# How can we adjust the ADC rate in usrp2 in ofdm benchmark example?

**URL:** <https://www.ruby-forum.com/t/how-can-we-adjust-the-adc-rate-in-usrp2-in-ofdm-benchmark-example/229943>\
**Category:** GNU Radio\
**Created:** [May 23, 2014, 10:36am UTC](https://www.ruby-forum.com/t/how-can-we-adjust-the-adc-rate-in-usrp2-in-ofdm-benchmark-example/229943 "2014-05-23T10:36:58Z")\
**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, 10:36am UTC](https://www.ruby-forum.com/t/how-can-we-adjust-the-adc-rate-in-usrp2-in-ofdm-benchmark-example/229943/1 "2014-05-23T10:36:58Z")

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Hi guy,

Thanks in advance. I am a new comer to gnuradio. Now I am handling the  
project based on ofdm benchmark. I want to down-sample ADC to  
2M/s(default  
is 100M/s) to capture the low frequency signal, 1Mhz in our case. I  
guess  
the USRP capture all the signal using the maximal ADC rate by default.  
Does  
anyone know how to do that? Any help will be greatly appreciated.

Best,  
Kay

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**Author:** ![Yingjie\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/f14d63/32.png) [@Yingjie\_C](https://www.ruby-forum.com/u/Yingjie_C)\
**Post date:** [May 23, 2014, 10:45am UTC](https://www.ruby-forum.com/t/how-can-we-adjust-the-adc-rate-in-usrp2-in-ofdm-benchmark-example/229943/2 "2014-05-23T10:45:37Z")

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On 05/23/2014 10:35 AM, Yingjie C. wrote:

> Hi guy,
> 
> Thanks in advance. I am a new comer to gnuradio. Now I am handling the  
> project based on ofdm benchmark. I want to down-sample ADC to  
> 2M/s(default is 100M/s) to capture the low frequency signal, 1Mhz in our  
> case. I guess the USRP capture all the signal using the maximal ADC rate  
> by default. Does anyone know how to do that? Any help will be greatly  
> appreciated.

If you specify a sampling rate of 1 MHz, the USRP will downsample for  
you. No reason to worry about the 100Msps.

Which device are you using?

M