Apparatus and method for code tracking in an IS-95 spread spectrum communications system

A method for code tracking in a spread spectrum communications system, comprising:

• receiving a spread spectrum signal;
• generating an early component and a late component of a pseudo-noise signal in response to an error signal;
• subtracting the late component from the early component to form a difference signal;
• multiplying the difference signal with the received signal to form a product signal that is based on the difference signal and the received signal only;
• and
• integrating the product signal to form the error signal based on the product signal only.

An apparatus for code tracking in a spread spectrum communications system, comprising:

• means for receiving a spread spectrum signal;
• means for generating an early component and a late component of a pseudo-noise signal in response to an error signal;
• means for subtracting the late component from the early component to form a difference signal;
• means for multiplying the difference signal with the received signal to form a product signal that is based on the difference signal and the received signal only;
• and
• means for integrating the product signal to form the error signal based on the product signal only.

A computer-useable medium embodying computer program code for causing a computer to perform code tracking in a spread spectrum communications system by:

• receiving a spread spectrum signal;
• generating an early component and a late component of a pseudo-noise signal in response to an error signal;
• subtracting the late component from the early component to form a difference signal;
• multiplying the difference signal with the received signal to form a product signal that is based on the difference signal and the received signal only;
• and
• integrating the product signal to form the error signal based on the product signal only.

A spread-spectrum communications system comprising:

• a receiver that is configured to provide a received signal corresponding to a transmitted signal having a transmit phase,
• a differential device that is configured to provide a difference signal based on an early pseudo-noise signal and a late pseudo-noise signal,
• a correlation device that is configured to provide an error-signal based on a correlation between the received signal and the difference signal only,
• a pseudo-noise generator that is configured to provide the early and late pseudo-noise signals based on the error-signal so as to provide a receiver pseudo-noise signal that is in phase with the transmit phase.