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| From: | Olivier Goyette |
| Subject: | Re: [Discuss-gnuradio] File source problem |
| Date: | Wed, 15 Jun 2016 16:24:54 -0400 |
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 !
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:
What's wrong seriously ? If I can't even modulate properly, how am I suppose to make this work ?When I interleave both ones and zeros '1' & '0' , this is what I get : https://www.dropbox.com/s/a1cfs0tebmywz0l/interleave.png?dl=0When I send only ones '1' this is what I get : https://www.dropbox.com/s/g38hgrtc7s6exyt/ones.png?dl=0This is non sense seriously. This is my flowgraph : https://www.dropbox.com/s/4cfptq5419kvyhz/file_source.png?dl=0When I send only zeros '0', this is what I get : https://www.dropbox.com/s/aipf6wsj5ekwxnb/zeros.png?dl=0
2016-06-14 9:54 GMT-04:00 Olivier Goyette <address@hidden>:
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 ?
Thank you
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