Galileo (satellite navigation)

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Galileo logo
Galileo agency is based in Prague

Galileo is a European global satellite navigation and timing system under civil control (European GNSS ). Galileo supplies data for precise positioning worldwide and is similar to the US NAVSTAR GPS , the Russian GLONASS system and the Chinese Beidou system. The systems differ mainly in terms of the frequency usage / modulation concepts, the type and number of services offered and the type of operator: GLONASS, Beidou and GPS are militarily operated, whereas Galileo is civilian and is financed by the European Union. The headquarters of the Agency for the European GNSS (Galileo Agency, GSA) has been in the Czech capital Prague since 2014 .

As of July 25, 2018, 26 satellites have been in orbit. Another 12 satellites are to be launched with Ariane 6 rockets in the coming years . The satellite navigation system has been available to the public since December 15, 2016 and can now be received by all modern chipsets (e.g. in smartphones).

The originally chargeable and encrypted service ( Commercial Service - CS) is to be rededicated to the public High Accuracy Service (HAS - high-precision service). This means that in the future all users will have access to three frequency bands free of charge and unencrypted, with which a worldwide accuracy of 20 cm can be achieved. Galileo would thus enable all users to achieve an accuracy that exceeds GPS, GLONASS and Beidou by a factor of 10.

States involved

Letter from Paul Wolfowitz to the defense ministers of the EU member states from December 2001, part of the US lobbying campaign against a Galileo that could not have been disrupted without influencing the military GPS signal

Galileo is the first of the European Union (EU) and the European Space Agency (ESA) jointly executed the project and part of the TEN - transport project . Both organizations took on the financing of the development in equal parts. On May 27, 2003 the member states of the ESA agreed on the financing.

The following countries outside the European Union also took part:

  • The People's Republic of China is involved in the project with EUR 280 million; a joint training center for satellite navigation was opened at Peking University .China People's RepublicPeople's Republic of China 
  • IndiaIndia India agreed to work together in September 2005. In October 2006 India questioned the cooperation and the co-financing of 300 million euros due to security-relevant aspects. (See also IRNSS )
  • IsraelIsrael Israel
  • MoroccoMorocco Morocco
  • Saudi ArabiaSaudi Arabia Saudi Arabia
  • SwitzerlandSwitzerland Switzerland (member of ESA), originally involved with 30 million euros, supplied (via Temex , which existed until 2006 , today (2019) Orolia ) for the four IOV and 22 FOC1 satellites the extremely precise Rubidium - (deviation from one second in 760,000 years) and hydrogen maser atomic clocks (deviation of one second in three million years)
  • NorwayNorway Norway (member of ESA)
  • Korea SouthSouth Korea South Korea
  • UkraineUkraine Ukraine

The following states are negotiating or negotiating to participate and may now be involved in the project:

Between October 21, 2011 and June 24, 2016, Russia launched the first 14 Galileo satellites into space with a Soyuz-2-1b Fregat-MT from the European Space Center in French Guiana .

Great Britain was excluded from the Galileo project after the United Kingdom left the EU because the EU does not share sensitive data with countries that are not part of the EU. This includes in particular the use of the non-public Public Regulated Service (PRS) and the participation of British companies in the development and integration of the satellites. Instead, the orders were re-awarded to ESA ESTEC in the Netherlands and OHB in Bremen.

The United States was initially skeptical of Galileo, especially with regard to the dangers of uncontrolled military use. After concerns about a technical interference with the NAVSTAR GPS system have been resolved, the USA is or was endeavoring to gain access to Galileo's military service (PRS).

Basics

Galileo is based on a basic constellation of 30 satellites (27 plus three continuously operational additional satellites, plus the ongoing replacement of satellites), which orbit the earth at an altitude of around 23,260 km at 3.6 km / s, and a network of ground stations that control the satellites. Receivers the size of mobile handheld devices such as smartphones or navigation systems can use the radio signals from the satellites to determine their own position with an accuracy of around four meters. When using additional information or services, similar to other satellite-based navigation systems ( GNSS ), the position accuracy can be increased to the centimeter range ( DGPS ).

Galileo was originally designed for civilian purposes only, but will also be “available” for operations under the European Security and Defense Policy (ESDP) through the resolution on space and security adopted by the European Parliament in July 2008 .

Satellite constellation

Constellation of the Galileo satellites without reserve satellites (click for animation)

30 satellites are planned. The current constellation can be seen in the list of Galileo satellites . The active satellites should form a Walker constellation (56 °: 24/3/1). Eight satellites are provided on three orbit levels with an inclination of 56 °. There are also reserve satellites. The distance between the satellites is 45 ° with a maximum deviation of 2 °. At an altitude of 23,222 km above the earth's surface, the satellites need about 14 hours for one orbit.

After 17 cycles or 10 days, the pattern of the ground track repeats itself .

Ground segment

Compared to other satellite systems, a satellite navigation system requires a large number of infrastructure elements on the ground. These are listed below:

  • Two equal control centers (GCC) in Oberpfaffenhofen ( Germany ) and Fucino ( Italy ). Oberpfaffenhofen nominally monitors and controls the satellite constellation, while Fucino is responsible for the provision of the navigation data as well as the highly precise orbit determination and time synchronization. In the event of a serious failure, the two control centers can serve as a backup for each other.
  • The GCC ensures that the satellites receive new navigation data at least every 100 minutes.
  • Six worldwide distributed ground stations (TTC) for satellite communication with 13-meter antennas in the S-band (2 GHz)
  • 30 reference receiving stations (GSS) distributed around the world for recording Galileo signals in the L-band . The control center uses these signals to calculate the navigation data (paths and time differences) every ten minutes.
  • Ten up-link stations (ULS) distributed around the world for the transmission of the Galileo navigation signals broadcast by the satellites, communication with 3-meter antennas in the C-band (5 GHz)
  • The security center (GSMC) in France ( St. Germain-en-Laye ) with a backup in Madrid. These are responsible for the official service (PRS) and system security.
  • Furthermore, additional service centers for performance monitoring, time referencing, geodetic services, coordination centers for the SAR service ...

The elements distributed around the world are largely installed on European territory, the French overseas territories are used to a large extent , but also stations on Norwegian territory (although Norway is not an EU member). Stations that were originally set up on UK territory (Ascension, Falklands) have now been removed in the wake of Brexit.

Financing and costs

Initially it was planned to finance the project through a public-private partnership (PPP). In 2007 the PPP broke up. The financing of Galileo was cleared on November 24, 2007. The money is said to come mainly from the savings in the EU agricultural sector.

Up to 2007, 1.5 billion euros had been invested in development. For the final expansion by 2013, 3.4 billion euros were originally planned from the EU budget.

According to the mid-term review by the EU Commission in January 2011, the costs will probably be significantly higher at 5.3 billion euros by 2020.

For the period 2014–2020, the European Union has provided funds totaling EUR 7 071.73 million for the Galileo and EGNOS programs. This envelope covers the management of the program, the establishment and operation of Galileo, the operation of EGNOS and the risks associated with these activities. By the end of 2016, the Galileo and EGNOS programs were well on their way to complying with the budget limits set by the GNSS Regulation for the period 2014–2020.

With the country leaving the EU , the United Kingdom will also lose the rights to use the Galileo system. At the 2018 G20 summit , the British government under Theresa May said it wanted to build its own satellite navigation system for around £ 5 billion. At that time, the country had already invested £ 1.2 billion in the joint project.

Project phases

First and second phase: planning

The ESA is financing the first project phase to define the tasks with around 100 million euros. The planning and definition phase concluded with the start and commissioning of two test satellites and the associated ground stations in January 2006. The test of the transmission frequencies had to take place before June 10, 2006, because otherwise the reservation for the Galileo frequency bands with the International Telecommunication Union (ITU) would have expired. The second phase of 2011 will end with the development, launch and testing of four Galileo satellites ( In Orbit Validation , IOV). At the beginning of 2003, the space agencies in Europe and Russia agreed to use the GLONASS satellites to test selected parts of the Galileo system. The compatibility of both systems should also be checked.

The European Union and ESA will jointly bear the costs of the second phase (development phase), which is expected to be 1.5 billion euros .

Within the ESA, Germany , Italy , France and Great Britain each take 17.5%. Spain pays 10% of the costs. Belgium pays € 26.5 million, the rest is shared among the other 15 ESA member states. The remaining EUR 750 million comes from the budget for trans-European networks of the European Union (TEN). Germany has a stake of around 25% in TEN through its EU contribution payments, making it the largest donor of the project. Phase C / D includes the operation of three to four fully functional satellites, the space segment, and the ground operating facilities, the ground segment . The ground segment consists of networked receiving and transmitting stations.

The German Aerospace Center (DLR) based in Neustrelitz and its facilities of the Remote Sensing Data Center and the Institute for Communication and Navigation played a key role in the development and operation of the Galileo predecessor system.

The first test satellite GIOVE-A1 (Galileo In-Orbit Validation Element) was launched on December 28, 2005 at 05:19  UTC from the space center in Baikonur (Kazakhstan) and started its scheduled operation at an altitude of 23,222 km. GIOVE-A transmitted the first navigation signal for test purposes on May 2, 2007.

GIOVE-B , the second test satellite, was also launched from the Baikonur Cosmodrome on April 26, 2008 at 22:16 UTC. As a new payload, it has laser retroreflectors for precise orbit measurement and a highly accurate passive hydrogen maser atomic clock. GIOVE-B's initial problems with aligning it to the sun due to a software problem were quickly resolved. On May 7th, 2008 he sent the first high-precision navigation signals.

The first major test phase began on February 4, 2011. The German Federal Transport Minister Peter Ramsauer (CSU) put the first European test region into operation in Berchtesgaden . The GATE project enables Galileo receivers to be tested. It operates terrestrial radio systems in the Berchtesgaden area that send out signals as will later be expected by Galileo. From then on, developers carried out practical tests under real operational and environmental conditions.

Test satellites

GIOVE-A1 - first test satellite

Designation: GIOVE-A ( Italian for Jupiter or Galileo In-Orbit Validation Element); Designation before the start: GSTB-v2 A (Galileo System Test Bed)
Payload: Signal generator, rubidium atomic clock , radiation monitor, navigation receiver
Manufacturer: Surrey Satellite Technology
Takeoff mass: 600 kg
Power: 700 W
Size: 1.3 m × 1.8 m × 1.65 m
Begin: December 28, 2005, 5:19 UTC
Decommissioning:  July 3, 2012 (but see below)
ID: COSPAR / WWAS Int Id: 2005-051A
ID: USStratCom Cat #: 28922
Carrier: Soyuz-FG / Fregat
Operating time: 87 months (planned 27 months)

GIOVE-B - second test satellite

Designation: GIOVE-B; Previous designation: GSTB-v2 B
Payload: Signal generator, rubidium atomic clock, radiation monitor, two passive hydrogen maser atomic clocks, laser retroreflector
Manufacturer: Galileo Industries consortium
Takeoff mass: 523 kg
Power: 943 W.
Size: 0.955 m × 0.955 m × 2.4 m
Begin: April 26, 2008, 10:16 pm UTC
Decommissioning:  July 23, 2012
ID: COSPAR / WWAS Int Id: 2008-020A
ID: USStratCom Cat #: 32781
Carrier: Soyuz frigate
Lifespan: 5 years

GIOVE-A2 - third test satellite

Manufacturer: Surrey Satellite Technology
Operating time:  27 months
Value: 25-30 million euros
Same construction as GIOVE-A1, extended signal generator. Since the start of GIOVE-B was successful, GIOVE-A2 has been canceled.

After its decommissioning, GIOVE-A1 was still used to demonstrate navigation in high orbits. The experimental GPS receiver on board was put into operation for the first time and the position was determined at an altitude of 23,300 km.

Test ground stations

Designation: GSTB-V1 - Sensor Stations Network
Number: 30

Third phase: construction

In the third phase, the construction phase, the system is completed.

Partial construction

Launch of the Soyuz rocket with the first two IOV satellites on October 21, 2011

In a first step, the In Orbit Validation (IOV), a first subsystem consisting of 4 satellites and the ground segments Ground Mission Segment (GMS) and Ground Control Segment (GCS) was established.

The first two satellites were launched on October 21, 2011 with the first Soyuz ST rocket launch from the European Space Center in French Guiana under the COSPAR designation 2011-060A and B. This was also the first launch of a Russian carrier rocket from a space center of the ESA . The other two IOV satellites were launched from Kourou on October 12, 2012 - again with a Soyuz rocket.

In March 2013, ESA reported that these four satellites could be used for the first time to determine the position independently and solely with the European system.

The creation of the full system configuration Full Operational Configuration (FOC) is divided into 6 work packages (Workpackage WP1-6). Contracts for WP1: System Support (system support), WP4: Satellites (initially 18) and WP5: Satellite launches were signed in January 2010, WP6: Operation followed on October 25, 2010. At the Paris Air Show 2011, the EU Commission announced the Contracts for WP2: Ground Mission Segment and WP3: Ground Control Segment concluded.

On November 20, 2013, the European Parliament approved the further financing of Galileo and EGNOS amounting to seven billion euros for the period 2014 to 2020.

The first launch of two FOC satellites took place on August 22, 2014. The sequence of the launches can be seen in the list of Galileo satellites .

Pilot operation

The Open Service , Public-State Service (PRS) and Search and Rescue Service went into pilot operation on December 15, 2016 with a constellation of 18 satellites. At this stage the system is not yet intended for critical applications.

In July 2019 there was a one-week total failure of the system. The trigger was a malfunction in the Precise Time Facility (PTF) in the Fucino control center, which provides the time information for the Galileo satellites. Although there is a redundant PTF in the Oberpfaffenhofen control center, it was not ready for use because the software was being updated. According to information from the Inside GNSS satellite navigation service , the PTF had already caused two disruptions in previous years.

completion

The completion of the FOC constellation is planned for 2021.

Fourth phase: operation

The fourth phase includes the operation and maintenance of the complete system. In January 2011, annual operating costs of 800 million euros were calculated for Galileo and EGNOS .

Satellites

On January 7, 2010, the EU Commission ordered the next 14 satellites for the Galileo system from the German space company OHB Technology , Bremen, for a total of around 566 million euros.

  • On October 21, 2011, the first two satellites built by EADS-Astrium in Ottobrunn, IOV-1 and -2, were successfully launched in their orbit at an altitude of 23,222 km. It was the first launch of a Russian Soyuz rocket from the ELS launch pad near Kourou.
  • On February 2, 2012, the EU Commission commissioned eight more satellites from OHB through ESA. Astrium was also commissioned to prepare Ariane 5 for the launch of four Galileo satellites each.
  • When launched on August 22, 2014, the first two FOC satellites (full operational capability) were deployed in an orbit that was significantly too low with high eccentricity and too low inclination (orbit inclination) ( perigee (proximity to the earth) 13,700 instead of 23,522 km, apogee (distance from the earth) 25,900 instead of 23,522 km, inclination 49.7 ° instead of 55.040 °). Initial analyzes indicate a wrong thrust vector of the Fregat upper stage in the apogee ignition. The cause of the wrong thrust was a frozen hydrazine line which, due to an assembly error, was attached directly to a deep-frozen helium line and which came into play due to the flight profile. An inspection at the manufacturer Lavochkin revealed the fault in one of four mounted Fregat upper stages. Both the inclination and the current orbital time of 11.7 hours are incompatible with the projected satellite constellation . The publication of the first results of the appointed investigative commission was postponed after an initial appointment to September 8 in favor of reports of success and postponed to the end of September. Once the solar panels have been deployed, the satellites are under full control of the ESA-CNES team. Other ESA teams are discussing ways to maximize the use of the satellites under non-scheduled orbits. Since they have high-precision atomic clocks on board, they are to be converted into measuring stations and test Einstein's theory of relativity with unprecedented accuracy. It is to be checked whether these clocks actually go faster in more distant areas of the terrestrial gravity field. Due to their unintentionally elliptical orbit, the satellites change their distance to the earth twice a day by around 8500 kilometers, and their position can be determined with lasers to within a few centimeters. This makes it possible to determine how the speed of the clocks depends on the distance to the earth's surface. On 27./28. September 2014, the satellites were handed over to the Galileo Control Center by ESOC. With eleven navigation maneuvers within 17 days it was possible to raise the perigee of Galileo 5 to around 17,235 km, on November 29, 2014 its first navigation signals could be received.
  • On January 18, 2017, ESA announced the failure of a total of nine of the atomic clocks on board several Galileo satellites. It was at that time six hydrogen maser clocks and three rubidium - atomic clocks failed. ESA announced that the phenomenon is being investigated. Since every Galileo satellite has 4 clocks and one of the satellites concerned is out of order, there are no restrictions on the navigation services. A tenth failed atomic clock could be restarted. The function of the Galileo navigation satellite network is not affected by this. The reason for the failures should be the conditions in space, which will be counteracted in the future by changing the operating voltage and temperature.
  • Galileo IOV 1-4
Manufacturer: EADS Astrium
Takeoff mass: 640 kg
Power: approx. 1.4 kW
Size: 3.02 m × 1.58 m × 1.59 m
Start date: October 21, 2011 (IOV 1,2), October 12, 2012 (IOV 3,4)
Carrier: Soyuz frigate
Lifespan: more than 12 years
Span of solar panels:  14.5 m
  • Galileo 1–22 satellites
Manufacturer: OHB System AG , payload: Surrey Satellite Technology
Takeoff mass: 680 kg
Power: 1.5 kW (after 12 years)
Size: 2.7 m × 1.2 m × 1.1 m
Start date: August 2014– July 2018
Carrier: Soyuz Fregat , Ariane 5
Lifespan: more than 12 years
Span of solar panels:  14.8 m

Each satellite is named after a child who won the European Commission's Galileo painting competition , with a winner being selected from each member country.

See also: List of Galileo satellites

Supervisory organizations and operators

IOV phase

On May 25, 2003, the EU and ESA founded the Galileo Joint Undertaking (GJU). It coordinated the development of the Galileo system in the IOV phase. This includes the first two test satellites GSTB-V2 (GIOVE-A and B), the commissioning of the first four satellites of the constellation in the IOV phase.

The GJU was to select the concessionaire for the construction and operation phase of Galileo in an open, multi-stage tendering process for a period of 20 years. As a result of the tendering process, it proposed cooperation between the competing consortia Eurely and iNavSat. The concession consortium at the beginning of 2007 comprised the following companies:

  1. AENA (Spanish public body responsible for air traffic control and airport management, among other things)
  2. Alcatel
  3. EADS Astrium
  4. Leonardo
  5. Hispasat
  6. Inmarsat
  7. Thales
  8. TeleOp
  9. and dozens of other associated companies.

At the end of 2006 the liquidation of the GJU was initiated. She did not achieve her goal of selecting a concessionaire for Galileo. The Agency for the European GNSS (GSA) of the European Commission took over the tasks of the GJU on January 1, 2007. ESA is no longer directly involved in it.

FOC phase

After the agreement in the Council for Economic and Financial Affairs of the EU on the financing of Galileo in the FOC phase, the GSA remains primarily responsible for the Galileo system on behalf of the EU. It commissions the Galileo Service Operating Company (GSOP) to operate the system. The ESA, however, is commissioned to further develop the system. This structure is to be retained beyond the end of the FOC phase.

Responsible operator Spaceopal

Spaceopal GmbH in Munich has been primarily responsible for the Galileo operation since 2010 . It is a joint venture between the DLR Society for Space Applications in Munich and the Italian space company Telespazio Spa based in Rome, which in turn is a joint venture between the Italian Leonardo SpA and the French Thales Group . Spaceopal has Galileo control centers in Oberpfaffenhofen and in the Fucino space center near Avezzano , Italy.

services

Galileo offers the following services:

This article or section needs to be revised: The High Accuracy Service does not yet exist, see discussion
Please help us to improve it , and then remove this flag.

Surname Abbr. German translation description Frequency ranges
Open service OS Open service Is in competition with or as a supplement to other systems such as GPS or GLONASS. It is free and can be received free of charge. License fees for the production of receivers are not charged. The open service enables you to determine your own position to within a few meters. It also provides the time according to an atomic clock (better than 10 −13 ). This also enables the speed at which the recipient is moving (e.g. in a motor vehicle) to be calculated.

It provides two transmission frequencies. This allows two-frequency receivers to take into account the dependence of the signal transit times on inhomogeneities in the ionosphere and to determine the position with an accuracy of approx. 4 meters. For this reason, GPS also uses two transmission frequencies (1227.60 MHz and 1575.42 MHz). The higher number of satellites, 27 compared to 24 for GPS, is intended to increase reception coverage in cities from 50% to 95%. A combination of several satellite systems (GPS, GLONASS) allows significantly better coverage of 15 satellites at any time. The constant availability of the service is not guaranteed.

1164-1214 MHz 1563-1591 MHz

High Accuracy Service

(formerly Commercial Service CS)

HAS Highly accurate service Complement to open service; unencrypted and freely receivable, but with an option for any subsequent encryption. Provides additional transmission frequencies and thus higher transmission rates of 448 bit / s. For example, correction data for increasing the position accuracy by one to two orders of magnitude can be received. Guarantees for the constant availability of this service are also planned. Optimizing application in industries such as mining, surveying, and cartography.

1164-1214 MHz 1260-1300 MHz 1563-1591 MHz

Public Regulated Service PRS Publicly regulated service or government service Is only available to users who have been approved by a special authority, e.g. B. armed forces , police , coast guard or intelligence services , but also operators of private critical infrastructure ( BOS and KRITIS ). As a dual-use service, it is also available for military applications, e.g. for controlling drones. The very strongly encrypted signal is largely secured against interference and falsification and is characterized by high accuracy and reliability.

1260-1300 MHz 1563-1591 MHz

Search and Rescue SAR Search and rescue service Complements the COSPAS-SARSAT system with a component in the Medium Earth Orbit ( MEOSAR ) and enables a significant improvement in the fast and global location of emergency transmitters on ships or aircraft. Since January 2020, Galileo has for the first time been able to reply from the rescue center to the emergency transmitter. MEOSAR uplink:
406.0-406.1 MHz

signal

GIOVE-A , L1 signal, sent January 2006

Galileo and GPS use the frequency band L1 at 1575.42 MHz and L5 at 1176.45 MHz. The L2 band at 1227.6 MHz is only available to GPS, for Galileo it is the E6 band at 1278.75 MHz. The spectrum shows the first test signal from GIOVE-A, which a high gain antenna received in January 2006.

Galileo satellites transmit at 50 watts. The transmission power is so low that a navigation receiver at a distance of 20,000 km with a simple rod antenna almost only receives noise from at least four satellites at the same time. Their signals are Doppler shifted. It also receives signals from GPS satellites on the same frequencies.

The recovery of the navigation data succeeds because each satellite z. B. on the L1 frequency a characteristic pseudo-noise signal, the spreading code with 1 MHz bandwidth, sends, which is modulated at a bit rate of 50 bit / s. By correlating with the pseudo-noise signal, receivers filter out the signals from the individual satellites.

The table lists the frequency bands, frequencies and modulation methods that Galileo uses. The two peaks of the L1 signal are labeled in the spectrum, as are the side maxima of the frequencies E1 and E2. The blue arrows mark the position of the GPS signals in the L1 band. Thanks to the different modulation ( BOC , BPSK ) there is little crosstalk between the signals.

Services and frequencies

tape Frequency name modulation Center frequency / maxima (1) [MHz] Frequency width commitment
L1 1575.42
L1B, L1C BOC (1.1) ± 1.023 1 OS, HAS
E1, E2 BOC (15,2.5) ± 15.345 2.5 PRS
L5 1191.795
E5a, E5b altBOC (15.10) ± 15.345 10 OS, HAS
E6 1278.75
E6b BPSK (5) 0 5 HAS
E6a BOC (10.5) 10.23 5 PRS

(1) Center frequency of the frequency band, position of the maxima in relation to the center frequency (in MHz)

GPS for comparison

tape Frequency name modulation Center frequency / maxima (1) [MHz] Frequency width commitment
L1 C / A BPSK (1) 1575.42 civil
P (y) BPSK (10) military (encrypted)
M code BOC (10.5) new military
L2 C / A BPSK (1) 1227.60 new civil
P (y) BPSK (10) military (encrypted)
M code BOC (10.5) new military
L5 new Civil BPSK (10) 1176.45 very new civil

(1) Center frequency of the frequency band, position of the maxima in relation to the center frequency (in MHz)

receiver

Older GNSS receivers can only receive GPS and GLONASS, as Galileo allows more precise position determination due to its more complex signal form, but is not directly compatible. Most modern receivers, however, are Galileo capable. A list of devices, services and applications that support Galileo is maintained by the GSA.

The open source project GNSS-SDR provides software that can be used to decode Galileo signals that have previously been recorded with a software-defined radio . In November 2013, a position with a scattering circle radius of 1.9 meters could be calculated from four satellite signals .

Other navigation systems

Performance comparison

Galileo competes with other navigation systems. The US-American GPS is used as the reference system. Compared to GPS, the Galileo satellites send a much stronger signal and that on three different frequency bands. The correction signals from EGNOS , a network of ground stations, enable a number of high-precision applications. Quality leaps are possible through the combination of the different information sources of different systems (GPS, GLONASS, Beidou, Galileo etc.) in the consumer segment since the appearance of the first Galileo / Beidou-compatible smartphone BQ Aquaris X5 +.

GPS (USA)

After years of negotiations, on June 26, 2004, during the USA-EU summit in Newmarket-on-Fergus ( Ireland ), the then US Secretary of State Colin Powell and the then Chairman of the EU Foreign Minister Brian Cowen signed a treaty on equality for GPS satellite navigation systems , GLONASS and Galileo. It is agreed that Galileo will be compatible with GPS III. This has the advantage that the combination of GPS and Galileo signals should achieve significantly improved coverage, with the availability of 15 satellites at any time. After completion of the Galileo setup, the possibility of combining the two systems will make a total of around 60 navigation satellites available. There are already GPS receivers (with U-blox5 or AsteRx chipset) that can also be used for Galileo after the firmware has been updated.

The prerequisite for the conclusion of the contract was that the EU renounced the BOC (1, 5) ( Binary Offset Carrier ) channel coding with a stronger band spread and instead used the BOC (1, 1) intended for future GPS satellites. BOC (1, 1) and the significantly lower frequency spread in contrast to BOC (1, 5) ensure that broadband interference of the Galileo signal to the extent of the civilian bandwidth does not simultaneously lead to interference of around a factor of 10 spread band military signal comes from GPS. This is because the same HF center carrier frequencies are used for both civil and military use (differentiation by means of code division multiplexing ) - the differentiation is only made using different coding methods. The resulting spectral coverage between BOC (1, 1) and the military GPS P / Y code or M code is only around 8%, while BOC (1, 5) would have resulted in over 50% spectral coverage. However, around 50% loss of decoders is associated with too many reception errors for the secure reception of the broadband GPS code used by the military, while in the event of disruptions in the narrowband civil navigation signal, a failure of only around 10% in the military code can be compensated for, among other things, through error correction procedures.

This adaptation in the channel coding of Galileo makes it possible, in addition to the C / A code of the GPS, to disrupt the civil Galileo navigation signal if necessary in locally limited areas by means of special GPS jammers , without the broadband GPS signal used by the military at the same time is significantly impaired. However, this contradicts Galileo's original idea, unlike GPS, to provide a jam-safe signal for safety-critical applications. Critics complain that the USA exerted pressure for military as well as economic reasons to make the Galileo signal disruptive.

The use of BOC (1, 1) with Galileo has no influence on the positional accuracy that can be achieved.

Similar to the NAVSTAR GPS system, Galileo offers a completely free service. With NAVSTAR-GPS , however, the freely receivable signal was deliberately deteriorated up to May 2, 2000 ( Selective Availability ). In addition to the freely available service, a commercial service is planned for Galileo, which is currently being defined. This service, which allows additional accuracy and security, can be limited to licensed users who also allow a payment model. However, a final decision has not yet been made.

The military GPS service, like the Galileo government service, is limited to selected users.

GLONASS (Russia)

Russia started commercial use of the GLONASS satellite system in 2010. The system gained full global coverage in October 2011.

Beidou / Compass (China)

China has been launching satellites for the Beidou navigation system into space since 2007 . Beidou is in direct competition with Galileo because it uses the same frequencies. The frequencies that are exclusively available to state security and rescue services are disputed. Although it was shown in a test that these do not interfere with each other, there is a possibility of deliberately interfering with the other system.

jammer

GPS Jammer (Engl. Jammer : jammers ) are similar to the GPS, probably the Galileo signals can be used to disrupt. These superimpose the signals from the satellites at the same frequency. Ideally, the same code sequences that are used for the code division multiplex method are transmitted with an invalid user data stream. This means that the receiver can no longer receive the actual navigation data from the satellite. Due to the interference of the code division multiplexing method by simulated code sequences, a transmission failure can be achieved with a significantly lower transmission power on the part of the jammer in the relevant frequency ranges than with noise uncorrelated to the code sequence or other uncorrelated interference signals.

Variants of jammers can also send out incorrect satellite position data to falsify the received satellite signal. Based on GPS, these are also referred to as GPS spoofers . Generating valid and plausible but incorrect satellite position data is, however, much more time-consuming than simply jamming using GPS jammers, because this requires, among other things, an exact time base on the jammer.

Galileo will, at least in the commercial areas and in the PRS, offer authentication to detect falsified satellite position data.

Abbreviations

At the Galileo project dozens involved various institutions. Accordingly, there are many names for the sub-projects, project phases, business areas and infrastructures. The most important abbreviations are:

  • GCC (Galileo Control Center): Control centers of the Galileo system
  • GCS (Ground Control Segment ): Part of the ground segment that is responsible for the operation of the satellites
  • GJU (Galileo Joint Undertaking): ESA / EU supervisory body for the preparation of Galileo (2003–2006), successor: GSA
  • GSA ( European G lobal Navigation S atellite Systems A gency ): Galileo supervisory authority, see European GNSS Agency
  • GMS (Ground Mission Segment): Part of the ground segment that is responsible for the orbit and time calculation and the provision of the content of the navigation signals
  • GRC (Ground Receiver Chain): Receiver for the navigation signals in the GSS in order to derive correction signals from them
  • GSS (Galileo Sensor station): GMS element: Reference receiving stations for navigation signals that send their measurement data (via cable or VSAT via geostationary satellites) to the GCC
  • GSTB-v2 A + B (Galileo System Test Bed v2): two test satellites to prepare the Galileo frequency ranges
  • GSTB-V1 (Galileo System Test Bed v1): Test infrastructure for the Galileo system
  • IPF (Integrity Processing Facility): GMS element for checking the Galileo navigation data integrity (not further developed with the removal of the SoL service in FOC)
  • OSPF: Orbit and Synchronization Processing Facility: GMS element that predicts the orbit parameters and the clock synchronization parameters for the individual satellite navigation signals
  • TTC (telemetry, tracking and command): satellite orbit tracking and satellite control
  • ULS (Up-Link Stations): GMS Element: The ground stations that supply the Galileo satellites with current navigation data from the OSPF

Further abbreviations for elements of the floor segment:

  • SCF: Satellite Control Facility (GCS)
  • SPF: Service Products Facility: Interface of the GMS to external facilities (GMS)
  • MUCF: Mission Control & Uplink Control Facility: Responsible for mission planning, monitoring the Galileo services and planning the ULS uplinks (GMS)
  • MSF: Mission Support Facility: Responsible for the calibration of the navigation algorithms (GMS)
  • MGF: Message Generation Facility: Element that converts the outputs of the IPF and OSPF into the navigation messages that are sent to the satellites via the ULS (GMS)
  • PTF: Precision Timing Facility: Element that generates the Galileo system time scale (GMS)
  • GACF: Ground Assets Control Facility: Technical monitoring and control of the GMS elements, also contains the archive (GMS)
  • KMF: Key Management Facility: Management of the PRS service and internal security tasks (GMS)

See also

literature

  • A positioning system. Galileo - Strategic, Scientific, and Technical Stakes. Académie de Marine, Bureau des Longitudes, Académie Nationale de l'Air et de l'Espace, Toulouse 2005.
  • François Barlier: Galileo. Un Enjeu Stratégique, Scientifique et Technique. L'Harmattan, Paris 2008, ISBN 978-2-296-05139-3 .
  • Scott W. Beidleman: GPS versus Galileo. Balancing for Position in Space. In: Astropolitics , July 3, 2005, 2, ISSN  1477-7622 , pp. 117-161.
  • Gustav Lindström, Giovanni Gasparini: The Galileo Satellite System and its Security Implications. In: European Union Institute for Security Studies - Occasional Paper , 44, ISSN  1608-5000 , ( PDF, 400 kB )
  • René Oosterlinck: Tracking by Satellite: GALILEO. In: The Security Economy , Papers from a forum meeting held on December 8, 2003 in the Paris Headquarters of the OECD. OECD, Paris 2004, ISBN 92-64-10772-X , pp. 77-90, ( PDF, 1.4 MB ).
  • Jean-Marc Piéplu, Olivier Salvatori: GPS et Galileo: Systèmes de navigation par satellites. Eyrolles, Paris 2006, ISBN 2-212-11947-X .
  • Torben Schüler, Stefan Wallner, Bernd Eissfeller: GALILEO development status with an outlook on the combination with GPS for fast RTK positioning. In: zfv - Journal for Geodesy, Geoinformation and Land Management , Issue 6/2009 (134, 2009, 6), Wißner-Verlag, Augsburg 2009, ISSN  1618-8950 , pp. 363-371.
  • Bernhard Hofmann-Wellenhof: Is Galileo late? In: zfv - Journal for Geodesy, Geoinformation and Land Management , Issue 4/2013 (138, 2013, 4), Wißner-Verlag, Augsburg 2013, ISSN  1618-8950 , pp. 241–248.
  • Seidler, C. (2015) European Navigation System: What Happened to… Galileo? Spiegel Online, September 10, 2015
  • Franziska Konitzer: Galileo, where am I? In: zfv - magazine for geodesy, geoinformation and land management , issue 3/2017, p. 131/132

Web links

Commons : Galileo (satellite navigation)  - collection of images, videos and audio files

Individual evidence

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