Abstract: An electrical circuit for measuring the phase difference between a pair of nput signals by uniformly limiting selected properties of the waveforms describing the input signals and modulating an output signal in dependence upon the duration of contrariety between the unlimited properties of the input signals whereby error in the output signal due to "jitter" (i.e., abrupt, spurious variations in pulse amplitude or duration caused by superimposition of noise) is substantially eliminated. Various output means produce either a continuous wave analog signal or a digital bit signal in dependence upon the modulation of the output signal. Coupled ancillary circuitry monitors one input signal in comparison with the other input signal and provides an output signal signifying which input signal has a leading phase angle.