how to find the phase of an RF signal

[neezaket]

Hello,
I have an RF signal whose frequency I do not know and I need to find its phase and frequency characteristics.
I have tried iq demodulation.
1- x = input signal
2- take fft of x and find the frequency where the power is maximumand use that value as demodulation frequency.
3-perform iq demodulation. (mix with demod frequency and low pass filtering)
4- find the phase and frequency.

Unfortunately, i can not find the exact frequency of the signal thus there occurs an error in demodulation frequency. This error prevents to find the phase characteristics correctly. For example in order to see the phase constant, phase seems to change linearly.

i hope my explanation is enough. I really need some ideas. maybe i am in a wrong wat for determining the phase characteristicf of an RF signal. Any help is appreciated.

 

[FvM]

I agree that it's necessary to know the basic signal characteristic.

The phase measurement point sounds unclear. If the phase is constant (which would be the case e.g. for a unmodulated carrier or an AM signal), measuring phase is meaningless. For signals with non-constant phase, e.g. phase shift keyed, FM, SSB or DSB with supressed carier, the refernce phase would be usually recovered from the signal itself by a PLL.