General Design Methodology Of Code Multi-Correlator Discriminator For Gnss Multi-Path Mitigation

Multi-path becomes a main source of positioning errors in new-generation global navigation satellite systems (GNSS). Code multi-correlator discriminators (MCD), represented by narrow early-minus-late (NEML) and double delta (DD) discriminators which are designed for binary phase offset keying (BPSK) signals, are one of the main multi-path mitigation techniques. However, because of the complicated auto-correlation function and intricate relationships among multiple correlators, it is hard to implement a trial and error approach, which is the conventional design method of discriminator structures, to specifically design code MCD structures for new GNSS signals which have complicated spreading waveforms. In this article, instead of a trial and error approach, a general design methodology for designing code MCD structures based on heuristic optimisation for multi-path mitigation is proposed. The proposed method can specifically design code MCD structures for signals with various modulations and receivers with different bandwidths, indicating the adaptability of the proposed method. Multi-path mitigation performances of such designed structures are better than those of traditional code discriminator structures with strong tracking robustness and slight degradation of thermal noise performance. Designed code MCD structures are also insensitive to multi-path relative amplitudes and bandwidths of receivers, ensuring the practicality of the designed code MCD structures.