Mapping GPS multipath: a case study for the lunar laser ranger timing antenna at HartRAO

Munghemezulu, Cilence; Combrinck, Ludwig; Botai, Joel Ongego; Mashaba, Zinhle

doi:10.4314/sajg.v5i2.4

Cited by 2 publications

(1 citation statement)

References 21 publications

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“…The former describe the state-ofthe-art choke-ring and Trimble's Zephyr antennas which mitigate multipath by minimising the gain of a low-elevation signal. Recent studies in multipath mitigation techniques have also assisted researchers to undertake feasibility studies to aid proper selection of antenna for Continuously Operating Reference Station (CORS) (Munghemezulu et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Pseudorange multipath at Zomba geodynamics Continuously Operating Reference Station (CORS) in Malawi

suya¹,

Soko²,

Chilembwe³

et al. 2022

SA J of Geomatics

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Multipath effects are mostly regarded as a nuisance in Global Navigation Satellite System (GNSS) receiver measurements and it is of utmost relevance to expose the magnitude this error has on observations. The impact of multipath is characterized in the context of a given environment and application. In Malawi, Zomba geodynamics Continuously Operating Reference Station (CORS) is in a multipath prone environment. The GNSS observations for this station have been used in geodynamics studies in Malawi without an understanding of multipath affecting the positioning accuracy. Taking this as an advantage, this paper evaluated pseudorange multipath (MP) and signal noise ratio (SNR) on both L1 (MP1 and SNR1) and L2 (MP2 and SNR2) for the station. This was specifically addressed by computing the elevation mask with minimum and maximum multipath effects. In addition, the number of satellite vehicles (SVs) and their associated Geometric Dilution of Precision (GDOP) are also determined to define their relationship with respect to elevation angles. One week GNSS observations spanning a twenty-four hour interval for DOY 001 to DOY 007 in January 2018 were analysed in Translation Editing and Quality Check (TEQC) software at four (10º, 15º, 20º and 25º) cut-off angles. Results indicate high multipath effects for both MP1 and MP2 at 10º elevation mask among the four elevation masks. The least MP1 and MP2 multipath effects were detected at an elevation angle of 25º. In addition, MP1 multipath was worse than MP2 all the angles. Moreover, statistical results demonstrated an increase in both SNR1 and SNR2 with respect to elevation angle. For these days, L2 signal was more affected by noise than L1. Further to this, an assessment of SVs and GDOP for the CORS show that at least ten (10) satellites were observed in each day at 10º and 15º elevation cut-off. The number of satellites dropped to five (5) at the elevation angle of 25º resulting into a larger GDOP value of 4.5 (a decrease by about 38% from 1.7 at 10º and 15º elevation cut-off angles). Therefore, to increase both the number of satellites and precision, Zomba CORS may be upgraded to a multi-constellation CORS by including other navigation systems such as GLONASS, Galileo and BeiDou. While it is possible to reject GNSS satellite observations below the horizon, it is recommended that post-processing of GNSS data for Zomba geodynamics CORS be done at elevation masks above 15º. Considering that multipath repeats itself every sidereal day, it is thus recommended to model or remove multipath affecting Zomba geodynamics CORS. In addition, the study also recommends that trees very close to Zomba CORS antenna be removed to reduce signal scattering.

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Section: Introductionmentioning

confidence: 99%

Pseudorange multipath at Zomba geodynamics Continuously Operating Reference Station (CORS) in Malawi

suya¹,

Soko²,

Chilembwe³

et al. 2022

SA J of Geomatics

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A case study of the application of GPS to lunar laser ranging timing systems

Munghemezulu

Combrinck

Botai

2018

Journal of Applied Geodesy

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The Hartebeesthoek Radio Astronomy Observatory is currently building a Lunar Laser Ranging station. This geodetic technique requires a good timing system to measure a round trip of laser photons from the telescope to the Moon and back to the telescope. We test the newly acquired timing system using examples of the Global Positioning System applications. Data in Receiver Independent Exchange Format was processed using GAMIT/GLOBK software. The results were compared against those derived from the Global Positioning System receivers that were integrated with a frequency standard from a hydrogen maser and a standard internal quartz. The results indicate that (i) the rubidium clock operates optimally and the clock drifted to within error margins of sub-centimetre level during the period of 2.5 seconds, (ii) the selected site for the permanent installation of the timing antenna has minimal multipath effect and (iii) we observed no improvement in Global Positioning System products derived from receivers that were integrated with different frequency standards.

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Mapping GPS multipath: a case study for the lunar laser ranger timing antenna at HartRAO

Abstract: Accounting for multipath in Global Navigation Satellite Systems (GNSS) is a difficult task and an important one, especially during the pre-investigation phase for the installation of a permanent GNSS

Cited by 2 publications

References 21 publications

Pseudorange multipath at Zomba geodynamics Continuously Operating Reference Station (CORS) in Malawi

Pseudorange multipath at Zomba geodynamics Continuously Operating Reference Station (CORS) in Malawi

A case study of the application of GPS to lunar laser ranging timing systems

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