---------- Forwarded message ---------- From: Songsong Gee <gee.songs...@gmail.com> Date: 2011/4/1 Subject: Re: [Discuss-gnuradio] DPSK mod/demod block work well? To: Tom Rondeau <trondeau1...@gmail.com>
I have an additional problem Here is a flow graph: https://picasaweb.google.com/lh/photo/vwkkNZP_WFKGJQSP48MoOQ?feat=directlink It did not change much. And here are scope plots https://picasaweb.google.com/lh/photo/Zx49Z_3au8uj9H7xxUmJHQ?feat=directlink Everything is fine, but at the beginning, There are ""3"" points which are not in the source. Does DPSK demod block add some extra information? Currently, I solved this problem just adding Skip 3 Head block. However, if I change DPSK to DQPSK? or D8PSK? I think that this value ""3"" might be also changed. This extra 3 bits are inevitable? 2011/3/31 Songsong Gee <gee.songs...@gmail.com> > Thank you for your answer > > It was a simple problem! > But I couldn't think of that :) > > Thanks > > > 2011/3/31 Tom Rondeau <trondeau1...@gmail.com> > >> On Thu, Mar 31, 2011 at 9:07 AM, Songsong Gee <gee.songs...@gmail.com>wrote: >> >>> I just made very simple dpsk mod/demod testing flow graph >>> >>> you can see flow graph in following link: >>> https://picasaweb.google.com/lh/photo/76z3sTbLs9Srz1N-wJhNzw?feat=directlink >>> >>> When I run it, I found strange outcome from it: >>> https://picasaweb.google.com/lh/photo/U0_S_71HzkL9t9RbeEBP2Q?feat=directlink >>> >>> I didn't change any parameters in mod/demod blocks. >>> >>> How can I get a good signal after mod/demodulation? >>> >> >> Well, the secret is that you really are getting good signals out of the >> demodulator, it's just not in the form that you think it should be. >> >> The modulator takes in packed bits; that is, characters between 0 and 255. >> You are only giving it 0's and 1's. The output of the demodulator is >> providing you with unpacked bits, so each character represents a single bit. >> You will want to put an unpacked_to_packed block after the demod to put them >> in the same format as your input. >> >> The reason why you are getting the zeros at the output is because a '1' in >> the input is really a '00000001' and a '0' is really '00000000', which is >> what you see in your sink. >> >> Tom >> >> > -- Seokseong Jeon (aka Songsong Gee) -- Seokseong Jeon (aka Songsong Gee)
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