title: Optimal Divergence-Free Hatch Filter for GNSS Single-Frequency Measurement.
abstract: The Hatch filter is a code-smoothing technique that uses the variation of the carrier phase. It can effectively reduce the noise of a pseudo-range with a very simple filter construction, but it occasionally causes an ionosphere-induced error for low-lying satellites. Herein, we propose an optimal single-frequency (SF) divergence-free Hatch filter that uses a satellite-based augmentation system (SBAS) message to reduce the ionospheric divergence and applies the optimal smoothing constant for its smoothing window width. According to the data-processing results, the overall performance of the proposed filter is comparable to that of the dual frequency (DF) divergence-free Hatch filter. Moreover, it can reduce the horizontal error of 57 cm to 37 cm and improve the vertical accuracy of the conventional Hatch filter by 25%. Considering that SF receivers dominate the global navigation satellite system (GNSS) market and that most of these receivers include the SBAS function, the filter suggested in this paper is of great value in that it can make the differential GPS (DGPS) performance of the low-cost SF receivers comparable to that of DF receivers.
authors.affiliation: School of Aerospace Engineering, Sejong University, Seoul 05006, Korea. byungwoon@sejong.ac.kr.
authors.forename: Byungwoon
authors.initials: B
authors.lastname: Park
authors.affiliation: School of Aerospace Engineering, Sejong University, Seoul 05006, Korea. csleem@sju.ac.kr.
authors.forename: Cheolsoon
authors.initials: C
authors.lastname: Lim
authors.affiliation: KASS (Korean SBAS) Development Team/Satellite Navigation Team, Korea Aerospace Research Institute, Daejeon 34133, Korea. ysyun@kari.re.kr.
authors.forename: Youngsun
authors.initials: Y
authors.lastname: Yun
authors.affiliation: Mechanical and System Design Engineering Department, Hongik University, Seoul 04066, Korea. atomstan@gmail.com.
authors.forename: Euiho
authors.initials: E
authors.lastname: Kim
authors.affiliation: Institute of Advanced Aerospace Technology, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 08826, Korea. kee@snu.ac.kr.
authors.forename: Changdon
authors.initials: C
authors.lastname: Kee
keywords: GNSS; Hatch filter; SBAS; divergence-free Hatch filter; smoothing window width