10 research outputs found

    Regulated-element Frost Beamformer for Vehicular Multimedia Sound Enhancement and Noise Reduction Applications

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    A key requirement of an adaptive sensor array involves the ability to deterministically adjust the directional response of the array to reduce noise and reverberations, null interferences and enhance the gain and recognition of the desired signal. This paper presents a low-carbon adaptive broadband beamforming algorithm called the regulated-element Frost beamformer. It enhances the desired signal based on the noise conditions of the individual omnidirectional sensors deployed in a complex dynamic environment that is prone to steering errors. The investigation of this algorithm was carried out in an interference-dominant, noisy automobile environment characterised by diffuse noise conditions. An embedded system measurement of real-time signals was carried out using omnidirectional acoustic sensors mounted in a model convertible F-Type car driven at speed limits of 20 to 50 mph. The simulation results indicate an array gain enhancement of 2 dB higher than the conventional Frost beamformer and it requires less sensors and filter taps for real-time reconfigurable implementations. The experimental results reveal that the average array gain of the regulated-element beamformer is 2.9 dB higher than the conventional Frost beamformer response. The minimum floor array gain of the regulated-element beamformer is 5 dB, representing 70 % noise reduction than the conventional adaptive beamformers

    Design of a Multiband RF Slotted-Antenna for Biosensing Applications

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    There is an expanding demand for adaptive contactless label-free biosensors for point-of-care, multi-user, health risk-free applications. This paper introduces the design of an elliptically-slotted patch antenna (ESPA) for bio-sensing applications. The resonance frequency difference of the ESPA is 2.5% compared with the basic slot-less patch antenna of 6.6%. Hence, the proposed model compares with the conventional slot-less patch antenna and exhibited a vast improvement in its bandwidth efficiency by over 62%. The simulated ESPA design yields a total gain of 7.5 dBi and can be utilized for simultaneous bio-sample detection and signal transmission applications. The miniaturized size of this system promises a portable label-free, reliable, realtime detection with a cost-effective fabrication

    Engineering Subsystems Analysis of Adaptive Small Satellites

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    The current point-based satellite electronic subsystem engineering design process is insufficient to address the dynamic operations and post-mission reuse of small satellites. Also, space systems and missions require an adaptive architecture(s) that can withstand the radiation-prone flight environment and respond to in-situ environmental changes using onboard resources while maintaining optimal performance. This enormous conceptual design variables space/task of highly adaptive small satellite (HASS) system can be too large to explore, study, analyse and qualify. This research involved a parametric electronic subsystem engineering design process and methodology development for the production of sustainable capability-based small satellites. Consequently, an adaptive multifunctional architecture with five levels of in-orbit spacecraft customisations that eliminate subsystem boundaries at the system level is presented. Additive manufacturing methods are favoured to fabricate the proposed adaptive multifunctional monolithic structures. The initial system engineering analyses reveal that the HASS system has mass-, cost- and power-savings over the conventional small satellite implementation. An adaptive small satellite link performance improvement satisfying a less than 2 dB link margin loss for a 0.1 dB in-band noise figure ripple has been established. Moreover, a power budget model for HASSs that ensures a reliable solar array design and eliminates undue equipment oversizing has been developed. An adaptive broadband beamformer that can improve the satellite link margin has been designed. Also, an estimating relationship has been developed and practically validated for the operational times analysis of small satellite subsystems. The reported novel findings promise to enable capability-based, adaptive, cost-effective, reliable, multifunctional, broadband and optimal-performing space systems with recourse to post-mission re-applications

    Thermal Subsystem Operational Times Analysis for Ubiquitous Small Satellites Relay in LEO

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    The success of the satellite subsystems engineering depends on the optimal design, modeling, simulation, and validation of the deliverables of the conceptual and mission design objectives. This paper presents the operational times analysis of the thermal control subsystem onboard a 97-kg microsatellite in low-Earth orbit during an eclipse period. Power-storing, communication downlink and uplink, payload processing, and thermal control overpower modes were implemented for a communication mission under worst-case orbital patterns. An embedded digital temperature and lighting controller circuitry was designed and practically validated to effect a desired logic. For an average eclipse period of 34.4 mins, the operational times of the thermal subsystem at altitudes of 400 km, 500 km, and 600 km are 38.6 mins, 38.1 mins, and 37.7 mins respectively. Moreover, the thermal control subsystem simulation reveals that reducing the operational times of non-thermal control subsystems during the eclipse period by 50 % can result in an operational factor of safety of over 1.5. At least 10 dB data link transmission margin can be achieved. The reported findings show that the operational times of spacecraft subsystems overpower modes can be reconfigured in orbit to reliably sustain the operating conditions of the capability-based satellite components for ubiquitous communication

    8-12 GHz pHEMT MMIC Low-Noise Amplifier for 5G and Fiber-Integrated Satellite Applications

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    The fifth-generation (5G) radio access technology promises to revolutionise integrated earth-space communications applications for ubiquitous, seamless and broadband services. The assigned sub-6 GHz and millimetre-wave 5G frequencies require the sensitivity of the receiver front-end subsystem(s) to detect and amplify the desired signal at a noise floor of less than -90 dBm for a cost-effective infrastructure deployment. This paper presents a broadband monolithic microwave integrated circuit (MMIC) low-noise amplifier (LNA) design based on a 0.15 µm gate length Indium Gallium Arsenide (InGaAs) pseudomorphic high electron mobility transistor (pHEMT) technology for 5G and fiber-integrated satellite communications applications. The designed three-stage 8-12 GHz LNA implements a common-source topology. The MMIC LNA subsystem performance demonstrates an industry-leading in-band gain response of 40 dB; a noise figure of 1.0 dB; and a power dissipation of 43 mW. For a constant bandwidth receiver, the sensitivity changes by approximately 1.5 dB over the operating satellite signal frequency. Similarly, for a variable bandwidth receiver, the sensitivity changes by approximately 1.5 dB over the channel bandwidth. Moreover, the sensitivity margin of the designed LNA is 40 dB and this holds a great promise for real-time radio access component-level reconfiguration applications

    Parametric System Engineering Analysis of Capability-based Small Satellite Missions

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    To achieve appropriate link budget and system engineering analyses of capability-based small satellites (CSSs) missions, an objective assessment and computation of the component-, subsystem-, and system-levels parameters requirements must be carried out. This paper presents the parametric models for the system engineering analysis of communication, meteorology, planetary, and other small satellite programmes with recourse to the initial mission, conceptual design, and post-mission objectives. Mass and power margins are the critical resources under investigation for achieving an economical and sustainable capability-based small satellite mission. Case study systems engineering analyses for meteorology, communication and planetary missions indicate a transmit power for communication uplink and downlink of at least 33 dBm. The parametric model also reveals a signal-to-noise ratio of at least 16 dB per radio communication link for worst-case noise floor and path loss. This holds a great promise for the development of adaptive subsystems for reconfigurable multiband, and multistandard transceivers for multipurpose missions and post-mission applications

    Switchable wideband receiver frontend for 5G and satellite applications

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    Modern day communication architectures provides the requirement for interconnected devices offering very high data rate (more than 10 Gbps), low latency, and support for multiple service integration across existing communication generations with wideband spectrum coverage. An integrated satellite and 5G architecture switchable receiver frontend is presented in this thesis, consisting of a single pole double throw (SPDT) switch and two low noise amplifiers (LNAs) spanning X-band and K/Ka-band frequencies. The independent X-band LNA (8-12 GHz) has a gain of 38 dB at a centre design frequency of 9.8 GHz, while the K/Ka-band (23-28 GHz) has a gain of 29 GHz at a centre design frequency of 25.4 GHz. Both LNAs are a three-stage cascaded design with separated gate and drain lines for each transistor stage. The broadband high isolation single pole double throw (SPDT) switch based on a 0.15 μm gate length Indium Gallium Arsenide (InGaAs) pseudomorphic high electron transistor (pHEMT) is designed to operate at the frequency range of DC-50 GHz with less than 3 dB insertion loss and more than 40 dB isolation. The switch is designed to improve the overall stability of the system and the gain. A gain of about 25 dB is achieved at 9.8 GHz when the X-band arm is turned on and the K/Ka-band is turned off. A gain of about 23 dB is achieved at 25.4 GHz when the K/Ka-band arm is turned on and the X-band arm is off. This presented switchable receiver frontend is suitable for radar applications, 5G mobile applications, and future broadband receivers in the millimetre wave frequency range

    Proceedings of the Fifth International Mobile Satellite Conference 1997

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    Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments

    Abstracts on Radio Direction Finding (1899 - 1995)

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    The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

    Technology 2001: The Second National Technology Transfer Conference and Exposition, volume 1

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    Papers from the technical sessions of the Technology 2001 Conference and Exposition are presented. The technical sessions featured discussions of advanced manufacturing, artificial intelligence, biotechnology, computer graphics and simulation, communications, data and information management, electronics, electro-optics, environmental technology, life sciences, materials science, medical advances, robotics, software engineering, and test and measurement
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