Europe’s Quest for Satellite Navigation: The Structure of EGNOS and Galileo Dominic De Mello April 24, 2006

Europe and Satellite Navigation Search for a system started in 1995 Search for a system started in 1995 Developed the framework for EGNOS Developed the framework for EGNOS EGNOS went into operation in 2004 EGNOS went into operation in 2004 EGNOS technology will be integrated into Galileo in EGNOS technology will be integrated into Galileo in

EGNOS European Geostationary Navigation Overlay Service European Geostationary Navigation Overlay Service Precursor to Galileo Precursor to Galileo Enhances GPS/GLONASS Enhances GPS/GLONASS Has 3 segments: Has 3 segments: Space Segment Space Segment Ground Segment Ground Segment User Segment User Segment

Space Segment 3 Geostationary Earth Orbiting (GEO) satellites. 3 Geostationary Earth Orbiting (GEO) satellites. Their range stretches over Europe, the Mediterranean Sea and Africa Their range stretches over Europe, the Mediterranean Sea and Africa Connects to the Ground Segment Connects to the Ground Segment

Ground Segment Consists of: Consists of: 4 Mission Control Centers which contain a Central Processing Facility (CPF) 4 Mission Control Centers which contain a Central Processing Facility (CPF) 34 Ranging and Integrity Monitoring Stations (RIMS) 34 Ranging and Integrity Monitoring Stations (RIMS) 6 Navigation Land Earth Stations 6 Navigation Land Earth Stations Utilizes the EGNOS Network Time (ENT) Utilizes the EGNOS Network Time (ENT)

User Segment Consists of one of two receivers; one that uses GPS or one that uses GLONASS. Consists of one of two receivers; one that uses GPS or one that uses GLONASS. EGNOS is also programmed into that receiver. EGNOS is also programmed into that receiver. EGNOS helps sharpen the receiver’s position from 20 meters of error to as little as 5 meters of error. EGNOS helps sharpen the receiver’s position from 20 meters of error to as little as 5 meters of error.

EGNOS in Galileo EGNOS will be used when Galileo is operational in order to decrease errors. EGNOS will be used when Galileo is operational in order to decrease errors. The systems will use independent technology to ensure that both systems will not fail at the same time if an error occurs. The systems will use independent technology to ensure that both systems will not fail at the same time if an error occurs. This will ensure that Europe will always have some form of functioning satellite navigation. This will ensure that Europe will always have some form of functioning satellite navigation.

Europe and Satellite Navigation Search for their own system commenced in Search for their own system commenced in By 1999, planning was under way, and the name Galileo was chosen for the system. By 1999, planning was under way, and the name Galileo was chosen for the system. Was supposed to be fully operational by the end of 2008; looks like 2010 is more realistic Was supposed to be fully operational by the end of 2008; looks like 2010 is more realistic

Why was it developed? As opposed to GPS, which was developed primarily for military uses, Galileo was developed exclusively for civilian use. As opposed to GPS, which was developed primarily for military uses, Galileo was developed exclusively for civilian use. There are zero militarily uses for Galileo as of right now, and no plans for military use in the future. There are zero militarily uses for Galileo as of right now, and no plans for military use in the future.

Galileo Joint venture of European Space Agency (ESA) and European Union (EU) Joint venture of European Space Agency (ESA) and European Union (EU) Estimated cost of 3.2 billion euros Estimated cost of 3.2 billion euros 1.1 billion euros for the development. 1.1 billion euros for the development. 2.1 billion euros for the deployment. 2.1 billion euros for the deployment. 2 phases: EGNOS and Galileo 2 phases: EGNOS and Galileo

Galileo Technology 2 aspects of Galileo: 2 aspects of Galileo: Space Segment Space Segment Ground Segment Ground Segment

Space Segment Contains a total of 30 satellites; 27 are operational Contains a total of 30 satellites; 27 are operational 3 spare satellites 3 spare satellites Satellites are in 3 different planes, equally spaced around the plane. Satellites are in 3 different planes, equally spaced around the plane. Altitude = 23, 600 km Altitude = 23, 600 km Satellites are in Medium Earth Orbit (MEO) Satellites are in Medium Earth Orbit (MEO)

Space Segment Each satellite has a period of 14 hours and 22 minutes Each satellite has a period of 14 hours and 22 minutes Each satellite can last for 20 years, although they may be replaced every 12 years Each satellite can last for 20 years, although they may be replaced every 12 years At any point on earth, at least 6 satellites will be in view. At any point on earth, at least 6 satellites will be in view.

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Ground Segment 2 Control Stations Satellite control – monitors if the satellite orbits are on path Satellite control – monitors if the satellite orbits are on path Mission control - maintains the synchronization of satellite clocks Mission control - maintains the synchronization of satellite clocks

Galileo’s Services Galileo’s transmitted signals are used to provide 5 distinct services: Galileo’s transmitted signals are used to provide 5 distinct services: Open Service (OS) Open Service (OS) Safety of Life Service (SOLS) Safety of Life Service (SOLS) Commercial Service (CS) Commercial Service (CS) Public Regulated Service (PRS) Public Regulated Service (PRS) Search and Rescue Support Service (SAR) Search and Rescue Support Service (SAR)

Open Service OS can determine speed, velocity, and timing information OS can determine speed, velocity, and timing information Is free of charge and can be used on a handheld receiver Is free of charge and can be used on a handheld receiver Can also be used in car navigation systems Can also be used in car navigation systems Will never be intentionally jammed, Will never be intentionally jammed, Will have few ionospheric and tropospheric delays Will have few ionospheric and tropospheric delays Accurate to 15 meters Accurate to 15 meters

Safety of Life Service Utilized mainly for marine, rail or aeronautical purposes Utilized mainly for marine, rail or aeronautical purposes Guarantees a level of accuracy and authenticity that OC does not. Guarantees a level of accuracy and authenticity that OC does not. Offered openly, just like OS. Offered openly, just like OS. Accurate to 4-6 meters Accurate to 4-6 meters

Commercial Service Is encoded Is encoded Must pay fee in order to get encryption key Must pay fee in order to get encryption key Is much more precise than Open Service Is much more precise than Open Service Is accurate to 1 meter Is accurate to 1 meter Generates revenue for Galileo Generates revenue for Galileo

Public Regulated Service The PRS is used for governmental purposes The PRS is used for governmental purposes PRS is encoded; can be utilized by intelligence services, law enforcement, etc... PRS is encoded; can be utilized by intelligence services, law enforcement, etc... Is guaranteed to always have a continuous signal; this is its main strength over OS. Is guaranteed to always have a continuous signal; this is its main strength over OS. By utilizing “appropriate interference mitigation technologies”, the PRS is more accurate than OS. By utilizing “appropriate interference mitigation technologies”, the PRS is more accurate than OS. However, it is only accurate to about 10 meters However, it is only accurate to about 10 meters

Search and Rescue Support Service Detects emergency beacons Detects emergency beacons Pinpoints the location of incoming distress signals Pinpoints the location of incoming distress signals Allows rescuers to know exactly where a victim is. Allows rescuers to know exactly where a victim is. 10 minute period between distress signal and Galileo response. 10 minute period between distress signal and Galileo response.

Galileo Frequencies Each satellite transmits 6 navigational signals over 4 carrier frequencies Each satellite transmits 6 navigational signals over 4 carrier frequencies The Carriers are: The Carriers are: E5a ( Mhz) E5a ( Mhz) E5b ( Mhz) E5b ( Mhz) E6 ( Mhz) E6 ( Mhz) E2-L1-E1 ( Mhz) (same frequency as GPS L1) E2-L1-E1 ( Mhz) (same frequency as GPS L1)

Navigation Signals L1F Signal- OS; unencrypted L1F Signal- OS; unencrypted L1P Signal- PRS; encrypted L1P Signal- PRS; encrypted E6C Signal- Commercial Service; encrypted E6C Signal- Commercial Service; encrypted E6P Signal- PRS; encrypted E6P Signal- PRS; encrypted E5a- OS; unencrypted E5a- OS; unencrypted E5b- OS; unencrypted E5b- OS; unencrypted

Navigation Data Ephemeris data Ephemeris data Time parameters Time parameters Almanacs Almanacs Using this data, positioning for any user on earth can be derived. Using this data, positioning for any user on earth can be derived.

Ephemeris Data Indicates the position of the satellite which is nearest the user. Indicates the position of the satellite which is nearest the user. Provides 17 different parameters from each satellite Provides 17 different parameters from each satellite

Ephemeris Data

Time Parameters By accurately measuring the time between transmission and reception, the location of a receiver can be determined. By accurately measuring the time between transmission and reception, the location of a receiver can be determined. Galileo Standard Time (GST) is the time that Galileo uses. Galileo Standard Time (GST) is the time that Galileo uses. Each satellite broadcasts a Time of Transmission (TOT) Each satellite broadcasts a Time of Transmission (TOT) Satellite Time Corrections are employed. Satellite Time Corrections are employed.

Time Parameters Time Correction Formula: Time Correction Formula: “TOT(X)c=TOT(X)m-(ΔtSV) X “TOT(X)c=TOT(X)m-(ΔtSV) X ♦ TOT(X)C is the corrected satellite signal X TOT in GST time ♦ TOT(X)C is the corrected satellite signal X TOT in GST time ♦ TOT(X)m is the physical satellite signal X TOT, which is retrieved through pseudo-range measurements. ♦ TOT(X)m is the physical satellite signal X TOT, which is retrieved through pseudo-range measurements. ♦ (ΔtSV) X is the Satellite Time Correction for a specific signal X computed by the user using the data” ♦ (ΔtSV) X is the Satellite Time Correction for a specific signal X computed by the user using the data”

Galileo Standard Time Encrypted in Weeks and Time of Week Encrypted in Weeks and Time of Week 4096 weeks (78 years) 4096 weeks (78 years) The Weeks integer will be set back to zero after 4096 weeks elapse The Weeks integer will be set back to zero after 4096 weeks elapse Time of Week is encrypted in seconds Time of Week is encrypted in seconds 604,800 seconds in a week. 604,800 seconds in a week. The seconds integer is set back to zero after a week elapses. The seconds integer is set back to zero after a week elapses.

Almanacs Used to identify the position of all of the satellites that are in orbit. Used to identify the position of all of the satellites that are in orbit. Will identify: Will identify: Mean of Semi-Major Access Mean of Semi-Major Access Eccentricity Eccentricity Inclination Inclination Right Ascension of the Ascending Node Right Ascension of the Ascending Node Argument of Perigree Argument of Perigree Mean Anomaly Mean Anomaly

Satellite Signals Consist of a ranging code and data Consist of a ranging code and data Ranging code – “sequence of +1 and -1 with specific characteristics in the time (code length) and frequency (chip rate)” Ranging code – “sequence of +1 and -1 with specific characteristics in the time (code length) and frequency (chip rate)” Each satellite transmits a ranging code, but part of that sequence will always be unique to one satellite, so a receiver can identify from which satellite the data came from. Each satellite transmits a ranging code, but part of that sequence will always be unique to one satellite, so a receiver can identify from which satellite the data came from.

Encoding The signals are either encoded for OS, CS, or PRS. The signals are either encoded for OS, CS, or PRS. Based on what service you have, your receiver will decode the signal, and you will receive your coordinates. Based on what service you have, your receiver will decode the signal, and you will receive your coordinates.

Conclusion EGNOS and Galileo will ensure that there Europe will always have a functioning form of Satellite Navigation. EGNOS and Galileo will ensure that there Europe will always have a functioning form of Satellite Navigation. Europe will not be reliant on other countries since Galileo’s signal will never be interrupted Europe will not be reliant on other countries since Galileo’s signal will never be interrupted

Works Cited Lindstrom, Gustav. “The Galileo Satellite System and its Security Implications”. European Union Institute for Security Studies: 2003 Lindstrom, Gustav. “The Galileo Satellite System and its Security Implications”. European Union Institute for Security Studies: 2003

Works Cited Prasad, Ramjee. “Applied Satellite Navigation Using GPS, Galileo, and Augmentation Systems”. Artech House, “Program Galileo”. Galileo Joint Undertaking andardisation%20document%20for%203GP P.pdf andardisation%20document%20for%203GP P.pdf andardisation%20document%20for%203GP P.pdf