Broadcasting GPS integrity information using Loran-C

The United States Federal Aviation Administration (FAA) will adopt the Global Positioning System (GPS) as its primary navigation systems for aviation as stated by the Federal Radionavigation Plans (FRP) of 1996 and 1999. The FRP also proposes the reduction or termination of some existing radionavigation system in favor of GPS and satellite navigation. It may be beneficial to retain some of these existing terrestrial navigation systems if they can provide increased safety and redundancy to the GPS based architecture. One manner in which this can be done is by using or creating a data link on these existing radionavigation systems. These systems thus can provide both navigation and an additional broadcast of GPS integrity information. This thesis examines the use of terrestrial data links to provide Wide Area Augmentation System (WAAS) based GPS integrity information for aviation. The thesis focuses on using Loran-C to broadcast WAAS data. Analysis and experimental results demonstrating the capabilities of these designs are also discussed.; Using Loran for this purpose requires increasing its data capacity. Many Loran modulation schemes are developed and analyzed. The data rates developed significantly increased the Loran data capacity. However, retaining compatibility with Loran legacy users resulted in data rates below the WARS data rate of 250 bps. As a result, this thesis also examines means of reducing the data requirements for WAAS information. While higher data rates offer improved performance and compatibility with WAAS, this thesis demonstrates that higher rates incur greater interference. Therefore, this work develops and considers a 108 bps and 167 bps Loran GPS integrity channel (LOGIC) design. The performance of the two designs illustrates some of the advantages and disadvantages of using a higher data rate.; Analysis demonstrated means of maintaining integrity with these low data rate systems and determined the theoretical capabilities of the systems. The system was tested empirically by developing software that generated the LOGIC message and applied these messages to a GPS user. The resulting 108 bps and 167 bps systems demonstrated capability to provide lateral navigation/vertical navigation (LNAV/VNAV) and approach with vertical guidance (APV) respectively.