Techniques are provided for improved precision timekeeping for a global positioning system (GPS) receiver. A methodology implementing the techniques according to an embodiment includes generating a system clock signal at a reference frequency, the system clock signal having a first frequency stability. The method also includes generating an auxiliary clock signal at an auxiliary clock frequency, the auxiliary clock signal having a second frequency stability that is greater than the first frequency stability, wherein the auxiliary clock frequency differs from the reference frequency by a frequency offset. The method further includes calculating corrections to the auxiliary clock signal based on a measure of error in the frequency offset and on an estimate of error in the auxiliary clock frequency. The method further includes using the calculated corrections to generate a timing signal, during absence of received GPS satellite signals (e.g., during times when less than four satellite signals are received).

Techniques are provided for improved precision timekeeping for a global positioning system (GPS) receiver. A methodology implementing the techniques according to an embodiment includes generating a system clock signal at a reference frequency, the system clock signal having a first frequency stability. The method also includes generating an auxiliary clock signal at an auxiliary clock frequency, the auxiliary clock signal having a second frequency stability that is greater than the first frequency stability, wherein the auxiliary clock frequency differs from the reference frequency by a frequency offset. The method further includes calculating corrections to the auxiliary clock signal based on a measure of error in the frequency offset and on an estimate of error in the auxiliary clock frequency. The method further includes using the calculated corrections to generate a timing signal, during absence of received GPS satellite signals (e.g., during times when less than four satellite signals are received).

A frequency control assist device is configured to: calculate an average value of pulse numbers each of which is a pulse number of a reference signal generated by an oscillator in one cycle of a PPS signal generated based on a GPS signal, from a total of the pulse numbers counted for a time period whose length is a predetermined number times the one cycle, the average value being an average value of the pulse numbers each for the one cycle; and every time a deviation between a specified value of a reference frequency of the reference signal and the average value falls below a target value, reduce the target value from the current value and increase, from the current value, the predetermined number that specifies the time period for obtaining the total of the pulse numbers from which the average value is to be calculated by an averaging circuit.

A frequency control assist device is configured to: calculate an average value of pulse numbers each of which is a pulse number of a reference signal generated by an oscillator in one cycle of a PPS signal generated based on a GPS signal, from a total of the pulse numbers counted for a time period whose length is a predetermined number times the one cycle, the average value being an average value of the pulse numbers each for the one cycle; and every time a deviation between a specified value of a reference frequency of the reference signal and the average value falls below a target value, reduce the target value from the current value and increase, from the current value, the predetermined number that specifies the time period for obtaining the total of the pulse numbers from which the average value is to be calculated by an averaging circuit.