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DGNSS of Korea, South Korea's industrial positioning Leading to the Ministry of Maritime Affairs and Fisheries Satellite Navigation Central Office

GALIILEO PROJECT

GALILEO is a global navigation satellite system (GNSS) intended primarily for civilian use that is currently being built by the European Union (EU) and European Space Agency (ESA) and is also referred to as the next-generation Global Navigation Satellite System (GNSS-2).

  • Europe’s GNSS Project
  • GNSS-1
  • GNSS-2
    • GALILEO Development Plan
    • GALILEO Services
    • Orbit formation
    • Signal
    • TCAR
    • Degree
    • Search and rescue service
    • Ground segment

Europe’s GNSS Project

Europe’s GNSS will service the entire area that is visible from the geostationary satellite. It will be comprised of GNSS-1 for wide-area DGPS positioning with accuracy of several meters by transmitting the corrected GPS and GLONASS data to aircrafts and ships and GNSS-2, which it is developing independently.

Europe’s GNSS Project
Name Purpose of use Target Commencement of services
GNSS-1 EGNOS Transmit the corrected GPS and GLONASS information Europe 1998
GNSS-2 GALILEO GNSS independently developed for civilian use Global 2008
  • In Europe, the European Geostationary Navigation Overlay System (EGNOS), a satellite based augmentation system (SBAS) similar to the Wide Area Augmentation System (WAAS), was developed. This is another name of GNSS-1, which was the first phase of the plan to develop next-generation GNSS. The European countries recognized the need to develop a new GNSS for civilian use that can substitute GPS and GLONASS, and began the GNSS project in response to the navigation satellite systems developed by the U.S. and Russia.

GNSS-1

GNSS-1 is comprised of the following three systems:

GBAS
  • Independent Regional Satellite Augmentation System (for transmission of corrected GPS and GLONASS data)
SBAS
  • Europe has developed EGNOS as a wide-area augmentation system. The ground stations are located in all the areas where EGNOS service is provided to measure and correct GPS signals, and they are connected to the main control station. The France Telecom's earth station in Aussaguel and that of Deutsche Telekom in Raisting will be used as primary access stations. AOR-E , IOR (Indian Ocean) and ARTEMIS will act as navigation transponders transmitting the corrected GPS and GLONASS information. Once the development of GALILEO is complete, EGNOS will be used to supplement the system.

GNSS-2

GALILEO is the first GNSS to be developed primarily for civilian use. It was initially developed because of the limitations in civilian and commercial uses of GPS (U.S.) and GLONASS (Russia), which had been developed for military use, and GALILEO could be a system that European nations could rely on, independently from GPA and GLONASS.

Although GALILEO itself is an independent system, its information can be analyzed together with GPS and GLONASS information. GTRF is measured, taking into account ITRF. GALILEO tells time in Coordinated Universal Time (UTC). The navigation information and messages it transmits include weather warnings, traffic information and accident warnings. Integrity information will be provided independently from the navigation information.

GALILEO Development Plan
  • EU and ESA initially planned to complete the overall technical design by the end of 2000, but is currently requesting assistance from countries around the world including the U.S., Russia and Japan. It is actively seeking assistance from Russia, the developer of GLONASS, due to the advantage of using FDMA-type frequency band. A joint pace testing of GALILEO by Germany and Russia were scheduled for 2003. Once it is in full operation, it is expected to provide high-precision location information with 4m 2DRMS and make an instantaneous determination of ambiguity using a carrier wave positioning method with three band carrier waves.
GALILEO Development Plan
Phase Description of development
Early stage (1999.10∼2000.12) GALILEO system design (equipment, development model, etc.)
Development (2001.01∼2001.12) Satellite design verification
Testing (2002.01∼2004.12) Production and launch of 3 MEO satellites, proof of hardware of some development equipment of ground stations and satellites
Development (2005.01∼2007.12) Orbit determination, production and launch of adjusted satellite, completed satellite arrangement and pilot system operation by ground stations
Supply (2008 ∼          ) Began supplying to European countries
  • Scope of Development by Organization
Scope of Development by Organization
GALA GALILEO General supervision of system development
GalileoSat Development of satellite system
GEMINUS Development of service system
INTEG Integrated development with EGNOS
SAGA Standardization process
SARGAL Satellite tracking and repair
GUST Development of GALILEO receivers
GALILEO Service
  • Information on user demand was systematically collected and analyzed to be reflected on service level, and the four basic service criteria were identified. Position, velocity and time (PVT) information will be provided for application by the mass market.
  • The GALILEO service was defined as follows based on the essential conditions of AI (Accuracy and Integrity) for subscribers in the specialized market, RT (Range and Time) for subscribers in the specialized market requiring highly accurate signals for subscribers in the market requiring stability in operation (highest reliability, potential and sustainability with resistance to interrupting signals):
GALILEO Service OAS
OAS(Open Service)
CAS(Control Service) CAS1(Commercial Service)
CAS2(Control Service) SAS(High-precision Service)
GAS(Non-civilian Service)
  • Both the Open Access Service (OAS) and Control Access Service (CAS) have global scope of application with maximum mask angle (under 25°), good probability (over 70%) and high precision (error of less than 10m). OAS will be provided to the mass market using low-cost receivers and is in direct competition against GPS. CAS, on the other hand, will be a commercial service with controlled access provided to paying subscribers (requiring Three Carrier Ambiguity Resolution, guarantee of services and fidelity). SAS will have a global scope of application with low mask angle (under 5°), high probability (over 99.9%) and high precision (error of less than 4m), and is controlled access service where the directors assume no responsibility. It is high-quality service with high fidelity and sufficient precision for Cat 1 stage.
    • The Government Access Service (GAS) will be a controlled access service provided at an independent frequency (C-band, if possible) with high integrity and security ensured by encrypted signals.
    • The services related to time will ensure high temporal precision (error of less than 33ns) in relation to OSA, CAS1 and SAS.
    • The fidelity service of Europe will be independent, and it will take a short time (less than 6 seconds) to send warnings to the system for CAS1 and SAS.
    • The search and rescue (selective) service will have two types of communication features of the COSPAS-SARST program.
    • Selective communication service for small scope and navigation-related communication
Orbit Formation
  • A large number of orbits were assessed through mock experiments that took into consideration the aspects of scope of application, accuracy, probability and cost. The orbits are to be comprised of 30 MEO satellites in a 3-dimensional space with an inclination angle of 56° located at an altitude of 23.616km. The time it takes to complete an orbit is 14 hr 21 min 6 sec. There are still disputes regarding the satellite arrangements; one side arguing for even arrangements of 10 satellites on each orbit or even arrangements of 9 satellites with one reserve satellite in case of malfunction or failure. It is still unknown how many satellites will be placed in the stationary orbits additionally for other purposes. The reasons for this were the high costs and inappropriate scope of application of high altitudes.
Signal
  • The signal structure can be explained by the quadrature method (the method of creating a rectangle with the same area as a circle) where the square root of the chip shaping cosine is taken to make effective use of the 4/Tc frequency band. The suggested round-off number of 0.2. The benefit of such shaping is that the chip duration is reduced by the perpendicular chip under comparison by about 50% for the delay-lock-loop early-rate shaping of a chip at frequency of 4/Tc. This flexibility improved the multi-pass resistance and noise differentiation to a corresponding level. However, chip shaping also means that the minimum point of automatic precision function (reducing the benefits of using the mutual precision relationship at the receiver) moderate. The navigation message can only be adjusted by the carrier within the steps. The carrier in the quadrature stage not only acquires the arrayed codes easily but also uses it as a pilot channel for code and transport stage arrangement. All data are encrypted by the encryption code in a ratio of 1/2. Three data flows were considered.
    • The effective ratio of 750bps of improved navigation data are separated as the data for the second satellite and as common data.
    • In the second segment, it is possible to process data simultaneously received from multiple satellites.
    • The improved navigation data changed to 1,500bps is commonly applied to all satellites.
    • The improved augmented navigation data (C-band carrier wave; approx. 12kbps) do not include time or assessment information.
Ground Segment
  • Monitoring of the ground segment of GALILEO and control of the satellite segment allows provision of faithful services and augments selective services such as search and rescue. The major functions are largely divided into two groups. The ground control and 성실의 결정체계 ground control system have the following functions:
    • Observations of satellite orbit (e.g., supplements number and satellite location)
    • Satellite adjustment (e.g., TT&C, two types of arrangements, orbiting practice)
    • Navigation adjustment (e.g., orbit prediction and decision, timing decision and time synchronization, SISA decision, uploading of navigation messages, execution control)
    • Service sharing functions (e.g., boundaries between the external users (실제들) and service providers)
  • The fidelity determining system has the following functions:
    • Fidelity decisions (e.g., data collection, calculation of fidelity, controlling the implementation of fidelity services)
    • Fidelity information uploading
  • There is a boundary between the fidelity determining systems between Europeans and non-Europeans. There are boundaries in the satellite arrangement, geodetic supplier and domestic and international time-determining services. All GALILEO satellites have laser range reflectors.