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EGNOS Project Office EGNOS Demonstration in CHINA 1 EGNOS Training Course EGNOS Demonstration in China EGNOS Demonstration in China O. Perrin, Tianjin,

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Presentation on theme: "EGNOS Project Office EGNOS Demonstration in CHINA 1 EGNOS Training Course EGNOS Demonstration in China EGNOS Demonstration in China O. Perrin, Tianjin,"— Presentation transcript:

1 EGNOS Project Office EGNOS Demonstration in CHINA 1 EGNOS Training Course EGNOS Demonstration in China EGNOS Demonstration in China O. Perrin, Tianjin, 2 December 2003

2 EGNOS Project Office EGNOS Demonstration in CHINA 2 Contents Short GPS Refresher Short GPS Refresher What exactly is this EGNOS Project ? What exactly is this EGNOS Project ? How does EGNOS work ? How does EGNOS work ? What is EGNOS transmitting ? What is EGNOS transmitting ? What is the user computing with the EGNOS signal ? What is the user computing with the EGNOS signal ?

3 EGNOS Project Office EGNOS Demonstration in CHINA 3 Contents Short GPS Refresher Short GPS Refresher What exactly is this EGNOS Project ? What exactly is this EGNOS Project ? How does EGNOS work ? How does EGNOS work ? What is EGNOS transmitting ? What is EGNOS transmitting ? What is the user computing with the EGNOS signal ? What is the user computing with the EGNOS signal ?

4 EGNOS Project Office EGNOS Demonstration in CHINA 4 GPS Basics NAVSTAR GPS NAVSTAR GPS Navigation Signal Timing and Ranging, Global Positioning System Navigation Signal Timing and Ranging, Global Positioning System USA Satellite Navigation System USA Satellite Navigation System Developed in the 60s Developed in the 60s Merge of Transit and Timation projects Merge of Transit and Timation projects Military system made available free of charge to the civil user community Military system made available free of charge to the civil user community

5 EGNOS Project Office EGNOS Demonstration in CHINA 5 GPS Space Segment Currently 28 operational satellites Currently 28 operational satellites Block I not available any more Block I not available any more Currently block II and IIA satellites only Currently block II and IIA satellites only Currently launched satellites IIR (in the future IIR-M with new L2C and M codes) Currently launched satellites IIR (in the future IIR-M with new L2C and M codes) Evolutions: block IIF (L5) and GPS III Evolutions: block IIF (L5) and GPS III Fitted with atomic clocks (Rubidium or Caesium) for stable frequency reference Fitted with atomic clocks (Rubidium or Caesium) for stable frequency reference

6 EGNOS Project Office EGNOS Demonstration in CHINA 6 GPS orbits Medium Earth Orbits (MEO) Medium Earth Orbits (MEO) 6 orbital planes, inclination 55 degrees 6 orbital planes, inclination 55 degrees 4 operational plus 1 spare per plane 4 operational plus 1 spare per plane Altitude of ~20200 km Altitude of ~20200 km Orbital period of ~12 hours Orbital period of ~12 hours Repetition of orbits in ~24 hours (23 hours 56 minutes) Repetition of orbits in ~24 hours (23 hours 56 minutes)

7 EGNOS Project Office EGNOS Demonstration in CHINA 7 GPS Signal Structure Carrier frequencies Carrier frequencies L MHz L MHz L MHz L MHz Ranging codes Ranging codes L1: C/A (civil) and P (military) L1: C/A (civil) and P (military) L2: P (military) L2: P (military) Right Hand Circularly Polarized Signal Right Hand Circularly Polarized Signal

8 EGNOS Project Office EGNOS Demonstration in CHINA 8 C/A ranging code Pseudo Random Noise (PRN) to identify the satellites (CDMA) Pseudo Random Noise (PRN) to identify the satellites (CDMA) Navigation data Navigation data 50 bps 50 bps Satellite ephemeris Satellite ephemeris Satellite almanacs (whole constellation) Satellite almanacs (whole constellation) Satellite health status Satellite health status UTC information UTC information Ionospheric parameters Ionospheric parameters Satellite clock correction Satellite clock correction

9 EGNOS Project Office EGNOS Demonstration in CHINA 9 GPS Ground Segment 1 Master Control Station 1 Master Control Station Located in Colorado Springs, USA Located in Colorado Springs, USA 5 Monitoring Stations 5 Monitoring Stations Hawaii, Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs Hawaii, Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs However, constant tracking of all satellites is not achieved However, constant tracking of all satellites is not achieved One of the reasons for lack of integrity One of the reasons for lack of integrity Need for an augmentation for safety-of-life users Need for an augmentation for safety-of-life users

10 EGNOS Project Office EGNOS Demonstration in CHINA 10 GPS User Segment (receivers) Measure the travel time of the signal and multiply it by the speed of light (one-way ranging) Measure the travel time of the signal and multiply it by the speed of light (one-way ranging) Computation of 3D position by triangulation Computation of 3D position by triangulation Rx clock is usually not an atomic clock Rx clock is usually not an atomic clock Rx clock offset is an additional unknown Rx clock offset is an additional unknown Rx measure pseudo-distances Rx measure pseudo-distances 4 satellites are needed to compute a position (3 coordinates plus receiver clock) 4 satellites are needed to compute a position (3 coordinates plus receiver clock)

11 EGNOS Project Office EGNOS Demonstration in CHINA 11 Contents Short GPS Refresher Short GPS Refresher What exactly is this EGNOS Project ? What exactly is this EGNOS Project ? How does EGNOS work ? How does EGNOS work ? What is EGNOS transmitting ? What is EGNOS transmitting ? What is the user computing with the EGNOS signal ? What is the user computing with the EGNOS signal ?

12 EGNOS Project Office EGNOS Demonstration in CHINA 12 EGNOS Background European Geostationary Navigation Overlay Service European Geostationary Navigation Overlay Service Global Navigation Satellite System of the 1 st generation (GNSS-1) Global Navigation Satellite System of the 1 st generation (GNSS-1) Augmentation of the existing GPS (US) and GLONASS (Russia) constellations Augmentation of the existing GPS (US) and GLONASS (Russia) constellations Project launched in 1998 Project launched in 1998 Service for safety-of-life users Service for safety-of-life users

13 EGNOS Project Office EGNOS Demonstration in CHINA 13 EGNOS Partners European Tripartite Group European Tripartite Group European Space Agency ESA European Space Agency ESA Part of ARTES 9 program Part of ARTES 9 program European Commission European Commission Multimodal users and funding Multimodal users and funding Eurocontrol Eurocontrol Civil aviation users Civil aviation users

14 EGNOS Project Office EGNOS Demonstration in CHINA 14 EGNOS Schedule Critical Design Review Critical Design Review January 2002 January 2002 EGNOS design frozen EGNOS design frozen Operational Readiness Review Operational Readiness Review Technical validation of EGNOS Technical validation of EGNOS Start of initial operations Start of initial operations

15 EGNOS Project Office EGNOS Demonstration in CHINA 15 And the ESTB ? EGNOS System Test Bed EGNOS System Test Bed Prototype system of EGNOS available since early 2000 Prototype system of EGNOS available since early 2000 Reduced system Reduced system Allows users to gain experience by tests and demonstrations Allows users to gain experience by tests and demonstrations Allows testing of expansion capability Allows testing of expansion capability System used for the Chinese tests System used for the Chinese tests

16 EGNOS Project Office EGNOS Demonstration in CHINA 16 Contents Short GPS Refresher Short GPS Refresher What exactly is this EGNOS Project ? What exactly is this EGNOS Project ? How does EGNOS work ? How does EGNOS work ? What is EGNOS transmitting ? What is EGNOS transmitting ? What is the user computing with the EGNOS signal ? What is the user computing with the EGNOS signal ?

17 EGNOS Project Office EGNOS Demonstration in CHINA 17 EGNOS Architecture

18 EGNOS Project Office EGNOS Demonstration in CHINA 18 Ground Segment: RIMS Ranging and Integrity Monitoring Stations Ranging and Integrity Monitoring Stations Channels A and B for redundancy Channels A and B for redundancy Some stations have a channel C Some stations have a channel C Equipped with an L1/L2 receiver and atomic clock for precise timing Equipped with an L1/L2 receiver and atomic clock for precise timing Track GPS, GLONASS and GEO Track GPS, GLONASS and GEO EGNOS: 34, ESTB: 12 (+ 3 China) EGNOS: 34, ESTB: 12 (+ 3 China)

19 EGNOS Project Office EGNOS Demonstration in CHINA 19 Ground Segment: MCC Master Control Centres Master Control Centres Central Processing Facility (CPF) Central Processing Facility (CPF) Automatic processing of raw data coming from RIMS Automatic processing of raw data coming from RIMS Independent check of measurements of RIMS A by RIMS B Independent check of measurements of RIMS A by RIMS B Central Control Facility (CCF) Central Control Facility (CCF) Monitoring and control of EGNOS Monitoring and control of EGNOS EGNOS: 4, ESTB: 1 EGNOS: 4, ESTB: 1

20 EGNOS Project Office EGNOS Demonstration in CHINA 20 What is the CPF computing ? Integrity Information Integrity Information For each satellite monitored For each satellite monitored Differential Corrections Differential Corrections Pseudo-range corrections Pseudo-range corrections Orbit and clock corrections Orbit and clock corrections Ionospheric Corrections Ionospheric Corrections Single layer ionospheric model for L1 Single layer ionospheric model for L1

21 EGNOS Project Office EGNOS Demonstration in CHINA 21 Ground Segment: NLES Navigation Land Earth Station Navigation Land Earth Station Transmitting the augmentation message to each GEO satellite Transmitting the augmentation message to each GEO satellite EGNOS: 6 (2 per GEO), ESTB: 1 EGNOS: 6 (2 per GEO), ESTB: 1

22 EGNOS Project Office EGNOS Demonstration in CHINA 22 Space Segment Existing GPS and GLONASS Existing GPS and GLONASS 3 Geostationary Satellites 3 Geostationary Satellites Inmarsat AOR-E (PRN 120) Inmarsat AOR-E (PRN 120) Inmarsat IOR-W (PRN 126) Inmarsat IOR-W (PRN 126) Artemis (PRN 124) Artemis (PRN 124) Broadcasting an augmentation signal on GPS frequency L1 Broadcasting an augmentation signal on GPS frequency L1 EGNOS: 3 GEOs, ESTB: 1 (IOR, 131) EGNOS: 3 GEOs, ESTB: 1 (IOR, 131)

23 EGNOS Project Office EGNOS Demonstration in CHINA 23 User Segment Any user equipped with a GPS receiver with firmware able to process SBAS data (EGNOS is broadcast on L1) Any user equipped with a GPS receiver with firmware able to process SBAS data (EGNOS is broadcast on L1) Mainly navigation applications Mainly navigation applications Civil aviation Civil aviation Road transports Road transports Maritime Maritime Rail Rail

24 EGNOS Project Office EGNOS Demonstration in CHINA 24 What is EGNOS providing ? Improved availability Improved availability The GEOs can be used as additional ranging sources (GPS-like) The GEOs can be used as additional ranging sources (GPS-like) Improved accuracy Improved accuracy Thanks to differential corrections Thanks to differential corrections Improved integrity Improved integrity Thanks to real-time monitoring (6s TTA) Thanks to real-time monitoring (6s TTA) Improved continuity Improved continuity

25 EGNOS Project Office EGNOS Demonstration in CHINA 25 Contents Short GPS Refresher Short GPS Refresher What exactly is this EGNOS Project ? What exactly is this EGNOS Project ? How does EGNOS work ? How does EGNOS work ? What is EGNOS transmitting ? What is EGNOS transmitting ? What is the user computing with the EGNOS signal ? What is the user computing with the EGNOS signal ?

26 EGNOS Project Office EGNOS Demonstration in CHINA 26 EGNOS/ESTB signal Specifications in RTCA MOPS DO229 Specifications in RTCA MOPS DO229 EGNOS SIS is broadcast on the GPS L1 ( MHz) EGNOS SIS is broadcast on the GPS L1 ( MHz) GEOs use GPS-like PRN code (ESTB: IOR, PRN 131) GEOs use GPS-like PRN code (ESTB: IOR, PRN 131) Data rate 250 bits per second Data rate 250 bits per second 5 times faster than GPS data rate 5 times faster than GPS data rate Forward Error Correction code Forward Error Correction code

27 EGNOS Project Office EGNOS Demonstration in CHINA 27 Message Structure 1 message = 250 bits = 1 second 1 message = 250 bits = 1 second 250-bit message structure 250-bit message structure 8-bit message preamble (for data acquisition purposes) 8-bit message preamble (for data acquisition purposes) 6-bit message type identifier (0 – 63) 6-bit message type identifier (0 – 63) 212-bit message data 212-bit message data 24-bit message parity (Cyclic Redundancy Check) 24-bit message parity (Cyclic Redundancy Check)

28 EGNOS Project Office EGNOS Demonstration in CHINA 28 Message Type 0 Do not use the GEO for safety applications Do not use the GEO for safety applications Transmitted every time there is a major problem and the system is completely unavailable Transmitted every time there is a major problem and the system is completely unavailable Transmitted during testing phases Transmitted during testing phases In ESTB, MT0 contains pseudorange corrections (1 MT 2 in each MT 0 for bandwidth saving reasons) In ESTB, MT0 contains pseudorange corrections (1 MT 2 in each MT 0 for bandwidth saving reasons)

29 EGNOS Project Office EGNOS Demonstration in CHINA 29 Message Type 1 Mask for assignation of the satellites Mask for assignation of the satellites GPS (PRN 1-37) GPS (PRN 1-37) GLONASS (PRN 38-61) GLONASS (PRN 38-61) SBAS (PRN ) SBAS (PRN ) Application of the corrections to the right satellite (maximum 51) Application of the corrections to the right satellite (maximum 51)

30 EGNOS Project Office EGNOS Demonstration in CHINA 30 Fast Corrections Correction of the fast changing errors (S/A) Correction of the fast changing errors (S/A) Pseudorange correction for each satellite Pseudorange correction for each satellite MT 2-5: Fast Corrections for 13 satellites MT 2-5: Fast Corrections for 13 satellites Fast correction to be applied to the pseudorange Fast correction to be applied to the pseudorange Integrity: User Differential Range Error Indicator (UDREI) (quality of the pseudorange after the application of corrections) Integrity: User Differential Range Error Indicator (UDREI) (quality of the pseudorange after the application of corrections) Referring to UDRE (upper bound on the pseudorange error after application of the fast corrections, with 99.9% probability) Referring to UDRE (upper bound on the pseudorange error after application of the fast corrections, with 99.9% probability)

31 EGNOS Project Office EGNOS Demonstration in CHINA 31 UDREI Can be transmitted in Can be transmitted in MT 2-5 (normal case) MT 2-5 (normal case) MT 6 (all UDREIs, case of an alarm) MT 6 (all UDREIs, case of an alarm)

32 EGNOS Project Office EGNOS Demonstration in CHINA 32 Long Term Corrections Corrections for slow varying errors (satellite position, satellite clock) Corrections for slow varying errors (satellite position, satellite clock) MT 25: Long-term Satellite Error Corrections MT 25: Long-term Satellite Error Corrections Satellite position correction (3 parameters) Satellite position correction (3 parameters) Satellite velocity correction (3 parameters) Satellite velocity correction (3 parameters) Satellite clock correction (2 parameters) Satellite clock correction (2 parameters) If no velocity information 4 satellites otherwise only 2 satellites If no velocity information 4 satellites otherwise only 2 satellites MT 24: Mixed Fast Corrections / Long-term Satellite Error Corrections (not ESTB) MT 24: Mixed Fast Corrections / Long-term Satellite Error Corrections (not ESTB)

33 EGNOS Project Office EGNOS Demonstration in CHINA 33 Ionospheric Corrections MT 18: ionospheric mask MT 18: ionospheric mask Ionospheric Grid Points (IGP) mask Ionospheric Grid Points (IGP) mask 1808 IGPs (11 bands) all around the world at an altitude of 350 km (pre-defined) 1808 IGPs (11 bands) all around the world at an altitude of 350 km (pre-defined) MT 26: L1 ionospheric corrections MT 26: L1 ionospheric corrections Vertical delay estimate for 15 IGPs (imaginary satellite exactly above the IGP, 90° elevation) Vertical delay estimate for 15 IGPs (imaginary satellite exactly above the IGP, 90° elevation) Integrity: Grid Ionospheric Vertical Error Indicator (GIVEI) (0-15) is also transmitted Integrity: Grid Ionospheric Vertical Error Indicator (GIVEI) (0-15) is also transmitted Refers to GIVE ( m 2 - Not Monitored) Refers to GIVE ( m 2 - Not Monitored)

34 EGNOS Project Office EGNOS Demonstration in CHINA 34 IGPs for the world

35 EGNOS Project Office EGNOS Demonstration in CHINA 35 Ionospheric Delay Computation Ionospheric Pierce Point (IPP) Ionospheric Pierce Point (IPP)

36 EGNOS Project Office EGNOS Demonstration in CHINA 36 Ionospheric Delay Computation Interpolation and slant delay computation Interpolation and slant delay computation

37 EGNOS Project Office EGNOS Demonstration in CHINA 37 Degradation parameters In case the user misses one or more messages In case the user misses one or more messages MT 7: Fast Corrections Degradation MT 7: Fast Corrections Degradation UDRE degradation UDRE degradation How quick the corrections change How quick the corrections change MT 10: Degradation Factors MT 10: Degradation Factors 15 parameters to evaluate the degradation of long-term and ionospheric corrections 15 parameters to evaluate the degradation of long-term and ionospheric corrections

38 EGNOS Project Office EGNOS Demonstration in CHINA 38 GEO Navigation Message MT 9: GEO Ranging Function Parameters (Ephemeris) for 1 GEO MT 9: GEO Ranging Function Parameters (Ephemeris) for 1 GEO GEO satellite position (X, Y, Z) GEO satellite position (X, Y, Z) GEO satellite velocity (V X, V Y, V Z ) GEO satellite velocity (V X, V Y, V Z ) GEO satellite acceleration (a X, a Y, a Z ) GEO satellite acceleration (a X, a Y, a Z ) GEO clock offset a Gf0 and drift a Gf1 GEO clock offset a Gf0 and drift a Gf1

39 EGNOS Project Office EGNOS Demonstration in CHINA 39 GEO Almanacs Message MT 17: GEO Satellite Almanacs for 3 GEOs MT 17: GEO Satellite Almanacs for 3 GEOs PRN code number PRN code number Health and status (Ranging, Corrections, Integrity) Health and status (Ranging, Corrections, Integrity) Service provider (WAAS, EGNOS, MSAS) Service provider (WAAS, EGNOS, MSAS) GEO satellite position (almanac) GEO satellite position (almanac) GEO satellite velocity (almanac) GEO satellite velocity (almanac)

40 EGNOS Project Office EGNOS Demonstration in CHINA 40 SBAS Network Time MT 12: SBAS Network Time / UTC Offset Parameters MT 12: SBAS Network Time / UTC Offset Parameters UTC parameters to relate EGNOS time to UTC time (offset, drift, leap seconds) UTC parameters to relate EGNOS time to UTC time (offset, drift, leap seconds) Time information (GPS week number, GPS TOW,) Time information (GPS week number, GPS TOW,)

41 EGNOS Project Office EGNOS Demonstration in CHINA 41 SBAS Service Message MT 27: SBAS Service Message MT 27: SBAS Service Message 1 to 5 Regions can be defined 1 to 5 Regions can be defined Increase UDRE values in selected regions in order to guarantee integrity Increase UDRE values in selected regions in order to guarantee integrity New definition (DO229C) implies a triangular or rectangular shape region New definition (DO229C) implies a triangular or rectangular shape region In China, ESTB uses the DO229A definition, which creates a circular region In China, ESTB uses the DO229A definition, which creates a circular region

42 EGNOS Project Office EGNOS Demonstration in CHINA 42 Clock-ephemeris Covariance MT 28: Covariance matrix (10 terms) MT 28: Covariance matrix (10 terms) Expansion of UDRE as a function of the user location Expansion of UDRE as a function of the user location Provides increased availability inside the service area and increased integrity outside Provides increased availability inside the service area and increased integrity outside MT 27 and MT 28 cannot be used together MT 27 and MT 28 cannot be used together Optional message not broadcast by ESTB Optional message not broadcast by ESTB

43 EGNOS Project Office EGNOS Demonstration in CHINA 43 Additional Messages MT 62 MT 62 Internal Test Message Internal Test Message Meaningless content Meaningless content Not used in ESTB Not used in ESTB MT 63 MT 63 Null Message Type Null Message Type Filler message if no other message available Filler message if no other message available

44 EGNOS Project Office EGNOS Demonstration in CHINA 44 Tropospheric Corrections Local phenomenon Local phenomenon Not sent as part of the EGNOS SIS Not sent as part of the EGNOS SIS Tropospheric Correction depends from Tropospheric Correction depends from Receiver altitude Receiver altitude Pressure, temperature, humidity Pressure, temperature, humidity Day of year Day of year Latitude Latitude General model to determine these parameters General model to determine these parameters

45 EGNOS Project Office EGNOS Demonstration in CHINA 45 Contents Short GPS Refresher Short GPS Refresher What exactly is this EGNOS Project ? What exactly is this EGNOS Project ? How does EGNOS work ? How does EGNOS work ? What is EGNOS transmitting ? What is EGNOS transmitting ? What is the user computing with the EGNOS signal ? What is the user computing with the EGNOS signal ?

46 EGNOS Project Office EGNOS Demonstration in CHINA 46 Position Computation Satellite selection process Satellite selection process Choice of satellites with SBAS corrections Choice of satellites with SBAS corrections If not enough, choice of other satellites If not enough, choice of other satellites If no solution is possible with SBAS, Pegasus does not compute a solution If no solution is possible with SBAS, Pegasus does not compute a solution Pseudorange smoothing Pseudorange smoothing Smoothing filter using carrier phase measurements (before corrections) Smoothing filter using carrier phase measurements (before corrections) Pseudorange correction Pseudorange correction

47 EGNOS Project Office EGNOS Demonstration in CHINA 47 Measurement Model 3D distance equation 3D distance equation 4 unknowns 4 unknowns User position (X u, Y u, Z u ) User position (X u, Y u, Z u ) Receiver clock offset ( T) Receiver clock offset ( T) The user needs to observe at least four satellites (same as GPS) The user needs to observe at least four satellites (same as GPS)

48 EGNOS Project Office EGNOS Demonstration in CHINA 48 Solving the equations Linearisation of the equation system Linearisation of the equation system Least Square Adjustment using a weight matrix Least Square Adjustment using a weight matrix

49 EGNOS Project Office EGNOS Demonstration in CHINA 49 Integrity Mechanism Integrity is the measure of the trust that can be placed in the correctness of the information supplied by the system Integrity is the measure of the trust that can be placed in the correctness of the information supplied by the system It protects the user against misleading or wrong information It protects the user against misleading or wrong information Integrity has to be assessed by each user, depending on the requirement of his application Integrity has to be assessed by each user, depending on the requirement of his application

50 EGNOS Project Office EGNOS Demonstration in CHINA 50 Integrity Mechanism The Protection Levels The Protection Levels Depend on the user and satellites position (geometry) Depend on the user and satellites position (geometry) Computed by the user receiver based on information sent by EGNOS Computed by the user receiver based on information sent by EGNOS Compared to Alert Limits Compared to Alert Limits Alert Limits are fixed for a particular type of operation Alert Limits are fixed for a particular type of operation PL < AL integrity is assured PL < AL integrity is assured PL AL integrity can not be assured PL AL integrity can not be assured

51 EGNOS Project Office EGNOS Demonstration in CHINA 51 Protection Levels Protection Levels Protection Levels Horizontal and Vertical Protection Levels Horizontal and Vertical Protection Levels Bound on position error at the level Bound on position error at the level Multiplication of estimated errors Multiplication of estimated errors Computed using the projection matrix Computed using the projection matrix HPL VPL

52 EGNOS Project Office EGNOS Demonstration in CHINA 52 Reference Documents SBAS Specifications SBAS Specifications Radio Technical Commission for Aeronautics (RTCA): Minimum Operational Performance Standards (MOPS): DO229 C Radio Technical Commission for Aeronautics (RTCA): Minimum Operational Performance Standards (MOPS): DO229 C Detailed Implementation of MOPS Detailed Implementation of MOPS Pegasus Technical Note (TN) Pegasus Technical Note (TN) Provided under Pegasus/Documentation Provided under Pegasus/Documentation


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