# Question about the sampling rate

**URL:** <https://www.ruby-forum.com/t/question-about-the-sampling-rate/217269>\
**Category:** GNU Radio\
**Created:** [February 26, 2012, 6:12pm UTC](https://www.ruby-forum.com/t/question-about-the-sampling-rate/217269 "2012-02-26T18:12:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![luislavena](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/0ea827/32.png) [@luislavena](https://www.ruby-forum.com/u/luislavena)\
**Post date:** [February 26, 2012, 6:12pm UTC](https://www.ruby-forum.com/t/question-about-the-sampling-rate/217269/1 "2012-02-26T18:12:46Z")

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Hi all,  
I am new to gnuradio and i am trying to make simple transmission and  
reception.  
I want to understand the sampling rate of the uhd sink and source and  
how  
to choose it  
and the sampling rate of the blocks in the flow graph.

when running on sine of 100 kHZ and sampling rate of 0.5 MHz and same  
sampling rate for uhd  
I get UUUUUUUUUUUUUUUUUUUUUUUUUU ,it means under sampling,Right?  
How to avoid it ???  
Thanks

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**Author:** ![amabdelsalam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/958977/32.png) [@amabdelsalam](https://www.ruby-forum.com/u/amabdelsalam)\
**Post date:** [February 26, 2012, 7:10pm UTC](https://www.ruby-forum.com/t/question-about-the-sampling-rate/217269/2 "2012-02-26T19:10:11Z")

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On 02/26/2012 12:11 PM, Ahmed A. wrote:

> How to avoid it ???  
> Thanks

Sample rate is really only relevant at the edges, and when calling the  
filter synthesis modules, most interior blocks have no concept of  
sample rate.

‘U’ means under-run the producer (in this case, your program) can’t keep  
up with the consumer–the UHD device.

–  
Marcus L.  
Principal Investigator  
Shirleys Bay Radio Astronomy Consortium

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**Author:** ![amabdelsalam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/958977/32.png) [@amabdelsalam](https://www.ruby-forum.com/u/amabdelsalam)\
**Post date:** [February 27, 2012, 1:00pm UTC](https://www.ruby-forum.com/t/question-about-the-sampling-rate/217269/3 "2012-02-27T13:00:28Z")

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hi all,

the usrp final samling rate coming out from the codec is 128 Msps so i  
think that you should follow this equation : sample rate\* interpolation  
=128 msps you can set the sampling rate =1 msps and the interpolation  
rate =128  
try it and inform me of the result  
yours,  
osama riad