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US 2001/0055330 A1Published application
Method and apparatus for code phase tracking
AssigneeKoninklijke Philips Electronics N.V.
InventorChristopher J. Goodings
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AssigneeKoninklijke Philips Electronics N.V.
InventorChristopher J. Goodings
Estimating the term…
A method of code phase tracking for CDMA type communication is disclosed together with apparatus including a GPS receiver (10 to 15) for the same. The method uses a modified early-minus-late correlation function to determine the code phase error between a target pseudorandom noise code of an incoming signal and locally generated replica codes. The early-minus-late correlation function is modified compared to the true function whereby the gradient of the modified function at zero code phase error is increased. This may be achieved my modifying the early-minus-late correlation function after its derivation. Alternatively, it may be modified by modifying variables from which it is derived and in particular, by modifying the either or both of the power spectrums of the subject signal or the early and late replica code signals whereby at least one odd harmonic is reduced in size or removed; at least one even harmonic is increased in size: or the bandwidth is truncating between harmonics so as to excise an adjacent even harmonic.
A method of code phase tracking comprising the steps of:
A method of code phase tracking substantially as hereinbefore described with reference to the figures.
A receiver comprising an antenna for receiving a subject signal containing a target pseudorandom noise code;
A receiver comprising a signal processor for modifying the power spectrum of a received subject signal containing a target pseudorandom noise code so that the power spectrum of the subject signal has either at least one odd harmonic which is reduced in size or removed;
A receiver comprising an antenna for receiving a subject signal containing a target pseudorandom noise code and a signal processor, the signal processor comprising a generator for generating a series of signals containing early and late replica codes corresponding to the target code, a correlator for correlating the subject signal with the early and late replica code signals and returning respective early and late correlation values, and means for determining the code phase error between the target code and the replica codes from a modified early-minus-late correlation function derived from the early and late correlation values, such that the gradient of the modified early-minus-late correlation function at zero code phase error is increased compared to the true early-minus-late correlation function.
A receiver substantially as hereinbefore described with reference to the figures.
Dependencies are inferred from the claim text.