5,287 research outputs found

    MODIS information, data and control system (MIDACS) level 2 functional requirements

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    The MODIS Information, Data and Control System (MIDACS) Level 2 Functional Requirements Document establishes the functional requirements for MIDACS and provides a basis for the mutual understanding between the users and the designers of the EosDIS, including the requirements, operating environment, external interfaces, and development plan. In defining the requirements and scope of the system, this document describes how MIDACS will operate as an element of the EOS within the EosDIS environment. This version of the Level 2 Requirements Document follows an earlier release of a preliminary draft version. The sections on functional and performance requirements do not yet fully represent the requirements of the data system needed to achieve the scientific objectives of the MODIS instruments and science teams. Indeed, the team members have not yet been selected and the team has not yet been formed; however, it has been possible to identify many relevant requirements based on the present concept of EosDIS and through interviews and meetings with key members of the scientific community. These requirements have been grouped by functional component of the data system, and by function within each component. These requirements have been merged with the complete set of Level 1 and Level 2 context diagrams, data flow diagrams, and data dictionary

    MODIS information, data and control system (MIDACS) operations concepts

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    The MODIS Information, Data, and Control System (MIDACS) Operations Concepts Document provides a basis for the mutual understanding between the users and the designers of the MIDACS, including the requirements, operating environment, external interfaces, and development plan. In defining the concepts and scope of the system, how the MIDACS will operate as an element of the Earth Observing System (EOS) within the EosDIS environment is described. This version follows an earlier release of a preliminary draft version. The individual operations concepts for planning and scheduling, control and monitoring, data acquisition and processing, calibration and validation, data archive and distribution, and user access do not yet fully represent the requirements of the data system needed to achieve the scientific objectives of the MODIS instruments and science teams. The teams are not yet formed; however, it is possible to develop the operations concepts based on the present concept of EosDIS, the level 1 and level 2 Functional Requirements Documents, and through interviews and meetings with key members of the scientific community. The operations concepts were exercised through the application of representative scenarios

    Millimeter communication propagation program, volume I Final report, 1 Nov. 1964 - 1 Nov. 1965

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    Millimeter wave propagation experiment design for space communicatio

    The detection and tracking of portable GSM handset using a 5-element circular array

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    Includes bibliographical references (leaves 130-131)Direction Finding (OF) is a process that involves estimating the directions of the arrival for propagating wavefronts impinging on an antenna array from arbitrary directions relative to that antenna array. By understanding how the signals captured relate to the geometry of the OF antenna, one can separate out these signals spatially, and provide their directions of arrival with some degree of certainty. GSM, the Global System for Mobile Communications is a mobile digital communications system which has rapidly gained acceptance on a global scale since the early 1990s. Because the communications standard is made use of throughout the world today, it would be desirable to investigate the feasibility of the detection and tracking of such signals as an extension for OF platforms that are used by monitoring authorities such as the police or service providers. This thesis presents and discusses the implications of detecting and tracking GSM mobile handsets. Because the thesis was commissioned by a company that already manufactures broadband surveillance equipment with a particular OF implementation, the thesis approaches the problem with their specific implementation in mind assessing its competency in detecting and tracking GSM mobile phones. To understand the nature of GSM, a simulator was developed to convey information about the structure of the datasets that would be recorded in the field, and is compared to datasets captured with the OF equipment. Conclusions are drawn from the recordings, and recommendations for future work in this field are discussed

    Millimeter communication propagation program, volume III Final report, 1 Nov. 1964 - 1 Nov. 1965

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    Annotated bibliography for millimeter wave communication propagation program for space-earth communication

    Investigation into synchronization for partial response signals and the development of a clock recovery scheme for 49QPRS signals

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    ThesisData communication is used increasingly in modern society. It is against this background that research is conducted worldwide toward the improvement of existing, as well as the development of new, improved communication techniques. Correlative encoding of data before transmission IS a very frequency-effective communication technique. The extent to which any communication technique is used, however, is dependent on a wide variety of factors. This study regarding the synchronisation of 49QPRS signals was undertaken with this in mind. Since digital signal processing (DSP) is used increasingly in modern communication systems, both a data transmitter and receiver were implemented by making use of this technique. Not only would this result in a system with all the desirable characteristics inherent to DSP, but, by making limited changes to the supporting software, the evaluation of a wide variety of alternatives became feasible. During the study a system making use of a pilot tone at one third the frequency of the carrier frequency was developed. The receiver recovers this signal by means of DSP techniques and its frequency is tripled. The phase of this recovered signal is crosscorrelated every 650 ~s in time with a locally generated signal of the correct frequency - and the phase of the locally generated signal is adjusted accordingly. It was found that the accuracy and stability of the locally generated signal were such that sufficient synchronisation was obtained in this manner. The quality of synchronisation is a function of the level of the pilot tone and if this tone should decrease to below a certain value, unacceptably large phase adjustments have to be made. This results in a senous degradation of the spectral purity of the recovered signal. However, the system as described exhibits extremely good noise immunity. During the development of the clock frequency recovery system, a baseband filter with a unique frequency response was defined. Making use of this, in conjunction with a limited amount of pre-processing, and an absolute value rectifier, recovery of the clock frequency becomes possible. In order to limit the amount of processing by the receiver, the baseband filter was implemented in its entirety in the transmitter. The recovered signal showed a moderate amount of amplitude variation, but an extremely stable synchronising signal could be derived from this. During the study both levels of synchronisation required by a hypothetical 49QPRS data communication system were therefore investigated fully and solutions found

    3D orbital tracking microscopy: from cells to organisms

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    A fluorescent nanodiamond foundation for quantum sensing in cells

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    Free radicals play a major role in the aging process as well as a most diseases. However, we barely know anything about them. These tiny molecules have an extremely short lifespan and are difficult to measure, while their role in health related processes is considerable. Fluorescent nanodiamonds are very small diamonds which can shed a light on this research question. These diamonds emit a constant light in a controlled setting. This is possible due to a small defect in the structure of the diamond, which makes it fluorescent. When free radicals are present, the light changes, which allows measurement of the radicals. During my PhD I have laid the basis for these biological measurements. Not all cells automatically take up diamonds or the diamonds tend to aggregate in cellular medium. By changing the solutions in which we administer the diamonds, we can prevent these obstacles. I have also performed a very detailed analysis of the cellular response on diamond uptake. Conveniently, the cells hardly show any response to the diamond uptake, an important result for our future measurements. In addition, I have developed new ways of targeting the diamonds to specific places in the cells, to obtain location specific information. Finally I have determined the subcellular location of the diamonds using a new technique, based on integrated electron microscopy. During my work I have laid the foundation for promising cellular research of ageing and disease using fluorescent nanodiamonds

    Millimeter Communication Propagation Program First quarterly report, 1 Nov. 1964 - 1 Feb. 1965

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    Effects of propagation medium on millimeter-wave space-earth communication
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