How to Determine Amplitude and Phase of a Time-Varying Sinusoidal Signal?

[umarkhan]

hello,
if I have a sinusoidal signal that has changing amplitude and phase with respect to time, how can I find the amplitude and phase with respect to time?

So given x(t) the probem is to find a(t) and p(t)?

Thanks.

 

[Togli]

There are various ways of estimating instantaneous amplitude and phase. Hilbert transform might be a good choice for that.

 

[n.karthick]

There are many methods available. Short time Fourier transform, Wavelet transform, least squares method, auto regressive methods etc.

 

[Bob S]

Are you comparing this signal to a reference signal with constant amplitude and phase/frequency? Are you looking for a software solution, or a hardware circuit?