709 research outputs found
Galileo and EGNOS as an asset for UTM safety and security
GAUSS (Galileo-EGNOS as an Asset for UTM Safety and Security) is a H2020 project1 that aims at designing and developing high performance positioning systems for drones within the U-Space framework focusing on UAS (Unmanned Aircraft System) VLL (Very Low Level) operations. The key element within GAUSS is the integration and exploitation of Galileo and EGNOS exceptional features in terms of accuracy, integrity and security, which will be key assets for the safety of current and future drone operations. More concretely, high accuracy, authentication, precise timing (among others) are key GNSS (Global Navigation Satellite System) enablers of future integrated drone operations under UTM (UAS Traffic Management) operations, which in Europe will be deployed under U-Space [1].
The U-Space concept helps control, manage and integrate all UAS in the VLL airspace to ensure the security and efficiency of UAS operations. GAUSS will enable not only safe, timely and efficient operations but also coordination among a higher number of RPAS (Remotely Piloted Aircraft System) in the air with the appropriate levels of security, as it will improve anti-jamming and anti-spoofing capabilities through a multi-frequency and multi-constellation approach and Galileo authentication operations.
The GAUSS system will be validated with two field trials in two different UTM real scenarios (in-land and sea) with the operation of a minimum of four UTM coordinated UAS from different types (fixed and rotary wing), manoeuvrability and EASA (European Aviation Safety Agency) operational categories. The outcome of the project will consist of Galileo-EGNOS based technological solutions to enhance safety and security levels in both, current UAS and future UTM operations. Increased levels of efficiency, reliability, safety, and security in UAS operations are key enabling features to foster the EU UAS regulation, market development and full acceptance by the society.Peer ReviewedPostprint (author's final draft
PERFORMANCE EVALUATION OF LOW-COST PRECISION POSITIONING METHODS FOR FUTURE PORT APPLICATIONS
In recent times, a lot of research has been conducted to improve the accuracy of various positioning systems. The motivation behind this trend is to ensure high quality GNSS services for various applications. In particular, emphasis has been placed on improving the level of accuracy of consumer grade GNSS receivers. Significant improvements in the quality of signal reception of these receivers would enable low-cost solutions for asset management in for example, harbor areas. Research in Receiver Autonomous Integrity Monitoring - Fault Detection and Exclusion (RAIM-FDE) algorithms give users the ability to exclude satellites with degraded signals, hereby improving the performance of the GNSS solution. This research investigates and evaluates the performance of various customer grade GNSS positioning systems intended for port applications. Various high precision techniques such as Precise Point Positioning and Real-Time Kinematic were conducted and accuracy levels were noted on Multi-band receivers, Single frequency receivers, and GNSS-enabled smartphone. Our final conclusion suggests optimal low-cost GNSS solutions for asset monitoring and management
Performance Analysis of Using the Next generation Australian SBAS with Precise Point Positioning Capability for Intelligent Transport Systems
ยฉ 2019 IEEE. In 2018, a next-generation Satellite-Based Augmentation System (SBAS) test-bed was launched in Australia/New-Zealand in preparation for building an operational system. This new generation SBAS includes Ll legacy SBAS, new dual-frequency multi-constellation (DFMC) SBAS, and orbit and clock corrections for precise point positioning (PPP) using GPS and Galileo. In this paper, the next generation SBAS and its models are first presented, and the benefits of using its new components are discussed. Test results for lane identification applications in Intelligent Transport Systems (ITS) are presented and analyzed. Kinematic tests were performed in different ITS environments. These are characterized by different levels of sky-visibility and multipath, including clear sky, suburban, low-density urban, and high-density urban environments. Performance analysis show that results vary widely depending on the operational conditions but all SBAS solutions have better positioning accuracy compared with the standalone solutions that are currently used in transport applications. The DFMC SBAS slightly outperformed the Ll SBAS, with accuracy at sub-meter, and it has advantages during periods of fluctuations of the ionosphere with an extended coverage area. As expected, the SBAS-based PPP solutions have shown to give the best positioning precision and accuracy among all tested solution types, with sub-decimeter level accuracy, provided that enough convergence time is available. The paper concluded by giving remarks on the use of this new technology for ITS
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Client-server-based LBS architecture: A novel positioning module for improved positioning performance
Permission to distribute obtained from publisher.This work presents a new efficient positioning module that operates over client-server LBS architectures. The
aim of the proposed module is to fulfil the position information requirements for LBS pedestrian applications
by ensuring the availability of reliable, highly accurate and precise position solutions based on GPS single
frequency (L1) positioning service. The positioning module operates at both LBS architecture sides; the client
(mobile device), and the server (positioning server). At the server side, the positioning module is responsible
for correcting userโs location information based on WADGPS corrections. In addition, at the mobile side,
the positioning module is continually in charge for monitoring the integrity and available of the position
solutions as well as managing the communication with the server. The integrity monitoring was based on
EGNOS integrity methods. A prototype of the proposed module was developed and used in experimental trials
to evaluate the efficiency of the module in terms of the achieved positioning performance. The positioning
module was capable of achieving a horizontal accuracy of less than 2 meters with a 95% confidence level
with integrity improvement of more than 30% from existing GPS/EGNOS services
Second Generation SBAS โ Performance Analysis and Bridging Positioning and Integrity Monitoring during SBAS Outages in the Urban Environment
Improved SBAS is expected to be a primary positioning method for many land applications such as Intelligent Transport Systems (ITS). In 2017, a second-generation SBAS test-bed was initiated in Australia and New-Zealand in preparation for building an operational system. In addition to the traditional L1 legacy SBAS signals, the Australian/NZ SBAS provides dual-frequency multi-constellation (DFMC) SBAS signals and SBAS-based PPP service for GPS and Galileo observations. This article addresses the use of SBAS in land applications from three important aspects. Firstly, the performance of the different SBAS solution methods is assessed in two main applications, transportation and mining. Tests were conducted under various environments, including open sky, low- and high-density urban, and mining. Performance analysis showed that SBAS solutions provide better positioning than single point positioning, and the DFMC SBAS solutions have better precision than L1 SBAS solutions. Furthermore, SBAS-based PPP solutions delivered a few-dm accuracy, which is a bit worse than traditional PPP with corrections received via the Internet. It is shown that SBAS performance is strongly dependent on the application environment. Secondly, tests show that SBAS outages may occur in urban areas, thus, the paper proposed prediction of the SBAS orbit and clock corrections as time series to enable positioning. The orbits are predicted using Holt-Wintersโ method and clock corrections were predicted using a second order polynomial with sinusoidal components. A position error due to prediction grow with time, but was less than 0.26m after 15 minutes of prediction. Finally, the impact of SBAS outages on computation of the protection levels (PL) needed for integrity monitoring of the new DFMC SBAS is illustrated. It is shown that Horizontal-PLs can reach more than 10 m, which is not suitable for ITS when the previous SBAS parameters before the outage were used, and thus methods are proposed for future research
์ผํฐ๋ฏธํฐ ๊ธ ๊ด์ญ ๋ณด๊ฐํญ๋ฒ ์์คํ ์ ๋ฐ์กํ ์์ ๊ธฐ๋ฐ ๋ณด์ ์ ๋ณด ์์ฑ ์๊ณ ๋ฆฌ์ฆ์ ๊ดํ ์ฐ๊ตฌ
ํ์๋
ผ๋ฌธ(๋ฐ์ฌ)--์์ธ๋ํ๊ต ๋ํ์ :๊ณต๊ณผ๋ํ ๊ธฐ๊ณํญ๊ณต๊ณตํ๋ถ,2020. 2. ๊ธฐ์ฐฝ๋.Recently, the demand for high-precision navigation systems for centimeter-level service has been growing rapidly for various Global Navigation Satellite System (GNSS) applications. The network Real-Time Kinematic (RTK) is one of the candidate solution to provide high-accuracy position to user in real-time. However, the network RTK requires a lot of reference stations for nationwide service. Furthermore, it requires high-speed data-link for broadcasting their scalar-type corrections.
This dissertation proposed a new concept of satellite augmentation system called Compact Wide-Area RTK, which provides centimeter-level positioning service on national or continental scales to overcoming the limitation of the legacy network RTK methods. Using the wide-area network of multiple reference stations whose distance is 200~1,000 km, the proposed system generates three types of carrier-phase-based corrections: satellite orbit corrections, satellite code/phase clock (CPC) corrections, tropospheric corrections. Through the strategy of separating the scalar-type corrections of network RTK into vector forms of each error component, it is enable to expand network RTK coverage to continental scale using a similar number of reference stations as legacy meter-level Satellite-Based Augmentation System (SBAS). Furthermore, it is possible to broadcast their corrections over a wide-area using geosynchronous (GEO) satellite with extremely low-speed datalink of 250 bps likewise of legacy SBAS. To sum up, the proposed system can improve position accuracy by centimeter-level while maintaining the hardware infrastructure of the meter-level legacy SBAS.
This study mainly discussed on the overall system architecture and core algorithms for generating satellite CPC corrections and tropospheric corrections. This study proposed a new Three-Carrier Ambiguity Resolution (TCAR) algorithm using ionosphere-free combinations to correctly solve the integer ambiguity in wide-area without any ionospheric corrections. The satellite CPC corrections are calculated based on multiple stations for superior and robust performance under communication delay and outage. The proposed algorithm dramatically reduced the latency compensation errors and message amounts with compare to conventional RTK protocols. The tropospheric corrections of the compact wide-area RTK system are computed using GPS-estimated precise tropospheric delay and weather data based model together. The proposed algorithm adopts spherical harmonics function to significantly reduce the message amounts and required number of GPS reference stations than the network RTK and Precise Point Positioning-RTK (PPP-RTK), while accurately modeling the spatial characteristic of tropospheric delay with weather data together.
In order to evaluate the user domain performance of the compact wide-area RTK system, this study conducted the feasibility test on mid-west and south USA using actual GPS measurements. As a result, the 95% horizontal position error is about 1.9 cm and the 95% vertical position error is 7.0 cm after the integer ambiguity is correctly fixed using GPS-only signals. The user ambiguity resolution takes about 2 minutes, and success-fix rate is about 100 % when stable tropospheric condition. In conclusion, the compact wide-area RTK system can provide centimeter-level positioning service to wide-area coverage with extremely low-speed data link via GEO satellite. We hope that this new system will consider as candidate solution for nationwide centimeter-level service such as satellite augmentation system of the Korea Positioning System (KPS).์ต๊ทผ ์์จ์ฃผํ์๋์ฐจ, ๋ฌด์ธ ๋๋ก ๋ฐฐ์ก, ์ถฉ๋ ํํผ, ๋ฌด์ธํธ๋ํฐ๋ฅผ ์ด์ฉํ ์ค๋งํธ ๋ฌด์ธ ๊ฒฝ์ ๋ฑ ์์ฑํญ๋ฒ์์คํ
(GNSS, Global Navigation Satellite System)์ ์ฌ์ฉํ๋ ๋ค์ํ ์์ฉ๋ถ์ผ์์ ์ cm ์์ค์ ์ ๋ฐ ์์น ์ ๋ณด์ ๋ํ ์๊ตฌ๊ฐ ๊ธ๊ฒฉํ ์ฆ๊ฐํ๊ณ ์๋ค. ๋ณธ ํ์๋
ผ๋ฌธ์์๋ 1 m ๊ธ์ ์ ํํ๊ณ ์ ๋ขฐ์ฑ ๋์ ์์น ์๋น์ค๋ฅผ ์ ๊ณตํ๋ ๊ธฐ์กด์ ์ ์ง๊ถค๋์์ฑ ๊ธฐ๋ฐ ๊ด์ญ ๋ณด๊ฐํญ๋ฒ ์์คํ
(SBAS, Satellite-Based Augmentation System)์ ๊ธฐ์ค๊ตญ ์ธํ๋ผ๋ฅผ ์ ์งํ๋ฉด์ ํญ๋ฒ ์ฑ๋ฅ์ ์ cm ์์ค์ผ๋ก ํฅ์์ํค๊ธฐ ์ํด ๋ฐ์กํ ์์ ๊ธฐ๋ฐ์ ์ด์ ๋ฐ ๋ณด์ ์ ๋ณด ์์ฑ ์๊ณ ๋ฆฌ์ฆ์ ๊ดํ ์ฐ๊ตฌ๋ฅผ ์ํํ์๋ค.
์ค์๊ฐ ์ ๋ฐ ์ธก์(RTK, Real-Time Kinematic)๋ ๋ฐ์กํ ์์ ์ธก์ ์น์ ํฌํจ๋ ๋ฏธ์ง์ ์๋ฅผ ์ ํํ๊ฒ ๊ฒฐ์ ํ์ฌ ์ cm ์์ค์ ์ ๋ฐ ํญ๋ฒ ์๋น์ค๋ฅผ ๊ฐ๋ฅํ๊ฒ ํ๋ ๋ํ์ ์ธ ๊ธฐ๋ฒ์ด๋ค. ๊ทธ ์ค์์๋ ์ฝ 50~70 km ๊ฐ๊ฒฉ์ผ๋ก ๋ถํฌ๋ ๋ค์์ ๊ธฐ์ค๊ตญ ์ ๋ณด๋ฅผ ํ์ฉํ๋ Network RTK ๊ธฐ๋ฒ์ ๋์ ์ฌ์ฉ์์ ๋น ๋ฅด๊ณ ์ ํํ ์์น ๊ฒฐ์ ์ด ๊ฐ๋ฅํ ์ธํ๋ผ๋ก์ ์ฃผ๋ชฉ๋ฐ๊ณ ์๋ค. ํ์ง๋ง ์ค์นผ๋ผ ํํ๋ก ๊ตฌ์ฑ๋ Network RTK ๋ณด์ ์ ๋ณด๋ ๊ฐ ๊ธฐ์ค๊ตญ ๋ณ๋ก ๊ด์ธก๋ ์์ฑ ์์ ๋ฐ๋ผ ์์ฑ์ด ๋๊ธฐ ๋๋ฌธ์ ๋ณด์ ๋ฐ์ดํฐ ๋์ด ์๋นํ ๋ฐฉ๋ํ๋ค. ๋ฉ์์ง ์ ์ก์ ํ์ํ ๋ฐ์ดํฐ ๋์ด ๋ง์์๋ก ๊ณ ์์ ํต์ ํ๊ฒฝ์ ํ์๋ก ํ๋ฉฐ, ๋ฉ์์ง ์๊ฐ ์ง์ฐ์ด๋ ํต์ ๋จ์ ์ ๋งค์ฐ ์ทจ์ฝํ ๋ฌธ์ ๋ฅผ ๊ฐ์ง๊ณ ์๋ค. ๋ํ ์ค์นผ๋ผ ํํ์ ๋ณด์ ์ ๋ณด๋ ์ฌ์ฉ์์ ๊ธฐ์ค๊ตญ ๊ฐ์ ๊ฑฐ๋ฆฌ๊ฐ ๋ฉ์ด์ง์๋ก ๋ณด์ ์ค์ฐจ๊ฐ ํฌ๊ฒ ๋ฐ์ํ๊ธฐ ๋๋ฌธ์ ๋๋ฅ ํน์ ๋๋ผ ๊ท๋ชจ์ ๊ด์ญ์์ ์๋น์คํ๊ธฐ ์ํด์๋ ์์ญ~์๋ฐฑ ๊ฐ ์ด์์ ๊ธฐ์ค๊ตญ ์ธํ๋ผ ๊ตฌ์ถ์ด ํ์์ ์ด๋ค. ์๋ฅผ ๋ค์ด, SBAS๊ฐ ํ๋ฐ๋ ์ง์ญ ์๋น์ค๋ฅผ ์ํด 5~7๊ฐ์ ๊ธฐ์ค๊ตญ์ด ํ์ํ ๋ฐ๋ฉด Network RTK๋ 90~100๊ฐ์ ๊ธฐ์ค๊ตญ์ด ํ์ํ๋ค. ์ฆ Network RTK๋ ์์คํ
๊ตฌ์ถ ๋ฐ ์ ์ง ๋น์ฉ์ด SBAS ๋๋น ์ฝ 15๋ฐฐ ์ ๋ ๋ง์ด ๋ค๊ฒ ๋๋ค.
๋ณธ ๋
ผ๋ฌธ์์๋ ๊ธฐ์กด Network RTK์ ๋ฌธ์ ์ ์ ํด๊ฒฐํ๊ธฐ ์ํ ๋ฐฉ๋ฒ์ผ๋ก ๋๋ฅ ๊ธ ๊ด๋ฒ์ํ ์์ญ์์ ์ค์๊ฐ์ผ๋ก cm๊ธ ์ด์ ๋ฐ ์์น๊ฒฐ์ ์๋น์ค ์ ๊ณต์ด ๊ฐ๋ฅํ Compact Wide-Area RTK ๋ผ๋ ์๋ก์ด ๊ฐ๋
์ ๊ด์ญ๋ณด๊ฐํญ๋ฒ์์คํ
์ํคํ
์ฒ๋ฅผ ์ ์ํ์๋ค. Compact Wide-Area RTK๋ ์ฝ 200~1,000 km ๊ฐ๊ฒฉ์ผ๋ก ๋๊ฒ ๋ถํฌ๋ ๊ธฐ์ค๊ตญ ๋คํธ์ํฌ๋ฅผ ํ์ฉํ์ฌ ๋ฐ์กํ ์์ ๊ธฐ๋ฐ์ ์ ๋ฐํ ์์ฑ ๊ถค๋ ๋ณด์ ์ ๋ณด, ์์ฑ Code/Phase ์๊ณ ๋ณด์ ์ ๋ณด, ๋๋ฅ์ธต ๋ณด์ ์ ๋ณด๋ฅผ ์์ฑํ๋ ์์คํ
์ด๋ค. ๊ธฐ์กด ์ค์นผ๋ผ ํํ์ Network RTK ๋ณด์ ์ ๋ณด ๋์ ์ค์ฐจ ์์ ๋ณ ๋ฒกํฐ ํํ์ ์ ๋ฐ ๋ณด์ ์ ๋ณด๋ฅผ ์์ฑํจ์ผ๋ก์จ ๋ฐ์ดํฐ ๋์ ํ๊ธฐ์ ์ผ๋ก ์ ๊ฐํ๊ณ ์๋น์ค ์์ญ์ ํ์ฅํ ์ ์๋ค. ์ต์ข
์ ์ผ๋ก SBAS์ ๋ง์ฐฌ๊ฐ์ง๋ก 250 bps์ ์ ์ ํต์ ๋งํฌ๋ฅผ ๊ฐ์ง ์ ์ง๊ถค๋์์ฑ์ ํตํด ๊ด์ญ์ผ๋ก ๋ณด์ ์ ๋ณด ๋ฐฉ์ก์ด ๊ฐ๋ฅํ๋ค.
๋ณธ ๋
ผ๋ฌธ์์๋ 3๊ฐ์ง ๋ณด์ ์ ๋ณด ์ค ์์ฑ Code/Phase ์๊ณ ๋ณด์ ์ ๋ณด์ ๋๋ฅ์ธต ๋ณด์ ์ ๋ณด ์์ฑ์ ์ํ ํต์ฌ ์๊ณ ๋ฆฌ์ฆ์ ๋ํด ์ค์ ์ ์ผ๋ก ์ฐ๊ตฌํ์๋ค. ๋ฐ์กํ ์์ ๊ธฐ๋ฐ์ ์ ๋ฐ ๋ณด์ ์ ๋ณด ์์ฑ์ ์ํด์๋ ๋จผ์ ๋ฏธ์ง์ ์๋ฅผ ์ ํํ๊ฒ ๊ฒฐ์ ํด์ผ ํ๋ค. ๋ณธ ๋
ผ๋ฌธ์์๋ ์ผ์ค ์ฃผํ์ ๋ฐ์กํ ์์ ์ธก์ ์น์ ๋ฌด-์ ๋ฆฌ์ธต ์กฐํฉ์ ํ์ฉํ์ฌ ์ ๋ฆฌ์ธต ๋ณด์ ์ ๋ณด ์์ด๋ ์ ํํ๊ฒ ๋ฏธ์ง์ ์ ๊ฒฐ์ ๊ฐ๋ฅํ ์๋ก์ด ๋ฐฉ๋ฒ์ ์ ์ํ์๋ค.
์์ฑ Code/Phase ์๊ณ ๋ณด์ ์ ๋ณด๋ ํต์ ์ง์ฐ ๋ฐ ๊ณ ์ฅ ์ ์ฐ์ํ๊ณ ๊ฐ๊ฑดํ ์ฑ๋ฅ์ ์ํด ๋ค์ค ๊ธฐ์ค๊ตญ์ ๋ชจ๋ ์ธก์ ์น๋ฅผ ํ์ฉํ์ฌ ์ถ์ ๋๋ค. ์ด ๋ ๊ฐ ๊ธฐ์ค๊ตญ ๋ณ ์๋ก ๋ค๋ฅธ ๋ฏธ์ง์ ์ ๋๋ฌธ์ ๋ฐ์ํ๋ ๋ฌธ์ ๋ ์์ ์ ํํ๊ฒ ๊ฒฐ์ ๋ ๊ธฐ์ค๊ตญ ๊ฐ ์ด์ค์ฐจ๋ถ ๋ ๋ฏธ์ง์ ์๋ฅผ ํ์ฉํ์ฌ ์์ค์ ์กฐ์ ํ๋ ๊ณผ์ ์ ํตํด ํด๊ฒฐ์ด ๊ฐ๋ฅํ๋ค. ๊ทธ ๊ฒฐ๊ณผ ์์ฑ๋ ์์ฑ Code/Phase ๋ณด์ ์ ๋ณด ๋ฉ์์ง์ ํฌ๊ธฐ, ๋ณํ์จ, ์ก์ ์์ค์ด ํฌ๊ฒ ๊ฐ์ ๋์๊ณ , ํต์ ์ง์ฐ ์ ์ค์ฐจ ๋ณด์ ์ฑ๋ฅ์ด ๊ธฐ์กด RTK ํ๋กํ ์ฝ ๋ณด๋ค 99% ํฅ์ ๋จ์ ํ์ธํ์๋ค.
๋๋ฅ์ธต ๋ณด์ ์ ๋ณด๋ ์ ์ ์์ ๊ธฐ์ค๊ตญ ๋ง์ ํ์ฉํ์ฌ ์ ํํ๊ฒ ๋๋ฅ์ธต์ ๋ชจ๋ธ๋งํ๊ธฐ ์ํด ์๋ ๊ธฐ์๊ด์ธก์์คํ
์ผ๋ก๋ถํฐ ์์งํ ๊ธฐ์ ์ ๋ณด๋ฅผ ์ถ๊ฐ๋ก ํ์ฉํ์ฌ ์์ฑ๋๋ค. ๋ณธ ๋
ผ๋ฌธ์์๋ GNSS ๊ธฐ์ค๊ตญ ๋คํธ์ํฌ๋ก๋ถํฐ ์ ๋ฐํ๊ฒ ์ถ์ ๋ ๋ฐ์กํ ์์ ๊ธฐ๋ฐ ์์ง ๋๋ฅ์ธต ์ง์ฐ๊ณผ ๊ธฐ์์ ๋ณด ๊ธฐ๋ฐ์ผ๋ก ๋ชจ๋ธ๋ง ๋ ์์ง ๋๋ฅ์ธต ์ง์ฐ์ ํจ๊ป ํ์ฉํ ์ ์๋ ์๋ก์ด ์๊ณ ๋ฆฌ์ฆ์ ์ ์ํ์๋ค. ๊ตฌ๋ฉด์กฐํํจ์๋ฅผ ์ฌ์ฉํ์ฌ Network RTK ๋ฐ PPP-RTK ๋ณด๋ค ํ์ํ ๋ฉ์์ง ์๊ณผ ๊ธฐ์ค๊ตญ ์๋ฅผ ํฌ๊ฒ ๊ฐ์์ํค๋ฉด์๋ RMS 2 cm ์์ค์ผ๋ก ์ ํํ ๋ณด์ ์ ๋ณด ์์ฑ์ด ๊ฐ๋ฅํจ์ ํ์ธํ์๋ค.
๋ณธ ๋
ผ๋ฌธ์์ ์ ์ํ Compact Wide-Area RTK ์์คํ
์ ํญ๋ฒ ์ฑ๋ฅ์ ๊ฒ์ฆํ๊ธฐ ์ํด ๋ฏธ๊ตญ ๋๋ถ ์ง์ญ 6๊ฐ ๊ธฐ์ค๊ตญ์ ์ค์ธก GPS ๋ฐ์ดํฐ๋ฅผ ํ์ฉํ์ฌ ํ
์คํธ๋ฅผ ์ํํ์๋ค. ๊ทธ ๊ฒฐ๊ณผ ์ ์ํ ์์คํ
์ ๋ฏธ์ง์ ์ ๊ฒฐ์ ์ดํ ์ฌ์ฉ์์ 95% ์ํ ์์น ์ค์ฐจ 1.9 cm, 95% ์์ง ์์น ์ค์ฐจ 7.0 cm ๋ก ์์น๋ฅผ ์ ํํ๊ฒ ๊ฒฐ์ ํ์๋ค. ์ฌ์ฉ์ ๋ฏธ์ง์ ์ ๊ฒฐ์ ์ฑ๋ฅ์ ๋๋ฅ์ธต ์์ ์ํ์์ ์ฝ 2๋ถ ๋ด๋ก 100% ์ ์ฑ๊ณต๋ฅ ์ ๊ฐ์ง๋ค. ๋ณธ ๋
ผ๋ฌธ์์ ์ ์ํ ์์คํ
์ด ํฅํ ํ๊ตญํ ์์ฑํญ๋ฒ ์์คํ
(KPS, Korean Positioning System)์ ์ ๊ตญ ๋จ์ ์ผํฐ๋ฏธํฐ ๊ธ ์๋น์ค๋ฅผ ์ํ ์๊ณ ๋ฆฌ์ฆ์ผ๋ก ํ์ฉ๋๊ธฐ๋ฅผ ๊ธฐ๋ํ๋ค.CHAPTER 1. Introduction 1
1.1 Motivation and Purpose 1
1.2 Former Research 4
1.3 Outline of the Dissertation 7
1.4 Contributions 8
CHAPTER 2. Overview of GNSS Augmentation System 11
2.1 GNSS Measurements 11
2.2 GNSS Error Sources 14
2.2.1 Traditional GNSS Error Sources 14
2.2.2 Special GNSS Error Sources 21
2.2.3 Summary 28
2.3 GNSS Augmentation System 29
2.3.1 Satellite-Based Augmentation System (SBAS) 29
2.3.2 Real-Time Kinematic (RTK) 32
2.3.3 Precise Point Positioning (PPP) 36
2.3.4 Summary 40
CHAPTER 3. Compact Wide-Area RTK System Architecture 43
3.1 Compact Wide-Area RTK Architecture 43
3.1.1 WARTK Reference Station (WRS) 48
3.1.2 WARTK Processing Facility (WPF) 51
3.1.3 WARTK User 58
3.2 Ambiguity Resolution and Validation Algorithms of Compact Wide-Area RTK System 59
3.2.1 Basic Theory of Ambiguity Resolution and Validation 60
3.2.2 A New Ambiguity Resolution Algorithms for Multi-Frequency Signals 65
3.2.3 Extra-Wide-Lane (EWL) Ambiguity Resolution 69
3.2.4 Wide-Lane (WL) Ambiguity Resolution 71
3.2.5 Narrow-Lane (NL) Ambiguity Resolution 78
3.3 Compact Wide-Area RTK Corrections 83
3.3.1 Satellite Orbit Corrections 86
3.3.2 Satellite Code/Phase Clock (CPC) Corrections 88
3.3.3 Tropospheric Corrections 89
3.3.4 Message Design for GEO Broadcasting 90
CHAPTER 4. Code/Phase Clock (CPC) Correction Generation Algorithm 93
4.1 Former Research of RTK Correction Protocol 93
4.1.1 Observation Based RTK Data Protocol 93
4.1.2 Correction Based RTK Data Protocol 95
4.1.3 Compact RTK Protocol 96
4.2 Satellite CPC Correction Generation Algorithm 100
4.2.1 Temporal Decorrelation Error Reduced Methods 102
4.2.2 Ambiguity Level Adjustment 105
4.2.3 Receiver Clock Synchronization 107
4.2.4 Averaging Filter of Satellite CPC Correction 108
4.2.5 Ambiguity Re-Initialization and Message Generation 109
4.3 Correction Performance Analysis Results 111
4.3.1 Feasibility Test Environments 111
4.3.2 Comparison of RTK Correction Protocol 113
4.3.3 Latency Compensation Performance Analysis 116
4.3.4 Message Data Bandwidth Analysis 119
CHAPTER 5. Tropospheric Correction Generation Algorithm 123
5.1 Former Research of Tropospheric Correction 123
5.1.1 Tropospheric Corrections for SBAS 124
5.1.2 Tropospheric Corrections of Network RTK 126
5.1.3 Tropospheric Corrections of PPP-RTK 130
5.2 Tropospheric Correction Generation Algorithm 136
5.2.1 ZWD Estimation Using Carrier-Phase Observations 138
5.2.2 ZWD Measurements Using Weather Data 142
5.2.3 Correction Generation Using Spherical Harmonics 149
5.2.4 Correction Applying Method for User 157
5.3 Correction Performance Analysis Results 159
5.3.1 Feasibility Test Environments 159
5.3.2 Zenith Correction Domain Analysis 161
5.3.3 Message Data Bandwidth Analysis 168
CHAPTER 6. Compact Wide-Area RTK User Test Results 169
6.1 Compact Wide-Area RTK User Process 169
6.2 User Performance Test Results 173
6.2.1 Feasibility Test Environments 173
6.2.2 User Range Domain Analysis 176
6.2.3 User Ambiguity Domain Analysis 182
6.2.4 User Position Domain Analysis 184
CHAPTER 7. Conclusions 189
Bibliography 193
์ด ๋ก 207Docto
Performance Evaluation of Different GNSS Positioning Modes
This paper gives a comparison of different GPS positioning modes using RTKLIB which is free and open-source software. The modes tested in this work are Single point positioning (SPP), precise point positioning (PPP), Satellite-based augmentation system (SBAS), Differential GPS (DGPS), and Real-Time Kinematic (RTK). The data for tests were obtained from NetR9 receivers, these types of receivers are multi-frequencies and multi-constellation receivers that provide carrier and phase measurements. The SPP mode is the very simplest mode, it can be used for applications where accuracy is not less than 5m, and it can be improved to achieve 1m by using SBAS corrections but only in the coverage area of the system. The DGPS can also provide 1m accuracy using a second receiver as a base station which can increase the cost of the operation. For applications that need very high accuracy, RTK and PPP can be used to reach centimeter-level accuracy. RTK needs a base station in addition to the rover receiver used for the positioning; PPP uses precise orbital and clock solutions which are not available in real time for all users
Using PPP Information to Implement a Global Real-Time Virtual Network DGNSS Approach
Global Navigation Satellite Systems (GNSS) provide positioning services for
connected and autonomous vehicles. Differential GNSS (DGNSS) has been
demonstrated to provide reliable, high quality range correction information
enabling real-time navigation with sub-meter or centimeter accuracy. However,
DGNSS requires a local reference station near each user, which for a
continental or global scale implementation would require a dense network of
reference stations whose construction and maintenance would be prohibitively
expensive. Precise Point Positioning (PPP) affords more flexibility as a public
service for GNSS receivers, but its State Space Representation (SSR) format is
not currently supported by most receivers. This article proposes a novel
Virtual Network DGNSS (VN-DGNSS) design that capitalizes on the PPP
infrastructure to provide global coverage for real-time navigation without
building physical reference stations. Correction information is computed using
data from public GNSS SSR data services and transmitted to users by Radio
Technical Commission for Maritime Services (RTCM) Observation Space
Representation (OSR) messages which are accepted by most receivers. The
real-time stationary and moving platform testing performance, using u-blox M8P
and ZED-F9P receivers, surpasses the Society of Automotive Engineering (SAE)
specification (68% of horizontal error 1.5 m and vertical error
3 m) and shows significantly better horizontal performance than
GNSS Open Service (OS). The moving tests also show better horizontal
performance than the ZEDF9P receiver with Satellite Based Augmentation Systems
(SBAS) enabled and achieve the lane-level accuracy which requires 95% of
horizontal errors less than 1 meter.Comment: 14 pages, 8 tables, 4 figures, Code and data are available at
https://github.com/Azurehappen/Virtual-Network-DGNSS-Projec
Performance Analysis of GPS Aided Geo Augmented Navigation (GAGAN) Over Sri Lanka
Satellite-Based Augmentation Systems (SBAS) are being developed worldwide due to their unique advantage of wide area coverage. GPS Aided Geo Augmented Navigation (GAGAN) is an Indian implementation of SBAS, with three (03) geo stationary satellites in space covering a huge area even beyond Indian Territory. This study focused on analyzing the improvement in position solution with GAGAN corrections over Sri Lanka. In order to test its performances, several dual and single frequency GNSS receivers have been used for this experiment and one receiver is configured as SBAS receiver and other two were kept as GPS stand-alone receivers. For investigate its coverage over Sri Lanka; observations were carried out over seven (07) known control stations of 6 different districts. At each of the tested stations the GAGAN active L1 receiver has always shown a significant accuracy improvement over L1 uncorrected observations. Further, five out of the 7 observation locations the calculated average 3D positional errors are lower than 1m. Almost 79% of observations (out of 24 hours of observations) have shown acceptable 3D positional accuracy, of less than 1m, for many spatial data collection applications. However, the local DGPS correction has shown higher reliability than GAGAN corrections with almost 85% of observations with less tan 1m, 3D positional error.Satellite-Based Augmentation Systems (SBAS) are being developed worldwide due to their unique advantage of wide area coverage. GPS Aided Geo Augmented Navigation (GAGAN) is an Indian implementation of SBAS, with three (03) geo stationary satellites in space covering a huge area even beyond Indian Territory. This study focused on analyzing the improvement in position solution with GAGAN corrections over Sri Lanka. In order to test its performances, several dual and single frequency GNSS receivers were used in this experiment, one receiver was configured as SBAS receiver and other two were kept as GPS stand-alone receivers. Observations were carried out over seven (07) known control stations of six (6) different districts to investigate its coverage over Sri Lanka. At each of the tested stations the GAGAN active L1 receiver has always shown a significant accuracy improvement over L1 uncorrected observations. Further, five out of the seven (7) observation locations the calculated average 3D positional errors were lower than 1 m. Almost 79% of observations (out of 24 hours of observations) have shown acceptable 3D positional accuracy, of less than 1m, for many spatial data collection applications. However, the local DGPS correction has shown higher reliability than GAGAN corrections with almost 85% of observations with less than 1 m, 3D positional error
Precise Orbit Determination of CubeSats
CubeSats are faced with some limitations, mainly due to the limited onboard power and the quality of the onboard sensors. These limitations significantly reduce CubeSats' applicability in space missions requiring high orbital accuracy. This thesis first investigates the limitations in the precise orbit determination of CubeSats and next develops algorithms and remedies to reach high orbital and clock accuracies. The outputs would help in increasing CubeSats' applicability in future space missions
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