On Tue, Jun 16, 2015 at 12:05 PM, Washbourne, Logan < lwas...@ostatemail.okstate.edu> wrote:
> So would a good solution to this be the packet encoder and packet decoder > blocks? Since they utilize a preamble and access code? I tried to use the > simple framer block in conjunction with the unpacked to packed byte block > but was unsuccessful in getting a matching output, I will continue to play > around with that configuration but for now do you think the packet encoder > route would be a good solution? > > Again, I really appreciate everyone's willingness to help. > > Logan Washbourne > Electrical Engineering Graduate Student > (Electromagnetics) > Yep, those two blocks should handle this issue for you. It's a simplistic approach to the problem, but it should work for just what you are talking about here. Tom > On Tue, Jun 16, 2015 at 10:14 AM, Tom Rondeau <t...@trondeau.com> wrote: > >> On Tue, Jun 16, 2015 at 11:01 AM, Washbourne, Logan < >> lwas...@ostatemail.okstate.edu> wrote: >> >>> Hello, >>> >>> I know a similar question has been asked before on this mailing list but >>> I didn't quite get a solution out of it. I am generating a random byte >>> source, either ones or zeroes, modulating them with DBPSK and immediately >>> demodulating them. The problem I am running into is that I get roughly 8 >>> times the number of bytes out of the demodulation block than I am inputting >>> into the modulation block. I believe its a packed vs. unpacked byte problem >>> but every attempt at packing the output bytes yields an output that doesn't >>> match the input. >>> >>> Attached are the GRC file, and the output file streams. >>> >>> Does anyone have any suggestions? I appreciate all of your time, >>> >>> >>> >>> Logan Washbourne >>> Electrical Engineering Graduate Student >>> (Electromagnetics) >>> >> >> >> The problem is that you don't know which bit to put where in the byte. So >> just packing the output bits into 8 bits per byte doesn't necessarily give >> you the right information. Say you transmit a byte with bits [a b c d e f g >> h]. After the delays introduced by the transmit and receiver filter and the >> channel, when you pack the results, you could get something like [x x x a b >> c d e] [f g h 0 0 0 0 0], for some unknown number of x's. >> >> You need some logic that knows how to discover the start of your >> information and get rid of those x's. The framer blocks do this with some >> assumed formatting and expectations. Johnathan and I have been working on a >> better version of this, but we haven't had a chance to finish it off. >> >> Tom >> >> >
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