calculating phase using ARCTAN(Q/I)

[sweethomela8]

I'm trying to calculate the phase of a signal by digitizing the inphase and quadrature parts and then doing an digital ARCTAN(Q/I) function on it. My question is, what happens when the inphase component=0? and is there anything you can do about it.

Thanks.

 

[FvM]

Standard C has a function atan2() fot this purpose.

 

[zorx]

You can always do the check (I wrote it in pseudocode):

if (I = 0)
then angle = 90
else angle = arctan(Q/I)

 

[FvM]

I !=0 doesn't actually guarantee that Q/I is a valid float value. That's one reason why atan2() is provided by most C compiler math libraries.