# Dc offset is different from unit to unit

**URL:** <https://www.ruby-forum.com/t/dc-offset-is-different-from-unit-to-unit/220218>\
**Category:** GNU Radio\
**Created:** [June 2, 2012, 5:58am UTC](https://www.ruby-forum.com/t/dc-offset-is-different-from-unit-to-unit/220218 "2012-06-02T05:58:18Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Gurdipe\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/b77776/32.png) [@Gurdipe\_D](https://www.ruby-forum.com/u/Gurdipe_D)\
**Post date:** [June 2, 2012, 5:58am UTC](https://www.ruby-forum.com/t/dc-offset-is-different-from-unit-to-unit/220218/1 "2012-06-02T05:58:18Z")

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Hi list,  
I need to compensate usrp dc offset. but the dc offset is different  
from unit to unit. so do I need to calibrate each unit dc offset or  
there is a universal value that work  
for each unit?

Regards

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**Author:** ![James\_Jordan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/f07891/32.png) [@James\_Jordan](https://www.ruby-forum.com/u/James_Jordan)\
**Post date:** [June 2, 2012, 8:19am UTC](https://www.ruby-forum.com/t/dc-offset-is-different-from-unit-to-unit/220218/2 "2012-06-02T08:19:42Z")

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James,

In the case of DC calibration for tx, we’d recommend running the dc  
calibration routines provided with UHD for each unit. The cal routines  
make it a relatively easy process.

In theory, if the average DC offset is non-zero you may be able to apply  
an average correction and see some improvement - but less than a  
per-unit calibration. I don’t have have any data on hand for an average  
DC offset.

I’m cross-posting to the usrp-users list, which is more oriented to USRP  
specific questions.

Best Regards  
John M.

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<div class="post-metadata">

**Author:** ![James\_Jordan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/f07891/32.png) [@James\_Jordan](https://www.ruby-forum.com/u/James_Jordan)\
**Post date:** [June 3, 2012, 4:48am UTC](https://www.ruby-forum.com/t/dc-offset-is-different-from-unit-to-unit/220218/3 "2012-06-03T04:48:13Z")

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Hi John,  
Thanks. But how to deal with rx dc offset?