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Precise Time Reference: Difference between revisions
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GNSS technologies have a design dependence on accurate timing. The resolution of positioning equations depend on accurate time references and the four variables resolved are time plus the 3D coordinates. Each navigation satellite has atomic clocks that are synchronized from a master clock on the ground and the navigation messages are timestamped with the transmission time of the signal. | |||
This allows GNSS receiver to act as a worldwide synchronized time source with a precision that could only be maintained during long periods by expensive equipments. This enabled a wide set of applications that rely on synchronized and precise time sources. These applications can range from network synchronization and optimization to encryption and digital signature of electronic data. | |||
== Application Architecture == | == Application Architecture == | ||
Navigation satellites have extremely precise atomic clocks on board, which are so named because they use the oscillations of a particular atom as their “metronome”. This form of timing is the most stable and accurate reference that has ever been developed<ref name="Atomic">[http://www.esa.int/esaCP/SEMDG8ADFZD_Improving_0.html Atomic clocks for Galileo] ESA Portal, September 2004</ref>. | |||
The operation of satellite navigations systems is based on the method of triangulation. Knowing the distance from at least three points, i.e. three satellites, the receiver on the ground can calculate its position. The distances are calculated by measuring the time that a certain signal, known to the receiver and transmitted by the satellite, takes to travel the distance between the satellite and the user. Each signal contains information on the time reference of the atomic clock on board the satellite and information on the satellite’s orbit. This allows the user to determine the position of the satellite and his own distance from it with a high degree of accuracy<ref name="Atomic"/>. | |||
For this system of measurement to work, all satellites need to be synchronized so that they can start transmitting their signals at precisely the same time. This is achieved by continuously synchronizing all on-board atomic clocks with a master clock on the ground<ref name="About">[http://www.esa.int/esaNA/SEMMU7ARR1F_index_0.html About satellite navigation] ESA Portal, May 2011</ref>. | |||
== Application Characterization == | == Application Characterization == | ||
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== Application Examples == | == Application Examples == | ||
=== Network | === Network synchronization for power generation and distribution === | ||
The growing integration of networks for energy distribution and the emphasis on energy savings and efficiency require increasingly precise and accurate synchronisation. GNSS can provide the | The growing integration of networks for energy distribution and the emphasis on energy savings and efficiency require increasingly precise and accurate synchronisation. GNSS can provide the synchronization to achieve efficient power flow. For example, measurements of perturbations must be time-tagged with errors of less than 0.001 sec. Moreover, the management of high-power generators, such as large turbo gas and large steam turbines, requires strict timing<ref name="Energy">[http://www.galileoic.org/la/files/Energy.pdf Galileo Application Sheet - Energy Applications], ESA and European Commission, June 2002</ref>. | ||
Electrical energy is not easily stored and, in the case of malfunctions, current or voltage surges propagate along the lines. There is a tremendous potential for cost savings through the reliable remote reading of meters. Surges are sometimes large enough to damage line equipment and cause long interruptions in service. For tracing the origin of the problem and deciding on what action to take, time-tagging the individual events is mandatory. With time synchronisation at the microsecond level, the fault can be located to within 300 m – the distance between power line towers<ref name="Energy"/>. | Electrical energy is not easily stored and, in the case of malfunctions, current or voltage surges propagate along the lines. There is a tremendous potential for cost savings through the reliable remote reading of meters. Surges are sometimes large enough to damage line equipment and cause long interruptions in service. For tracing the origin of the problem and deciding on what action to take, time-tagging the individual events is mandatory. With time synchronisation at the microsecond level, the fault can be located to within 300 m – the distance between power line towers<ref name="Energy"/>. | ||
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Also satellite-navigation techniques could improve the communication capacity of networks. This is especially relevant for the UMTS third-generation using CDMA techniques. A precise time-synchronisation of the different base stations (the UMTS emitter-antennas) can significantly increase the traffic capability of the system. GNSS can be a reliable tool not only for positioning but also for timing. It will provide the mobile communications operator with a reliable and precise tool, with service guarantee, for increasing their network performance<ref name="Telecom"/>. | Also satellite-navigation techniques could improve the communication capacity of networks. This is especially relevant for the UMTS third-generation using CDMA techniques. A precise time-synchronisation of the different base stations (the UMTS emitter-antennas) can significantly increase the traffic capability of the system. GNSS can be a reliable tool not only for positioning but also for timing. It will provide the mobile communications operator with a reliable and precise tool, with service guarantee, for increasing their network performance<ref name="Telecom"/>. | ||
=== Data encryption and security | === Data encryption and security === | ||
The latest technologies for electronic encryption, signature and time-stamping rely on highly precise time references – at performance levels obtainable only from atomic clocks – so they are not affordable to mass-market users. The spread of the use of GNSS as a timing service enables the secure transmission via inexpensive terminals, thus bringing data security within the reach of us all<ref name="Finantial">[http://www.galileoic.org/la/files/Finantial.pdf Galileo Application Sheet - Finance, Banking, Insurance Applications], ESA and European Commission, June 2002</ref>. | The latest technologies for electronic encryption, signature and time-stamping rely on highly precise time references – at performance levels obtainable only from atomic clocks – so they are not affordable to mass-market users. The spread of the use of GNSS as a timing service enables the secure transmission via inexpensive terminals, thus bringing data security within the reach of us all<ref name="Finantial">[http://www.galileoic.org/la/files/Finantial.pdf Galileo Application Sheet - Finance, Banking, Insurance Applications], ESA and European Commission, June 2002</ref>. | ||
Revision as of 11:54, 28 July 2011
| Applications | |
|---|---|
| Title | Precise Time Reference |
| Author(s) | GMV. |
| Level | Medium |
| Year of Publication | 2011 |
GNSS technologies have a design dependence on accurate timing. The resolution of positioning equations depend on accurate time references and the four variables resolved are time plus the 3D coordinates. Each navigation satellite has atomic clocks that are synchronized from a master clock on the ground and the navigation messages are timestamped with the transmission time of the signal.
This allows GNSS receiver to act as a worldwide synchronized time source with a precision that could only be maintained during long periods by expensive equipments. This enabled a wide set of applications that rely on synchronized and precise time sources. These applications can range from network synchronization and optimization to encryption and digital signature of electronic data.
Application Architecture
Navigation satellites have extremely precise atomic clocks on board, which are so named because they use the oscillations of a particular atom as their “metronome”. This form of timing is the most stable and accurate reference that has ever been developed[1].
The operation of satellite navigations systems is based on the method of triangulation. Knowing the distance from at least three points, i.e. three satellites, the receiver on the ground can calculate its position. The distances are calculated by measuring the time that a certain signal, known to the receiver and transmitted by the satellite, takes to travel the distance between the satellite and the user. Each signal contains information on the time reference of the atomic clock on board the satellite and information on the satellite’s orbit. This allows the user to determine the position of the satellite and his own distance from it with a high degree of accuracy[1].
For this system of measurement to work, all satellites need to be synchronized so that they can start transmitting their signals at precisely the same time. This is achieved by continuously synchronizing all on-board atomic clocks with a master clock on the ground[2].
Application Characterization
Application Examples
Network synchronization for power generation and distribution
The growing integration of networks for energy distribution and the emphasis on energy savings and efficiency require increasingly precise and accurate synchronisation. GNSS can provide the synchronization to achieve efficient power flow. For example, measurements of perturbations must be time-tagged with errors of less than 0.001 sec. Moreover, the management of high-power generators, such as large turbo gas and large steam turbines, requires strict timing[3].
Electrical energy is not easily stored and, in the case of malfunctions, current or voltage surges propagate along the lines. There is a tremendous potential for cost savings through the reliable remote reading of meters. Surges are sometimes large enough to damage line equipment and cause long interruptions in service. For tracing the origin of the problem and deciding on what action to take, time-tagging the individual events is mandatory. With time synchronisation at the microsecond level, the fault can be located to within 300 m – the distance between power line towers[3].
Communication networks
New digital technologies and value-added time-sensitive services (real-time video, video conferencing, bank-to-bank encrypted exchange) need reliable network architectures (GSM, UMTS, Internet, ATM). Subscriber growth and consumer demand are driving the operators to emphasize quality, reliability and breadth of services. It is therefore imperative that network timing is addressed and that synchronization problems are solved. GNSS can provide high-precision timing and frequency information without the need to invest in expensive atomic clocks[4].
Also satellite-navigation techniques could improve the communication capacity of networks. This is especially relevant for the UMTS third-generation using CDMA techniques. A precise time-synchronisation of the different base stations (the UMTS emitter-antennas) can significantly increase the traffic capability of the system. GNSS can be a reliable tool not only for positioning but also for timing. It will provide the mobile communications operator with a reliable and precise tool, with service guarantee, for increasing their network performance[4].
Data encryption and security
The latest technologies for electronic encryption, signature and time-stamping rely on highly precise time references – at performance levels obtainable only from atomic clocks – so they are not affordable to mass-market users. The spread of the use of GNSS as a timing service enables the secure transmission via inexpensive terminals, thus bringing data security within the reach of us all[5].
These encryption, electronic signatures and time-stamping technologies can be used for securing and authenticate electronic documentation that have become an effective alternative to paper. Many applications for electronic documentation can be enabled by the use of GNSS technology for encryption, electronic signature and time-stamping[5]. Such approach is already being used in the financial sector where security, data integrity, authenticity and confidentiality depend on the accurate time stamps that can be enabled by GNSS[6]
Notes
References
- ^ a b Atomic clocks for Galileo ESA Portal, September 2004
- ^ About satellite navigation ESA Portal, May 2011
- ^ a b Galileo Application Sheet - Energy Applications, ESA and European Commission, June 2002
- ^ a b Galileo Application Sheet - Telecommunications Applications, ESA and European Commission, June 2002
- ^ a b Galileo Application Sheet - Finance, Banking, Insurance Applications, ESA and European Commission, June 2002
- ^ Europe’s Satellite Navigation Programmes - Galileo and EGNOS, GSA, 2008