Described are a method for generating a metric that is a function of a phase difference between a modulated carrier and a local carrier, and a phase detector for performing such a method. A baseband symbol is obtained from the modulated carrier, and the phase of the symbol is determined. Assuming that the modulation used to modulate the modulated carrier has a constellation diagram with M-fold rotational symmetry, the metric can be generated from the phase by evaluating a base function that includes a triangle wave having positively and negatively sloped linear segments whose slopes have identical absolute values and that is periodic with a period of 2π/Μ radians. Alternatively or additionally, if the ideal symbol phases are uniformly distributed, the metric can be generated by evaluating a version of the base function in which the ideal symbol phases correspond to identically valued metrics located on the triangle wave.