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## Re: [Discuss-gnuradio] question in source code of gr_sig_source_f

**From**: |
Eric Blossom |

**Subject**: |
Re: [Discuss-gnuradio] question in source code of gr_sig_source_f |

**Date**: |
Thu, 6 Aug 2009 13:41:33 -0700 |

**User-agent**: |
Mutt/1.5.18 (2008-05-17) |

On Thu, Aug 06, 2009 at 12:39:15PM -0700, Milo Wong wrote:
>* Hi,*
>* *
>* I was browsing the GNU radio C++ API. Here I have a couple of questions*
>* about the class reference of gr_sig_source_f. (Signal generator)*
>* *
>* 1) For the type of public member function waveform(), i.e. gr_waveform_t*
>* waveform () const. Where can I refer to the definition of "gr_waveform_t"?*
Hi Milo,
You can find it in gnuradio-core/src/lib/gengen/gr_sig_source_waveform.h
(Given that there were only 3 includes in gr_sig_source_f, it didn't
take long to find it... grep would have worked too)
http://gnuradio.org/doc/doxygen/gr__sig__source__f_8h-source.html
http://gnuradio.org/doc/doxygen/gr__sig__source__waveform_8h.html
>* Is there any description of how waveforms(sine wave) are generated?*
Use the source Luke!
gnuradio-core/src/lib/gengen/gr_sig_source_f.cc
>* 2) I am going to generate a set of sine waves at different frequencies. If*
>* these sine waves are obtained from the iteration equations of harmonious*
>* oscillators: v(t+dt)=v(t) - omega^2 * x(t)dt ; x(t+dt)=x(t) + v(t)dt, is*
>* that different from the way of sine wave generation in gnu radio. Do I need*
>* to create a new sine wave generation block instead of the defaut one? (x(t)*
>* - displacement, v(t) - velocity)*
>* *
>* Thank you,*
>* Milo*
No, there's no reason to reimplement the sine generator unless
you enjoy that kind of thing. First thing to remember is that the
block does what it says: it generates a sine wave of the specified
frequency and amplitude.
We also have blocks to generate sinusoids with frequency a function
of its input stream. See e.g, gr_frequency_modulator_fc or gr_vco_f
Eric