Method and apparatus for code phase correlation
AssigneeU.S. Philips Corporation
InventorsIan A. Marsden, Andrew T. Yule
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Abstract
A method of code phase correlation and apparatus (10 to 15) implementing the same is disclosed, the method comprising the steps of (a) receiving a subject signal comprising a target pseudorandom noise code; (b) generating early and late replica code signals corresponding to the target code; (c) correlating the subject signal with the early and late replica code signals and returning respective early and late correlation values; and (d) calculating a code phase discriminator for determining whether the target code has been acquired as a function of the sum of the early and late correlation values.
Claims12
A method of code phase correlation comprising the steps of:
- (a) receiving a subject signal containing a target pseudorandom noise code;
- b) generating early and late replica code signals corresponding to the target code;
- (c) correlating the subject signal with the early and late replica code signals and returning respective early and late correlation values;
- and
- (d) calculating a code phase discriminator for determining whether the target code has been acquired as a function of the sum of the early and late correlation values.
A method according to any preceding claim further comprising the steps of:
- (e) applying a threshold test to the code phase discriminator to determine whether the target code has been acquired;
- and
- (f) in the event that the target code has not been acquired, cyclically phase shifting the target code relative to the replica codes and recalculating the code phase discriminator until the target code is acquired.
Apparatus comprising signal processing means (11 to 15) adapted to implement a method of code phase correlation according to any preceding claim.
A GPS receiver comprising receiver means for receiving a subject signal containing a target pseudorandom noise code;
- and processing means for generating early and late replica code signals corresponding to the target code, correlating the subject signal with the early and late replica code signals and returning respective early and late correlation values, and calculating a code phase discriminator for determining whether the target code has been acquired as a function of the sum of the early and late correlation values.
A GPS receiver as hereinbefore described with reference to the accompanying drawings.
Dependencies are inferred from the claim text.