WAAS
Wide Area Augmentation System

Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System(GPS), with the goal of improving its accuracy, integrity, and availability. WAAS is essentially intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area.

WAAS uses a network of ground-based reference stations, in North America and Hawaii, to measure small variations in the GPS satellites' signals in the western hemisphere. Measurements from the reference stations are routed to master stations, which queue the received Deviation Correction (DC) and send the correction messages to geostationary WAAS satellites in a timely manner (every 5 seconds or better). Those satellites broadcast the correction messages back to Earth, where WAAS-enabled GPS receivers use the corrections while computing their positions to improve accuracy.

ETI worked with the FAA to design and manufacture UPS systems and provide power backup for the WAAS ground stations' sensative equipment.

ETI's ETI0001-1473 and 1473AA were custom designed to meet the stringent requirements of FAA programs including WAAS.