Abstract Since the first pair of BeiDou satellites was deployed in 2000, China has made continuous efforts to establish its own independent Navigation Satellite System (BDS) provide regional radio determination satellite service as well and global navigation services, which rely on high quality orbit clock products. This article summarizes achievements precise (POD) BDS past decade with focus observation dynamic models. First, disclosed metadata is presented contribution POD addressed. The...

By the end of 2012, China had launched 16 BeiDou-2 navigation satellites that include six GEOs, five IGSOs and MEOs. This has provided initial precise pointing services ability in Asia-Pacific regions. In order to assess positioning performance system, Wuhan University built up a network BeiDou Experimental Tracking Stations (BETS) around World. The Position Navigation Data Analyst (PANDA) software was modified determine orbits provide orbit satellite clock bias products from system for user...

The main objective of this research was to examine the feasibility Multi-GNSS precise point positioning (PPP) in precision agriculture (PA) through a series experiments with different working modes (i.e. stationary and moving) under observation conditions (e.g. open sky, buildings or canopy). For test carried out space UK, accuracy achieved 13.9 mm one dimension by PPP approach, repeatability results improved from 19.0 6.0 using respect GPS only. moving similar location almost same...

By end-2018, the Chinese BeiDou satellite system (BDS) has entered its third phase of global scale coverage (BDS-3). This study presents and validates a modified modeling aspect concerning an intersatellite link (ISL) hardware delay estimation. The precise orbit determination (POD) results BDS-3 demonstrate this along with calibrated center offsets (PCOs) ISL terminal to help improve accuracy. After onboarding data, two additional sets POD solutions using regional ground stations are...

In order to simplify the attitude control for inclined geosynchronous orbit (IGSO) and medium earth (MEO) satellites of BeiDou Navigation Satellite System (BDS) in eclipse seasons, two modes, namely yaw-steering (YS) orbit-normal (ON) mode are used. Significant accuracy degradation is observed orbits determined with purely empirical CODE solar radiation pressure (SRP) model when these switch ON mode. addition, even though BDS IGSO YS mode, SRP show undesirable systematic errors that depend...

The fractional order PID (FOPID) controller has been found to have the potential provide more flexibility in design options than integer (IOPID) controller. However, FOPID practice, investigations are still required selecting achievable specifications and parameters. In obtain a practical tuning method for controller, taking first plus integral systems as plants, complete regions of collected analyzed. addition, selectable derivative orders also modeled. With prior knowledge obtained,...

We introduce a method, known as one-dimensional sonomyography (1-D SMG), that uses A-mode ultrasound signals to detect dynamic thickness changes in skeletal muscle during contraction.We custom-designed 1-D SMG system collect synchronized ultrasound, joint angle, and surface electromyography (EMG) of forearm muscles wrist extension.We extracted the signal from by automatically tracking corresponding echoes, which we then used calculate changes.We tested right nine nondisabled young subjects...

A key limitation for precise orbit determination of BeiDou satellites, particularly satellites in geostationary (GEO), is the relative weak geometry ground stations. Fortunately, data from a low earth orbiting satellite with an onboard GNSS receiver can improve compared to using only data. The Chinese FengYun-3C (FY3C) carries Occultation Sounder equipment both dual-frequency GPS (L1 and L2) (B1 B2) tracking capacity. satellite-induced variations pseudoranges have been estimated multipath...

Abstract To overcome spatial and temporal limitations of sea surface height instruments such as tide gauges, satellite altimetry, Global Navigation Satellite Systems (GNSS) buoys, we investigate the use an unmanned, self‐propelled Wave Glider vehicle equipped with a geodetic GNSS receiver. Centimetric precision instantaneous measurement is demonstrated from 13‐day deployment in North Sea, during which glider traversed track about 600 km. Ellipsoidal heights were estimated at 5 Hz using...

Abstract The Precise Point Positioning (PPP) technique uses a single Global Navigation Satellite System (GNSS) receiver to collect carrier-phase and code observations perform centimeter-accuracy positioning together with the precise satellite orbit clock corrections provided. According used, there are basically two approaches, namely, ionosphere-free combination approach raw observation approach. former eliminates ionosphere effects in domain, while latter estimates using uncombined...

Abstract Inter-satellite link (ISL) plays an essential role in current and future Global Navigation Satellite System (GNSS). In this study, we investigate the impact of ISL observations on precise orbit determination for BeiDou-3 (BDS-3) Medium Earth Orbit (MEO) satellites based different Extended CODE Models (ECOM). Thanks to better observation geometry Ka-band data compared L-band BDS-3 MEO satellites, solution substantially reduces Boundary Discontinuity (OBD) errors, except C30, which...

Abstract The orbit quality of BDS-3 inclined geosynchronous (IGSO) satellites is limited by the observation geometry as well dynamic models. Regarding ground L-band data, maximum nadir angle for IGSO approximately 9°. However, with Ka-band inter-satellite link (ISL) can reach up to 45°, which significantly improves conditions. This study investigates impact ISL data on 5-parameter reduced extented CODE model (ECOM1) compared that from only. It observed estimates ECOM1 parameter become more...

The distribution of isotopically heavy ozone in the stratosphere has been obtained from an analysis balloon‐based high‐resolution thermal emission spectra far infrared. mixing ratio profiles 16 O 18 and retrieved inversion several limb sequences a number spectral lines 39–76 cm −1 region, indicate enhancements over expected values 25‐ to 37‐km altitude range. total isotopic 50 3 normal 48 shows ∼45% at 37 km, decreasing minimum ∼13% ∼29 increasing ∼18% 25 km. results this work are compared...