Ok, well thank you for the fast answer. I'll keep looking around but this is a serious issue for me, it means I can't use my two USRP to send and receive any useful traffic.
2013/3/6 Alex Zhang <cingular.a...@gmail.com> > I don't believe this problem can be solved by adjusting the loop > bandwidth. > Applying faster tracking algorithm may solve this problem, but I think it > takes long time to develop for a new guy. > > > On Wed, Mar 6, 2013 at 3:44 AM, Jawad Seddar <jawad.sed...@gmail.com>wrote: > >> Hello, >> >> I am getting the same problem you described here i.e very high packet >> loss in discontinuous mode (first and last packet received with ok=False). >> >> Could you please elaborate on how to adjust the synchronisation loops >> bandwidth? >> I have tried adjusting the --timing-bw and --phase-bw parameters on the >> benchmark-rx example, but I don't know if that is what you were talking >> about. >> >> >> *From:* Adeel Anwar <address@hidden> >>> *To:* Alex Zhang <address@hidden> >>> *Cc:* address@hidden >>> *Sent:* Monday, 4 March 2013 5:51 PM >>> *Subject:* Re: [Discuss-gnuradio] Very low packet loss rate for the >>> discontinuous BPSK communications- the analysis and looking for solution >>> >>> Alex, >>> >>> 1: U can try adjusting the synchronization loops bandwidth (Phase/Timing >>> etc) see PFB_Timing documentation >>> 2: Try reducing the receiver gain (for a constant tx-amplitude/gain) or >>> reduce transmission amplitude/gain (for constant rx gain) >>> >>> -Adeel >>> >>> >>> >>> >>> >>> >>> On Sat, Mar 2, 2013 at 10:21 AM, Alex Zhang <address@hidden> wrote: >>> >>> I think you may rarely get the correct packet with pktno = 0, in >>> continuous mode, as my guess. Your received correct packet starts from >>> pktno = 1. >>> Could you also try the discontinuous mode for the BPSK communications? >>> >>> My question is actually a problem that how to implement a more reliable >>> BPSK mod/demod in burst mode. The current bpsk example in GNURadio does not >>> work well in burst mode. >>> >>> >>> On Fri, Mar 1, 2013 at 11:12 PM, Manu T S <address@hidden> wrote: >>> >>> Alex, >>> >>> If it was about loosing sync, we would mostly loose the first packet >>> even if we are sending in continuous mode. I personally face no such issues. >>> >>> >>> On Sat, Mar 2, 2013 at 3:25 AM, Alex Zhang <address@hidden> wrote: >>> >>> Seems no one can shed a light on this topic? >>> >>> >>> On Thu, Feb 28, 2013 at 10:25 PM, Alex Zhang <address@hidden> wrote: >>> >>> Hello, >>> >>> In the current gr-digital/narrowband, I am using the benchmark_tx.py and >>> rx.py to test the bpsk communications. >>> It is found that the packet loss rate is very high (70% loss) in >>> discontinuous mode where every 5 packets are in a burst. But in continuous >>> mode, the paket loss rate is less than 10% for the same point to point >>> link. >>> >>> I captured the waveform data. From the observed result, it seems that >>> for each burst (5 packet), the bpsk receiver needs to re-do the >>> frequency/time sync. This will directly causes that the first packet of >>> each burst will definitely be crashed. Also, some burst can not be >>> demodulated correctly at all. For the same reason, even in the continuous >>> mode, the very first packet is also crashed at the receiver. >>> >>> I have tried to add very long preamble for each packet to ensure the >>> data part of the packet can be received in well sync status. But the result >>> is not very good. >>> >>> Before I get further investigation on the solutions, just wondering if >>> any ideas or existing work within this community. >>> >>> -- >>> >>> Alex, >>> *Dreams can come true – just believe.* >>> >>> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> > > > -- > > Alex, > *Dreams can come true – just believe.* >
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