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I have seen that to get the phase angle of a signal, we have to use PLLs. this PLL is modeling in order to get the phase angle about one frequency, which is the free running frequency of the VCO.

If I search a phase angle but I don't know what is the frequency of my signal, and I know that the free running frequency of a signal is far from the signal frequency, how can I do?

Thank's

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  • $\begingroup$ What you mean by far? Higher? sample your signal in a rate that is at least twice the expected frequency and calculate the FFT. Assuming you have low noise, estimate accurately the high frequency - you need iterations that will get you the desired accuracy of the frequency. By sampling now at twice or more, in such a way to get your desired frequency in a bin center, the ratio of the real and imaginary components will provide you with tan(angle). You need to describe some your system and requirements, such as values, rates, purpose... than you will get effective responses... may be $\endgroup$ – Moti Aug 21 '15 at 21:43
  • $\begingroup$ I want to apply PLL to a signal in order to get the phase information of that signal. The problem I encountered is the following: How the PLL can get the frequency? $\endgroup$ – Ahmed Abrous Aug 24 '15 at 19:05
  • $\begingroup$ Get what frequency? $\endgroup$ – Moti Aug 25 '15 at 4:25
  • $\begingroup$ The frequency of the signal in question $\endgroup$ – Ahmed Abrous Aug 26 '15 at 17:36
  • $\begingroup$ I want to do it with a PLL? $\endgroup$ – Moti Aug 26 '15 at 20:59

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