Non PLL based Phase measurement Technique

[curious_mind]

I have two signals, Vsinwt and Vsin(wt+theta). I need to find the value of theta with the accuracy of 0.05 degrees. Can anybody suggest method for phase difference determination without the use of PLL. I found several methods such as hilbert, kalman filter etc but not sure whether they would meet my accuracy requirement

 

[KlausST]

Hi,

* Some kind of lock in amplifier
* DFT
* Comparators, XOR, LPF

Klaus

 

[FvM]

You are posting in digital signal processing forum, do I expect correctly that you are asking about digitized input signals. If not, please clarify.

In any case, the phase noise spectrum of input signals determines the maximal bandwidth of phase measurement and required filtering in the phase detector. If you don't want a PLL, you can bandpass filter the signals before sending it to the detector.

 

[danadakk]

https://iopscience.iop.org/article/10.1088/1742-6596/224/1/012159/pdf

Whats the freq range you are trying to measure phase of ?


Regards, Dana.

 

[psoc77]

I have two signals, Vsinwt and Vsin(wt+theta). I need to find the value of theta with the accuracy of 0.05 degrees. Can anybody suggest method for phase difference determination without the use of PLL. I found several methods such as hilbert, kalman filter etc but not sure whether they would meet my accuracy requirement

Apparently, you have found few methods of calculating the phase offset. Theoretically, they all should give same accuracy limited only by acquisition S/N, and number of samples and effective bandwidth.

 

[D.A.(Tony)Stewart]

That is simply a resolution of 1/0.05 deg * 360 >= 7200 x signal frequency for a time interval counter that is harmonically related. Injection locked loop)

If optical , it could be an interferometer.

Perhaps the easiest is an XOR gate with very stable peak voltage such that the duty cycle average filtered DC voltage can be measured with 80 dB SNR which requires as many samples as the inverted resolution ratio.