The author addresses the effect on the performance of the DTTL (data transition tracking loop) symbol synchronizer of the signal transition variation due to signal transition density, data asymmetry, and sinusoidal modulation. It is shown that the combination of these factors will indeed affect the DTTL performance, e.g. clock jitter and cycle slippage rate, and that worst-case performance may result if the parameters are not well selected. Typical numerical results are shown.<>
{"title":"Bit synchronizer performance in the presence of signal transition variation","authors":"C. Tsang","doi":"10.1109/AERO.1989.82426","DOIUrl":"https://doi.org/10.1109/AERO.1989.82426","url":null,"abstract":"The author addresses the effect on the performance of the DTTL (data transition tracking loop) symbol synchronizer of the signal transition variation due to signal transition density, data asymmetry, and sinusoidal modulation. It is shown that the combination of these factors will indeed affect the DTTL performance, e.g. clock jitter and cycle slippage rate, and that worst-case performance may result if the parameters are not well selected. Typical numerical results are shown.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123228249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Ku-band satellite communications network using very small aperture terminals (VSAT) has emerged as a cost-effective means for reliable data communications. The authors describe how the Ku-band satellite can satisfy the user's performance criteria for data communications for a variety of network designs. Two subsystems are considered, the access and the backbone of the Ku-band satellite network architecture. It is noted that various forms of design of the Ku-band satellite network can exist depending on the user's traffic characteristics and geographical coverage, and that the Ku-band satellite system provides dynamic adaptive accommodation of long- or short-range traffic demand and noninterference with the terrestrial system. It is expected that the Ku-band satellite communications' dynamic handling of both high and low data rate, along with voice communications, will also provide cost-effective solutions for ISDN (integrated services digital network) networks.<>
{"title":"Ku-band satellite systems for large scale data communications networks","authors":"R.R. Roy, A. Shah","doi":"10.1109/AERO.1989.82418","DOIUrl":"https://doi.org/10.1109/AERO.1989.82418","url":null,"abstract":"The Ku-band satellite communications network using very small aperture terminals (VSAT) has emerged as a cost-effective means for reliable data communications. The authors describe how the Ku-band satellite can satisfy the user's performance criteria for data communications for a variety of network designs. Two subsystems are considered, the access and the backbone of the Ku-band satellite network architecture. It is noted that various forms of design of the Ku-band satellite network can exist depending on the user's traffic characteristics and geographical coverage, and that the Ku-band satellite system provides dynamic adaptive accommodation of long- or short-range traffic demand and noninterference with the terrestrial system. It is expected that the Ku-band satellite communications' dynamic handling of both high and low data rate, along with voice communications, will also provide cost-effective solutions for ISDN (integrated services digital network) networks.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128676184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel approach that could meet the requirements of up to 220 GHz reception in the severe thermal environment of space is described which relies on a combination of the classical wrapped rib and electrostatic membrane technology. The wrapped rib configuration can be employed to support the membrane and its associated controlling electrodes. Once deployed, the membrane contour can be electrostatically reconfigured to correct for thermal distortion and off-axis beam scan (i.e. change from parabolic to spherical). The wrap-rib, electrostatic-membrane reflector is several orders of magnitude lighter than the nondeployed rigid reflectors and does not have an aperture constrained by the 4.4-m diameter of a launch vehicle envelope. A multipolarization and multiband cluster feed array used to achieve electronic scan over the millimeter-wave frequency spectrum is also described.<>
{"title":"Large aperture antenna concepts for millimeter wave applications","authors":"W. Gregorwich, H. Malliot","doi":"10.1109/AERO.1989.82411","DOIUrl":"https://doi.org/10.1109/AERO.1989.82411","url":null,"abstract":"A novel approach that could meet the requirements of up to 220 GHz reception in the severe thermal environment of space is described which relies on a combination of the classical wrapped rib and electrostatic membrane technology. The wrapped rib configuration can be employed to support the membrane and its associated controlling electrodes. Once deployed, the membrane contour can be electrostatically reconfigured to correct for thermal distortion and off-axis beam scan (i.e. change from parabolic to spherical). The wrap-rib, electrostatic-membrane reflector is several orders of magnitude lighter than the nondeployed rigid reflectors and does not have an aperture constrained by the 4.4-m diameter of a launch vehicle envelope. A multipolarization and multiband cluster feed array used to achieve electronic scan over the millimeter-wave frequency spectrum is also described.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"170 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132885145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The author has developed a network architecture called FTN which is highly fault tolerant and can be designed for any number of processors N. The network possesses many other desirable properties, cumulatively not possessed by any other network. An FTN-network-based parallel/distributed system can tolerate up to (log/sub 2/N)-1 failed processors. In a fault configuration it is easy to generate secondary paths; the corresponding algorithms are developed and proven correct. The network can be constructed using simple rules for an arbitrary N>or=2. To increase the number of processors in the system by one is possible and easy. It is shown that in general the connectivity (log/sub 2/N)>
{"title":"FTN, a fault tolerant network architecture for all N, theory and applications","authors":"R. R. Seban","doi":"10.1109/AERO.1989.82413","DOIUrl":"https://doi.org/10.1109/AERO.1989.82413","url":null,"abstract":"The author has developed a network architecture called FTN which is highly fault tolerant and can be designed for any number of processors N. The network possesses many other desirable properties, cumulatively not possessed by any other network. An FTN-network-based parallel/distributed system can tolerate up to (log/sub 2/N)-1 failed processors. In a fault configuration it is easy to generate secondary paths; the corresponding algorithms are developed and proven correct. The network can be constructed using simple rules for an arbitrary N>or=2. To increase the number of processors in the system by one is possible and easy. It is shown that in general the connectivity (log/sub 2/N)<or=k<or=(log/sub 2/N). The total number of edges grows much slower with N in the FTN then in the generalized hypercube.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121026681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The author outlines a statistical formulation of the average directivity and sidelobe levels for antennas of general or triangular element grid in terms of the standard deviations of amplitude and phase errors in element modules and the percentage of random failures thereof. Statistical average sidelobe levels are also displayed as a family of curves for routine engineering use. The theoretical formulation was tested to ascertain its validity in view of the assumptions invoked in its derivation. It was verified by direct numerical calculations or averaging from radiation patterns of an antenna similar to one that was planned for a space-based radar with various known amounts of errors. The averaging process used is based on a concept of graded resolution in UV space which provides better accuracy than other methods and should be considered for possible applications in the design calculation of large antennas of all types. The analysis showed that, for well-designed large phased-array antennas, the far-out sidelobe level is sensitive to errors in element excitation and failures of element modules.<>
{"title":"Performance of phased array antennas under error conditions","authors":"H.S.C. Wang","doi":"10.1109/AERO.1989.82429","DOIUrl":"https://doi.org/10.1109/AERO.1989.82429","url":null,"abstract":"The author outlines a statistical formulation of the average directivity and sidelobe levels for antennas of general or triangular element grid in terms of the standard deviations of amplitude and phase errors in element modules and the percentage of random failures thereof. Statistical average sidelobe levels are also displayed as a family of curves for routine engineering use. The theoretical formulation was tested to ascertain its validity in view of the assumptions invoked in its derivation. It was verified by direct numerical calculations or averaging from radiation patterns of an antenna similar to one that was planned for a space-based radar with various known amounts of errors. The averaging process used is based on a concept of graded resolution in UV space which provides better accuracy than other methods and should be considered for possible applications in the design calculation of large antennas of all types. The analysis showed that, for well-designed large phased-array antennas, the far-out sidelobe level is sensitive to errors in element excitation and failures of element modules.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132730740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The author presents a powerful technique to treat the problem of wave propagation along weakly guiding optical waveguides. The technique is based on the numerical solution of the scalar wave equation by a forward-marching fast Fourier transform method (SW-FFT). This solution yields the spatial configuration of the fields as well as its modal characteristics in and around the guiding structure. The technique is applicable to dielectric waveguides with arbitrary shape and three-dimensional index variations as long as their weakly guiding character is preserved. This technique is applied to several optical waveguides such as step-index circular fiber, graded-index circular fiber, elliptical, and rectangular dielectric waveguides. The computed dispersion characteristics of these structures are then compared with solutions obtained by using other known techniques, and an excellent agreement is established. It is shown that the scalar wave solutions are extremely accurate for all practical cases where the core refractive index differs from the cladding index by a few percent.<>
{"title":"A technique for computation of propagation characteristics of optical fiber structures","authors":"F. Manshadi","doi":"10.1109/AERO.1989.82417","DOIUrl":"https://doi.org/10.1109/AERO.1989.82417","url":null,"abstract":"The author presents a powerful technique to treat the problem of wave propagation along weakly guiding optical waveguides. The technique is based on the numerical solution of the scalar wave equation by a forward-marching fast Fourier transform method (SW-FFT). This solution yields the spatial configuration of the fields as well as its modal characteristics in and around the guiding structure. The technique is applicable to dielectric waveguides with arbitrary shape and three-dimensional index variations as long as their weakly guiding character is preserved. This technique is applied to several optical waveguides such as step-index circular fiber, graded-index circular fiber, elliptical, and rectangular dielectric waveguides. The computed dispersion characteristics of these structures are then compared with solutions obtained by using other known techniques, and an excellent agreement is established. It is shown that the scalar wave solutions are extremely accurate for all practical cases where the core refractive index differs from the cladding index by a few percent.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123612373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The author described a way to dramatically increase the speed of a popular desk top computer, the Apple Macintosh II, so that it becomes an effective and inexpensive simulation workstation. The design is based on the use of concurrent high-speed floating-point microprocessor chips on boards that plug into the NuBus card slots of the Macintosh II. The MPU chosen for the implementation is the Motorola DSP96002, a very high speed 32-bit microprocessor with on-chip floating-point hardware. The 40.5 Mflops (million floating-point operations per second) peak performance of the DSP96002 makes it well suited for simulation applications. Each board contains two DSP96002 processor nodes, an interface to the NuBus of the Macintosh II, and an interface to a proprietary high-speed data bus for connection to other DSP96002 boards. From one to five boards can be used in a system, resulting in a maximum of ten nodes for the simulator. A fully expanded workstation has a maximum sustained rate of 400 Mflops, which approaches the speed of a supercomputer.<>
作者描述了一种方法，可以极大地提高流行的台式计算机Apple Macintosh II的速度，使其成为一种高效且廉价的仿真工作站。该设计基于在插入Macintosh II的NuBus卡槽的主板上使用并发高速浮点微处理器芯片。为实现选择的MPU是摩托罗拉DSP96002，一个非常高速的32位微处理器与片上浮点硬件。DSP96002的峰值性能为40.5 Mflops(每秒百万次浮点运算)，非常适合仿真应用。每块DSP96002单板包含两个DSP96002处理器节点，一个与Macintosh II的NuBus接口，一个与专用高速数据总线的接口，用于与其他DSP96002单板连接。在一个系统中可以使用1到5个板，从而为模拟器提供最多10个节点。一个完全扩展的工作站的最大持续速率为400 Mflops，接近超级计算机的速度
{"title":"A desk-top simulation workstation designed around the DSP96002","authors":"A. Jackson","doi":"10.1109/AERO.1989.82425","DOIUrl":"https://doi.org/10.1109/AERO.1989.82425","url":null,"abstract":"The author described a way to dramatically increase the speed of a popular desk top computer, the Apple Macintosh II, so that it becomes an effective and inexpensive simulation workstation. The design is based on the use of concurrent high-speed floating-point microprocessor chips on boards that plug into the NuBus card slots of the Macintosh II. The MPU chosen for the implementation is the Motorola DSP96002, a very high speed 32-bit microprocessor with on-chip floating-point hardware. The 40.5 Mflops (million floating-point operations per second) peak performance of the DSP96002 makes it well suited for simulation applications. Each board contains two DSP96002 processor nodes, an interface to the NuBus of the Macintosh II, and an interface to a proprietary high-speed data bus for connection to other DSP96002 boards. From one to five boards can be used in a system, resulting in a maximum of ten nodes for the simulator. A fully expanded workstation has a maximum sustained rate of 400 Mflops, which approaches the speed of a supercomputer.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134131366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The authors investigate the throughput of an ALOHA land mobile satellite network operating in a vegetative shadowing environment. The fading statistic is represented by a lognormal probability density function which is incorporated in the throughput analysis. Both slotted and unslotted ALOHA protocols are considered. With the use of numerical analysis, it is shown that vegetative shadowing or lognormal shadowing improves the throughput considerably by reducing the mutual packet interference and thus enhanced the capture probability of a shared satellite receiver.<>
{"title":"Capacity of a land mobile satellite system","authors":"T. Beck, T. Ha","doi":"10.1109/AERO.1989.82416","DOIUrl":"https://doi.org/10.1109/AERO.1989.82416","url":null,"abstract":"The authors investigate the throughput of an ALOHA land mobile satellite network operating in a vegetative shadowing environment. The fading statistic is represented by a lognormal probability density function which is incorporated in the throughput analysis. Both slotted and unslotted ALOHA protocols are considered. With the use of numerical analysis, it is shown that vegetative shadowing or lognormal shadowing improves the throughput considerably by reducing the mutual packet interference and thus enhanced the capture probability of a shared satellite receiver.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"135 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120863233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Radar Systems Group, a semiautonomous unit of Hughes Aircraft Company consisting of about 12000 employees, has been using personal computers since 1980. A study on PC usage was commissioned in February 1987; some of the questions considered were: (1) are PCs counterproductive; (2) is too much money being spent on them; (3) why are so many unused; (4) what should be the strategy for the effective use of PCs. The author presents the results of this study and the conclusions drawn.<>
雷达系统集团(Radar Systems Group)是休斯飞机公司(Hughes Aircraft Company)旗下的半自主部门，拥有约12000名员工，自1980年以来一直在使用个人电脑。1987年2月，政府委托进行一项有关个人电脑使用情况的研究;考虑的一些问题是:(1)pc是否适得其反;(2)在他们身上花了太多的钱;(3)为什么有那么多闲置的;(4)有效使用个人电脑的策略是什么?作者介绍了本研究的结果和结论。
{"title":"Application of personal computers in an aerospace company","authors":"J.M. Colebank","doi":"10.1109/AERO.1989.82408","DOIUrl":"https://doi.org/10.1109/AERO.1989.82408","url":null,"abstract":"The Radar Systems Group, a semiautonomous unit of Hughes Aircraft Company consisting of about 12000 employees, has been using personal computers since 1980. A study on PC usage was commissioned in February 1987; some of the questions considered were: (1) are PCs counterproductive; (2) is too much money being spent on them; (3) why are so many unused; (4) what should be the strategy for the effective use of PCs. The author presents the results of this study and the conclusions drawn.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"239 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123721578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The author discusses the advantages and drawbacks of two logical implementations: voltage-based radix-2 logic (VBL) and current-mode redundant radix-2 logic (CML). He then explores the basic elements of a CML implementation and discusses application options and optimizations. The advantages inherent to this type of implementation are portrayed in data storage, arithmetic combinations and, to a limited extent, information routing. The feasibility of utilizing this technology was proven through SPICE simulations of each cell. The performance of individual units, even under loaded conditions, is sufficient. However, extensive SPICE simulations may be required for creating combinatorial cells. Consequently, it is concluded that further work needs to be investigated into the expansion of the present knowledge of current-mode mult-values logic.<>
{"title":"Foundational elements and functional analysis of multi-valued logic","authors":"B. Arnold","doi":"10.1109/AERO.1989.82419","DOIUrl":"https://doi.org/10.1109/AERO.1989.82419","url":null,"abstract":"The author discusses the advantages and drawbacks of two logical implementations: voltage-based radix-2 logic (VBL) and current-mode redundant radix-2 logic (CML). He then explores the basic elements of a CML implementation and discusses application options and optimizations. The advantages inherent to this type of implementation are portrayed in data storage, arithmetic combinations and, to a limited extent, information routing. The feasibility of utilizing this technology was proven through SPICE simulations of each cell. The performance of individual units, even under loaded conditions, is sufficient. However, extensive SPICE simulations may be required for creating combinatorial cells. Consequently, it is concluded that further work needs to be investigated into the expansion of the present knowledge of current-mode mult-values logic.<<ETX>>","PeriodicalId":414116,"journal":{"name":"IEEE Aerospace Applications Conference","volume":"448 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115613760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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