# Varying the bandwidth of a signal in GRC

**URL:** <https://www.ruby-forum.com/t/varying-the-bandwidth-of-a-signal-in-grc/233341>\
**Category:** GNU Radio\
**Created:** [December 5, 2014, 2:10pm UTC](https://www.ruby-forum.com/t/varying-the-bandwidth-of-a-signal-in-grc/233341 "2014-12-05T14:10:05Z")\
**Posts on this page:** 5\
**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:** [December 5, 2014, 2:10pm UTC](https://www.ruby-forum.com/t/varying-the-bandwidth-of-a-signal-in-grc/233341/1 "2014-12-05T14:10:05Z")

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Hi ,  
Can anyone kindly tell that how i can vary the bandwidth of my  
transmitted signal in GRC??I am using B210 which has a instantaneous  
bandwidth of 56MHz…

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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:** [December 5, 2014, 2:14pm UTC](https://www.ruby-forum.com/t/varying-the-bandwidth-of-a-signal-in-grc/233341/2 "2014-12-05T14:14:59Z")

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Hi Ali,

the Nyquist bandwidth of a complex signal is equal to its sample rate.  
You can set the sample rate of your usrp\_sink during flowgraph  
construction in the properties dialog,  
using stream tags, using asynchronous messages or simple method calls:  
[http://gnuradio.org/doc/doxygen/page\_uhd.html](http://gnuradio.org/doc/doxygen/page_uhd.html)

Greetings,  
Marcus

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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:** [December 6, 2014, 8:07am UTC](https://www.ruby-forum.com/t/varying-the-bandwidth-of-a-signal-in-grc/233341/3 "2014-12-06T08:07:33Z")

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Thnx Marcus…u mean that if i change the sample rate of USRP sink  
block in the properties dialog box then the bandwidth will be equal to  
the changed sample rate??

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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:** [December 6, 2014, 11:09am UTC](https://www.ruby-forum.com/t/varying-the-bandwidth-of-a-signal-in-grc/233341/4 "2014-12-06T11:09:36Z")

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Hi Jason,

Please go through this,

[http://gnuradio.org/redmine/projects/gnuradio/wiki/TutorialsCoreConcepts#Sampling-rates](http://gnuradio.org/redmine/projects/gnuradio/wiki/TutorialsCoreConcepts#Sampling-rates)

Try

1. Varying USRP sample rate and observe the output using FFT sink
2. In the flowgraph use an interpolator (rational resampler) just before  
your USRP sink, vary the interpolation factor and check the output.

Things will be more clear then.

Thanks  
Sreeraj

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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:** [December 6, 2014, 11:22am UTC](https://www.ruby-forum.com/t/varying-the-bandwidth-of-a-signal-in-grc/233341/5 "2014-12-06T11:22:28Z")

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yes.