In the context of mobile phones, local optimal global navigation satellite systems (GNSS) shadow matching algorithm, which is based on urban three-dimensional model, can effectively reduce error GNSS pseudo-range single-point positioning. However, positioning accuracy this algorithm susceptible to noise, and its continuous signal-to-noise ratio (SNR) scoring method does not fully exploit probability density distribution information contained in SNR. Therefore, paper proposes two improvements...

This paper focuses on sea surface wind speed estimation based cyclone global navigation satellite system reflectometry (GNSS-R) data. In order to extract useful information from delay-Doppler map (DDM) data, three delay waveforms are presented for estimation. The waveform without Doppler shift is defined as central (CDW), and the integral of with different values (IDW), while difference between normalized IDW (NIDW) CDW (NCDW) differential (DDW). We first propose a data filtering method...

Global Navigation Satellite System (GNSS)-Reflectometry (GNSS-R) technology has opened a new window for ocean remote sensing because of its unique advantages, including short revisit period, low observation cost, and high spatial-temporal resolution. In this article, we investigated the potential estimating swell height from delay-Doppler maps (DDMs) data generated by spaceborne GNSS-R. Three observables extracted DDM are introduced estimation, map average (DDMA), leading edge slope (LES)...

With the advances and modernization of GPS, GLONASS, BDS, Galileo QZSS, multi-frequency multi-system joint positioning has become mainstream navigation. Therefore, it is great importance to perform a comprehensive assessment signal quality performance multi-GNSS. In this work, we used multi-GNSS observation data collected by Multi-GNSS Experiment (MGEX) International GNSS Service (IGS), Hong Kong CORS, Research Centre Curtin University. Firstly, evaluated analyzed. Then, five-system...

Regarding the terrestrial water storage anomaly (TWSA) gap between Gravity Recovery and Climate Experiment (GRACE) GRACE Follow-on (-FO) gravity satellite missions, a BEAST (Bayesian estimator of abrupt change, seasonal change trend)+GMDH (group method data handling) gap-filling scheme driven by hydrological meteorological is proposed. Considering these driving usually cannot fully capture trend changes TWSA time series, we propose first to use algorithm perform piecewise linear detrending...

Reliable rainfall information is very important for hydro climatology research, industrial and agricultural production, construction, drought flood prediction. As a new remote sensing technology, Global Navigation Satellite System-reflectometry (GNSS-R) can be used to retrieve geophysical parameters due its unique advantages of high spatial temporal resolution, low cost, large coverage, all-weather operation. Existing studies have confirmed that GNSS-R technology detect on the ocean surface,...

In complex urban environments, a single Global Navigation Satellite System (GNSS) is often not ideal for navigation due to lack of sufficient visible satellites. Additionally, the heading angle error GNSS/micro-electro-mechanical system–grade inertial measurement unit (MIMU) tightly coupled integration based on antenna large, and attitude angle, velocity, position calculated therein all have large errors. Considering above problems, this paper designs GNSS/MIMU two GNSS antennas proposes...

Based on its unique sensitivity to Earth's temporal gravity, and since 2002, the gravity recovery climate experiment (GRACE) twin satellites, successor, GRACE follow-on (GRACE-FO) missions have accumulated a two-decade-long continuing mass change data record. Additionally, Chinese gravimetry mission was launched as last polar-pair satellite formation in 2021. With opportunity of two existing formations (EPGF) operations, we explore ideal configuration launch third-pair construct triple-pair...

In Global Navigation Satellite System (GNSS) community, pseudorange observables, without integer ambiguity, have large measurement noise, while carrier phase with high accuracy, which restricts the direct use either of them for high‐accuracy navigation and positioning. this regard, fusing ambiguity‐free time‐differenced (TDCP) is a popular data processing technique. Letter, least‐squares fusion studied. A theoretical analysis steady performance conducted. set formulas derived, based on...

GNSS has become a widely accessible technique for vehicle instantaneous velocimetry. time difference carrier phase (TDCP) velocimetry can provide high-accuracy displacement increments, through which the between-epoch average velocity be derived. However, there are always so-called modelling errors in such velocity, i.e., deviation between and one. Doppler offers exactly but its measurement is much noisier. In this work, we propose to integrate TDCP with estimating vehicle's velocity. The...

High-frequency and correlated noise filtering is one of the important preprocessing steps for GRACE level-2 products before calculating mass anomaly. Decorrelation denoising kernel (DDK) filters are usually considered as such optimal to solve this problem. In work, a sparse DDK filter proposed. This achieved by replacing Tikhonov regularization in traditional with weighted L1 norm regularization. The proposed adopts time-varying error covariance matrix, while equivalent signal matrix...

A refined triple-frequency cycle slip detection and repair algorithm for GPS/BDS undifferenced observables under high ionospheric disturbances is proposed.In this method, three linearindependent optimal combinations are selected.The residual delay estimated from a "calculation-prediction mechanism", namely flexibly determine whether to calculate by themselves or predict feedforward neural network (FNN), used compensate the values.Additionally, we devise an adaptive threshold based on actual...

Regularization is often necessary in parameter estimation of spherical radial basis function (SRBF) based regional gravity modelling. In this work, a new regularization method, namely the L1-norm regularization, also called least absolute shrinkage selection operator (Lasso), employed. This different from commonly used L2-norm Tikhonov regularization. The solution produced by Lasso sparse, with part parameters being exactly zero. A sparse model would be beneficial terms better...

Filtering for GRACE temporal gravity fields is a necessary step before calculating surface mass anomalies. In this study, we propose new denoising and decorrelation kernel (DDK) filtering scheme called adaptive DDK filter. The involved error covariance matrix (ECM) adopts nothing but the monthly time-variable released by several data centers. signal (SCM) also. Specifically, it parameterized into two parameters, namely regularization coefficient power index of covariances, which are...

SUMMARY Point-mass inversion is widely employed in GRACE level-2 data processing. Conventionally, the spherical harmonic (SH) coefficients are used indirectly: a set of pseudo measurements generated first using SH through synthesis; then point-mass done with these measurements. To be statistically optimal, covariance matrix should calculated and to appropriately weigh parameter estimation. In this work, we propose optimal scheme by directly as We prove equivalence between direct approach...