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Publications

Publications by CTM

2012

Transmission of differential GPS signals over fiber for aircraft attitude determination

Authors
Pessoa, LM; Oliveira, JMB; Coelho, D; Castro, JCS; Salgado, HM; Fames, M;

Publication
2012 IEEE Avionics, Fiber- Optics and Photonics Technology Conference, AVFOP 2012

Abstract
The Daphne project has been addressing the adoption of an optical fiber infrastructure for future aircrafts. Beyond the obvious motivation of reduced weight and electromagnetic interference, the availability of a huge amount of bandwidth makes the optical fiber well suited to transport Radio Frequency (RF) signals transparently, while avoiding cumbersome dedicated RF cabling. An integrated optical network may be exploited to transport radio signals from diverse aircraft antennas ranging from satellite/earth communications, collision avoidance, GPS signals for positioning and attitude determination, weather/detection RADAR to corrosion sensors. Such network can also support passenger infotainment and mobile communication services, such as cellular GSM/UMTS/LTE, broadband Wi-Fi (IEEE 802.11) and Ultra-Wide-Band Wimedia/WiGig. Specifically, the optical fiber infrastructure may provide connectivity from external antennas (through remote nodes) to RF transceivers installed in the cockpit and avionics bay (head-end nodes); in the context of the present paper, the transmission of differential GPS signals used to provide aircraft attitude information will be discussed. The use of GPS for aircraft attitude determination has been under discussion for more than 20 years [1]. It consists in performing carrier-phase differential processing of measurements from GPS antennas affixed to the frame of the aircraft, which yields centimeter- or millimeter-level accuracies, provided that integer phase ambiguities are resolved [2]. The attitude algorithm consists in a highly accurate real time kinematic (RTK) technique, given the short baseline distance between antennas, in which the main antenna acts as a Base station and two auxiliary antennas as Rovers. In the present experiment, we used a setup consisting of two-antennas (Base and Rover), which is enough to evaluate the RTK performance. A particular aspect of concern stems from the fact that the transmission of optical signals through a complex optical fiber network is subject to the occurrence of reflections in the multitude of connectors spanning the path between a remote node and a head-end node. Therefore, we will focus our analysis on the performance impact of optical reflections affecting the power level stability of the optical source. © 2012 IEEE.

2012

Experimental assessment of WLAN performance supported in a fiber-radio network

Authors
Pessoa, LM; Oliveira, JMB; Coelho, D; Castro, JCS; Salgado, HM;

Publication
2012 Future Network and Mobile Summit, FutureNetw 2012

Abstract
In this paper we experimentally evaluate the performance of a fiber supported radio application, namely WiFi IEEE802.11n, using a low power consumption base-station based on a reflective electro absorption modulator and commercial transceivers. We conclude that the proposed setup is suitable to achieve a transmission of 20 Mbit/s over a 4m wireless channel. A theoretical signal to noise ratio analysis is also carried out, based on experimental results. Finally, we evaluate the possibility of employing the proposed setup in a passive optical network, concluding that this solution may not be cost effective. © 2012 IIMC Ltd.

2012

Advanced delivery of sensitive multimedia content for better serving user expectations in Virtual Collaboration applications

Authors
Andrade, MT; Dogan, S; Carreras, A; Barbosa, V; Arachchi, HK; Delgado, J; Kondoz, AM;

Publication
MULTIMEDIA TOOLS AND APPLICATIONS

Abstract
A major challenge when accessing protected multimedia content in heterogeneous usage environments is the ability to provide acceptable levels of quality of experience to all involving users. Additionally, different levels of protection should be possible to be addressed when manipulating the content towards the quality of experience maximization. This paper describes the use of a context-aware and Digital Rights Management (DRM)-enabled content adaptation platform towards meeting these challenges. The platform was conceived to deliver advanced content adaptation within different application scenarios, among which Virtual Collaboration (VC) was central. Descriptions of use cases implemented by the platform in heterogeneous VC environments are provided. Conducted experiments have highlighted the benefits to users when compared to an operation without the platform. Results of different adaptations suitable to sensed context conditions are also provided and analyzed. A brief description of the platform functionality is included together with pointers to additional information.

2012

Converging podcasts: A proposal for a content-centric approach for social learning environments

Authors
Hang, A; Almeida, F; Castro, H; Andrade, MT; Chiariglione, L; Blefari Melazzi, N; Hussmann, H;

Publication
International Conference on Information Society, i-Society 2012

Abstract
Universities are continually pursuing ways to adapt their educational practices, looking to develop new learning culture that encourages creativity and active engagement. The adoption of augmented lecture podcast scenarios, based on a content-centric paradigm, looks a promising way to reach a new level of interactivity. This paper analyzes the main advantages provided by this innovative approach comparing it with the traditional podcasting developing model. Additionally, it proposes possible business models based on content distribution and augmentation, to enable wider exploitation of the approach within university environments. © 2012 Infonomics Society.

2012

Analysis of error detection schemes: Toolchain support and hardware/software implications

Authors
Azarian, A; Ferreira, JC; Werner, S; Petrov, Z; Cardoso, JMP; Hübner, M;

Publication
2012 NASA/ESA Conference on Adaptive Hardware and Systems, AHS 2012, Erlangen, Germany, June 25-28, 2012

Abstract
Meeting safety requirements typically require substantial invasive extensions to applications. Even in the absence of faults, the overhead associated with these invasive extensions may unacceptably increase execution time. In this paper we focus on a number of experiments with schemes for error detection, having a 3D Path Planning application for an avionics system as case study. We analyze how these error detection schemes can be implemented to meeting system's time budget. The experiments allowed us to acquire the requirements for automating the application of the error detection schemes in the context of a hardware/software design-flow, and to determine how those schemes can be addressed using a novel approach where safety requirements are described using an aspect- and strategy-oriented programming language, named LARA. For our experiments and validation, we consider an FPGA-based embedded system consisting of a general purpose processor (GPP) coupled to custom computing units which are primarily used for hardware acceleration and for implementing fault detection schemes. © 2012 IEEE.

2012

A Wearable Sensor Network for Human Locomotion Data Capture

Authors
Zambrano, A; Derogarian, F; Dias, R; Abreu, MJ; Catarino, A; Rocha, AM; da Silva, JM; Ferreira, JC; Tavares, VG; Correia, MV;

Publication
pHealth 2012 - Proceedings of the 9th International Conference on Wearable Micro and Nano Technologies for Personalized Health, Porto, Portugal, June 26-28, 2012

Abstract
A new wearable data capture system for gait analysis is being developed. It consists of a pantyhose with embedded conductive yarns interconnecting customized sensing electronic devices that capture inertial and electromyographic signals and sends aggregated information to a personal computer through a wireless link. The use of conductive yarns to build the myoelectric electrodes and the interconnections of the wired sensors network, as well as the topology and functionality of the sensor modules are presented.

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