Análisis de la modulación por ruido en las señales de tiempo de sistemas DVB-T para su utilización en radioposicionamiento
- Autores: Carlos Fernández López
- Directores de la Tesis: Ángel Alonso Álvarez (dir. tes.)
- Lectura: En la Universidad de León ( España ) en 2015
- Idioma: español
- Número de páginas: 167
- Títulos paralelos:
- Analysis of the noise modulation on time signals in DVB-T systems for its use in radiopositioning
- Tribunal Calificador de la Tesis: José Ángel Hermida Alonso (presid.), Francisco Javier de Cos Juez (secret.), María-Carmen Meizoso-López (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: BULERIA
- Resumen
- español
El objetivo de esta tesis doctoral es la caracterización de las señales de tiempo extraídas de las tramas transmitidas por sistemas de radiodifusión DVB-T que cumplen especificaciones normalizadas en Europa. Para la caracterización en el dominio del tiempo se ha utilizado la varianza de Allan que, cincuenta años después de su introducción, y habiéndose desarrollado otras varianzas para propósitos específicos, sigue siendo la herramienta más utilizada. El resultado obtenido permitirá estimar la incertidumbre de posición asociada a la obtenida en la medida del tiempo. Pero, para el autor, evaluar la exactitud de las señales de tiempo es un fin en sí mismo que permite pensar en otras aplicaciones, que pueden incluir tiempo, espacio y, consecuentemente, velocidad
- English
Measurement of time has always been a human necessity, in all stages of human civilization. All activities have a chronogram, and all planifications are associated to some time scale.
Measurement of this magnitude permits its being applied to uses which require more and more stable clocks. The exact measurement of time and the characterization of clock signals in order to evaluate its uncertainty have given rise to a branch of metrology of huge importance.
The relation between space and time, which identifies the relative speeds of objects, reaches a special meaning when it affects radioelectric signals. Two circumstances are particularly significant. The first one is the fact that the speed of radioelectric signals in the void is an absolute magnitude, well known by everyone. The second one is the fact that it is time we are able to measure with the highest accuracy. The attempt to extend this accuracy to the measurement of space is almost immediate. This is the foundation for the positioning systems based on the measurement of time.
Global positioning systems based on satellite allow receivers to know their positions thanks to the exact measurement of the time of flight of a radioelectric signal. But here accuracy is never absolute, and uncertainty in all original magnitudes conditions the positioning results.
There are local radiating systems with fixed-position transmitters, whose location can be known with little uncertainty and which transmit clock signals of great accuracy. However, these are not designed for positioning issues. Mobile telephony and television broadcasting stations spin incredibly dense networks. The question is, if it is posible to build local positioning systems which are exact enough, by using signals transmitted by the nodes in these networks.
This study is aimed at the characterization of the time signals obtained from frames transmitted by broadcasting DVB-T systems, which meet the standard European specifications. The results will allow us to estimate the uncertainty of position associated to that obtained from the measurement of time. But evaluating the accuracy in time signals is an end in itself which allows us to think of other applications, including time, space, and consequently, speed.
The tools to characterize high stability clocks have been developed mainly in the last sixty years. The patterns of noise linked to these signals have been identified. They have been characterized in the domain of frequency, by studying their power density spectrum, and in the domain of time, being various specific dispersion estimators able to separate the types of noise.
In order to characterize the domain of time, we will use Allan’s variance which, fifty years after its introduction, and having other variances for specific purposes been developed, remains as the most used tool.
- español
