A New Method for GNSS Multipath Mitigation with an Adaptive Frequency Domain Filter.

Area of Science:

• Geomatics Engineering
• Satellite Navigation Systems
• Signal Processing

Background:

• Multipath interference is a primary error source affecting Global Navigation Satellite Systems (GNSS) accuracy, particularly impacting pseudorange measurements.
• Reducing multipath effects in high-accuracy GNSS positioning remains a significant challenge due to the complex nature of signal reflections.

Purpose of the Study:

• To develop and validate a novel method for mitigating pseudorange multipath errors in GNSS positioning.
• To analyze the frequency spectrum characteristics of code-minus-carrier divergence (CMCD) across different GNSS constellations and environments.

Main Methods:

• Analysis of the frequency spectrum of code-minus-carrier divergence (CMCD) for GPS, GLONASS, and BeiDou Navigation Satellite System (BDS) satellites.
• Application of short-time Fourier transformation (STFT) to estimate time-varying local frequency spectra of GNSS signals.
• Development of a spectrum peak extraction method combined with interpolation and inverse Fourier transformation to eliminate periodic multipath components.

Main Results:

• Periodic fluctuations, appearing as frequency domain peaks, were identified in CMCD for various GNSS satellites and environments.
• The proposed frequency domain filtering method effectively reduced the impact of these periodic multipath effects.
• Experimental results demonstrated a significant improvement in pseudorange precision after applying the mitigation technique.

Conclusions:

• The novel frequency domain filtering approach offers an effective solution for reducing pseudorange multipath errors in GNSS.
• Accurate identification and elimination of spectral peaks associated with multipath are crucial for enhancing GNSS positioning accuracy.
• This method shows promise for improving the reliability of high-accuracy GNSS applications in challenging environments.