Attitude Determination by

A Global Positioning System (GPS) based attitude determination system has never been used as the primary source of attitude information for a spacecraft application. The fundamental reason for this is that a spacecraft attitude determination system must achieve fast attitude acquisition and near perfect solution reliability. Existing GPS based attitude systems cannot meet these requirements, so GPS has only been used as a secondary sensor for spacecraft missions. In this thesis, an attitude determination system is developed which meets spacecraft performance requirements using GPS as the primary source of attitude information. System hardware includes a multiple antenna GPS receiver and a low cost three axis gyro assembly. The attitude determination software consists of an integer ambiguity solution algorithm, an Extended Kalman Filter and an integrity monitoring architecture to improve robustness of the design