The cost and schedule time expended to design and develop modern computer-based systems has grown dramatically over the past decade. Advanced system engineering development methods and automation techniques are requir...
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The cost and schedule time expended to design and develop modern computer-based systems has grown dramatically over the past decade. Advanced system engineering development methods and automation techniques are required to manage the complexity inherent in the design of large, complex computer-based systems and to provide an efficient mechanism for evaluating various design options. Simulation-based design (SBD) is a system design approach centered upon the creation of virtual system prototypes and virtual environments within an integrated system design capture and simulation framework. A methodology is presented in this paper which supports SBD for complex real-time computer-based systems including: (1) a multi-domain approach to capturing system design information and (2) a mechanism for simulation of the conceptual, functional and implementation aspects of the design as captured. Finally, selected opportunities for automation support of the SBD approach are discussed.< >
Starting with the See-Saw and Problem Solving diagrams (H. Lawson, 1994), a useful definition of the major constituents of architecture for computer-based systems engineering, was made. This definition extends previou...
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Starting with the See-Saw and Problem Solving diagrams (H. Lawson, 1994), a useful definition of the major constituents of architecture for computer-based systems engineering, was made. This definition extends previous results. A first evaluation of the definition was based upon examining the properties of the British Aerospace DORIS approach as presented by H.R. Simpson (1994).< >
In considering the issues for successful implementation of Digital Terrestrial Television Broadcasting, we can draw on a foundation of NTL's experience as the provider of the NTL 2000 digital video compression sys...
In considering the issues for successful implementation of Digital Terrestrial Television Broadcasting, we can draw on a foundation of NTL's experience as the provider of the NTL 2000 digital video compression system world-wide, and over five years of study on the SPECTRE project in the United Kingdom. SPECTRE is concerned with all aspects of Digital Television including the low-bit rate video coding, modulation, frequency planning, and perhaps most important, practical field trials. The work was initiated under the Independent Broadcasting Authority, but since the IBA was abolished in 1990, it has been carried out by NTL, under contract from the Independent Television Commission in the UK.
Introducing new or enhancing current radio services is dependent on the ability of the service to coexist with other services. Introduction of digital TV must also respect other services and international agreements c...
Introducing new or enhancing current radio services is dependent on the ability of the service to coexist with other services. Introduction of digital TV must also respect other services and international agreements concerning the use of spectrum. In some countries digital terrestrial TV will be introduced as enhancements of existing services, and new spectrum is not likely to be made available. This may even be true where the digital TV system is used for new services, because TV broadcasting is seen by many regulators as a spectrum inefficient service and because no free spectrum is available. As a consequence we have to face the fact that digital terrestrial TV must be able to coexist with present TV services in shared bands. This paper discusses the questions related to introduction of digital terrestrial TV, and in particular the possible trade-offs which will be necessary to make the service work. Will we accept a slightly reduced quality of the analogue service? What is the noise figure of new receivers? Should it be scalable? Can it be portable? What is the power range? Can it use adjacent channels? Other questions could be whether a worldwide scenario is possible. Are the constraints the same all over the world? Are the trade-offs equally acceptable anywhere? Yet another will be if one modulation scheme is superior to another, and must it carry HDTV from the start or would standard or enhanced definition do? There are questions about coverage, graceful degradation, service availability and so on. This paper deals with such problems as factors affecting the planning process.
The MPEG standard address the compression and decompression (restoration) of moving pictures (video) and sound (audio) and the formation of a multiplexed common data stream that includes the compressed video and audio...
The MPEG standard address the compression and decompression (restoration) of moving pictures (video) and sound (audio) and the formation of a multiplexed common data stream that includes the compressed video and audio data plus any associated ancillary service data. The MPEG standard further addresses the synchronization of the video, audio, and ancillary data during playback of the decompressed signals.
One of the key technical challenges to providing a terrestrial high definition broadcast television service in the United States is to simulcast the new service into the same spectrum space occupied by present day NTS...
One of the key technical challenges to providing a terrestrial high definition broadcast television service in the United States is to simulcast the new service into the same spectrum space occupied by present day NTSC television. Since both NTSC and high definition television must coexist during a transition period, the optimum utilization of available spectrum for HDTV requires achieving a low level of interference between NTSC and HDTV stations. Both single carrier and dual carrier transmission systems have been proposed for HDTV and the present paper examines some of their fundamental strengths and weaknesses. Based on an overall consideration of the latest computer analysis of HDTV and NTSC service areas, and other factors, it is concluded that a single carrier approach is preferred.
In the process of defining a new system for digital terrestrial TV broadcasting, operational constraints related to frequency management, as well as service concepts in agreement with current and future trends, consti...
In the process of defining a new system for digital terrestrial TV broadcasting, operational constraints related to frequency management, as well as service concepts in agreement with current and future trends, constitute the original requirements on which the broadcasters have to base their developments.
An ECBS Task Force activity of prime importance is the case study initiative. We report on its history and conceptual deficits and summarize the results of the Stockholm Workshop working group sessions about that topic.
An ECBS Task Force activity of prime importance is the case study initiative. We report on its history and conceptual deficits and summarize the results of the Stockholm Workshop working group sessions about that topic.< >
The system concept is presented as a structure constituted from objects from the categories mission, operator, software and hardware. It is shown how Ada's semantics and syntax can be used in the pseudo language O...
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The system concept is presented as a structure constituted from objects from the categories mission, operator, software and hardware. It is shown how Ada's semantics and syntax can be used in the pseudo language Odel to describe system structure and object behaviour, regardless of object category. Experience form 10 years of Ada-based methods work has led to an understanding of the evolutionary and iterative nature of systems work, expressed in the O4S method with its "ball-bearing" development model. It is shown how the method makes it possible to unify system and project structure and thus optimize project resource utilization. Application areas for the O4S are shown concentrating on system development with cooperation between users and developers.< >
The concepts presented in this paper propose a pre-planned and integrated development process for large, complex, and possibly distributed systems-so-called "mega-systems". A mega-system is partitioned into ...
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The concepts presented in this paper propose a pre-planned and integrated development process for large, complex, and possibly distributed systems-so-called "mega-systems". A mega-system is partitioned into systems which are developed very independently but interoperate in an integrated manner to provide comprehensive functionality within an application domain, e.g. in the form of a so-called "system of systems". To support this concept, we specify a generic systems integration framework (GenSIF) that provides an additional level of control and coordination for the otherwise independent projects. Based on this idea of a distributed but well-guided systems development effort, a process model that enacts the suggested framework and its system development philosophy is discussed. This process model is a natural extension of already-existing, more traditional development models, and allows the engineer to preserve existing know-how in this area. To support flexibility and easy adaptation, domain modeling and domain architecture design are incorporated into the proposed framework.< >
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