Times RINEX data files tag measurements by reception time as given by the receiver clock The error in the receiver time must be determined iteratively For linearized least squares or kalman filter need to establish non-linear model and then estimator determines adjustments to parameters of model (e.g. receiver site coordinates) and initial clock error estimates that "best" match the data 04/01/02 12.540Lec14 Non-linear model Basics of non -linear model Rinex data file time tags give approximate time measurement was made Using this time initially, position of satellite can be computed Range computed from receiver and satellite position Difference between observed pseudorange and computed ranges, gives effects of satellite and receiver clock errors. In oint positioning satellite clock error is assumed known and When removed from difference error in receiver clock determined With new estimate of receiver clock, process can be iterated If receiver position poorly known, then whole system can be iterated with updated receiver coordinates 04/01/02 2.540Lec1404/01/02 12.540 Lec 14 5 Times reception time as given by the receiver clock. The error in the receiver time must be determined iteratively least squares or Kalman filter need to establish non-linear model and then estimator determines adjustments to parameters of model (e.g. receiver site coordinates) and initial clock error estimates that “best” match the data. 04/01/02 12.540 Lec 14 6 Non-linear model • was made. In point positioning, satellite clock error is assumed known and when removed from difference, error in receiver clock determined. iterated with updated receiver coordinates. • RINEX data files, tag measurements by • For linearized Basics of non-linear model: – Rinex data file time tags give approximate time measurement – Using this time initially, position of satellite can be computed – Range computed from receiver and satellite position – Difference between observed pseudorange and computed ranges, gives effects of satellite and receiver clock errors. – With new estimate of receiver clock, process can be iterated. – If receiver position poorly known, then whole system can be