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.* > >
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