A solution of the stationary, mod-2π-reduced phaseerror probability density function for the second-order phase-lock loop is derived, based on a mean square fit to a certain unknown conditional expectation term. The resulting phase variance obtained from this density function yields an error that is negligible for

and an error no greater than 0.06 rad
2for signal-to-noise ratios (SNRs)≥ 2 dB by comparison with actual measurements, and it appears to be the most accurate to date. The usefulness of the result lies in the fact that an accurate estimate of the phase-error variance for arbitrary parameter values is easily obtained without the use of a computer.