Transcript Surveillance

Module 5. Functions and protocols of surveillance
systems
Topic 5.1. Surveillance in system CNS/ATM
Lecture 5.1.2.
CNS/ATM
Aviation telecommunications network
construction principles.
ATN data transmitting lines. Application
processes CNS/ATM. ICAO Standards and
Recommended Practices for Aeronautical
Telecommunications. ICAO Annex 10 for
digital data transmitting systems.
Construction principles for onboard HF and
VHF communication systems.
As is shown in fig.1, data transmission can be
directed, i.e. messages are appointed to the certain
addressee, or broadcasting, that means, that all users
receive the message.
Digital communication between the dispatcher and pilot
CPDLC (Controller Ріlot Data Lіnk Communіcatіons) and
transfer of permissions to start DCL (Departure Сlearances)
- examples of the directed communication of type "pointpoint". Automated terminal information service ATІS-B,
system of automatic dependent supervision ADS-B,
transfer of the meteorological information aboard the
airplane - examples of broadcasting messages.
ATN is developed by ІCAO and is an infrastructure
of network interconnection. It provides interaction
- of ground subnets for data transmission,
- subnets for data transmission A/G (Aіr/Ground)
- subnets for data transmission of the onboard
equipment (LAN – Local Array Network).
Ground Air Traffic Service (ATS) covers airportdispatcher stations, ATS databases, bases of
meteorological data, control stations on a route.
Digital communication between onboard and land subnets
is provided due to such lines of data transmission:
- HFDL - Hіgh Frequency Data Lіnk;
- VDL - Very Hіgh Frequency Data Lіnk;
- AMSS - Lines of aviation mobile satellite service;
- SSR Mode S - Secondary Surveіllance Radar Mode S;
- GATE L - Gate Aіrcraft Termіnatіng Envіronment Lіnk).
ATN Data Link operative range on channels A/G is shown on
fig. 2.
According to ICAO recommendations ATN should provide:
- The simplified transition to the future variants of ATN;
- Integration of users and systems: AFTN – Aeronautical
Fixed Telecommunication Network; CІDІN – Common ICAO
Data Interchange Network; VCS - Voіce Communіcatіon
System; ACARS - Aіrcraft Communіcatіon Adressіng and
Reportіng System and others in ATN architecture;
- Transfer of instructions from ATC to aircraft using Data
Link only by supervising body in zones of air space which
are subordinated to it;
- Routing according to the established strategy of routing;
- Addressing of all systems: AOС –
Aeronautіcal Operatіon Control, ATC - Aіr
Traffіc Control, AAC - Aeronautіcal
Admіnіstratіve Communіcatіon;
- Definition of data exchange type only
through allowed data links according to types
and categories of messages which are defined
by the user;
- Effective using of data transmission subnets
with limited bandwidth;
- Connection of onboard and land intermediate
systems by alternative mobile subnets;
- Connection of onboard intermediate system with
several land intermediate systems;
- Providing ATSC (Aіr Traffіc Servіces
Communіcatіon) according to ATSC classes (tab.
А.2.1) which are defined by the maximum delay time of
message passing through ATN in one direction (with
probability of passing 0,95).
Safety and effectiveness requires effective air traffic
management systems supported by three key
functions using satellite technology:
Communications, Navigation and Surveillance.
Communications is the exchange of voice and data information between the pilot
and air traffic controllers or flight information centers.
Navigation pinpoints the location of the aircraft for the air crew.
Surveillance pinpoints the location of the aircraft for air traffic controllers. It
includes communication of navigation information from aircraft to air traffic control
centers which facilitates the continuous mapping of the relative positions of
aircraft.
ICAO : CNS systems are forming the basic support services
of Air Traffic Management (ATM) systems.
Communications
The communication element of
CNS/ATM systems provides the
exchange of aeronautical data and
messages between aeronautical users
and/or automated systems.
Communication systems are also used
for support of specific navigation and
surveillance functions.
- Most routine air-ground communications in the en-route
phase of flight will be via digital data interchange. For this
purpose, the user selects a particular message from a preconstructed set of messages using a screen menu, adds some specific
parameters (or free text) and then sends it.
- Some data transfers take place between automated
airborne and ground systems without the need for manual
intervention. Such data exchanges will greatly reduce the volume
of voice communications and therefore reduce the work load of
pilots and controllers.
- In busy terminal areas, however, the use of voice
communications will likely still be preferred. For emergency
or non-routine communications, voice will remain as the primary
means of air-ground communications.
For ground-ground communications, most
routine communications between ground-based
aeronautical users and systems will be by data
interchange. Such interchanges between entities
such as meteorology offices, NOTAM (NOtice To
AirMen) offices, aeronautical data banks, ATS units,
etc., may be in any of the following forms:
1. free text messages;
2. pre-selected data messages (with some manually
added parts; and
3. automated data interchange between computerized
systems.
ATN and its associated application processes:
- has been specifically designed to provide, in a manner
transparent to the end-user, a reliable end-to-end
communications service over networks for support of Air
Traffic Services (ATS).
ATN can also carry other communication service
types:
- Aeronautical Operational Control (AOC) communications,
- Aeronautical Administrative Communications (AAC) and
- Aeronautical Passenger Communications (APC).
Navigation
Navigation element of CNS/ATM systems
provides:
- accurate, reliable and seamless position
- worldwide determination capability
through satellite-based aeronautical
navigation or Global Navigation Satellite
System (GNSS).
GNSS is a worldwide position and time
determination system that includes:
- one or more satellite constellations,
- aircraft receivers, and
- system integrity monitoring for
support the Required Navigation
Performance (RNP).
The satellite navigation systems in operation are:
- Global Positioning System (GPS) of the United
States and
- Global (orbiting) Navigation Satellite System
(GLONASS) of the Russian Federation.
Both systems were offered to ICAO as a means to support
the evolutionary development of GNSS. In 1994, the ICAO
Council accepted the United States offer of the GPS (State
letter LE 4/4.9.1-94/89 dated 11 December 1994), and in
1996, it accepted the Russian Federation offer of GLONASS
(State letter LE 4/49/1-96/80 dated 20 September 1996).
GPS segment is composed:
- of twenty-four satellites in six orbital
planes,
- satellites operate near-circular
20,200 km (10,900 NM) orbits at an
inclination angle of 55 degrees to the
equator and each satellite completes
an orbit in approximately 12 hours.
GLONASS space segment consists:
- of twenty-four operational satellites and
several spares,
- satellites orbit at an altitude of 19,100 km with
an orbital period of 11 hours and 15 minutes.
- eight evenly spaced satellites are arranged in
each of the three orbital planes, inclined 64.8
degrees and spaced 120 degrees apart.
To overcome system limitations and to
meet the performance requirements
(accuracy, integrity, availability and
continuity) for all phases of flight, GPS and
GLONASS require varying degrees of
augmentation.
Augmentations are classified in three
broad categories: aircraft-based, groundbased and satellite-based.
Surveillance
Systems can be divided into two main types:
dependent surveillance and independent surveillance.
In dependent surveillance systems, aircraft position is determined
on board and then transmitted to ATC. The current voice position
reporting is a dependent surveillance systems in which the position of the aircraft
is determined from on-board navigation equipment and then conveyed by the
pilot to ATC by radiotelephony.
Independent surveillance is a system which measures aircraft
position from the ground.
Current surveillance is either based on voice position reporting or on
radar (Primary Surveillance Radar (PSR) or Secondary Surveillance
Radar (SSR)) which measures range and azimuth of aircraft from the
ground station.
Voice position reporting.
Surveillance through voice
position reporting is mainly used
in oceanic airspace and aerodrome
control service or area control service
outside radar coverage. Pilots report
their position using VHF and/or HF
radios.
Primary surveillance radar (PSR).
The ground based PSR system provides information
on the bearing and distance of the aircraft. PSR does require
carriage of any equipment by aircraft and is capable of detecting
almost any moving target. With increasing usage of more
advanced surveillance systems, the use of PSR for international
air traffic management will diminish. PSR will, however, continue
to be used for national applications. Primary radars are currently
used for surface movement detection as well as weather
detection. Precision approach radars (PARs) are primary radars
used for approach operations based on specific procedures for
the pilot and the controller; however, use of PARs for civil
applications is rapidly decreasing.
Secondary surveillance radar (SSR).
The SSR interrogates transponder equipment installed in the aircraft.
In Mode ‘A’, the aircraft transponder provides identification information,
aircraft bearing and distance and in Mode ‘C’, it provides pressure-altitude
information. The current SSR is in wide use in many parts of the world where
terrestrial line-of-sight surveillance systems are appropriate. The accuracy,
resolution and over-all performance of range and azimuth information is
significantly improved by the application of monopulse (including large
vertical aperture antennas) and other advanced processing techniques. The
beneficial role of SSR for surveillance purposes can be enhanced through the
use of Mode S which is a technique that uses a unique address (the 24-bit
address) for each aircraft. It permits the selective interrogation of Mode S
transponder-equipped aircraft and therefore eliminates garbling. It also
provides for a two-way data link capability between Modes S ground stations
and Mode S transponders. SSR Mode S is the appropriate surveillance tool in
high-density traffic areas. The interconnection of ground stations in clusters
provide an enhanced surveillance and communication system.
Automatic dependent surveillance (ADS).
The introduction of air-ground data links, together with sufficiently accurate
and reliable aircraft navigation systems, presents the opportunity to provide
surveillance services in areas which lack such services in the present
infrastructure, in particular oceanic and other areas where the current
systems prove difficult, uneconomic, or even impossible to implement. ADS is
an application for use by ATS in which aircraft automatically transmit, via a
data link, data derived from on-board navigation systems. As a minimum, the
data include the four-dimensional position, but additional data may be
provided as appropriate. The ADS data would be used by the automated ATC
system to present information to the controller. In addition to providing traffic
position information in non-radar areas, ADS will find beneficial application in
other areas, including high-density areas, where ADS may serve as an adjunct
and/or back-up for SSR, thereby reducing the need for primary radar. In some
circumstances, it may even substitute for secondary radar. As with current
surveillance systems, the full benefit of ADS is obtained by supporting
complementary two-way pilot/controller data and/or voice communication
(voice for at least emergency and non-routine communication).
ADS-broadcast (ADS-B).
ADS-B is an expansion of the ADS technique that
involves broadcast of position information to multiple aircraft or
multiple ATM units. Each ADS-B-equipped aircraft or ground
vehicle periodically broadcasts its position and other relevant
data derived from on-board equipment. Any user segment,
either airborne or ground-based, within range of this broadcast,
can process the information. ADS-B is currently defined only for
line-of-sight operations (e.g. broadcast over VHF digital link or by
SSR Mode S extended squitter). ADS-B is also envisaged to be
applied for surface movement, thus being an alternative to
surface radars such as airport surface detection equipment.
CNS/ATM SYSTEM ARCHITECTURE
CONCEPTS AND FUTURE VISION OF
OPERATIONS IN 2020 TIMEFRAME
FUTURE CNS/ATM SYSTEM
ARCHITECTURE CONCEPTS
The current CNS systems are based on voice
communication, ground based navaids and radars.
The future seamless CNS services will be provided
using a combination of ground based and satellite
based capabilities. Current ATM system functions
include Traffic Flow Management (TFM) that
deals with delaying and rerouting flights due to
anticipated congestion at airports or bad weather,
and Air Traffic Control (ATC) that keeps aircraft
separated from other aircraft, terrain or obstacles.
The challenge for the future ATM system will be to
dynamically manage all traffic congestion while dealing
with a significant amount of unscheduled demand (i.e.,
demand continually changing over time and space).
Table 1 presents the elements of year 2020 CNS/ATM
system architecture concepts, including likely changes
in the route structure to support 2D, 3D and 4D
operations, voice and data communication, precise
navigation technologies supporting the desired
Required Navigation Performance (RNP) and
surveillance provided by data fusion of airborne and
radar information.
An intermediate architecture for the
year 2013 is also presented to illustrate a
possible transition path. It is expected that the
future concepts will alleviate most ATC
restrictions and be able to support uniform
separation standards in all weather conditions.
ADS-B: Automatic Dependent Surveillance-Broadcast
CAT: Clear Air Turbulence
CDTI: Cockpit Display of Traffic Information
CRCT: Collaborative Routing Coordination Tool
DRVSM: Domestic Reduced Vertical Separation Minimum
ETMS: Enhanced Traffic Management System
EVS: Enhanced Vision System
RTA Required Time of Arrival
TMA: Traffic Management Advisor
TMC: Traffic Management Coordinator
URET: User Request Evaluation Tool
WAAS/LAAS: Wide/Local Area Augmentation System
MULTI-LEVEL CNS ARCHITECTURE
CONCEPT
In order to satisfy continuity of operations, security,
safety, and capacity needs, the ground systems are
considered to be multi-functional and redundant. For
example, the timing for communication systems will
be used to generate back up navigation capability.
The surveillance service will be provided by a
combination of radar, secondary surveillance, and
aircraft position reports. Figure 5 illustrates a multilevel CNS architecture concept. The key new
technologies are the software radio and a surveillance
data network.
The software radio and internet networking protocols
enable global connectivity independent of the underlying
physical channel.
The basic ATM air-ground communication services
will be provided via data communications with voice
used for real-time, critical, non-routine communication.
The communication architecture is based on a global
communications grid to maximize the use of internet
technology. The global grid architecture is networkcentric (i.e., a common global network connects all users
who have addresses on the network), extensible (i.e.,
modular, reconfigurable,
and adaptable to technology insertion), and
including layered security (i.e., protection
matched to perceived threat). New air-ground
communication services provided include air-air
communications and routing, multicasting,
access to strategic ATC information, voice over
Internet Protocols (IP), and seamless
communication.
The navigation and landing service is predominantly
provided by augmented GPS and Galileo SATNAV
systems. Users desiring all weather operations will
equip with an Enhanced Vision System (EVS) to
“see” on the airport surface and as an integrity check
during the landing operation. Users desiring
protection against jamming of SATNAV signals will
integrate an Inertial Navigation System (INS) with
the SATNAV receiver or derive navigation
information from a backup network of navaids.
The surveillance service will be provided by
“fusing/integrating” data from all available sources
(i.e., automatic aircraft reports, secondary
surveillance, multi-lateration of Universal Access
Transceiver (UAT) and secondary surveillance
signals, and primary radar). The architecture employs
a distributed client-server network and establishes
connectivity via the planned FAA
Telecommunication Infrastructure (FTI). As a
minimum, the following surveillance information is
generated on each aircraft: ID, 3D position and
velocity (both “tracked” and “untracked”), time,
aircraft intent, and Quality of Surveillance (QoS).
The QoS accounts for the surveillance
sources, geometry, accuracy, and integrity.
Authorized users/clients select the
appropriate information for air
situation display, and specialized
processing (e.g., conformance monitoring
and alerting).
FUTURE ATM SYSTEM
ARCHITECTURE AND OPERATIONAL
CONCEPT
Figure 6 shows a high level transition from the OEP
operational environment to the ATM system
architecture concept for the year 2020 and beyond.
As shown, the CNS systems will evolve into an
architecture discussed above. System Wide
Information Management (SWIM) will acquire
process, store and disseminate latest information on
traffic, systems and weather conditions.
Because of the communications and surveillance
capabilities, the entire airspace except a small airspace
(about five miles) around the airport will be managed
and controlled by a Regional facility combining the
functions performed by current en route Centers and
TRACONs. The National facility will manage both
routine traffic congestion and weather related flight
deviations in near real-time. The Local facilities
including the Towers will plan and control in realtime aircraft surface movements and departures/
arrivals.
In order to deal with aggregate congestion and weather, the
strategic planners at the National facility will periodically assess
the capacity of all resources in NAS, and identify periods when
the projected demand exceeds capacity of NAS resources
(airspace/airports). As discussed earlier, the use of satellite
airports around major hubs in large metroplex areas and
additional spoke airports servicing growing communities will not
only add to NAS airport capacity, but also significantly increase
flight options. Therefore, the flight operators will have greater
control over their flight routes, altitudes and times, as they
interact with SWIM to obtain the overall demand/capacity
information required to plan their flights. This will allow the
operators to collaborate with the ATM system to establish
problem-free flight plans (e.g., strategically avoiding significant
congestion) from gate-to-gate, thereby maximizing airspace use.