| This thesis deals with GPS receiver sensitivity analysis, characterization of interference sources prevalent in degraded signal environments and quantifies measurement availability, signal fading, pseudorange errors, positioning accuracy and position solution availability using an unaided high sensitivity GPS receiver. High sensitivity GPS utilizes total signal dwell times longer than the 20 ms maximum for conventional GPS receivers and results in more signal gain. A description of how this is accomplished is provided. Testing of the high sensitivity GPS receiver involved hardware simulations and extensive field testing in a forest, urban canyons, and in an indoor environment.;The high sensitivity receiver tested, developed by SiRF Technologies Inc., provides more measurements with fewer losses of signal tracking in all environments tested with a signal tracking sensitivity of -186 dBW. Increased tracking capability is highly beneficial in terms of solution availability and increased redundancy for reliability of navigation. However, reliable navigation is a primary concern as interference effects, namely signal cross-correlation, multipath, and echo-only signals, lead to large measurement errors. Navigation accuracy and reliability using a high sensitivity GPS receiver is discussed and recommendations are made for improvements. |
