# How To Change Tx Frequency During Transmission

**URL:** <https://www.ruby-forum.com/t/how-to-change-tx-frequency-during-transmission/233314>\
**Category:** GNU Radio\
**Created:** [December 3, 2014, 4:22pm UTC](https://www.ruby-forum.com/t/how-to-change-tx-frequency-during-transmission/233314 "2014-12-03T16:22:42Z")\
**Posts on this page:** 4\
**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 3, 2014, 4:22pm UTC](https://www.ruby-forum.com/t/how-to-change-tx-frequency-during-transmission/233314/1 "2014-12-03T16:22:42Z")

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Hello everyone,

Does anyone know how to change Tx frequency during transmission. I mean  
the  
transmitter operates at f0 GHz in some interval of time and then change  
to  
operate at f1 GHz.

Sincerely,  
Van-Ly

Van-Ly Nguyen,  
Research Assistant,  
Signals and Systems Laboratory - SSL  
Faculty of Electronics and Telecommunications - FET  
University of Engineering and Technology - UET  
Vietnam National University, Hanoi - VNU

Tel: (+84) 97 881 9406

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**Author:** ![NguySSSn\_VSSn\_LS\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@NguySSSn\_VSSn\_LS\_S](https://www.ruby-forum.com/u/NguySSSn_VSSn_LS_S)\
**Post date:** [December 3, 2014, 4:30pm UTC](https://www.ruby-forum.com/t/how-to-change-tx-frequency-during-transmission/233314/2 "2014-12-03T16:30:03Z")

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Hello Van-Ly,

what hardware are you using?  
If you’re using any USRP, then the gr-uhd [1] blocks [2] will allow you  
to tune using stream tags, asynchronous messages and method calls.  
From your problem description, it sounds like using stream tags is your  
best choice. If you want to know more about how to use these, I  
recommend going through the new guided tutorials [3], especially part 5  
(which kind of relies on you having read the first four parts, but since  
I think you’re already somewhat friends with GNU Radio, this might not  
be too much work).

Greetings,  
Marcus

[1] [GNU Radio Manual and C++ API Reference: UHD Interface](http://gnuradio.org/doc/doxygen/page_uhd.html)  
[2] sink:  
[GNU Radio Manual and C++ API Reference: gr::uhd::usrp\_sink Class Reference](http://gnuradio.org/doc/doxygen/classgr_1_1uhd_1_1usrp__sink.html)  
[3] [http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided\_Tutorials](http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials)

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<div class="post-metadata">

**Author:** ![NguySSSn\_VSSn\_LS\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@NguySSSn\_VSSn\_LS\_S](https://www.ruby-forum.com/u/NguySSSn_VSSn_LS_S)\
**Post date:** [December 23, 2014, 3:37pm UTC](https://www.ruby-forum.com/t/how-to-change-tx-frequency-during-transmission/233314/3 "2014-12-23T15:37:44Z")

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Hi Marcus,

I use bladeRF hardware, not USRP. So I have “osmocom” sink and source  
blocks in my flow graph. Do you have any idea about this.  
Thank you very much,

Best Regards,  
Van-Ly

Van-Ly Nguyen,  
Research Assistant,  
Signals and Systems Laboratory - SSL  
Faculty of Electronics and Telecommunications - FET  
University of Engineering and Technology - UET  
Vietnam National University, Hanoi - VNU

Tel: (+84) 97 881 9406

On Wed, Dec 3, 2014 at 10:28 PM, Marcus Müller  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)

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<div class="post-metadata">

**Author:** ![NguySSSn\_VSSn\_LS\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@NguySSSn\_VSSn\_LS\_S](https://www.ruby-forum.com/u/NguySSSn_VSSn_LS_S)\
**Post date:** [December 24, 2014, 10:19pm UTC](https://www.ruby-forum.com/t/how-to-change-tx-frequency-during-transmission/233314/4 "2014-12-24T22:19:05Z")

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Hi Ly, you might consider as an alternative solution shifting the  
frequency by multiplying with a sine wave if your application can sample  
at high rate.