Spitzer, C.R., Martinec, D.A., Leondes, C.T., Rana, A H, Check, W. " Aerosp The Electrical Engineering Handbook Ed. Richard C. dorf Boca Raton CRC Press llc. 2000
Spitzer, C.R., Martinec, D.A., Leondes, C.T., Rana, A.H., Check, W. “Aerospace Systems” The Electrical Engineering Handbook Ed. Richard C. Dorf Boca Raton: CRC Press LLC, 2000
102 Aerospace Systems Cary R. Spitzer Daniel a. martinec 102. 1 Avionics Systems Cornelius T Leondes University of California, San Diego Software in Avionics.CNS/ATM. Navigation Equipment Emphasis on Communications.Impact of "Free Flight Abdul Hamid Rana Avionics in the Cabin. Avionics Standards 102.2 Communications Satellite Systems: Applications Satellite Launch. Spacecraft and Systems. Earth Stations. VSAT William Check Communication System· Video· Audio· Second-Generation GE Spacenet 102.1 Avionics Systems Cary R. Spitzer, Daniel A. Martinec, and Cornelius T. Leondes Avionics(aviation electronics) systems perform many functions: (1)for both military and civil aircraft, avionics are used for flight controls, guidance, navigation, communications, and surveillance; and(2)for military aircraft, avionics also may be used for electronic warfare, reconnaissance, fire control, and weapons guidance and control. These functions are achieved by the application of the principles presented in other chapters of nis handbook, e.g., signal processing, electromagnetic, communications, etc. The reader is directed to these chapters for additional information on these topics. This section focuses on the system concepts and issues unique to avionics that provide the traditional functions listed in(1)above. Development of an avionics system follows the traditional systems engineering flow from definition and analysis of the requirements and constraints at increasing level of detail, through detailed design, construction validation, installation, and maintenance. Like some of the other aerospace electronic systems, avionics operate in real time and perform mission-and life-critical functions. These two aspects combine to make avionics system design and verification especially challenging though avionics systems perform many functions, there are three elements common to most systems: data buses, displays, and power. Data buses are the signal interfaces that lead to the high degree of integration found today in many modern avionics systems. Displays are the primary form of crew interface with the aircraft and in an indirect sense, through the display of synoptic information also aid in the integration of systems. Power, of course is the life blood of all electronics The generic processes in a typical avionics system are signal detection and preprocessing, signal fusion, computation, control/display information generation and transmission, and feedback of the response to the control/display information.(Of course, not every system will perform all of these functions. A Modern Example System The B-777 Airplane Information Management System(AIMS)is the first civil transport aircraft application of the integrated, modular avionics concept, similar to that being used in the U.S. Air Force F-22. Figure 102.1 shows the AIMS cabinet with eight modules installed and three spaces for additional modules to be added the AIMS functions are expanded. Figure 102.2 shows the AIMS architecture c 2000 by CRC Press LLC
© 2000 by CRC Press LLC 102 Aerospace Systems 102.1 Avionics Systems A Modern Example System • Data Buses • Displays • Power • Software in Avionics • CNS/ATM • Navigation Equipment • Emphasis on Communications • Impact of “Free Flight” • Avionics in the Cabin • Avionics Standards 102.2 Communications Satellite Systems: Applications Satellite Launch • Spacecraft and Systems • Earth Stations • VSAT Communication System • Video • Audio • Second-Generation Systems 102.1 Avionics Systems Cary R. Spitzer, Daniel A. Martinec, and Cornelius T. Leondes Avionics (aviation electronics) systems perform many functions: (1) for both military and civil aircraft, avionics are used for flight controls, guidance, navigation, communications, and surveillance; and (2) for military aircraft, avionics also may be used for electronic warfare, reconnaissance, fire control, and weapons guidance and control. These functions are achieved by the application of the principles presented in other chapters of this handbook, e.g., signal processing, electromagnetic, communications, etc. The reader is directed to these chapters for additional information on these topics. This section focuses on the system concepts and issues unique to avionics that provide the traditional functions listed in (1) above. Development of an avionics system follows the traditional systems engineering flow from definition and analysis of the requirements and constraints at increasing level of detail, through detailed design, construction, validation, installation, and maintenance. Like some of the other aerospace electronic systems, avionics operate in real time and perform mission- and life-critical functions. These two aspects combine to make avionics system design and verification especially challenging. Although avionics systems perform many functions, there are three elements common to most systems: data buses, displays, and power. Data buses are the signal interfaces that lead to the high degree of integration found today in many modern avionics systems. Displays are the primary form of crew interface with the aircraft and, in an indirect sense, through the display of synoptic information also aid in the integration of systems. Power, of course, is the life blood of all electronics. The generic processes in a typical avionics system are signal detection and preprocessing, signal fusion, computation, control/display information generation and transmission, and feedback of the response to the control/display information. (Of course, not every system will perform all of these functions.) A Modern Example System The B-777 Airplane Information Management System (AIMS) is the first civil transport aircraft application of the integrated, modular avionics concept, similar to that being used in the U.S. Air Force F-22. Figure 102.1 shows the AIMS cabinet with eight modules installed and three spaces for additional modules to be added as the AIMS functions are expanded. Figure 102.2 shows the AIMS architecture. Cary R. Spitzer AvioniCon Inc. Daniel A. Martinec Aeronautical Radio, Inc. Cornelius T. Leondes University of California, San Diego Abdul Hamid Rana GE LogistiCom William Check GE Spacenet
Generator FIGURE 102.1 Cabinet assembly outline and installation(typical installation).(Courtesy of Honeywell, Inc. AIMS functions performed in both cabinets include flight management, electronic flight instrument systen (EFIS)and engine indicating and crew alerting system(EICAS)displays management, central maintenance, irplane condition monitoring, communications management, data conversion and gateway(ARINC 429 and ARINC 629), and engine data interface AIMS does not control the engines nor flight controls, nor operate any internal or external voice or data link communications hardware but does select the data link path as part of the communications management function. Subsequent generations of AIMS may include some of these latter In each cabinet the line replaceable modules(LRMs)are interconnected by dual arinc 659 backplane data buses. The cabinets are connected to the quadraplex(not shown)or triplex redundant ARINC 629 fly-by-wire data buses and are also connected via the system buses to the three multifunction control units(MCDU)used by flight crew and maintenance personnel to interact with AIMS. The cabinets merged and processed data over quadruple redundant custom designed 100 Mhz buses to the EFIS and EICAS In the AIMS the high degree of function integration requires levels of system availability and integrity not found in traditional distributed, federated architectures. These extraordinary levels of availability and integrity are achieved by the extensive use of fault-tolerant hardware and software maintenance diagnostics and promise to reduce the chronic problem of unconfirmed removals and low mean time between unscheduled removals (MTBUR). Figure 102.3 is a top-level view of the U.S. Air Force F-22 Advanced Tactical Fighter avionics. Like many other aircraft, the F-22 architecture is hybrid, part federated and part integrated. The left side of the figure is the highly integrated portion, dominated by the two Common Integrated Processors(CIPs)that process, fuse, and distribute signals received from the various sensors on the far left. The keys to this portion of the architecture are the Processor Interconnect(PI)buses within the CIPs and the High Speed Data Buses(HSDBs).(There are provisions for a third CIP as the F-22 avionics grow in capability. The right side of the figure shows the federated systems including the Inertial Reference, Stores Management, Integrated Flight and Propulsion Con trol, and Vehicle Management systems and the interface of the latter two to the Integrated Vehicle System Control. The keys to this portion of the architecture are the triple or quadruple redundant AS 15531( formerly MIL-STD-1553)command/response two-way data buses. e 2000 by CRC Press LLC
© 2000 by CRC Press LLC AIMS functions performed in both cabinets include flight management, electronic flight instrument system (EFIS) and engine indicating and crew alerting system (EICAS) displays management, central maintenance, airplane condition monitoring, communications management, data conversion and gateway (ARINC 429 and ARINC 629), and engine data interface. AIMS does not control the engines nor flight controls, nor operate any internal or external voice or data link communications hardware but does select the data link path as part of the communications management function. Subsequent generations of AIMS may include some of these latter functions. In each cabinet the line replaceable modules (LRMs) are interconnected by dual ARINC 659 backplane data buses. The cabinets are connected to the quadraplex (not shown) or triplex redundant ARINC 629 system and fly-by-wire data buses and are also connected via the system buses to the three multifunction control display units (MCDU) used by flight crew and maintenance personnel to interact with AIMS. The cabinets transmit merged and processed data over quadruple redundant custom designed 100 Mhz buses to the EFIS and EICAS displays. In the AIMS the high degree of function integration requires levels of system availability and integrity not found in traditional distributed, federated architectures. These extraordinary levels of availability and integrity are achieved by the extensive use of fault-tolerant hardware and software maintenance diagnostics and promise to reduce the chronic problem of unconfirmed removals and low mean time between unscheduled removals (MTBUR). Figure 102.3 is a top-level view of the U.S. Air Force F-22 Advanced Tactical Fighter avionics. Like many other aircraft, the F-22 architecture is hybrid, part federated and part integrated. The left side of the figure is the highly integrated portion, dominated by the two Common Integrated Processors (CIPs) that process, fuse, and distribute signals received from the various sensors on the far left. The keys to this portion of the architecture are the Processor Interconnect (PI) buses within the CIPs and the High Speed Data Buses (HSDBs). (There are provisions for a third CIP as the F-22 avionics grow in capability.) The right side of the figure shows the federated systems including the Inertial Reference, Stores Management, Integrated Flight and Propulsion Control, and Vehicle Management systems and the interface of the latter two to the Integrated Vehicle System Control. The keys to this portion of the architecture are the triple or quadruple redundant AS 15531 (formerly MIL-STD-1553) command/response two-way data buses. FIGURE 102.1 Cabinet assembly outline and installation (typical installation). (Courtesy of Honeywell, Inc.)
CORTROL CONTROL 1I □□ R FIGURE 102.2 Architecture for AIMSbaseline configuration. Courtesy of Honeywell, Inc. Data buses As noted earlier, data buses are the key to the emerging integrated avionics architectures. Table 102. 1 summarizes the major features of the most used system buses. MIL-STD-1553 and ARINC 429 were the first data buses to be used for general aircraft data communications. These are used today widely in military and civil avionics, respectively, and have demonstrated the significant potential of data buses. The others listed in the table build on their success Displays All modern avionics systems use electronic displays, CRTs or flat-panel LCDs that offer exceptional flexibility in display format and significantly higher ity than electromechanical displays. Because of the ery bright ambient sunlight at flight altitudes the principal challenge for an electronic display is adequate brightness CRTs achieve the required brightness through the use of a shadow mask design coupled with narrow bandpass optical filters. Flat-panel LCDs also use narrow bandpass optical filters and a bright backlight to achieve the necessary brightness. e 2000 by CRC Press LLC
© 2000 by CRC Press LLC Data Buses As noted earlier, data buses are the key to the emerging integrated avionics architectures. Table 102.1 summarizes the major features of the most commonly used system buses. MIL-STD-1553 and ARINC 429 were the first data buses to be used for general aircraft data communications. These are used today widely in military and civil avionics, respectively, and have demonstrated the significant potential of data buses. The others listed in the table build on their success. Displays All modern avionics systems use electronic displays, either CRTs or flat-panel LCDs that offer exceptional flexibility in display format and significantly higher reliability than electromechanical displays. Because of the very bright ambient sunlight at flight altitudes the principal challenge for an electronic display is adequate brightness. CRTs achieve the required brightness through the use of a shadow mask design coupled with narrow bandpass optical filters. Flat-panel LCDs also use narrow bandpass optical filters and a bright backlight to achieve the necessary brightness. FIGURE 102.2 Architecture for AIMSbaseline configuration. (Courtesy of Honeywell, Inc.)
○ AIRDATA tutors Equipment Warno - Frequency FIGURE 102.3 F-22 EMD Architecture TABLE 102.1 Characteristics of Common Avionics Buses MIL-STD-1553 DOD-STD-1773 ARINC 629 002202 Fiber 50 Mb/s wire or fiber optic 2 Mb/s Wire or fiber optic ARINC 659 100 MB/s Because of the intrinsic flexibility of electronic displays, a major issue is the design of display formats. Care must be taken not to place too much information in the display and to ensure that the information is comprehendible in high workload(aircraft emergency or combat)situations Power Aircraft power is generally of two types: 28 vdc, and 115 vac, 400 Hz. Some 270 vdc is also used on military aircraft. Aircraft power is of poor quality when compared to power for most other electronics. Under normal conditions, there can be transients of up to 100% of the supply voltage and power interruptions of up to 1 second This poor quality places severe design requirements on the avionics power supply, especially where the avionics are performing a full-time, flight-critical function. Back-up power sources include ram air turbines and batteries, although batteries require very rigorous maintenance practices to guarantee long-term reliable per Software in avionics Most avionics currently being delivered are microprocessor controlled and are software intensive. The"power achieved from software programs hosted on a sophisticated processor results in very complex avionics with many functions and a wide variety of options. The combination of sophistication and flexibility has resulted e 2000 by CRC Press LLC
© 2000 by CRC Press LLC Because of the intrinsic flexibility of electronic displays, a major issue is the design of display formats. Care must be taken not to place too much information in the display and to ensure that the information is comprehendible in high workload (aircraft emergency or combat) situations. Power Aircraft power is generally of two types: 28 vdc, and 115 vac, 400 Hz. Some 270 vdc is also used on military aircraft. Aircraft power is of poor quality when compared to power for most other electronics. Under normal conditions, there can be transients of up to 100% of the supply voltage and power interruptions of up to 1 second. This poor quality places severe design requirements on the avionics power supply, especially where the avionics are performing a full-time, flight-critical function. Back-up power sources include ram air turbines and batteries, although batteries require very rigorous maintenance practices to guarantee long-term reliable performance. Software in Avionics Most avionics currently being delivered are microprocessor controlled and are software intensive. The “power” achieved from software programs hosted on a sophisticated processor results in very complex avionics with many functions and a wide variety of options. The combination of sophistication and flexibility has resulted FIGURE 102.3 F-22 EMD Architecture. TABLE 102.1 Characteristics of Common Avionics Buses Bus Name Word Length Bit Rate Transmission Media MIL-STD-1553 20 bits 1 Mb/s Wire DOD-STD-1773 20 bits TBS Fiber optic High-speed data bus 32 bits 50 Mb/s Wire or fiber optic ARINC 429 32 bits 14.5/100 kb/s Wire ARINC 629 20 bits 2 Mb/s Wire or fiber optic ARINC 659 32 bits 100 MB/s Wire
WEATHER INFORMATION SYSTEMS W is a critical factor in aircraft operations. It is the largest single contributor to flight and a major cause of aircraft accidents A study conducted for NASA by Ohio State University reported that the principal diffi- culties in making proper flight decisions are the timeliness and clarity of weather data dissemination. To advance the technology of in-flight weather reporting, Langley Research Center developed in the early 1990 s a cockpit weather information system known as CWIN ( Cockpit Weather Information). The system draws on several commercial data sensors to create radar maps of storms and lightning, together with eports of surface observations. Shown above is a cwin display in the simulation cock pit of Langley's Transport Sys- tems Research Vehicle, a modified jetliner used to test advanced technologies. The CWin display is the lower right screen among the four center panel screens. By push ing a button, the pilot may select from a menu of several displays, such as a ceiling and visibility map, rad ar storn map, or lightning strike map Courtesy of National Aeronau tics and Space Administration. in lengthy procedures for validation and certification. The brickwalling of software modules in a system during the initial development process to ensure isolation between critical and noncritical modules has been helpful in easing the certification process. There are no standard software programs or standard software certification procedures. RTCA has prepared Document Do-178 to provide guidance(as opposed to strict rules) regarding development and certification of avionics civil software. The techniques for developing, categorizing, and documenting avionics civil software in DO-178 are widely used For military avionics software, the principal document is DOD-STD-498. This standard defines a set of activities and documentation suitable for the development of both weapon systems and automated information stems. Many software languages have been used in the past in avionics applications; however, today there is a strong trend for both military and avionics civil software to use Ada wherever reasonably possible The evolving definition of a standards for Applications Exchange(APEX) software promises to provide a common software platform whereby the specialized requirements of varying hardware(processor)requirements are minimized. APEX software is a hardware interface that provides a common link with the functional software within an avionics system. The ultimate benefit is the development of software independent of the hardware platform and the ability to reuse software in systems with advanced hardware while maintaining most, if not all, of the original software design. e 2000 by CRC Press LLC
© 2000 by CRC Press LLC in lengthy procedures for validation and certification. The brickwalling of software modules in a system during the initial development process to ensure isolation between critical and noncritical modules has been helpful in easing the certification process. There are no standard software programs or standard software certification procedures. RTCA has prepared Document DO-178 to provide guidance (as opposed to strict rules) regarding development and certification of avionics civil software. The techniques for developing, categorizing, and documenting avionics civil software in DO-178 are widely used. For military avionics software, the principal document is DOD-STD-498. This standard defines a set of activities and documentation suitable for the development of both weapon systems and automated information systems. Many software languages have been used in the past in avionics applications; however, today there is a strong trend for both military and avionics civil software to use Ada wherever reasonably possible. The evolving definition of a standards for Applications Exchange (APEX) software promises to provide a common software platform whereby the specialized requirements of varying hardware (processor) requirements are minimized.APEX software is a hardware interface that provides a common link with the functional software within an avionics system. The ultimate benefit is the development of software independent of the hardware platform and the ability to reuse software in systems with advanced hardware while maintaining most, if not all, of the original software design. WEATHER INFORMATION SYSTEMS eather is a critical factor in aircraft operations. It is the largest single contributor to flight delays and a major cause of aircraft accidents. A study conducted for NASA by Ohio State University reported that the principal diffi- culties in making proper flight decisions are the timeliness and clarity of weather data dissemination. To advance the technology of in-flight weather reporting, Langley Research Center developed in the early 1990’s a cockpit weather information system known as CWIN (Cockpit Weather Information). The system draws on several commercial data sensors to create radar maps of storms and lightning, together with reports of surface observations. Shown above is a CWIN display in the simulation cockpit of Langley’s Transport Systems Research Vehicle, a modified jetliner used to test advanced technologies. The CWIN display is the lower right screen among the four center panel screens. By pushing a button, the pilot may select from a menu of several displays, such as a ceiling and visibility map, radar storm map, or lightning strike map. (Courtesy of National Aeronautics and Space Administration.) W
CNS/ATM The last decade of this century has seen much attention focused on Communication/Navigation/Surve for Air Traffic Management(CNS/ATM), a satellite-based concept developed by the Future Air System(FANS)Committees of the International Civil Aviation Organization (ICAO), a special agency of the United Nations. Many studies have predicted enormous economic rewards of CNS/ATM for both aircraft operators and air traffic services providers. The new CNS/ATM system should provide for: Global communications, navigation, and surveillance coverage at all altitudes and embrace remote, off- hore,and oceanic areas. Digital data exchange between air-ground systems( voice backup) Navigation/approach service for runways and other landing areas which need not be equipped wit precision landing aids Navigation Equipment A large portion of the avionics on an aircraft are dedicated to navigation. The following types of navigation and related sensors are commonly found on aircraft: Flight control computer(FCC) light management computer(FMC) Inertial navigation system(INS) Attitude heading and reference system(AHRS Low range radio altimeter(LRRA) Distance Measuring Equipment(DMe Microwave Landing System(MLS) VHF OmniRange(VOR) Receiver Emphasis on Communications rm of digital communications for either data transfer or digitized voice. Military aircraft typically use digital communications for security. Civil aircraft use digital communications to transfer data for improved efficiency of operations and RF spectrum utilization. Both types of aircraft are focusing more on enhanced communica tions to fulfill the requirements for better operational capability. Various types of communications equipment are used on aircraft. The following list tabulates typical com- munications equipment: VHF transceiver(118-136 MHZ UHF transceiver(225-328 MHz/335-400 MHz for military HF transceiver(2.8-24 MHZ) Satellite(1530-1559/1626.5-1660.5 MHz, various frequencies for military Aircraft Communications Addressing and Reporting(ACARS Joint Tactical Information Distribution System (TIDS) In the military environment the need for communicating aircraft status and for aircraft reception of crucial information regarding mission objectives are primary drivers behind improved avionics. In the civil environment e 2000 by CRC Press LLC
© 2000 by CRC Press LLC CNS/ATM The last decade of this century has seen much attention focused on Communication/Navigation/Surveillance for Air Traffic Management (CNS/ATM), a satellite-based concept developed by the Future Air Navigation System (FANS) Committees of the International Civil Aviation Organization (ICAO), a special agency of the United Nations. Many studies have predicted enormous economic rewards of CNS/ATM for both aircraft operators and air traffic services providers. The new CNS/ATM system should provide for: • Global communications, navigation, and surveillance coverage at all altitudes and embrace remote, offshore, and oceanic areas. • Digital data exchange between air-ground systems (voice backup). • Navigation/approach service for runways and other landing areas which need not be equipped with precision landing aids. Navigation Equipment A large portion of the avionics on an aircraft are dedicated to navigation. The following types of navigation and related sensors are commonly found on aircraft: • Flight control computer (FCC) • Flight management computer (FMC) • Inertial navigation system (INS) • Attitude heading and reference system (AHRS) • Air data computer (ADC) • Low range radio altimeter (LRRA) • Radar • Distance Measuring Equipment (DME) • Instrument Landing System (ILS) • Microwave Landing System (MLS) • VHF OmniRange (VOR) Receiver • Global Navigation Satellite System (GNSS) Emphasis on Communications An ever-increasing portion of avionics is dedicated to communications. Much of the increase comes in the form of digital communications for either data transfer or digitized voice. Military aircraft typically use digital communications for security. Civil aircraft use digital communications to transfer data for improved efficiency of operations and RF spectrum utilization. Both types of aircraft are focusing more on enhanced communications to fulfill the requirements for better operational capability. Various types of communications equipment are used on aircraft. The following list tabulates typical communications equipment: • VHF transceiver (118–136 MHz) • UHF transceiver (225–328 MHz/335–400 MHz for military) • HF transceiver (2.8–24 MHz) • Satellite (1530–1559/1626.5–1660.5 MHz, various frequencies for military) • Aircraft Communications Addressing and Reporting (ACARS) • Joint Tactical Information Distribution System (JTIDS) In the military environment the need for communicating aircraft status and for aircraft reception of crucial information regarding mission objectives are primary drivers behind improved avionics. In the civil environment
HIGH SPEED RESEARCH This McDonnell Douglas conceptual design for a Mach 2. 4 supersonic trans- port is sized to carry about 300 passengers over a distance of 5,000 nautical miles. A NASA/industry high speed civil transport research effort is a first step toward determining whether such a plane can be economically viable and environmentally acceptable. Photo Courtesy of National Aeronautics and space Administration. A ircraft manufacturers of several nations are developing technology for the next plateau of national aviation: the long-range, environmentally acceptable, second generation sup passenger transport, which could be flying by 2010 NASAs High Speed Research(HSR) program is intended to demonstrate the technical feasibility of a high speed civil transport(HSCT)vehicle. The program is being conducted as a national team effort with shared gov ernment The team has established a baseline design concept that serves as a common configuration for inves- igations. A full-scale craft of this design would have a maximum cruise speed of Mach 2. 4, only marginally faster than the Anglo-French Concorde supersonic transport. However, the HSCT would have double the capacity of the Concorde, and it would operate at an affordable ticket price.., challe c Phase I of the HSR program, which began in 1990, focused on environmental challenges: engine on effects on the atmosphere, airport noise, and sonic boom. Phase IL, initiated in 1994, focuses on the technology advances needed for economic viability, principally weight reductions in every aspect of the baseline configuration. In materials, the HSR team is developing, analyzing, and verifying the technology for trimming the baseline airframe by 30 to 40%. In aerodynamics, a major goal is to minimize air drag to enable a substantial increase in range. Phase II also includes computational and wind tunnel analyses of the baseline HSCT and alternative designs. Additional research involves ground and flight simulations aimed at development of advanced control systems, flight deck instrumentation, and displays Courtesy of National Aeronautics and Space Administration. (particularly commercial transport), the desire for improved passenger services, more efficient aircraft routing and operation, safe operations, and reduced time for aircraft maintenance are the primary drivers for improving The requirements for digital communications for civil aircraft have grown so significantly that the industry as a whole embarked on a virtually total upgrade of the communications system elements. The goal is to achieve a high level of flexibility in processing varying types of information as well as attaining compatibility between a wide variety of communication devices. The approach bases both ground system and avionics design on the ISO Open System Interconnect(OSI)model. This seven-layer model separates the various factors of commu nications into clearly definable elements of physical media, protocols, addressing, and information identification The implementation of the OSI model requires a much higher level of complexity in the avionics as compared to avionics designed for simple dedicated point-to-point communications. The avionics interface to the physical e 2000 by CRC Press LLC
© 2000 by CRC Press LLC (particularly commercial transport), the desire for improved passenger services, more efficient aircraft routing and operation, safe operations, and reduced time for aircraft maintenance are the primary drivers for improving the communications capacity of the avionics. The requirements for digital communications for civil aircraft have grown so significantly that the industry as a whole embarked on a virtually total upgrade of the communications system elements. The goal is to achieve a high level of flexibility in processing varying types of information as well as attaining compatibility between a wide variety of communication devices. The approach bases both ground system and avionics design on the ISO Open System Interconnect (OSI) model. This seven-layer model separates the various factors of communications into clearly definable elements of physical media, protocols, addressing, and information identification. The implementation of the OSI model requires a much higher level of complexity in the avionics as compared to avionics designed for simple dedicated point-to-point communications. The avionics interface to the physical HIGH SPEED RESEARCH This McDonnell Douglas conceptual design for a Mach 2.4 supersonic transport is sized to carry about 300 passengers over a distance of 5,000 nautical miles. A NASA/industry high speed civil transport research effort is a first step toward determining whether such a plane can be economically viable and environmentally acceptable. (Photo Courtesy of National Aeronautics and Space Administration.) ircraft manufacturers of several nations are developing technology for the next plateau of international aviation: the long-range, environmentally acceptable, second generation supersonic passenger transport, which could be flying by 2010. NASA’s High Speed Research (HSR) program is intended to demonstrate the technical feasibility of a high speed civil transport (HSCT) vehicle. The program is being conducted as a national team effort with shared government/industry funding and responsibilities. The team has established a baseline design concept that serves as a common configuration for investigations. A full-scale craft of this design would have a maximum cruise speed of Mach 2.4, only marginally faster than the Anglo-French Concorde supersonic transport. However, the HSCT would have double the capacity of the Concorde, and it would operate at an affordable ticket price. Phase I of the HSR program, which began in 1990, focused on environmental challenges: engine emission effects on the atmosphere, airport noise, and sonic boom. Phase II, initiated in 1994, focuses on the technology advances needed for economic viability, principally weight reductions in every aspect of the baseline configuration. In materials, the HSR team is developing, analyzing, and verifying the technology for trimming the baseline airframe by 30 to 40%. In aerodynamics, a major goal is to minimize air drag to enable a substantial increase in range. Phase II also includes computational and wind tunnel analyses of the baseline HSCT and alternative designs. Additional research involves ground and flight simulations aimed at development of advanced control systems, flight deck instrumentation, and displays. (Courtesy of National Aeronautics and Space Administration.) A
medium will generally possess a higher bandwidth. The bandwidth is required to accommodate the overhead of the additional information on the communications link for the purpose of system management. The higher bandwidths pose a special problem for aircraft designers due to weight and electromagnetic interference(Emi) considerations. Additional avionics are required to perform the buffering and distribution of the information received by the aircraft. Generally a single unit, commonly identified as the communications management unit (CMU), will perform this function The CMU can receive information via RF transceivers operating in conjunction with terrestrial, airborne, or space-based transceivers. The capability also exists for transceiver pairs employing direct wire connections or very short-range optical links to the aircraft. The CMU also provides the routing function between the avionics, when applicable. Large on-board databases, such as an electronic library, may be accessed and provid information to other avionics via the cmu The increasing demand on data communication system capacity and flexibility is dictating the development of a system without the numerous limitations of current systems. Current communication systems require rather rigid protocols, message formatting, and addressing. The need for a more flexible and capable system has led to the initial work to develop an Aeronautical Telecommunications Network(ATN). The characteristics envisaged for the ATN are the initiation, transport, and application of virtually any type of digital message in an apparently seamless method between virtually any two end systems. The atn is expected to be a continually ing syste Impact of“ Free flight Free Flight" is a term describing an airspace navigation system in which the"normal"air traffic controls are replaced by the regular transmission of position information from the airplane to the ground. The ground system, by projecting the aircraft position and time, can determine if the intended tracks of two aircraft would result in a cohabitation of the same point in the airspace. This is commonly called"conflict probe. If a potential conflict occurs, then a message is transmitted to one or more of the aircraft involved to make a change to course and/or speed. Free Flight"dictates special requirements for the avionics suite. a highly accurate navigation system high integrity is required. The communications and surveillance functions must exhibit an extremely high of availability. GNSS Avionics performing the position determination functions will require augmentation to achieve the necessary accuracy. The augmentation will be provided by a data communications system and will be in the form of positional information correction. a data communications system will also be required to provide the frequent broadcast of position information to the ground. A modified Mode S transponder squitter is expected to provide that function. The free flight concept will require the equipage of virtually all aircraft operating within the designated free flight airspace with a commensurate level of avionics capability. The early stages of the concept development uncovered the need to upgrade virtually all aircraft with enhanced CNS/ATM avionics. The air transport industry resolved this problem on older airplanes by developing improved and new avionics for retrofit applications. The new avionics design addresses the issues of increased accuracy of position and enhancement of navigation management in the form of the GNSS Navigation and Landing Unit(GNLU)housed in a single unit and designed to be a physical and functional replacement for the ILS and/or MLS receivers. A built-in navigator provides enhanced navigation functionality for the airplane. The GNSS can provide ILS lookalike signals and perform landing guidance functions equivalent to Category L. Avionics in the cabin Historically, the majority of avionics have been located in the electronics bay and the cockpit of commercial air transport airplanes. Cabin electronics had generally been limited to the cabin interphone and public address system,the sound and central video system, and the lighting control system. More recently the cabin has been updated with passenger telephones using both terrestrial and satellite systems. The terrestrial telephone system operates in the 900-MHz band in the United States and will operate near 1.6 GHz in Europe. The satellite e 2000 by CRC Press LLC
© 2000 by CRC Press LLC medium will generally possess a higher bandwidth. The bandwidth is required to accommodate the overhead of the additional information on the communications link for the purpose of system management. The higher bandwidths pose a special problem for aircraft designers due to weight and electromagnetic interference (EMI) considerations. Additional avionics are required to perform the buffering and distribution of the information received by the aircraft. Generally a single unit, commonly identified as the communications management unit (CMU), will perform this function. The CMU can receive information via RF transceivers operating in conjunction with terrestrial, airborne, or space-based transceivers. The capability also exists for transceiver pairs employing direct wire connections or very short-range optical links to the aircraft. The CMU also provides the routing function between the avionics, when applicable. Large on-board databases, such as an electronic library, may be accessed and provide information to other avionics via the CMU. The increasing demand on data communication system capacity and flexibility is dictating the development of a system without the numerous limitations of current systems. Current communication systems require rather rigid protocols, message formatting, and addressing. The need for a more flexible and capable system has led to the initial work to develop an Aeronautical Telecommunications Network (ATN). The characteristics envisaged for the ATN are the initiation, transport, and application of virtually any type of digital message in an apparently seamless method between virtually any two end systems. The ATN is expected to be a continually evolving system. Impact of “Free Flight” “Free Flight” is a term describing an airspace navigation system in which the “normal” air traffic controls are replaced by the regular transmission of position information from the airplane to the ground. The ground system, by projecting the aircraft position and time, can determine if the intended tracks of two aircraft would result in a cohabitation of the same point in the airspace. This is commonly called “conflict probe”. If a potential conflict occurs, then a message is transmitted to one or more of the aircraft involved to make a change to course and/or speed. “Free Flight” dictates special requirements for the avionics suite. A highly accurate navigation system with high integrity is required. The communications and surveillance functions must exhibit an extremely high level of availability. GNSS Avionics performing the position determination functions will require augmentation to achieve the necessary accuracy. The augmentation will be provided by a data communications system and will be in the form of positional information correction. A data communications system will also be required to provide the frequent broadcast of position information to the ground. A modified Mode S transponder squitter is expected to provide that function. The free flight concept will require the equipage of virtually all aircraft operating within the designated free- flight airspace with a commensurate level of avionics capability. The early stages of the concept development uncovered the need to upgrade virtually all aircraft with enhanced CNS/ATM avionics. The air transport industry resolved this problem on older airplanes by developing improved and new avionics for retrofit applications. The new avionics design addresses the issues of increased accuracy of position and enhancement of navigation management in the form of the GNSS Navigation and Landing Unit (GNLU) housed in a single unit and designed to be a physical and functional replacement for the ILS and/or MLS receivers. A built-in navigator provides enhanced navigation functionality for the airplane. The GNSS can provide ILS lookalike signals and perform landing guidance functions equivalent to Category I. Avionics in the Cabin Historically, the majority of avionics have been located in the electronics bay and the cockpit of commercial air transport airplanes. Cabin electronics had generally been limited to the cabin interphone and public address system, the sound and central video system, and the lighting control system. More recently the cabin has been updated with passenger telephones using both terrestrial and satellite systems. The terrestrial telephone system operates in the 900-MHz band in the United States and will operate near 1.6 GHz in Europe. The satellite
system, when completely operational, will also operate near 1.6 GHz. Additional services available to the passengers are the ability to send facsimiles(FAXes)and to view virtually real-time in-flight position reporting via connection of the video system with the flight system. Private displays at each seat will allow personal viewing of various forms of entertainment including movies, games, casual reading, news programming, etc. Avionics standards Standards play an important role in avionics. Military avionics are controlled by the various standards(mil TDs, DOD-STDs, etc. )for packaging, environmental performance, operating characteristics, electrical and data interfaces, and other design-related parameters. General aviation avionics are governed by fewer and less ringent standards. Technical Standard Orders(TSOs)released by the Federal Aviation Administration(FAA) re used as guidelines to ensure airworthiness of the avionics. TSOs are derived from and, in most cases, reference RTCA documents characterized as Minimum Operational Performance Standards and Minimum Avionics System Performance Standards. EUROCAE is the European counterpart of RTCA The commercial air transport industry adheres to multiple standards at various levels. The International Civil Aviation Organization(ICAO)is commissioned by the United Nations to govern aviation systems includ- ing but not limited to Data Communications Systems, On-Board Recorders, Instrument Landing Systems, Microwave Landing Systems, VHF OmniRange Systems, and Distance Measuring Equipment. The ICAO Stan dards and Recommended Practices(SARPS)control system performance, availability requirements, frequency utilization,etc. at the international level. The SARPS in general maintain alignment between the national avionics standards such as those published by EUROCAE and RTCA. The commercial air transport industry also uses voluntary standards created by the Airlines Electronic Engineering Committee and published by Aeronautical Radio Inc. (ARINC). The ARINC"characteristics define form, fit, and function of airline avionics. Defining Terms ACARS: A digital communications link using the VHF spectrum for two-way transmission of data between an aircraft and ground. It is used primarily in civil aviation applications Brickwalling: Generally used in software design in critical applications to ensure that changes in one area oftware will not impact other areas of software or alter their desired function Distance measuring equipment: The combination of a receiver and a transponder for determining aircraft distance from a remote transmitter. The calculated distance is based on the time required for the return of an interrogating pulse set initiated by the aircraft tra Fault tolerance: The built-in capability of a system to provide continued correct execution in the presence of a limited number of hardware or software faults JTIDS: Joint Tactical Information Distribution System using spread spectrum techniques for secure digital communication. It is used for military applications. Validation: The process of evaluating a product at the end of the development process to ensure compliance with requirements Verification: (1)The process of determining whether the products of a given phase of the software developme cycle fulfill the requirements established during the previous phase.(2)Formal proof of program correct ness.(3)The act of reviewing, inspecting, testing, checking, auditing, or otherwise establishing and documenting whether items, processes, services, or documents conform to specified requirements(IEeE Related Topic 78.1 Introduction References Airlines Electronic Engineering Committee Archives, Aeronautical Radio Inc. FANS Manual, International Air Transport Association, Montreal, Version 1.1, May 1995 e 2000 by CRC Press LLC
© 2000 by CRC Press LLC system, when completely operational, will also operate near 1.6 GHz. Additional services available to the passengers are the ability to send facsimiles (FAXes) and to view virtually real-time in-flight position reporting via connection of the video system with the flight system. Private displays at each seat will allow personal viewing of various forms of entertainment including movies, games, casual reading, news programming, etc. Avionics Standards Standards play an important role in avionics. Military avionics are controlled by the various standards (MILSTDs, DOD-STDs, etc.) for packaging, environmental performance, operating characteristics, electrical and data interfaces, and other design-related parameters. General aviation avionics are governed by fewer and less stringent standards. Technical Standard Orders (TSOs) released by the Federal Aviation Administration (FAA) are used as guidelines to ensure airworthiness of the avionics. TSOs are derived from and, in most cases, reference RTCA documents characterized as Minimum Operational Performance Standards and Minimum Avionics System Performance Standards. EUROCAE is the European counterpart of RTCA. The commercial air transport industry adheres to multiple standards at various levels. The International Civil Aviation Organization (ICAO) is commissioned by the United Nations to govern aviation systems including but not limited to Data Communications Systems, On-Board Recorders, Instrument Landing Systems, Microwave Landing Systems, VHF OmniRange Systems, and Distance Measuring Equipment. The ICAO Standards and Recommended Practices (SARPS) control system performance, availability requirements, frequency utilization, etc. at the international level. The SARPS in general maintain alignment between the national avionics standards such as those published by EUROCAE and RTCA. The commercial air transport industry also uses voluntary standards created by the Airlines Electronic Engineering Committee and published by Aeronautical Radio Inc. (ARINC). The ARINC “characteristics” define form, fit, and function of airline avionics. Defining Terms ACARS: A digital communications link using the VHF spectrum for two-way transmission of data between an aircraft and ground. It is used primarily in civil aviation applications. Brickwalling: Generally used in software design in critical applications to ensure that changes in one area of software will not impact other areas of software or alter their desired function. Distance measuring equipment: The combination of a receiver and a transponder for determining aircraft distance from a remote transmitter. The calculated distance is based on the time required for the return of an interrogating pulse set initiated by the aircraft transponder. Fault tolerance: The built-in capability of a system to provide continued correct execution in the presence of a limited number of hardware or software faults. JTIDS: Joint Tactical Information Distribution System using spread spectrum techniques for secure digital communication. It is used for military applications. Validation: The process of evaluating a product at the end of the development process to ensure compliance with requirements. Verification: (1) The process of determining whether the products of a given phase of the software development cycle fulfill the requirements established during the previous phase. (2) Formal proof of program correctness. (3) The act of reviewing, inspecting, testing, checking, auditing, or otherwise establishing and documenting whether items, processes, services, or documents conform to specified requirements (IEEE). Related Topic 78.1 Introduction References Airlines Electronic Engineering Committee Archives, Aeronautical Radio Inc. FANS Manual, International Air Transport Association, Montreal, Version 1.1, May 1995
