Analytical Derivation of Maximum Tolerable In-Band Interference Levels for Aviation Applications of GNSS*

Abstract

This paper presents an analytic derivation of the maximum levels of radio frequency interference (RFI) that can be tolerated for aviation applications of GNSS (global navigation satellite system). The derivation, which is included in the document of RTCA Special Committee-159 Working Group 6 on RFI to GNSS, includes consideration of many factors not addressed comprehensively in previous analyses. Such factors include quantization loss, intermediate frequency (IF) filtering losses, modulation imperfections in the navigation satellites (GPS, GLONASS, and Wide-Area Augmentation System [WAAS]), Doppler loop stress, processing gain losses due to realizable spreading codes, and oscillator phase noise. The goal of this paper is to demonstrate that the interference levels provided in RTCA's Minimum Operational Performance Standards (MOPS) are indeed close to the maximum levels that can be tolerated for aviation applications by moderate-cost modern digital receiver designs.