GPS PNT Flexible Satellite Modulation

ABSTRACT:The objective of this effort is to investigate designs and possible options for a Position, Navigation, and Timing (PNT) flexible satellite for GPS to enhance PNT capabilities at a low cost.A desired feature to help overcome GPS coverage issues due to terrain, spoofing, jamming and interference is to broadcast military signals at higher power than the civilian signals.Under the Phase I SBIR effort we demonstrated a flexible digital signal modulation approach, termed FlexMod, which modulates large numbers of codes on a single carrier with flexible relative power levels while maintaining a constant envelope modulation output.Under Phase II, we shall implement a FlexMod firmware module and assemble a test set including a prototype Digital Waveform Generator (DWG), GPS constellation simulator and High Power Amplifiers (HPA) for testing with civil and military GPS receivers.This will be used to demonstrate the flex power performance of the enhanced FlexMod modulation method and evaluate the expected M-code power level that FlexMod could deliver with state of the art HPA technology to a GPS receiver through an earth coverage antenna in GPS III.BENEFIT:When combined with digital waveform generation and state of the art L-band high power amplifiers the FlexMod technology will allow for broadcast of multiple GPS codes (civil and legacy) and a high power M-code signal through a single antenna.This would allow for delivery of NavWar high power signals under A2/AD conditions without requiring a separate spot beam on future GPS III satellites. Due to the cost effectiveness of this solution and the significant improvements this capability would provide, it is anticipated that significant interest will be garnered for this technology for future GPS III satellites and payloads.