Patent ID: 6651031
Filing Date: 2003-11-18
Classification: G01S,G04G

Abstract:
A method of providing an estimate of a current state of a clock assembly of at least two clocks including a first clock and a second clock, each clock having a clock phase and a clock fractional frequency, the method comprising:a) a step (51), responsive to a schedule of operations indicating a first time period in a cycle of operation when the first clock is operative and a second time period when the second clock is operative, of providing a clock measurement (z) indicating information about the clock assembly, and b) a step (52), responsive to the clock measurement (z) and also responsive to the schedule of operations, for providing the a estimate of a current state (xâ€²) of the clock assembly using a state filter adapted to use a clock model for the clock assembly, the clock model indicating a state (xâ€²) of the clock assembly via a state update process that includes a measure of process noise ({overscore (w)}(k+1,k)) and that propagates the state of the first clock to the end of the first time period in accordance with the schedule of operations using a state update process for the first clock, uses the state so obtained as the starting state for the second clock at the start of a second time period, and propagates the starting state for the second clock to the end of the second period using a state update process for the second clock, and also for providing a corresponding measure of process noise covariance (Qâ€²).