I modulate some data over sound in a 17.7Khz and 17.8Khz. It works like an FSK with a pulse duration of 0.015sec. When playing a string the speaker gives a very strange noise that it seems to be the phase 180 degrees change.

Is there any way to reduce this noice ?

  • $\begingroup$ Do you forget the phase when going across the frequency transition? $\endgroup$ – Olli Niemitalo Jun 3 '15 at 8:39
  • $\begingroup$ What do you mean to forget the phase? $\endgroup$ – axcelenator Jun 3 '15 at 8:54
  • $\begingroup$ I mean, if you generate the sinusoid by sin(phase), incrementing the phase by every sample, do you then reset the phase when you switch to a new frequency? $\endgroup$ – Olli Niemitalo Jun 3 '15 at 8:56
  • $\begingroup$ Ohh, thanks, now I understand it. So, you say I have to reset the phase when in the End and Start of a new freq? $\endgroup$ – axcelenator Jun 3 '15 at 8:58
  • $\begingroup$ No.... I just wanted to know how you do it. $\endgroup$ – Olli Niemitalo Jun 3 '15 at 8:59

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