Patent ID: 6456233
Filing Date: 2002-09-24
Classification: G01S,H04B

Abstract:
A method of detecting and correcting cycle slips in the phase measurements of a plurality n of satellite carrier signals (m=1 . . . n) made by a first navigation receiver (B) and a second navigation receiver (R), each of the navigation receivers tracking each satellite carrier signal with a phase lock loop, each phase lock loop capable of locking onto the satellite carrier signal at a plurality of separate points of steady balance which are spaced apart from one another by an respective interval â€˜&agr;mâ€™ of phase, a cycle slip being an unplanned transition from one point of steady balance to another, said method including the steps of:(a) receiving, for a plurality of sequential and discrete moments i of time, a plurality n of phase signals &phgr;i,mB (m=1 . . . n) representative of the phases of the satellite carrier signals as received by the first navigation receiver; (b) receiving, for each discrete time moment i, a plurality n of phase signals &phgr;i,mR(m=1 . . . n) representative of the phases of the satellite carrier signals as received by the second navigation receiver; (c) receiving, for each discrete time moment i, a plurality n of distances Di,mB(m=1 . . . n) between the satellites and the first receiver, a plurality n of distances Di,mR(m=1 . . . n) between the satellites and the second receiver; (d) generating, for each discrete time moment i, a plurality n of single-difference residual signals &Dgr;&phgr;i,m(m=1 . . . n) in the form of: &Dgr;&phgr;i,m=(&phgr;i,mBâˆ’&phgr;i,mR)âˆ’1/&lgr;mÂ·[Di,mBâˆ’Di,mR], where &lgr;m is the wavelength of the corresponding satellite carrier signal;(e) generating, for each discrete time moment i, a first estimate &Dgr;&phgr;i,S of a selected residual signal &Dgr;&phgr;i,S corresponding to a selected satellite carrier signal S (S being in the group of m=1 . . . n) as a function of the residual signals &Dgr;&phgr;i,m(m=1 . . . n); (f) generating, for each discrete time moment i, a first mismatch signal &dgr;&phgr;i,S as a difference between the selected residual signal &Dgr;&phgr;i,S and the estimate &Dgr;&phgr;i,S for it: &dgr;&phgr;i,S=&Dgr;&phgr;i,Sâˆ’&Dgr;&phgr;i,S; and (g) generating, for each discrete time moment i, a first correction signal &phgr;i,SC in relation to the first mismatch signal &dgr;&phgr;i,S according to the form: &phgr;i,SC=&agr;SÂ·round(&dgr;&phgr;i,S/&agr;S), where round(*) is the operation of rounding the quantity &dgr;&phgr;i,S/&agr;S to the nearest integer.