" I take the quotient, calculate the angle using the atan function ..."
This is mathematically correct, but programming-wise there's a function atan2 that does both at once, and also doesn't return infinity or give a divide-by-zero error if the denominator is zero. atan2 also does something else, it returns the angle in the correct quadrant for the signs of x and y. I don't know offhand if this is your problem, but it can only help. Here's more info: https://en.wikipedia.org/wiki/Atan2 https://www.johndcook.com/blog/2019/11/18/inverse-trig-functions/ On Wed, Mar 17, 2021 at 1:07 PM Detlef Schuecker via time-nuts <[email protected]> wrote: > > Hi time-nuts, > > a PLL takes the phase difference of the incoming signal and the > synthesized signal and feeds that in a loop filter. The output of the loop > filter is used to steer the local oscillator. > > In my setup I have an incoming complex signal and my local oscillator is > generating a complex signal as well. So calculation of the phase > difference is just the quotient of the incoming signal and the local > oscillator, it is a sampled system. I take the quotient, calculate the > angle using the atan function and then I feed it in the loop filter, a PI > controller. The output of the loop filter is converted to a complex phase > increment for the local oscillator with the sin and cos function. > > Now I have to get rid of the atan, cos and sin functions. > > I am looking for a loop filter which takes the quotient of the > incoming/synthesized signal as a complex value. The output of this loop > filter should be the phase increment for the local oscillator. It should > not use the angle of the complex value explicitly, as this will involve > the atan/cos/sin functions. > > Is someone aware of such a loop filter? I surfed through Gardners' > 'Phaselock Techniques' but did not find a hint. > > Thank you > Detlef Schücker > > DD4WV > > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send an > email to [email protected] > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
