GNSS degradation model in presence of continuous wave and pulsed interference

Abstract

In the Global Navigation Satellite System (GNSS) L5/E5a interference environment, RTCA DO-292 proposes a model to compute the C/N0 degradation due to the presence of interference signals, such as Distance Measuring Equipment/TACtical Air Navigation (DME/TACAN), Joint Tactical Information Distribution System/Multifunctional Information Distribution System (JTIDS/MIDS), etc., and due to the application of a temporal blanker to mitigate their impact. The C/N0 degradation is modeled as a function of the blanker duty cycle, bdc, and the equivalent noise-level contribution of the non-blanked interference, RI. However, in RTCA DO-292, the computation of these two terms has a reduced accuracy since a general statistical model of signal pulse collisions and an overbounded flat post-blanker pulsed interference signal Power Spectrum Density (PSD) are assumed. In this paper, the limitations of the applied pulse collisions mathematical model are commented, and the use of true post-blanker pulsed interference signal PSD is introduced through the application of the spectral separation coefficient. As a result, more accurate new formulas for RI and C/N0 degradation are derived. The new formulas are verified through simulations for DME/TACAN signals.