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Telesystems Conference, 1992. NTC-92., National

Date 19-20 May 1992

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Displaying Results 1 - 25 of 59
  • NTC-92. National Telesystems Conference (Cat. No.92CH3120-3)

    Publication Year: 1992
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    Freely Available from IEEE
  • Delay analysis for packet trains over computer communication networks

    Publication Year: 1992 , Page(s): 13/7 - 1314
    Cited by:  Patents (1)
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    A model for traffic arrival in a computer network is analyzed. This model is based on a train arrival process in which the traffic between each node pair consists of a certain number of trains, each having a random number of packets. With this scheme, the number of overhead bits per packet is reduced. The processing time at each node is reduced, because each node needs to make only one routing decision per train and does not need to make a separate routing decision for each packet. The scheme described can cope with the ever increasing amount of data being transferred over computer networks by decreasing processing times while maintaining maximum packet size restrictions. The model accurately describes the dependence suggested by observed correlation between successive arrivals of a train. The aggregate arrival process that results from multiplexing N sources to a multiplexer is characterized in detail. The relation of the proposed model to delay congestion and buffer sizes is described View full abstract»

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  • The Composite Analytic and Simulation Package for RFI (CASPR) on a coded channel

    Publication Year: 1992 , Page(s): 13/1 - 13/5
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    The Composite Analytic and Simulation Package for RFI (CASPR) is an analysis package that determines the performance of a coded signal in the presence of radio frequency interference (RFI) and additive white Gaussian noise. It can analyze a system with convolutional coding, Reed-Solomon coding, or a concatenation of the two. The signals can be either interleaved or noninterleaved. The model measures the system performance in terms of either the Eb/N0 required to achieve a given bit error rate (BER) or the BER needed for a constant E b/N0 View full abstract»

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  • A comparative study of clutter rejection techniques in airborne radar

    Publication Year: 1992 , Page(s): 1/1 - 1/6
    Cited by:  Papers (1)
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    The authors present radar detection, performance analysis results for targets in highly nonhomogeneous clutter environments where conventional adaptive array processing techniques are not feasible. For this case, the performance of an adaptive array processing technique which uses an angle-Doppler domain localized generalized likelihood ratio test is compared to that of a conventional displaced phase center aperture (DPCA) processor. When the measurement data available for estimation of clutter statistics is limited due to a severely nonhomogeneous environment, the conventional data-domain adaptive implementations of the joint domain optimal processor become undesirable because of their slow convergence (poor data efficiency) and heavy computation load. Under these conditions, the joint angle-Doppler domain localized generalized likelihood ratio test processor outperforms any conventional adaptive array processor, and is also shown to outperform the DPCA-based processor View full abstract»

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  • A performance model for realtime packet processing

    Publication Year: 1992 , Page(s): 12/29 - 12/33
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    A packet processing performance model has been derived from the development of a VLSI packet processor to support CCSDS (Consultative Committee for Space Data Systems) telemetry data processing. The model provides a powerful tool for characterizing the performance of a real-time packet processing system considering data rate, processing speed frame, and packet size. Using this model, a system processing boundary can be determined for a given set of operational conditions. It also points the way to further enhancement and optimization of the system design View full abstract»

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  • GE high density interconnect: a solution to the system interconnect problem

    Publication Year: 1992 , Page(s): 11/1 - 11/4
    Cited by:  Papers (3)
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    It is noted that the General Electric high density interconnect (GE-HDI) is an excellent solution to the digital multichip packaging problem, and it offers solutions to other difficult system interconnect problems in analog power, microwave, display, and sensors. GE-HDI offers the closest hybrid solution to wafer scale integration, achieving the benefits of performance and density without the limitations and yield problems of the monolithic approach. Relative to other hybrid applications, it offers significant advantages in performance and anticipated reliability due to its sputtered metal interconnection and excellent thermal properties while not sacrificing density or cost. Maskless adaptive lithography allows for rapid prototyping and flexibility in design and debugging. With the complete absence of tooling for mask or tape bonding, NRE costs are the lowest of any multichip module technology. HDI also requires the fewest processing steps, because there is no need to mount die on tape or to do lead or die bumping View full abstract»

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  • Low-cost TDRSS communications for NASA's Long Duration Balloon Project

    Publication Year: 1992 , Page(s): 8/23 - 8/27
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    A new low-cost non-space-qualified TDRSS user S-band transponder and RF ground support equipment have brought tracking and data relay satellite system (TDRSS) capabilities to a class of users who seek enhanced operations for low budget scientific investigations. The Goddard Space Flight Center (GSFC)/Wallops Flight Facility's Long Duration Balloon Project (LDBP) will take advantage of the new TDRSS user hardware for communications through the TDRSS S-band multiple access system during around-the-world scientific balloon flight campaigns. The balloon-class TDRSS user transponder and the TDRSS user RF test set (TURFTS) both achieve better performance and increased capabilities than their predecessors at a reduced cost. The balloon transponder is one-tenth the cost of the current generation space-qualified transponder and TURFTS is less than one-half the cost of the currently available transponder test equipment View full abstract»

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  • CLASS interference analysis system

    Publication Year: 1992 , Page(s): 12/1 - 12/7
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    The Communications Link Analysis and Simulation System (CLASS) project team of the NASA Goddard Space Flight Center Network Division, Code 530, has developed the CLASS interference analysis system (IAS) to support satellite communications scheduling by NASA's Network Control Center, IAS is designed to analyze communications problems arising from two or more spacecraft communicating with the same tracking and data relay satellite (TDRS) simultaneously. This system is currently composed of two major components: the CLASS automated conflict resolution system (ACRS) and the CLASS interference monitor (IM). ACRS is designed to be used in a mission-current manner, producing through interference estimates for any and all currently operating TDRS users. The IM is employed as a long-term interference predictor, taking planned spacecraft and producing broad-based statistical results concerning the resulting communications interference with and/or by other planned or existing spacecraft. Together, these two packages form a comprehensive tool for accurately analyzing potential interuser communications interference between concurrently operating space missions View full abstract»

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  • Action-oriented sensor fusion for telesystems

    Publication Year: 1992 , Page(s): 10/11 - 10/14
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    Work in sensor fusion for fully autonomous mobile robots that is expected to be useful for telesystems is discussed. Emphasis is placed on one product of this work, i.e. the sensor fusion effects (SFX) architecture, which can be extended into a control scheme for sensor fusion in telesystems. It can reduce the teleoperator's time in supervising the execution of a telerobot's sensing strategy and adapting that strategy to sensor malfunctions, changes in the environment, and other unanticipated sensing problems. It does this by autonomously monitoring the execution of the sensing strategy and looking for abnormalities. If an abnormality is detected, SFX initiates an exception handling process which tries to repair the sensing strategy autonomously. If that is not possible, the exception handling module gathers as much relevant information as possible and recommends a course of action for the operator. Experiments with sensor data collected from a Sony Hi8 color camcorder, a Pulnix black and white camera, an Inframetrics true infrared camera, Polaroid ultrasonic transducers, and a Hamamatsu ultraviolet light camera on a mobile robot show that SFX can autonomously monitor the execution of a sensing strategy and detect abnormalities View full abstract»

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  • Human-computer interface for the 21st century

    Publication Year: 1992 , Page(s): 6/21 - 6/23
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    An overview of current interfaces is presented, with attention given to icons, menus, hypermedia and hyperobjects, video, audio, virtual reality and animation. A prediction of the interfaces at the end of the next decade is also presented. It is predicted that the next decade will see a continuance of the universal user interface but with computers that have the capability of adapting to the human that uses them View full abstract»

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  • Low-Earth-orbit store-and-forward satellites in the amateur radio service

    Publication Year: 1992 , Page(s): 8/7 - 814
    Cited by:  Papers (2)
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    The authors review the current state of the art in amateur radio store-and forward satellite communications. Several operating satellite systems are described along with the procedures, equipment, and software required to access them. For PACSAT-1 empirical data have been used to estimate a downlink bit error probability of 6.0E-5. A further description of downlink performance is given through the examination of data-link layer frame retry rates encountered during file downloading operations. Typical examples of characteristics of downlink signal fading are given for PACSAT-1. A breakdown of downlink usage by data type is given for PACSAT-1. To show how the PACSAT-1 and UoSAT-5 satellites are utilized on a day-to-day basis, graphical summaries of two weeks of PACSAT-1 and three weeks of UoSAT-5 operation are included View full abstract»

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  • Video compression implemented using rigid and non-rigid object recognition and computer graphics animation

    Publication Year: 1992 , Page(s): 6/7 - 614
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    A video compression prototype system is described that significantly reduces the required bandwidth for video transmission by using intelligent terminals. The terminals used for video compression are trained to recognize what they see. Each computer contains a three-dimensional description of objects that might be in the scene. This description includes information about the objects, such as how they move and how they are constrained. The terminal is trained to recognize certain individuals, locations, and objects that have had their features scanned into an image library. The image library contains the physical description of the objects as well as a description of how they change and move over time. Results obtained with the system are presented View full abstract»

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  • Poled polymer integrated photonic interconnect networks for electronic systems

    Publication Year: 1992 , Page(s): 11/7 - 1110
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    Using straightforward extensions of semiconductor fabrication processes, multilayer structures of electrooptic (EO) polymers can be fabricated in large-area formats with high device packing densities. Furthermore, polymer EO devices can be fabricated directly on electronic substrates and assembled with IC's to permit true integration of photonics and electronics in a single highly compact and efficient package. Those applications that require very high levels of integration, high bandwidths, and hybrid assembly of photonic and electronic devices are described. The current status of the technology is illustrated by integrated optic devices based on EO polymer materials, notably a waveguide electrical-to-optical transmitter with a CMOS level drive integrated with an optical waveguide channel. Highly integrated structures, in which electronic and photonic functions operate in close proximity, place severe requirements on all materials parameters, and particularly on the thermal stability of the EO state of the polymer material. The materials requirements that have been derived for such systems are reviewed. One approach to achieving materials with the required stability is described View full abstract»

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  • Automated polarization measurement

    Publication Year: 1992 , Page(s): 2/13 - 2/15
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    The author describes a novel scheme of polarization measurement utilizing more than four antennas or photodetectors. In particular, he seeks configurations which possess the attractive features of conceptual and computational simplicity, robustness, and self-checking redundancy. Using a computationally convenient algorithm based on a six-port theory, digitized power meter indications are readily processed automatically to yield the desired polarimetric data View full abstract»

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  • Urban area performance of GPS receiver with simultrac capability

    Publication Year: 1992 , Page(s): 3/13 - 3/17
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    The theory of operation, practical applications, and technical performance of a Global Positioning System (GPS) receiver designed for urban area use are explained. Component-level system design choices are shown to support superior automotive vehicle location (AVL) performance, including optimum mobile communications with satellites and ground-based relays. The Humminbird GPS can be viewed as a mobile data system by virtue of its several optimization features for the AVL market. The design-to-cost and design-to-market philosophy behind the Humminbird GPS has resulted in a product uniquely able to satisfy the vehicle location needs of millions of buses, taxis, and cars View full abstract»

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  • Implementation of a programmable digital receiver multi-chip module

    Publication Year: 1992 , Page(s): 13/25 - 13/29
    Cited by:  Papers (1)
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    The authors discuss the theory, implementation, and applications of the programmable digital receiver (PDRx) multichip module. The PDRx module comprises four digital receiver channels. The 9-in2 module dissipates less than 25 W. The PDRx module accepts four 16-b-wide digital data streams at 33 MHz. The module then bandshifts, filters, and processes any signal in each input. These functions are all user programmable. The authors address the key innovative areas of the architecture as well as a number of applications. The applications include the digital demodulation of first, second, and M-level modulated signals, and cochannel interference reduction utilizing multiple receiver channels. The PDRx module contains multiple floating point processors which have a combined processing power of 100 million floating point operations per second. Utilizing these processors, the module supports a number of parallel processing configurations View full abstract»

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  • Amateur satellite telemetry: past, present and future

    Publication Year: 1992 , Page(s): 12/9 - 1217
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    The author examines the telemetry from the existing amateur satellites, discusses telemetry from a systems perspective, and looks at requirements for all parts of the system including spacecraft builders, telemetry users, and ground station software developers. He then introduces two proposed amateur telemetry standards, the first for downlinking of data, the second for interchanging data between different computers and long-term archiving of the data View full abstract»

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  • The Autonomous Data Optical Relay Experiment: first two way laser communication between an aircraft and submarine

    Publication Year: 1992 , Page(s): 14/27 - 14/30
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    The Autonomous Data Optical Relay Experiment (ADORE) was held at the Sea Test Range of the Pacific Missile Test Center off the coast of Southern California near San Nicolas Island during May 22-24 and May 28, 1991. The optical communication system operated with a green downlink based on a diode-pumped frequency-doubled Nd:YAG transmitter communicating with a quartz birefringent filter receiver and a blue uplink using an alexandrite laser wavelength shifted to the 455-nm doublet of cesium vapor sending information to a cesium filter receiver. Major achievements of the test included: first duplex laser communication with a submerged submarine; uplink initiated duplex laser communication from a submarine; demonstration of technologies which offer substantially higher performance at lower cost and risk compared with earlier efforts; extending the range and utility of laser communication by error correction coding and pulse summing; and establishing and experimental baseline for developing and investigating covert laser communication with submarine View full abstract»

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  • The Three-Dimensional Event-Driven Graphics Environment (3D-EDGE)

    Publication Year: 1992 , Page(s): 6/1 - 6/5
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    Stanford Telecommunications has developed the Three-Dimensional Event-Driven Graphics Environment (3D-EDGE) for the NASA Goddard Space Flight Center's Communications Link Analysis and Simulation System (CLASS). 3D-EDGE consists of a library of object-oriented subroutines, which allows engineers with little or no computer graphics experience to programmatically manipulate, render, animate and access complex three-dimensional objects. An example program is described, and results pertaining to a model of the Compton Gamma Ray Observatory satellite are discussed View full abstract»

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  • Land-mobile and aeronautical applications of ACTS technologies

    Publication Year: 1992 , Page(s): 5/13 - 5/22
    Cited by:  Papers (1)
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    It is pointed out that the Advanced Communication Technologies Satellite (ACTS) possesses unique technologies and features that will enable a host of proof-of-concept experiments which will demonstrate a variety of mobile applications. The authors identify the challenges facing Ka-band mobile satellite terminals and systems. They also identify the key ACTS technologies needed in support of their development and field characterization. They provide an overview of the land-mobile and aeronautical terminal technologies and system concepts under development and the ACTS experiments being planned for their demonstration View full abstract»

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  • Pulsed communication adaptive array processing

    Publication Year: 1992 , Page(s): 2/5 - 211
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    The application of adaptive arrays to communications is addressed for the specific case of known pulsed desired signal transition times. From this information, the adaptive antenna weights that beam up on the desired signal can be determined. Previously proposed approaches work well when the thermal noise power level and interferer power levels are constant versus time, i.e., the scenario is stationary. But these approaches degrade seriously when the environment is not stationary. The authors present extensions to conventional processing to allow for near-ideal performance with large variations in thermal noise and/or interferer power levels. Computer simulations verify that the algorithm is effective even for very large (>20 dB) changes in power levels View full abstract»

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  • Air Force construction automation/robotics

    Publication Year: 1992 , Page(s): 10/7 - 10/9
    Cited by:  Papers (1)
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    The US Air Force has several unique requirements that are being met through the development of construction robotic technology. The missions associated with these requirements place construction/repair equipment operators in potentially harmful situations. Additionally, force reductions require that human resources be leveraged to the maximum extent possible and more stringent construction repair requirements push for increased automation. To solve these problems, the US Air Force is undertaking a research and development effort to develop robotic construction/repair equipment. This development effort involves the following technologies: teleoperation, telerobotics, robotic vehicle communications, automated damage assessment, vehicle navigation, mission/vehicle task control architecture, and associated computing environment. The ultimate goal is the fielding of a robotic repair capability operating at the level of supervised autonomy. Current and planned efforts in construction/repair, explosive ordinance disposal, hazardous waste cleanup, and fire fighting are discussed View full abstract»

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  • Two-dimensional SAR imaging using linear arrays with transverse motion

    Publication Year: 1992 , Page(s): 7/17 - 7/20
    Cited by:  Papers (2)
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    The authors present a novel two-dimensional SAR (synthetic aperture radar) imaging technique using DFT (discrete Fourier transform) processing of linear arrays with transverse motion operating in the sequential mode (DFTSQM). High resolution images are generated without the need of range gating. Multiple target detection is performed on the basis of angular (azimuth and elevation) coordinates. No phase shifting or tapering hardware is required. Computer simulation and an example show the impulse invariance, and indicate that the new system's performance is better than standard SAR processing. The duration of the transmitted pulse can be increased substantially because range resolution does not depend on bandwidth. It follows that the average transmitted power is increased, which improves the signal-to-noise ratio of the system. In addition, the receiver and display devices can operate with a narrower bandwidth, which results in a major cost reduction View full abstract»

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  • Radio location through high resolution eigenstructure processing techniques that yield accurate multipath AOA and differential time delay estimates

    Publication Year: 1992 , Page(s): 3/9 - 312
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    An eigenstructure-based, doubly adaptive array processing algorithm is described. This algorithm was designed to resolve the differential time of arrival between a direct signal and a delayed replica that arrives via a different ray path. Simulations, using theoretical responses of a circular eight-element dipole array, demonstrates the characteristics of this doubly adaptive technique. Experiments have demonstrated robust differential time delay resolution of HF signals propagated to an array by two paths, a surface wave path and a skywave path. Differential time delays of approximately 1.9 milliseconds were observed for both pulse and phase modulated RF signals View full abstract»

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  • Communications satellite technology and services for the 90's

    Publication Year: 1992 , Page(s): 8/1 - 8/6
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    The future of satellite communications is addressed from the viewpoint of both commercial and military users. Technological advances and new services are discussed, and user requirements are assessed. It is pointed out that there are many different technologies that are available for implementation on future satellite systems. It appears that the field of satellite communications will move to serve the mobile low-data-rate users. The more traditional wide-bandwidth high-data-rate users will continue to migrate to cable. New niche markets will continue to develop and be served by specialized satellite networks specially suited to serve these niche markets. It is concluded that the field of satellite communications is about to rapidly expand in many new directions, driven by new user requirements and new technology View full abstract»

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