MODELING AND ANALYSIS FOR THE GPS PSEUDO-RANGE OBSERVABLE

In this paper, a digital system for the Global Positioning System (GPS) pseudo range observable is modeled and analyzed theoretically. The observable is measured in a GPS receiver by accurately tracking the pseudorandom noise (PRN) code phase of the input GPS signal using a digital energy detector and a digital delay lock loop (DDLL). The following issues are presented: 1) mathematical modeling of the digital PRN code acquisition and tracking system, 2) the closed-form expression derivation for the detection and false-alarm probabilities of the acquisition process and for the variance of code phase tracking error, and 3) the linear and nonlinear performance analysis of the DDLL for optimizing the receiver structures and parameters with tradeoff between the tracking errors due to receiver dynamics and due to input noise.