Capítols de llibre
http://hdl.handle.net/2117/5587
2016-05-31T12:05:59ZCalibration methods in large interferometric radiometers devoted to earth observation
http://hdl.handle.net/2117/22990
Calibration methods in large interferometric radiometers devoted to earth observation
Torres Torres, Francisco; Camps Carmona, Adriano José; Corbella Sanahuja, Ignasi; Bará Temes, Francisco Javier; Duffo Ubeda, Núria; Vall-Llossera Ferran, Mercedes Magdalena
This paper starts with a summary and classification of errors of any kind that corrupt the fundamental measurement performed by an InR (interferometric radiometer), the so-called visibilities. This summary is based on prior works from the authors concerning end-to-end rnodeling of the instrument. The paper follows with a
trade-off analysis of the capability of different calibration approaches to remove those errors and, at the end, to recover a map of brightness temperatures. In order to perform the trade-off analysis, extensive simulations have been undertaken to analyze the approaches found in the literature: the redundant space method, used in radio astronomy, the G-matrix method, used in ESTAR, and the Noise injection method. both centralized and distributed, proposed for MIRAS. A short description is made of each one and a comparative table is presented. The trade off is presented in terms of what kind of errors can be removed by each method, hardware requirements, robustness and on-ground/on-board input data required to perform such error correction.
2014-05-14T13:43:44ZTorres Torres, FranciscoCamps Carmona, Adriano JoséCorbella Sanahuja, IgnasiBará Temes, Francisco JavierDuffo Ubeda, NúriaVall-Llossera Ferran, Mercedes MagdalenaThis paper starts with a summary and classification of errors of any kind that corrupt the fundamental measurement performed by an InR (interferometric radiometer), the so-called visibilities. This summary is based on prior works from the authors concerning end-to-end rnodeling of the instrument. The paper follows with a
trade-off analysis of the capability of different calibration approaches to remove those errors and, at the end, to recover a map of brightness temperatures. In order to perform the trade-off analysis, extensive simulations have been undertaken to analyze the approaches found in the literature: the redundant space method, used in radio astronomy, the G-matrix method, used in ESTAR, and the Noise injection method. both centralized and distributed, proposed for MIRAS. A short description is made of each one and a comparative table is presented. The trade off is presented in terms of what kind of errors can be removed by each method, hardware requirements, robustness and on-ground/on-board input data required to perform such error correction.Sources of third–order intermodulation distortion in bulk acoustic wave devices: a phenomenological approach
http://hdl.handle.net/2117/15092
Sources of third–order intermodulation distortion in bulk acoustic wave devices: a phenomenological approach
Rocas Cantenys, Eduard; Collado Gómez, Juan Carlos
In this work, a model that uses several nonlinear parameters to predict harmonics and 3IMD distortion is presented. Its novelty lies in its ability to predict the nonlinear effects produced by self-heating in addition to those due to intrinsic nonlinearities in the material properties.
The model can be considered an extension of the nonlinear KLM model (originally proposed
by Krimholtz, Leedom and Matthaei) (Krimholtz et al., 1970) to include the thermal effects due to self-heating caused by viscous losses and electrode losses. For this purpose a thermal domain circuit model is implemented and coupled to the electro-acoustic model, which allows us to calculate the dynamic temperature variations that change the material properties. In comparison to (Rocas et al., 2009), this work describes the impact that electrode losses produce on the 3IMD, presents closed-form expressions derived from the circuit model and validates the model with extensive measurements that confirm the
necessity to include dynamic self-heating to accurately predict the generation of spurious
signals in BAW devices.
2012-02-13T12:16:51ZRocas Cantenys, EduardCollado Gómez, Juan CarlosIn this work, a model that uses several nonlinear parameters to predict harmonics and 3IMD distortion is presented. Its novelty lies in its ability to predict the nonlinear effects produced by self-heating in addition to those due to intrinsic nonlinearities in the material properties.
The model can be considered an extension of the nonlinear KLM model (originally proposed
by Krimholtz, Leedom and Matthaei) (Krimholtz et al., 1970) to include the thermal effects due to self-heating caused by viscous losses and electrode losses. For this purpose a thermal domain circuit model is implemented and coupled to the electro-acoustic model, which allows us to calculate the dynamic temperature variations that change the material properties. In comparison to (Rocas et al., 2009), this work describes the impact that electrode losses produce on the 3IMD, presents closed-form expressions derived from the circuit model and validates the model with extensive measurements that confirm the
necessity to include dynamic self-heating to accurately predict the generation of spurious
signals in BAW devices.