2002
Autores
da Silva, JM; Duarte, JS; Matos, JS;
Publicação
MEASUREMENT
Abstract
A method for the in-circuit functional testing of SigmaDelta modulators is described which can be built in large integrated circuits or systems-on-chip. It allows for measuring gain and phase, as well as total harmonic distortion and signal to noise and harmonic distortion ratio parameters. This method can be built in-circuit using existing computational resources, such as digital signal processors or (re)configurable logic, which can therefore be used to implement both mission and test operations. Both simulation and experimental results were obtained which are in close agreement with those expected from the theory.
2002
Autores
Ricardo, M; Dias, J; Carneiro, G; Ruela, J;
Publicação
13TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOL 1-5, PROCEEDINGS: SAILING THE WAVES OF THE WIRELESS OCEANS
Abstract
The paper presents an end-to-end Quality of Service (QoS) architecture suitable for IP communications scenarios that include UMTS access networks. The rationale for the architecture is justified and its main features are described, notably the QoS management functions on the terminal equipment, the mapping between IP and UMTS QoS parameters and the negotiation of these parameters.
2002
Autores
Ricardo, M; Soares, R; Dias, J; Ruela, J;
Publicação
MULTIACCESS, MOBILITY AND TELETRAFFIC FOR WIRELESS COMMUNICATIONS, VOLUME 6
Abstract
The paper presents the architecture of an UNITS terminal equipment optimised for IP based communications and describes the traffic control mechanisms required for supporting emerging 3G services.
2002
Autores
Rego, G; Romero, R; Frazao, O; Marques, PVS; Salgado, HM;
Publicação
PROCEEDINGS OF 2002 IEEE/LEOS WORKSHOP ON FIBRE AND OPTICAL PASSIVE COMPONENTS
Abstract
We report the use of the electric arc technique to apodise Fibre Bragg Gratings (FBG). Electric arc discharges applied at the ends of the grating produce a smoothing of the refractive index modulation profile which reduces the side lobes at longer wavelengths. Using this technique, a FBG was apodised with a side lobe reduction of 17 dB.
2002
Autores
Frazao, O; Romero, R; Rego, G; Marques, PVS; Salgado, HM; Santos, JL;
Publicação
ELECTRONICS LETTERS
Abstract
A new scheme is presented for simultaneous measurement of strain and temperature using a sampled fibre Bragg grating based on a long period structure written using the electric are technique. The temperature and strain measurement resolutions are estimated to be +/-0.50degreesC/rootHz and +/-3.38 muepsilon/rootHz, respectively.
2002
Autores
Melo, M; Teixeira, A; Frazao, O; Gomes, L; Lima, M; Santos, C; Pereira, D; Rocha, F; Salgado, HM;
Publicação
2002 IEEE/LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2
Abstract
We present and demonstrate a 20 nm tunable L-band fiber ring laser. Tunability is achieved by curving a simple taper which controls the intra-cavity loss.
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