GNSS-TS-NRS

GNSS-TS-NRS: An Open-source MATLAB-Based GNSS Time Series Noise Reduction Software

The global navigation satellite system (GNSS) has seen tremendous advances in
measurement precision and accuracy, and it allows researchers to perform geodynamics and
geophysics studies through the analysis of GNSS time series. Moreover, GNSS time series not only
contain geophysical signals, but also unmodeled errors and other nuisance parameters, which affect
the performance in the estimation of site coordinates and related parameters. As the number of globally
distributed GNSS reference stations increases, GNSS time series analysis software should be developed
with more flexible format support, better human–machine interaction, and with powerful noise
reduction analysis. To meet this requirement, a new software named GNSS time series noise reduction
software (GNSS-TS-NRS) was written in MATLAB and was developed. GNSS-TS-NRS allows users to
perform noise reduction analysis and spatial filtering on common mode errors and to visualize GNSS
position time series. The functions’ related theoretical background of GNSS-TS-NRS were introduced.
Firstly, we showed the theoretical background algorithms of the noise reduction analysis (empirical
mode decomposition (EMD), ensemble empirical mode decomposition (EEMD)). We also developed
three improved algorithms based on EMD for noise reduction, and the results of the test example
showed our proposed methods with better efect. Secondly, the spatial filtering model supported five
algorithms on a separate common model error: The stacking filter method, weighted stacking filter
method, correlation weighted superposition filtering method, distance weighted filtering method,
and principal component analysis, as well as with batch processing. Finally, the developed software
also enabled other functions, including outlier detection, correlation coeffcient calculation, spectrum
analysis, and distribution estimation. The software can be used for users to the GNSS time series noise reduction and application.