Upload
neil-randall
View
218
Download
1
Embed Size (px)
Citation preview
Enabling technologies
Pierre GAYRAUDTHALES Avionics
ASAS-TN Seminar
Brighton
11-13 October 2004
Content
ASAS
ADS-B
ADS-B Data Links• Mode S Extended Squitter• VDL Mode 4• UAT
TIS-B
On-board Sensors, Processing & Display
ASAS Enabling technologies
ASAS DisplayADS-B
ADS-B receiver ground station
TIS-B
Aircraft Sensors
ASASFunctional description
On-board systems and data sources(FMS, GPS, pilot
interface)
Airborne data processing, Display
Applications processing
ACAS
Aircraft N
ADS-B out
ADS-B in
On-board systems and data sources(FMS, GPS, pilot
interface)
Airborne data processing, Display
Applications processing
ACAS
Aircraft A
ADS-B out
ADS-B inNavigation information - any source including
GPS
Ground vehicle
ADS-B out
Ground systemsGround ADS-B
receiverATC
surveillance
Controller Working Position
ADS-B Definition
• ADS-B: « Automatic Dependent Surveillance – Broadcast »« A function on an aircraft or surface vehicle that broadcasts position, altitude, vector and other information for use by other aircraft, vehicles and by ground facilities » (Draft ICAO ASAS Circular)
• The broadcast is independent of any external stimuli• The originating aircraft does not know who receives and
uses its broadcast• Users: surrounding aircraft/vehicle and/or ATC• Three candidate data link technologies
– Secondary surveillance radar (SSR) Mode S Extended Squitter (SSR Mode S ES)
– VHF digital link Mode 4 (VDL Mode 4)– Universal Access Transceiver (UAT)
ADS-B Message content
• Data transmit by ADS-B generically defined by RTCA ADS-B MASPS DO-242A – Horizontal position and related data
– Lat/Long, Horizontal velocity, Ground speed, Heading on surface– Integrity (Navigation Integrity Category, Surveillance Integrity Level )– Optional: Airspeed, Heading while airborne
– Altitude and related data– Barometric altitude, Geometric altitude, Vertical rate, NIC baro
– Status – ICAO address, Call sign, Emitter category, Length and width– Emergency/priority, Capability class codes
– Target State: Target altitude and HDG/TRK– Trajectory Change (Under review)
• Arrangement within one or several transmissions according to the data link technology
ADS-BICAO data link policy
• Air Navigation Conference (2003) Recommendations • Strategy for the near-term
– ICAO encourages the selection of the SSR Mode S Extended Squitter as the initial data link
– Regional implementations• Europe: VDL Mode 4• US: UAT
• In the longer term– The current SSR Mode S extended squitter technology may
not be able to fully satisfy all of the requirements for ADS-B services in all airspaces
– Continue to develop standards for ADS-B link technologies, including VDL Mode 4 and UAT
SSR Mode S ESMain characteristics (1)
• On 1090 MHz channel – Secondary Surveillance radar (SSR) Mode A and C– Aircraft SSR Mode S responses to interrogations from
ground-based radars• Aircraft answers to ACAS interrogations including
transmission of non-solicited answers • ADS-B SSR Mode S Extended Squitters
• Based on (except Modes A and C)– Multiple Access: pseudo random timing of the
transmissions – Pulses modulated at 1 MHz able to convey 56 or 112-bit
messages– Downlink and Uplink predefined formats
SSR Mode S ESMain characteristics (2)
• Squitters– Aircraft broadcast non-solicited long squitters (112 bits)– Data to be transmit are prepared in « registers »– Different types of SSR Mode S Extended Squitters
• Airborne/Surface Position Squitter Content of registers 05/06 (rate: 0.5 s)
• Airborne Velocity Squitter: register 09 rate: 0.5 sAircraft Identification Squitter: register 08
• Event-Driven Squitter: register 0A
=> Several Squitters are necessary to transmit data
SSR Mode S ESStandardisation status
• ICAO SARPS: Annex 10 Vol III Ch 5 and Vol 4– The current standard is Amdt 77 – Plans to modify the content of some registers in order to
improve the characterisation of the safety level
• RTCA MOPS – DO-260: Minimum Operational Performance Standards
for 1090 MHz ADS-B– DO-260A: with proposed improvements on safety level
characterisation
SSR Mode S ESTransmitters
• On-board current Transponders– Mode S transponders transmit on 1090 MHz aircraft SSR
Mode S responses to interrogations from ground-based radars
– They are installed on most aircraft (mandatory on all IFR aircraft in Europe as of 31/03/2005)
• Evolution towards ADS-B Out Transmitters– Transmission of Extended Squitters is part of the
standard (provided Registers are loaded by the avionics)
SSR Mode S ESOn-board Receivers
• Current TCAS– The TCAS box includes a 1090 MHz reception function of
• answers of surrounding aircraft to ACAS interrogations• short squitters
• Evolution towards ADS-B receiver– SSR Mode S Extended Squitters can be received and
extracted by TCAS– Independency between TCAS and SSR Mode S
Extended Squitters reception is required: no common failure
VDL Mode 4 Main characteristics
• Frequency Band : 108-137 MHz (i.e. Nav and Comm bands)• Bandwidth : 25 KHz per channel• Time Division Multiple Access, self organised by the mean
of a common clock available to all users : UTC time (GPS)VDL4 user terminal checks available slots and make reservations in subsequent frames for transmission
• The VDL Mode 4 protocol allows to manage several VHF channels– 2 Global Signalling Channels (GSC) – Regional and Local Signalling Channels (LSC) for additional services
as required
• 4500 slots/minute• Bit rate : 19,200 bits/s
VDL Mode 4Standardisation Status
• ICAO SARPS: Annex 10 Vol III Ch 6.9+ Manual on VHF Digital Link (VDL) Mode 4
• Airborne MOPS: ED-108A in preparation• Ground: on-going ETSI standardisation
UAT Main characteristics
• Designed specifically for ADS-B with no constraints from legacy systems
• Single common wideband channel 2-3MHz 1 Mbps channel rate in 960-1215 MHz (ARNS band)
• Aircraft access the channel autonomously at random
• Transmission rate: 1/sec.
UAT Status
• Standardisation status– Frequency allocation: need to be co-ordinated on a world-
wide basis – SARPs not yet available– MOPS available (DO-282)
• Product status– UAT part of SafeFlight-21 Link Evaluation study– UAT selected by FAA Alaska Region (100-200
installations in Western Alaska)
TIS-BDefinition
• TIS-B« A service provided by ground stations, broadcasting information relating to aircraft based on surveillance carried out by ground systems, using ADS-B signals, formats and protocols, compatible with ADS-B receiving equipment » (Draft ICAO ASAS Circular)
• Data link technologies identical to ADS-B• Depends on a ground surveillance infrastructure
– e.g. SSR, PSR, ADS-B, multilateration, ASDE
• Users: surrounding Aircraft/Vehicle
TIS-B Role & Status
• Role– Provides aircraft with a complete picture of the traffic– Exact role to be defined (ADS-B gap filler, ADS-B data
validation, Bridge between different ADS-B data link technologies, Primary source for some ASAS applications?)
• Status– Elements in ICAO SARPS for SSR Mode S Extended
Squitters and VDL Mode 4 technologies– Complete SARPS to be developed– RTCA MASPS DO-280
On-boardSensors
• ADS-B requires on-board availability of– Aircraft position
• May be based on GPS or FMS multisensor position• Available on all RNAV capable aircraft• Integrity data from GPS (more difficult with FMS)
– Altitude and related data– Barometric altitude: always available
– Geometric altitude: if GPS
– Status• Ident: ICAO address and Call sign may require specific Control
Panel
On-boardProcessingSurveillance layer Applications layerData Link layer
Display
SurveillanceData
Processing
Own positionOther Systems (FMS, MCDU…)
ASAS tracks
ASAS tracks,Selected target, Guidance data
Display Management
ASAS Applications
TA/RAACAS tracksTA/RA
ACAS tracks
CAS LogicACAS Surveillance
Act
ive
repl
yA
ctiv
e In
terr
og
UA
T /
V
DL
M4
Rec
eive
rs
ADS-BTIS-B
109
0 M
Hz
Rec
eive
r
On-boardDisplay
• Cockpit Display of Traffic Information (CDTI)– Example of Navigation (FMS), TCAS and ASAS sharing
the same display