Method and apparatus for code phase tracking

• US 20050265494A1
• Filed: 07/08/2005
• Published: 12/01/2005
• Est. Priority Date: 05/13/2000
• Status: Abandoned Application

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Goodings, Christopher J.
• Application Number:
  US11/177,851
• Publication Number:
  US 20050265494A1
• Time in Patent Office: Days
• US Class Current: 375/343
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker

Abstract

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.

Claims

1-10. -10. (canceled)

11. 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;

at least one even harmonic which is increased in size;

or a reduced bandwidth which is truncated between harmonics so as to excise an adjacent even harmonic.

12-20. -20. (canceled)