Presentation on theme: "Introduction to Aeronautical Data Links Prepared by - Loftur Jónasson & Jennie Jónasson Iceland Telecom Seminar on the Implementation of Data Link and."— Presentation transcript:
Introduction to Aeronautical Data Links Prepared by - Loftur Jónasson & Jennie Jónasson Iceland Telecom Seminar on the Implementation of Data Link and Satcom Communications Bangkok, Thailand, November 2003
Introduction This presentation is intended to be a basic introduction to Air/Ground datalinks, based on the work done in ACP (formerly AMCP) WG-M, as well as our operations experience with Iceland Radio in the North Atlantic, where FANS-1/A is currently being utilised. This introduction highlights aspects on the following topics: FANS 1A –ACARS and ATN messages The use of ATN compatible data links: SATCOM (also called AMSS) HF data link (HFDL) VHF Digital Links: VDL Mode 2 VDL Mode 3 VDL Mode 4 The authors of this presentation have borrowed the work of many others in the aviation industry for this presentation. The authors would like to take this time to thank ARINC, SITA, the FAA, the Swedish CAA, Nav Canada, UK NATS and many others. The authors would like to thank them all for their contributions.
Free Flight - the end goal From the US FAA´s Architecture - Version 4.0, Section 6 Free Flight Phase 1, Safe Flight 21, and Capstone - Free Flight will allow pilots to change routes, speeds, or altitudes as needed, while in en route and oceanic air space. Air Traffic Controllers will not impose restrictions on pilot-initiated changes, except when there is a potential conflict with other aircraft or special use airspace. This capability will allow pilots to fly optimized profiles, the most efficient cruise speeds, wind-aided routes, and arrival descent profiles. Any activity that removes operational restrictions is a move towards Free Flight.
ATN and FANS 1/A
ARINC´s Explanation of Difference Between a FANS-1/A ACARS Message and an ATN Message 22 Protocol (Bit-to-hex, CRC) AT O8414C9640E4B0 CRC AT O8414C9640E4B0 CRC ACARS Protocol ATN Protocol 0
Character- vs. Bit-Oriented Messages Protocol Data Units (PDU) PDU n PDU m 8-bit ASCII character Arbitrary sized bit fields Character-oriented protocol Bit-oriented protocol
Transition of FANS 1/A (ACARS) to ATN
Transition from FANS 1/A to ATN using VDL Mode 2 Step 1: ACARSStep 2a: Character Applications over VDL Step 2b: VDLStep 3: VDL/ATN
ICAO data link systems that can be used during flight DepartureEn RouteApproachLandTaxi Taxi Take-Off VDL 2, 3, 4 Within l.o.s. VDL 2, 3, 4 Outside l.o.s. SATCOM HFDL VDL 2, 3, 4 l.o.s. : line of sight
DepartureEn RouteApproachLandTaxi Taxi Take-Off From Aircraft Link Test/Clock Update Fuel/Crew Information Delay Reports Out To Aircraft PDC ATIS Weight and Balance Airport Analysis V-Speeds Flight Plan-Hard Copy Load FMC From Aircraft Off From Aircraft Engine Start To Aircraft Flight Plan Update Weather Reports From Aircraft Position Reports Weather Reports Delay Info/ETA Voice Request Engine Information Maintenance Reports To Aircraft ATC Oceanic Clearances Weather Reports Reclearance Ground Voice Request (SELCAL) From Aircraft Provisioning Gate Requests Estimate Time-of-Arrival Special Requests Engine Information Maintenance Reports To Aircraft Gate Assignment Connecting Gates Passengers and Crew ATIS From Aircraft On From Aircraft In Fuel Information Crew Information Fault Data from Central Maintenance Computer Different types of data link messages as a flight progresses
Overview of the VDL Modes NameVDL Mode-2VDL Mode-3VDL Mode-4 Access methodCSMA Carrier Sense Multiple Access TDMA Time Division Multiple Access STDMA Self-Organising Time Division Multiple Access CapabilityData OnlyData and Voice simultaneously Data Only ModulationD8PSK GFSK Channel band- width 25 kHz
The VDL Modes The numbers mean what order they entered ICAO for standardising – they are not in succession VDL Mode-1 Taken out of Annex 10 before ever implemented – no longer exists VDL Mode-2 Data Only Successor to ACARS 25 kHz VDL Mode-3 Voice & Data together US FAA Program 25 kHz VDL Mode-4 Data Only Primary purpose is ADS-B Swedish design 25 kHz
The VDL Modes and 25 kHz/8.33 kHz voice systems MODE 2MODE 3 Voice Channels MODE 4 25kHz MODE 2MODE 3 Voice Channels MODE 4 DSB AM D8PSK DSB AM GFSK TDMA CSMA STDMA Analog Voice Data Only (ATN A/G) Simultaneou s Voice & Data (4 channels voice or ATN A/G data) Data Only (ATN A/G and ADS-B) DSB AM D8PSK DSB AM GFSK TDMA CSMA STDMA 8.33
Long range data link systems Propagation Paths of SATCOM and HFDL GES IONOSPHERE SCINTILLATION CLOUD HF SATCOM HFDL GS Propagation problems affecting HF and SATCOM are fairly independent (Satellite) GS=Ground station GES=Ground Earth Station Jónhvolf in Icelandic
HFDL (HF Data Link) HFDL - High Frequency Data Link With ground stations around the world Iceland Radio houses one of the Ground Stations Can accommodate ACARS or ATN Developed to be used in areas where satellite cannot be used Cheaper alternative to SATCOM
SATCOM (AMSS) Satellite Communications A system available for ACARS and for ATN Satellites can be used for Data Link and for voice - often referred to as SAT Voice Inmarsat is the current provider for aeronautical communications 1
ADS-C Automatic Dependent Surveillance-Contract The C stands for contract. An ADS-C message is only sent after a link contract between the aircraft and the ground has been established. ADS-C is currently used using SATCOM or HF data link.
ADS-B Automatic Dependent Surveillance-Broadcast ADS-B is a broadcast of the aircrafts position, mainly derived from the GNSS system. It provides the pilot of a properly equipped aircraft a display on his instrument panel of where other aircraft are in relation to his aircraft.
ADS-Broadcast Concept Situational Display Aircraft emits signal Aircraft 1 Aircraft 3 ATC Surveillance When Aircraft 1 sends a signal, Aircraft 2 and Aircraft 3 and ATC can see Aircraft 1 on their displays. In an ADS-B environment all aircraft will be broadcasting signals to other aircraft and the ground.
Mode-S Extended Squitter Mode-S was standardised by ICAO several years ago The ICAO 11 th Air Navigation Conference has decided that all ADS-B implementations should support the use of Mode-S squitter
ICAO Communications/Navigations Surveillance (CNS) Environment Air Traffic Management Centre Satellite Ground Earth Station VHF Voice and Data Mode-S – Secondary Surveillance Radar Radar would be surveillance Using satellites to determine your location would be navigation Using satellites or VHF to talk with airplanes is Communication
What is the ATN? The ATN concept emerged from a need to interchange bit-oriented digital data over dissimilar aeronautical data links, using, for interoperability purpose, the principles of the International Organization for Standardization (ISO) open systems interconnection (OSI) architecture.
Describe the ATN The ATN design supports the incorporation of different air-ground subnetworks and different ground- ground subnetworks, resulting in a common data transfer service. Furthermore, the ATN design is such that user communication services may be introduced in an evolutionary manner
OSI 7 Layer Protocol Reference Model System ASystem B Layer 7 Application Layer 6 Presentation Layer 5 Session Layer 4 Transport Layer 3 Network Layer 2 Data Link Layer 1 Physical Layer 7 Application Layer 6 Presentation Layer 5 Session Layer 4 Transport Layer 3 Network Layer 2 Data Link Layer 1 Physical