Patent ID: 6785321
Filing Date: 2004-08-31
Classification: H04B,H04W

Abstract:
A threshold tracking loop for detecting the time of arrival of a wireless communication signal comprising:a pseudo-noise (PN) generator for generating a receive PN code for use in spread spectrum decoding; a series of time delay units for adjusting a phase offset of the PN code; a first PN despreader coupled to the time delay units and the PN generator, the first PN despreader for dispreading an early pilot signal; a second despreader coupled to the time delay units and the PN generator, the second PN despreader for dispreading a late pilot signal; a first comparison circuit coupled to the first PN despreader for comparing a signal value of the early pilot signal with a preselected threshold value that is less than a peak value of a tracked signal and, in threshold tracking mode, for advancing the PN code phase offset if the early signal value is greater than the threshold value; a second comparison circuit coupled to the second PN despreader for comparing a signal value of the late pilot signal with the preselected threshold value and, in threshold tracking mode, for retarding the PN code phase offset if the late signal value is less than the threshold value; and mode control circuitry coupled to the first comparison circuit and the second comparison circuit to switch the loop operation between threshold tracking mode and peak tracking mode.