Transcript Data link in

Data link in
CNS/ATM
Data link
Aeronautical telecommunication network
(ATN) data link:
 Air-ground data link
 Error decreasing
 High reliability
 Data transmission in high speed
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Data link
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High accuracy in transmission
Print of information
Decreasing of traffic in communication
channels
Transmission of data in text or even in
media
To decrease of controllers workload
To decrease of crew workload
Data link
To understand the information easily and
rapidly.
 To display the information in any media
like windows.
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Data link
Data link is the basic component of
communication between air traffic
controller (ATC) and aircraft.
Data link in CNS/ATM
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Data link channels:
ATC Mode-S
 VHFDL(VDL)
 HFDL
 AMSS
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ATC Mode-S
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data link capability:
A/C to ground stations (downlink)
ground stations to A/C (uplink)
air to air
ATC Mode-S
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ATC Mode-S Transponders support:
all surveillance functions (UF 0,UF 4,UF 5,
DF 0,DF 4,DF 5,DF 11).
- bidirectional air to air data link (UF 16,
DF16)
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- ground to air data uplink (comm. A)
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- air to ground data downlink (comm. B)
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- uplink ELM & downlink ELM.
ATC Mode-S / ELS
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SI codes are the way to identify
interrogating stations in order that the A/C
can selectively answer to them. So, only
the interrogating station receives the
reply.
Also, the flight ID (flight number) is
downlinked to ground.
ATC Mode-S / ELS
ATC Mode-S / EHS
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ATC Mode-S Enhanced Surveillance (EHS)
was mandatory with effective date of
march 2007.
Enhanced Surveillance is the first stage in
making use of air derived data in the form
of Downlink Air Parameters (DAPs), either
directly to controller or to ATC systems.
ATC Mode-S / EHS
- magnetic heading
- selected altitude
- true track angle
- track angle rate
- indicated airspeed
- mach number
- true airspeed
- ground speed
- roll angle
- vertical rate
ATC Mode-S / EHS
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information transmitted to ground causes
the controller to supervise accurately on
the aircraft.
The controllers receive much more
information and the quality is increased.
In high density traffic like Europe, all of
the parameters will be easily available to
the controllers and so, the pilot has not to
report them.
ATC Mode-S / EHS
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Therefore, the pilot might not use the
VHF voice which causes decreasing of VHF
bands traffic.
The DAPs from different systems on the
A/C, are received by ATC Mode-S
Transponder. The Transponder downlink
them as the replies of the interrogations.
The project causes decreasing of the
errors in controllers supervision.
ATC Mode-S
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Extended Length Memory (ELM):
16 words 80 bits in each interrogation
16 words 80 bits in each reply
ATC Mode-S data link
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Long messages are transmitted using
Extended Length Message (ELM)
capability.
ELM is capable of transmitting up to
sixteen 80 bits message segments, air to
ground or ground to air. No surveillance
data is considered in ELM.
ELM can be acknowledged by a single
reply or interrogation.
ATC Mode-S data link
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ELMs uplinked need not be replied to
individually, but can be acknowledged in a
reply containing a summary of the
received interrogations.
Downlinked ELMs are transmitted only
after authorization by the interrogator. The
segments are transmitted in comm D
replies.
VHF Data Link
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In future, voice communication will be
used for critical messages:
To avoid traffic
Landing clearance at airports with heavy
traffic.
It will serve as back up for data link.
The VHF Data Link (VDL) operation
requires a VHF digital radio (VDR).
VHF Data Link
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VDL is essential for ATN implementation.
The VDL formats specify a protocol for
delivering data packets between airborne
equipment and ground systems.
The protocol is different to that used in the
aircraft communication addressing and
reporting system (ACARS).
VHF Data Link
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The difference is that the VDL provides a
capacity 13 times greater than the
equivalent of 25 KHz VHF channel.
VDL Mode-1
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This mode has been especially designed to
use ACARS.
VDL mode-1 is a low speed bit oriented
data transfer system.
It uses carrier sense multiple access
(CSMA) methodology.
VDL Mode- 1
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VHF analogue radios: for data exchange
since the late 70s.
ACARS system has been developed and
has grown considerably.
VDL Mode-1 has been especially designed
to use ACARS modulation equipment and
radio.
ACARS and VDL mode-1 is a low speed bit
oriented data transfer system.
VDL Mode-2
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VDL- Mode 2 uses same technology, but
is not capable of handling voice
communication.
Average data transmission is 31.5 kbps. It
employs a globally dedicated common
signaling channel of 136.975 MHz.
VDL Mode-2
VDL Mode-2 is the minimum requirement
in CNS/ATM.
 Commercial services are available at the
time being.
 VDL Mode-2 transmits coded data. (ie.
in CPDLC)
 It is not necessary to send letters and
numbers like ACARS.
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VDL Mode-2
The message “Climb to and maintain FL350”
requires about 10 bits.
This is the technology to speed transmission
of information.
 Bit rate: 31.5 kbps
 Modulation: D8PSK
 A/C address is the same as ATC Mode-S
Address (24 bits)
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VDL Mode-2
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A/C and ground stations exchanges the
information in frames.
Each four frames of information require
one acknowledgement.
Data link communication according to the
protocol specified in ICAO VDL Mode-2
and AMSS Data 3 standards.
VDL Mode-2
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VHF Digital Radios capable for ACARS
don’t meet the requirements of the
protocol ICAO VDL Mode-2.
VDL Mode-2 is not capable of handling
voice communication.
VDL Mode-2
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Communication Management Unit (CMU)
or Air Traffic Service Unit (ATSU) manage
transmission of digital information of
the following systems:
CPDLC (using VDL Mode-2)
ADS-B (in future VDL Mode-4 probabely)
ATC Mode-S
VDL Mode-2
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Communication Management Unit (CMU)
or Air Traffic Service Unit (ATSU) should
be capable to handle the ISO-8208 (X.25
protocol specified in ICAO VDL standard.
VDL Mode-3
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VDL Mode-3 is an integrated digital data
and communication system.
VDL Mode-3 uses four radio channels on a
carrier (with a 25 KHz spacing).
VDL Mode-3 uses a data link technology
called TDMA.
It is presently is not available for
operational use.
HF data link (HFDL)
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HF data link (HFDL) is another communication
channel to transmit data from ground station to
A/C and via versa.
HFDL uses HF frequencies.
HFDL is the only standby system for
aeronautical mobile satellite system (AMSS) in
oceanic / remote areas.
HF data link (HFDL)
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The propagation anomalies rarely affect
the entire HF frequency band.
HFDL communicates with a number of
adequate frequencies available in the HF
band, to find the best frequency for
transmission of data packages anywhere
and at any time.
HF data link (HFDL)
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Upon a suitable frequency is found, a
log-on message is sent to ground station.
Upon receiving of log-on confirmation, the
information is sent (downlink) to ground
station.
A new frequency search is initiated after
ground station has not acknowledged.
HF data link (HFDL)
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Bit rate: 300 to 1800 bps.
range: 6000 km
coverage: oceanic and polar region
HF data link (HFDL)
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In this mode aircraft can contact three or
more HFDL ground stations constantly and
its hub can become ATN routers.
HF data link (HFDL)
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The A/C equipped with:
HFDL Control Panel
HF Data Unit plus HF Voice Radio or
HF Data Radio
HF data link (HFDL)
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HFDL important role:
Not SATCOM equipped A/C , long range
Data link for polar regions
Aeronautical Mobile
Satellite Services (AMSS)
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VHF Data link /ATC Mode-S Data link:
- line-of sight restriction.
- certain range
- require support of ground stations,
electric power, maintenance, etc.
not appropriate for oceanic / long range
communication.
Aeronautical Mobile
Satellite Services (AMSS)
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HFDL it is unsafe, medium quality, technical
support, low speed, etc.
Satellite communication:
- high-quality voice and data communication
services.
Aeronautical Mobile
Satellite Services (AMSS)
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AMSS provides:
- digital voice and data services
Data link:
- communication services
- broadcast (WAAS, EGNOS)
AMSS
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Geostationary satellites
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Coverage: long range, oceanic, non-polar
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Bit rate: 10.5 kbps in max.
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Data link capability
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ICAO AMSS Standard data 3
AMSS
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L-band:
1545 to 1555 MHz
1646.5 to 1656.5 MHz.
AMSS
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Services:
- CPDLC
- ADS-B
- etc.
AMSS
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Current SDUs provide services to ACARS
will be replaced by SDUs which meet the
requirements specified in AMSS Data 3
standard.
Controller-Pilot Data Link
Communication (CPDLC)
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The Air Traffic Control (ATC) system relies
heavily on voice communications between
air traffic controllers and pilots.
It is to relay control instructions and other
information critical to safe and expeditious
flight.
Controller-Pilot Data Link
Communication (CPDLC)
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These communications are required to
support coordination of aircraft movement
in all phases of flight, to ensure:
Aircraft separation
Transmit advisories and clearances
To provide aviation weather services.
Controller-Pilot Data Link
Communication (CPDLC)
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As air travel continues to increase,
controller-pilot communication has
increased to the saturation point during
peak traffic periods at many locations.
The workload of controllers increased
more and more.
This wastes more time on the ATC voice
channel as repeated attempts to
communicate are made.
Controller-Pilot Data Link
Communication (CPDLC)
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Saturation: no additional aircraft can be
handled within the controller's assigned
airspace .
Controller-Pilot Data Link
Communication (CPDLC)
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Air Ground Data Link (AGDL): a means of
communications between pilots and
controllers, using data link instead of voice.
This type of communication between pilots
and controllers is often referred to as
Controller-Pilot Data Link Communications
(CPDLC).
Controller-Pilot Data Link
Communication (CPDLC)
Air Ground Data Link helps to solve the of
the voice channels, the important problem
for Air Traffic Controllers.
introducing an
 AGDL introduces an alternative means of
communication between the aircrew and
the controllers, data link.
 CPLDC is used to relay routine messages
from aircrew to controllers and via versa.
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Controller-Pilot Data Link
Communication (CPDLC)
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CPDLC Data link messages (uplinks):
- Check microphone (AMC)
- Change SSR code/- Squawk ident
- Contact (ACM)
- Direct flight to turn and heading
- Altimeter settings for conforming of flight
level instructions
Controller-Pilot Data Link
Communication (CPDLC)
- Initial contact altitude verification to ensure
that pilot and controller's
- Understanding of a flight's altitude clearance
agrees on check-in
- Voice frequency assignments for hand-offs or
radio transmitter problems
- Crossing restrictions for arrival and departure
transitions/to comply with airspace restrictions
Controller-Pilot Data Link
Communication (CPDLC)
- Menu text for weather alert or traffic flow
conditions.
- Route clearances
Controller-Pilot Data Link
Communication (CPDLC)
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CPDLC allows the information, such as
aircraft parameters, to be down linked to
the ground stations automatically.
Controller-Pilot Data Link
Communication (CPDLC)
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Data link messages (downlinks):
- Altitude
- Speed
- Heading
- Turn
- Climb/descent/maintain flight level (ACL)
- Flight plan
Controller-Pilot Data Link
Communication (CPDLC)
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Aircrew answer ATC instructions by data link
and request routings from ATC.
All of these messages will be exchanged
without the need for voice read-back.
CPDLC communication: not intended to be as
fast as voice. It is designed to pass routine
messages, where time is not an critical
factor.
Controller-Pilot Data Link
Communication (CPDLC)
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The best analogy one could make for
air/ground data link or CPDLC is that of a
mobile phone.
The use of CPDLC in high-density traffic
airspace offers the potential to reduce
voice channel traffic and to improve the
saturation.
Controller-Pilot Data Link
Communication (CPDLC)
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Using CPDLC reduces the pilot's and the
air traffic controller's communication
workload and allows them to concentrate
on other essential tasks.
CPDLC transmits the information through
VDL Mode-2 or geostationary satellites.
Controller-Pilot Data Link
Communication (CPDLC)
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CPDLC is windows-based for the controller.
All of the actions are performed via the
radar screen, using a mouse, the data link
window and pre-defined menus.
Controller-Pilot Data Link
Communication (CPDLC)
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Colors are used to highlight the different
states of a message.
Uplink message awaiting a response from
crew, is displayed in light green to the
controller.
Controller-Pilot Data Link
Communication (CPDLC)
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Downlink request from the aircrew will
display in white.
The colors show in the data link window.