Low Elevation Enhanced Tropospheric Effects Compensation (ETEC) GPS Antenna Array

Propagation Research Associates, Inc., (PRA) has combined its unique expertise in atmospheric physics and radar signal propagation to develop the Enhanced Tropospheric Effects Compensation (ETEC) System that will compensate for tropospheric bending errors when tracking long-range, low-elevation targets. The ETEC System will provide enhanced performance over existing techniques to permit greater detection range and longer time lines for these targets at low-elevation angles while enhancing target identification and discrimination. In Phase I, PRA will design the low-elevation ETEC GPS antenna array to extend the ETEC System operation to low-elevation targets. PRA will develop an antenna design and signal processing algorithms that mitigate multipath interference while maintaining a transportable antenna size and accurate angle-of-arrival measurements. To this end, PRA will implement an adaptive cancellation algorithm to mitigate multipath interference, and PRA will develop alignment and calibration algorithms that will permit the GPS array to accurately measure the bending angle of refracted GPS signals. In Phase II, PRA plans to fabricate the low-elevation ETEC antenna array and integrate the array with the ETEC hardware and software developed in contract W9113M-04-P-0042. PRA plans to test the fully integrated ETEC System at Vandenberg AFB using four C-band radars.