How to obtain frequency & phase values from I & Q Values

[sangoogle]

Hello Everyone,

I would like to know how to obtain frequency & phase measurements from Inphase & Quadrature values(IQ).

Consider IQ has got 1024 samples, I[1024], Q[1024] from the digitizer.

Please let me know the best way.

Thanks in advance....!

 

[FvM]

Your question seems to imply a particular signal waveform, e.g. a sine. If so, a frequency could be estimated. Phase would need a reference.

 

[sangoogle]

Thanks for the reply FvM...Yeah the input is a 2 FSK signal & 1 Khz frequency shift....is given a digitizer, which produces I&Q samples.....

The phase can be measured using TanInverse(Q/I), But I'm not able to find a way to calculate frequency...

 

[FvM]

You have to keep in mind, that the signal represented by the samples may be of any kind, not necessarily a single tone. You can either start with some information about the expected signal frequency and fit a sine waveform by minimizing least square error. You can track the frequency by a PLL. In the general case, without any previous knowledge a FFT will give you a spectral representation of the input signal.