A model for assessing the impact of linear and nonlinear distortions on a GNSS receiver

Model and implementation of pseudorange-bias-free linear channel

“…However, when the signal passes through the satellite-receiver channel, various imperfections of many components of the cascade channel can cause linear or nonlinear distortions of the signal arriving at the entrance of the digital receiver correlator. These distortions will lead to CCF deformations, making the code loop lock point deviate from the true code phase alignment point and thus resulting in pseudorange biases (Soellner et al 2002;Betz 2002;He et al 2020;Vergara et al 2020). Since different signal modulations, satellite-receiver channel characteristics, and signal processing methods have different effects on pseudorange biases, such biases cannot be eliminated by means of differential techniques and are hard to assimilate into existing system error parameters.…”

“…Pseudorange biases are of much concern to satellite navigation applications that use measurements from multiple satellites, multiple receivers, multiple signal components, multiple frequencies, or multiple systems (ICAO 2001;Arikan et al 2008;HaKansson et al 2017;Phelts et al 2014;Pagot et al 2018). For example, using the satellite-specific bias parameters in signal-in-space (SIS) interface control documents (ICDs) and limiting the receiver front-end bandwidth and correlator spacing cannot completely eliminate biases caused by channel imperfections because the impacts of nonideal characteristics of the receiver channel and the mechanism of its interaction with the satellite channel characteristics are neglected (Montenbruck et al 2017;Liu et al 2019b;Vergara et al 2020). In addition to the group delay (T GD ) parameters broadcast in live navigation messages, some branches of international GNSS service (IGS) also release post-processing differential code bias (DCB) products to correct pseudorange biases.…”

“…Liu et al (2019b) proposed a model for the effect of group delay variation characteristics on pseudorange biases. Vergara et al (2020) presented a model for the DLL tracking performance and derived an expression of the distorted discriminators, from which the zero-crossing point bias (namely, the pseudorange bias) can be determined. Even with these theoretical models, the pseudorange biases have to be calculated from the CCF or discriminator function by means of iteration and/or numerical simulation.…”