# BPSK Transmitter

**URL:** <https://www.ruby-forum.com/t/bpsk-transmitter/232346>\
**Category:** GNU Radio\
**Created:** [October 3, 2014, 10:13pm UTC](https://www.ruby-forum.com/t/bpsk-transmitter/232346 "2014-10-03T22:13:14Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [October 3, 2014, 10:13pm UTC](https://www.ruby-forum.com/t/bpsk-transmitter/232346/1 "2014-10-03T22:13:14Z")

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Hi ,  
I am trying to implement BPSK transceiver system on a USRP without  
the predefined blocks . I am currently testing my design using a file  
source ( as shown in the attachment) but i am not able to receive the  
same at the output . Can somebody help ?  
Will implement the Costas Loop and other advanced things on the receiver  
later .

Regards  
Abhinav J.

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**Author:** ![Abhinav\_J](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@Abhinav\_J](https://www.ruby-forum.com/u/Abhinav_J)\
**Post date:** [October 4, 2014, 1:11am UTC](https://www.ruby-forum.com/t/bpsk-transmitter/232346/2 "2014-10-04T01:11:42Z")

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Abhinav,

If you’re referring to the difference in file size, it’s 4096 bytes,  
which probably just means there was a little data left in a buffer that  
didn’t get pushed through when the flowgraph was done. A FIR may also  
eat some number of samples (not sure about this).

If you’re referring to the signal itself, there’s no way you’ll get an  
exact copy back after passing the signal through a filter.

- Jeff

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**Author:** ![Abhinav\_J](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4da419/32.png) [@Abhinav\_J](https://www.ruby-forum.com/u/Abhinav_J)\
**Post date:** [October 5, 2014, 5:45am UTC](https://www.ruby-forum.com/t/bpsk-transmitter/232346/3 "2014-10-05T05:45:07Z")

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Abhinav,

This doesn’t matter for a real world problem. You could add zeros to the  
end of your input if you need a certain number of samples out.

Please keep replies on the list.

- Jeff