Downlink Tracking Performance of Kalman Filter for the Enhanced Polar System (EPS)

The tracking performance of the Kalman filter (KF) for the downlink extra-fine synchronization sequence that supports high data rate (2.048 Mbps), transmitted by the Enhanced Polar System (EPS) in Molniya orbits, is investigated in the paper. At the receiver, a KF is used to track the range and range rate of the payload to estimate the payload clock and Doppler error. The tracking performance of the KF is characterized by the state error and measurement error. The state error is governed by the payload dynamics. The measurement error is governed by the signal-to-noise ratio (SNR), discrete time measurement, quantization error of the analog-to-digital converter (ADC), and the rate error. The rate error is governed by the oscillator frequency stability of the Rubidium or Cesium sources. Performance trade off between a 2nd and 3rd orders KF is investigated by computer simulation.