Temperature and Aging Compensated Kalman Filter Algorithm for High-Precision Timing System of Microsatellites

High-precision system time is crucial for applications in microsatellites, such as satellite-ground and multi-satellite cooperative missions. In practical on-orbit working condition, the frequency of the crystal oscillator in microsatellites varies with its temperature and aging. Traditional solution of timing system using Global Position System Receiver (GPSR) cannot compensate for this frequency offset. Thus, it is necessary to track the varying clock dynamically. In this work, we establish the clock skew model of crystal oscillator, and propose a temperature and aging compensated Kalman filter algorithm (TACK) for high-precision timing system of microsatellites. When the clock source of timing system changes from a constant-temperature crystal oscillator (OCXO) with ±0.01 parts per million (ppm) frequency stability to a temperature compensated crystal oscillator (TCXO) with ±3 parts per million (ppm) frequency stability, experimental and simulation results show that the time accuracy is better than 0.8 ms/d and the calibration time is less than 780s, which is better than the previous method.