On Sun, Jan 3, 2016 at 6:44 AM, Ekko <chai18740449...@gmail.com> wrote:
> hello all > i am using fec mode of gnuradio,and this is my grc > > <snip> > > when i run the grc i got the message-> > > Executing: '/usr/bin/python2 -u /home/cdl/gmsk_fec/gmsk_fec.py' > > Using Volk machine: sse4_2_32 > bits per symbol = 1 > M&M clock recovery omega = 10.000000 > M&M clock recovery gain mu = 0.175000 > M&M clock recovery mu = 0.500000 > M&M clock recovery omega rel. limit = 0.005000 > frequency error = 0.000000 > DEBUG: nout: 32768 nin: 400 ret: 812 > DEBUG: nout: 32768 nin: 400 ret: 812 > DEBUG: nout: 32768 nin: 400 ret: 812 > > > FATAL: Missing a required length tag on port 0 at item #812 > thread[thread-per-block[22]: <block fec_tagged_decoder (8)>]: Missing > length tag. > > this mean in the fec_decoder block ,there is no length tag, > but the tag debug block message is > > Tag Debug: > Input Stream: 00 > Offset: 11100 Source: n/a Key: packet_len Value: 50 > Offset: 11150 Source: n/a Key: packet_len Value: 50 > Offset: 11200 Source: n/a Key: packet_len Value: 50 > Offset: 11250 Source: n/a Key: packet_len Value: 50 > Offset: 11300 Source: n/a Key: packet_len Value: 50 > Offset: 11350 Source: n/a Key: packet_len Value: 50 > Offset: 11400 Source: n/a Key: packet_len Value: 50 > Offset: 11450 Source: n/a Key: packet_len Value: 50, > > i want to know what's the real problem of this grc,and how can i fix this > problem > > thank you > > --Ekko > The tagged stream blocks are very sensitive to the location of the tags. It expects a tag at a specific place and fails if it doesn't find it. My guess is that the problem lies in the use of the clock-recovery block. Those types of blocks where the relative rate is dynamic and can change within the work function have problems with proper tag placement. I just pushed a branch that fixes the problem for both the PFB and M&M based clock recovery blocks: https://github.com/trondeau/gnuradio/tree/tags_and_rate_changing_blocks Tom
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