# How to change a master clock rate on USRP B210

**URL:** <https://www.ruby-forum.com/t/how-to-change-a-master-clock-rate-on-usrp-b210/229956>\
**Category:** GNU Radio\
**Created:** [May 23, 2014, 6:29pm UTC](https://www.ruby-forum.com/t/how-to-change-a-master-clock-rate-on-usrp-b210/229956 "2014-05-23T18:29:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\
**Post date:** [May 23, 2014, 6:29pm UTC](https://www.ruby-forum.com/t/how-to-change-a-master-clock-rate-on-usrp-b210/229956/1 "2014-05-23T18:29:17Z")

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Hello All Gnu Radio user,  
To use a 2 TX, I want to change a clock rate to an accepted one, under  
30.72 MHz. I use the API with uhd\_usrp\_probe and it works only for this  
command. Can you give me the idea or python code to use this argument  
parameter with a python flowgraph?  
–args=“master\_clock\_rate=28”  
Thanks.

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**Author:** ![raf\_raf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/6bbea6/32.png) [@raf\_raf](https://www.ruby-forum.com/u/raf_raf)\
**Post date:** [May 24, 2014, 9:26am UTC](https://www.ruby-forum.com/t/how-to-change-a-master-clock-rate-on-usrp-b210/229956/2 "2014-05-24T09:26:27Z")

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In the device parameter write ‘set\_master\_clock\_rate=30e6’