James A. Hird

Date of Award

12-1992

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering

Department

Department of Electrical and Computer Engineering

First Advisor

Mark Mehalic, PhD

Second Advisor

Joseph Sachinni, PhD

Abstract

The purpose of this thesis is to investigate two types of tracking loops used in Global Positioning System (GPS) receiver design. The first loop, the Delay Lock Loop (DLL), is a code tracking loop used to synchronize a locally generated pseudo-noise (PN) sequence with the PN sequence in the GPS satellite broadcast. Synchronization of the PN sequences is essential for de-spreading the direct-sequence spread spectrum (DS/SS) broadcast and demodulating the transmitted data. The second loop, the Modified Tanlock Loop (MTLL), is a carrier tracking loop used to synchronize the phase of a voltage controlled oscillator (VCO) with the carrier of the GPS satellite broadcast. Carrier synchronization is essential for optimum data demodulation. This thesis derives equations predicting the theoretical performance of each loops' ability to track a GPS signal corrupted by noise and signal dynamics arising from transmitter and/or receiver motion. In addition, computer simulations of the DLL and MTLL were developed and the results are presented. The simulations display phenomena which were not present in the theoretical predictions.

AFIT Designator

AFIT-GE-ENG-92D-20

DTIC Accession Number

ADA259315

Comments

The author's Vita page is omitted.

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