sYM.rP/1 SYMPOSIUM ON FUTURE GLOBAL COMMUNICATIONS, NAVtcATtON AND SURVETLLANCE (CNS) SYSTEMS MONTREAL, 4.5 SEPTEMBER 1991 COMPILATION OF PRESENTATIONS Compilad by the ICAO Secretariat and published by authority of the Secrelary General. The views conta¡ned in this document ar€ those ol ¡ntornational €xperts and th6ir publication does nol ¡mply an €ndorsement by ICAO. INTERNATIONAL CIVIL AVIATION ORGANIZATION . CANADA MONTREAL
- sYM r P/l 2 . 3 s E s s r o N (AüSS) SERVICE SESSION 2.3 AERONAUTICAL I.ÍOBILE SATELLITE ( P r e s e n t e d b y D . D i e z ) l. FANS conclus ion the FANS From its study of new concepts and new technologies, 1.1 is the only technology Corunittee concluded that che exploitation of satellite of the enable one to overcone the shortcomings now víable solution that will (CNS) systern and to present conmunications, navigation, and surveillance on a g1obal basis future fulfil the needs and requirenents of the foreseeable (page 3, executive Doe 9524). summary, FANS/4 Report, 2. Present communications shortcomings system are: 2.1 The rnajor shortcomings of the present corununications of very high a) che line-of-sight propagation limitacion (VHF) and/or frequency the accuracy and reliability of propagation lirnitations imposed by the variability o f h i g h f r e q u e n c y ( H F ) ( s e e F i g u r e 1 ) ; c h a r a c t e r i s t i c s caused by a variety of reasons, to implenent b) the difficulty, Chen in a presenc communications systens and operate parcs of the world; and consistent rnanner in large cornmunications and the lack of c) the limitations of voice to support modern digital air-ground data interchange systens and on the ground. automated systems in the air 3 . A M S S m a i o r b e n e f i t s (MSS) will overcome 3.1 The aeronautical rnobile satellite service and wiIl provide: those Iirnitations global communications coverage from very low to very high a) altitudes, ernbracing remote, and oceanic areas, \^títh off-shore (see Figure the exception of extrerne polar regions 2 and F i g u r e 3 ) ; a n d to b) digital data interchange bet'reen the air-ground systens fu1ly exploit the automated eapabilities of both; one (ADS), in application, the automatic dependent surveillance which aircraft automatical-ly via the data 1ínk, transnit, positional systerns, will data derived fron on-board navigation also provide global surveillance coverage in the areas u n d e r a ) ( s e e F i g u r e 4 ) . s p e c í f i e d
sYM- IPll s E s s r o N 2 . 3 2 . 3 - 2 and t!¡o 3.2 The A.l'fS S will provide four service types, tlro safety (ATC) and aeronautical operational services. Air traffic control non-safety (AOC) are the safety control services, and aeronautical adninistrative (AAC) and aeronautical passenger (APC) are the communication communication r ¡ u r ' - s d r e L J ¡ u , r e > . 4. Al.rSSP The progress 4.1 toward uslng satellite communications for of Standards and aeronautical safety is being realized through the preparation (SARPs) and guídance material by the ICAO Aeronautical Reconmended Practices (AMSS) Panel. Mobile- SatelIite Service 4.2 INMARSAT The A¡,tS S Panel has adopted che systen defined in the Manual (SDM) and the Aeronautical (ARINC) Systen Definition Radio, Inc. Characteristic 741 . Both, the SDM and the ARINC 741 r¿i1l be continuously amended as SARPS develap. 4.3 lasked to prepare a sunnary doclrment on The A.!ÍSS Panel was also t h e s y s t e r ¡ a r c h i t e c t u r e , d e s i g n c h a r a c t e r i s t i c s , b e n e f i t s a n d a p p l i c a c i o n s o f AMSS, to be recommended for prornulgation by 1CA0 in the form of an advisory - . L : - L - ^ ^ 1 w i l l b e a v a i L a b l e . 5. A.I"ISS mai or elenents are the space segment (satellites), 5.L The rnajor elements of the AMSS ground earth (AESs) (see stations (GESS) , and aircraft earth stations F i g u r e 5 ) . 5 . 2 S p a c e s e s m e n t 5.2.1 AMSS satellites operace at 36 000 km altitude above the Equator in a Seostationary orbit. More than one-third surface is visíble of the earth's from this altitude, and three satellites approximarely equally spaced in Iongitude can provide global coverage. No line-of-sight radio coverage is available from geostationary satellites at the polar regions where, at latitudes greater than approxinately 80 degrees, the path to the satellite approaches the horizon (see Figure 3). - 2 Fl. 5.2.2 INMARSAT S Srandards r¡as firsr sarellire ro neer ICAO A.f,tS launched successfully on 31 October 1990, and placed on station ac 64.5 degrees east over the Indian Ocean. 5 . 2 , 3 A n u ¡ n b e r o f o r g a n i z a t i o n s a r e p l a n n i n g t o l a u n c h s a r e l - t i t e s i n ( inclined non- geos tacionary ) orbits that \ri1l also provide coverage of polar regions. The first of these should be operational in the late 1990s, providing coverage of the Norch Polar region, that It is not anticipated
rPll sYM- sE ssro N 2 .3 2 . 3 - 3 Polar region will be SouEh coverage of lhe exEreme continuous satellite covered by FANS. in che. tineframe available garth station (GES) 5.3 Ground dedlcated to The GEs consLsts of a dlsh antenna and eleccronics 5.3.1 It to and from the atrcraft' conmunLcations operaEions through the satelllte voice and terrestrial and fixed between ¿he satellite provides the interface the publlc data netlrorks such as conmon ICAO Data Incerchange Network (CIDIN), that might lines s\ritched telephone neEwork, priva¡e networks, and dedicated may or may not be located at ¿n A GES applicaEions. be used for Eine-crltical made and arrangenents depending on óperatlonal requlreÍIents ATS facility, (see authority provÍder and the civil aviation betveen the satellite servic; Figure 5). is 9 co 13 rnetres in diameter and s . 3 . 2 The GES antenna typically l ink feeder Alternative at C-band (4/6 CHz frorn/uo the satellice). operates sizes antenna GHz), perrnic smaller (ú/La example at Ku-band fiequencies, for o f a but at the expense and freedorn from potential terrestrial interference, preater effect of rain actenuation. ( A E S ) e a r t h s t a t i o n 5 . 4 A i r c r a f t unit that transnitter The AES is comprised of an on-board /teceivet 5.4.1 and voice codecs; processors demodulaEors, signal includes nodulators, and the Power arnplifiers, one or nore radio frequency internal concrollers: (see Flgure 5 and Figure 6). antenna sub-system 6. AMSS channels and band are imPle¡nented between satellice and aircraft The radio links 6.1 letter have been given the packet daEa which using three of channels for types C-channel , which designaces P, R and T; and a fourth, designated designations (see Figure voice and data 7). a circuic-¡rode channel for continuous is a time division nultiplexed 6-2 The P-channel P¿cket Aircraft and user data. data channel from GES Eo AES which carries signalling to a GES. this channel after log-on must continuously monitor is a rnultipl-e access channel , used in the AES to GES 6.3 The R-channel uses the "slotted and user dala. It direction, h'hich carríes signalling aircraft. A GES aloha" protocof to permic randorn access by multiple its R-channels. continuously monitors access is a reservation time division nultiPle 6.4 The T-channel a request from an (TDMA) channel used frorn AES to GES only. A GES receiving time slots for AES for T-channel capacity reserves AES through the R-channel
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