Carrier-Phase Multipath Calibration of GPS Reference Stations

Abstract

Based on available GPS reference network observations, a procedure for estimating carrier‐phase multipath corrections was developed, implemented, and tested. This procedure consists of three steps: detection and localization of multipath‐affected satellite signals, daily estimation of multipath errors, and combination of these daily estimates to obtain corrections for undifferenced L1 and L2 phase measurements. After application of these corrections, multipath errors can be significantly reduced for frequently used linear combinations of dual‐frequency observations, but not for the original L1 and L2 observations themselves. The reason lies in the relatively small multipath effects compared with the larger influence of remaining ionospheric errors in the multipath corrections. The variability of carrier‐phase multipath errors over 1 year showed that on some days with snow cover, multipath errors were altered. No similar effects could be found on days with continuous rainfall.

The carrier-multipath observable: a new carrier-phase multipath mitigation technique

“…A linear combination observable such as WL can be generalized by the following equation (Wanninger and May 2001):…”

Multipath Comparison for GPS Observation MASS Station Data and RTK Station

“…Satu isyarat adalah langsung dari satelit, manakala isyarat yang lainnya merupakan isyarat-isyarat tidak langsung yang dipantulkan oleh objekobjek di sekitar antena sebelum tiba di antena penerima (El-Rabbany 2002). Disebabkan multipath menjadi punca ralat yang besar, banyak kajian telah dilakukan bagi melihat kesan multipath ini (Abdi 2009;Satirapod & Rizos 2003;Soloviev & Graas 2009;Wanninger & May 2000). Multipath memberikan kesan yang berbeza terhadap pengukuran julat pseudo (15-150 m) dan fasa pembawa (£ 5 cm untuk L 1 ) kerana frekuensi isyaratnya yang berlainan di mana multipath adalah bergantung kepada frekuensi (Seeber 2003).…”

Integral GPS and QZSS Ambiguity Resolution

“…10,11) The error must be considered for analysis on ambiguity resolution in carrier phase measurement and it is estimated typically to be less than one centimeter in 1-sigma. The error in pseudorange measurement is estimated to be a few meters at the remote stations and 20% at the reference station.…”