****UPDATE**** Even without any Costa loop or clock recovery, it works. It seems that the trouble was only the TX amplitude.
2016-06-16 9:36 GMT-04:00 Olivier Goyette <olivier.goyett...@gmail.com>: > YEAAAAH ! it works now. > > Only 2 major things to do : > > 1st - I multiplied the TX amplitude by 0.5 with a multiply const block > > 2nd - I used a Costa loop before my demod and it works great. > > My video got a tiny bit of error but I guess that with a special coding > (reed solomon ) I could get it back in good shape. > > Now I gotta to test it but with CPFSK and see if I can get the same result > ! > > Thank you all :) ! > > 2016-06-16 3:36 GMT-04:00 Johannes Demel <de...@ant.uni-bremen.de>: > >> Hi Olivier, >> >> I guess Nick already pointed out the important bits. Also, the warnings >> GRC prints to the shell should help you. >> >> Could you solve your file source issues? Your questions here seem to be >> related to a different issue. >> >> Tx flowgraph: get rid of the throttle block. (also see the warning) >> spectrum: this seems inconsistent. the TX spectrum suggests OFDM at first >> glance. The MDO spectrum looks completely different. You should investigate >> this. >> Most importantly here, the RX spectrum looks a lot like >> clipping/saturation or alike. In any case non-linear effects seem to cause >> trouble here. >> TX time: It is important to keep the TX values < 1.0! Everything else >> will be clipped. Non-linear effects. >> RX time: looks like a frequency offset. You need synchronization first. >> Really tight synchronization, FLL, Costas-Loop etc. You may simulate that >> by multiplying with a signal source with a really low frequency like 10Hz >> (or maybe even 1Hz, play a bit around). >> Rx constellation: you can observe a frequency offset here. >> Rx time 2: my guess: it's the same as the other except for a scaling >> factor. Maybe a different radio channel, maybe because the other hardware >> behaves a bit differently. >> >> Cheers >> Johannes >> >> >> >> On 15.06.2016 22:24, Olivier Goyette wrote: >> >>> I'm giving a copy of the email I just sent to Ettus Research. I think >>> that it's been a hardware problem since the beginning but i'm waiting >>> for their response. >>> >>> Check it out, maybe some of view have already seen this kind of bug >>> >>> >>> *************************E-mail***************************************************** >>> >>> Hi ! >>> >>> My name is Olivier and I’m actually working with your USRP N210 and >>> GNURadio Companion. It’s been a couple of week since I started using >>> your equipment and yet, I already had issues with it. Doing a simple >>> modulation/demodulation seems impossible and everything I came up with >>> until now, suggest me that it’s a hardware problem. So, I took quite a >>> lot of pictures for you to see what’s wrong and I’ll share the links to >>> my dropbox so it will be easier like that. >>> >>> What I’m trying to do is a PSK mod and demod. I know it works because >>> one of my colleague is using a Nutaq Zepto SDR and he’s been using the >>> same flowgraph as mine in an other project and it works perfectly. So, >>> what we did is the following setup : >>> https://www.dropbox.com/s/ottq341sob5z90r/Actual_setup.jpg?dl=0 >>> >>> The upper radio represents the TX link (WBX card) and the one at the >>> bottom represent the RX link (SBX card). >>> >>> This is the flowgraph on the TX radio : >>> https://www.dropbox.com/s/ir5ehp6caiy525a/TX_side.jpg?dl=0 >>> >>> This is the flowgraph on the RX radio : >>> https://www.dropbox.com/s/tl95cwbstwzl4r8/RX_side.jpg?dl=0 >>> >>> What we’re trying to do is to transmit a video stream from one computer >>> to another. Unfortunately, on the RX computer, the file supposedly >>> containing the video is empty (0 bytes when you right click on it and go >>> to the properties panel). >>> >>> This is the TX spectrum : >>> https://www.dropbox.com/s/pzsn8oo74sgrehp/TX_spectrum.jpg?dl=0 and this >>> is the spectrum when you look at it with a spectrum analyser : >>> https://www.dropbox.com/s/5bks7aksih8ctzh/TX_MDO_spectrum.jpg?dl=0 >>> >>> This is the RX spectrum : >>> https://www.dropbox.com/s/dlsovfxovv4n9tm/RX_spectrum.jpg?dl=0 >>> >>> This is the TX time domain graph : >>> https://www.dropbox.com/s/q25sbjukyzsyymz/TX_time_domain.jpg?dl=0 >>> >>> This is the RX time domain graph : >>> https://www.dropbox.com/s/qetgf0cr4s7d5hb/RX_time_domain_1.jpg?dl=0 >>> >>> This is the TX constellation : >>> https://www.dropbox.com/s/gflb0f65oa0m1rl/TX_constellation.jpg?dl=0 >>> >>> This is the RX constellation : >>> https://www.dropbox.com/s/4j0hnhl97v2uj7g/RX_constellation.jpg?dl=0 >>> >>> What seems strange to me is the time domain graph at RX. It’s like if >>> the imaginary part and the real part of the signal were modulated onto >>> whatever signal that appears to be there. I tried my RX link on one of >>> the other radio I have and look at the result : >>> https://www.dropbox.com/s/f1al75vgo5z2wcf/RX_time_domain_2.jpg?dl=0 . >>> The time domain is completely different but still it is a SBX card and I >>> haven’t touch any settings in my flowgraph to keep consistency. >>> >>> So, now I’m asking for your help because my knowledge is pretty basic >>> with this equipment and I’d like to have your input about that. >>> >>> For your information, I did reload the firmware and the bitfile into the >>> FPGA before sending this email so it’s not necessary to ask me to do it. >>> >>> I sincerely hope this will lead somewhere as I’m out of options right >>> now. >>> >>> Thank you for your time and have a nice day ! >>> >>> 2016-06-15 13:58 GMT-04:00 Marcus Müller <marcus.muel...@ettus.com >>> <mailto:marcus.muel...@ettus.com>>: >>> >>> Hi Olivier, >>> >>> what does this mean: >>> >>>> The 1st file contains only '1' and the other only '0'. >>>> >>> How did you generate these files. Without knowing better, I'd say >>> this is a case for our File Format FAQ: >>> >>> >>> http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#What-is-the-file-format-of-a-file_sink-How-can-I-read-files-produced-by-a-file-sink >>> >>> Best regards, >>> Marcus >>> >>> On 06/15/2016 12:25 AM, Olivier Goyette wrote: >>> >>>> This is non sense seriously. This is my flowgraph : >>>> <https://www.dropbox.com/s/4cfptq5419kvyhz/file_source.png?dl=0> >>>> https://www.dropbox.com/s/4cfptq5419kvyhz/file_source.png?dl=0 >>>> >>>> When I send only zeros '0', this is what I get : >>>> <https://www.dropbox.com/s/aipf6wsj5ekwxnb/zeros.png?dl=0> >>>> https://www.dropbox.com/s/aipf6wsj5ekwxnb/zeros.png?dl=0 >>>> >>>> When I send only ones '1' this is what I get : >>>> <https://www.dropbox.com/s/g38hgrtc7s6exyt/ones.png?dl=0> >>>> https://www.dropbox.com/s/g38hgrtc7s6exyt/ones.png?dl=0 >>>> >>>> When I interleave both ones and zeros '1' & '0' , this is what I >>>> get : https://www.dropbox.com/s/a1cfs0tebmywz0l/interleave.png?dl=0 >>>> >>>> What's wrong seriously ? If I can't even modulate properly, how am >>>> I suppose to make this work ? >>>> >>>> 2016-06-14 9:54 GMT-04:00 Olivier Goyette >>>> <olivier.goyett...@gmail.com <mailto:olivier.goyett...@gmail.com>>: >>>> >>>> Hi >>>> >>>> I have a problem. On my first setup, I use 2 file source. The >>>> 1st file contains only '1' and the other only '0'. The 2 file >>>> sources go through a selector and end up in a CPFSK mod block. >>>> When I run this, switching from '1' to '0' makes the frequency >>>> drift from + to - FSK_deviation like it should do normally. >>>> Now, when I use a unique file source containing '1' and '0' >>>> (actually I wrote up the alphabet in a file) and I run this, >>>> this is what I get : >>>> >>>> https://www.dropbox.com/s/4tdswnmp79lj67c/unique_file_source.png?dl=0 >>>> . Any Idea why it's doing this. Is it the rate of transmission >>>> that does this, like if it was to fast ? >>>> >>>> my setup : >>>> https://www.dropbox.com/s/snamjalklskfdzh/single_file.png?dl=0 >>>> >>>> Thank you >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org> >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org> >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >>> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > >
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