, England. Web: www.toshiba.eu/research/trl > > > > ------------------------------ > This email has been scanned for email related threats and delivered safely > by Mimecast. > For more information please visit http://www.mimecast.com > ------------------------------ >
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
