Real-time Frequency Estimation of Local Oscillators Using GPS Timing Receivers

In this paper, we show that recently designed the finite impulse response (FIR) filtering algorithm provides realtime estimation of the fractional frequency offset of a local clock with high accuracy via GPS-based measurements of the time interval error (TIE). Such a splendid property of the algorithm is due to small produced noise in the estimates of the TIE. It is also shown that the algorithm applied to sawtooth measurements serves as a nice estimator of the Allan deviation. The latter cannot be estimated via sawtooth-less measurements.