# Transmiting a sequence of known bits using OFDM and file source

**URL:** <https://www.ruby-forum.com/t/transmiting-a-sequence-of-known-bits-using-ofdm-and-file-source/226472>\
**Category:** GNU Radio\
**Created:** [December 7, 2012, 3:35am UTC](https://www.ruby-forum.com/t/transmiting-a-sequence-of-known-bits-using-ofdm-and-file-source/226472 "2012-12-07T03:35:14Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jiajue\_ou](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/47e85d/32.png) [@jiajue\_ou](https://www.ruby-forum.com/u/jiajue_ou)\
**Post date:** [December 7, 2012, 3:35am UTC](https://www.ruby-forum.com/t/transmiting-a-sequence-of-known-bits-using-ofdm-and-file-source/226472/1 "2012-12-07T03:35:14Z")

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Discuss-gnuradio mailing list  
removed\_email\_address@domain.invalid  
[https://lists.gnu.org/mailman/listinfo/discuss-gnuradio](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio)

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**Author:** ![jiajue\_ou](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/47e85d/32.png) [@jiajue\_ou](https://www.ruby-forum.com/u/jiajue_ou)\
**Post date:** [December 10, 2012, 5:06pm UTC](https://www.ruby-forum.com/t/transmiting-a-sequence-of-known-bits-using-ofdm-and-file-source/226472/2 "2012-12-10T17:06:03Z")

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On Thu, Dec 6, 2012 at 9:34 PM, jiajue ou [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> Best,
> 
> Jia

Jia,

Use this as a guide:  
[http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#What-is-the-file-format-of-a-gr\_file\_sink](http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#What-is-the-file-format-of-a-gr_file_sink)

The file sources take the same structure of data and insert them into a  
flowgraph.

Tom

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**Author:** ![jiajue\_ou](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/47e85d/32.png) [@jiajue\_ou](https://www.ruby-forum.com/u/jiajue_ou)\
**Post date:** [December 11, 2012, 1:31pm UTC](https://www.ruby-forum.com/t/transmiting-a-sequence-of-known-bits-using-ofdm-and-file-source/226472/3 "2012-12-11T13:31:56Z")

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Tom R. wrote in post #1088538:

> On Thu, Dec 6, 2012 at 9:34 PM, jiajue ou  
> wrote:
> 
> > Best,
> > 
> > Jia
> 
> Jia,
> 
> Use this as a guide:

[http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#What-is-the-file-format-of-a-gr\_file\_sink](http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#What-is-the-file-format-of-a-gr_file_sink)

> The file sources take the same structure of data and insert them into a  
> flowgraph.
> 
> Tom

Hi Tom,

Thanks for your reply. Does it mean if I put a “0” in the .txt file,  
“00000000” will be inserted to the flowgraph? (Byte I/O type is chosen.)

File Source(Byte, repeat)–\>OFDM Mod–\>OFDM Demod–\>File Sink  
In such a simple transceiver GRC loop test in a single computer, I put  
one zero to the .txt in the File Source and modified  
gnuradio/gr-digital/lib/digital\_ofdm\_frame\_sink.cc to print real and  
imaginary part of “sigrot” (which I suppose is the received data complex  
symbols), the output, however, is not the corresponding symbols for  
repeated (00000000). So, am I wrong?  
If I want to get the received complex symbols for my specific data?  
Which variables should I print out?  
Thanks a lot!

Best,  
Jia