# FSK - implementation

**URL:** <https://www.ruby-forum.com/t/fsk-implementation/242931>\
**Category:** GNU Radio\
**Created:** [August 8, 2015, 11:59am UTC](https://www.ruby-forum.com/t/fsk-implementation/242931 "2015-08-08T11:59:26Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\
**Post date:** [August 8, 2015, 11:59am UTC](https://www.ruby-forum.com/t/fsk-implementation/242931/1 "2015-08-08T11:59:26Z")

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I have a question about BFSK/M-FSK modulations in GnuRadio.

If I have a symbol 1 or 0 and it has got 64 samples (2 periods of  
sin/cos) and I want to modulate it with 2 different frequencies for  
example: f1 = 175 KHz = 5,7 us f2 = 225 KHz = 4,4 us

Problem is that 0 or 1 binary are same width - 64 samples but width for  
cos/sin periods are diferent and longer period will be cut for shorter  
symbol.

Do I need to generate two diferent symbols width for 0 or 1 ? what with  
bigger M-FSK ?

thank you in advice 🙂

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**Author:** ![przemek\_l](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/ce73a5/32.png) [@przemek\_l](https://www.ruby-forum.com/u/przemek_l)\
**Post date:** [August 8, 2015, 2:15pm UTC](https://www.ruby-forum.com/t/fsk-implementation/242931/2 "2015-08-08T14:15:01Z")

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Hi Przemek,

so, first a hint: it’s easier (really, it is!) to use this mailing list  
directly via email, and not with the ruby-forum interface. We don’t  
really like ruby-forum, because it tends to mix up the order of replies  
and makes communication unnecessarily complicated. Sign up at:

> **[Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio)**

Then, I’ve already replied to you on stackOverflow [1]. I really don’t  
mind if you discuss this here, but maybe you’d want to address why my  
answer doesn’t actually answer your questions, so that you get the  
information you need faster.

Best regards,  
Marcus

[1]  
[http://stackoverflow.com/questions/31886310/gnu-radio-bfsk/31892042#31892042](http://stackoverflow.com/questions/31886310/gnu-radio-bfsk/31892042#31892042)  
Marcus M. wrote:

> You’re right, however, this is just barely a GNU Radio question. Maybe  
> you’re better of on the ham radio stack exchange, or the DSP stack  
> exchange site.