The choice of a stable time reference common to all the components of a distributed system (i.e. made up by stations or sensors placed in different sites), is a topic which applies to several telecommunication and electronic problems. In a distributed system, in fact, it is fundamental that all elements have a unique time reference so that they can exchange data in unambiguous way and for a possible subsequent data elaboration. In this work a distributed system, the multilateration (in short MLAT) will be considered, with particular attention to the generation of a common time reference and to the keeping of synchronization between the different elements. In a MLAT system the ground stations receive Mode S signals (reply/squitter) from transponders installed on board the cooperative targets (en route aircrafts, aircrafts and vehicles on airport surface) and determine the position of targets using the TDOA (Time Difference of Arrival) technique. In the first part of the thesis (chapters I – IV) the aspects related to the generation of a stable time reference by a local oscillator will be investigated. In particular the fluctuations of a generic oscillator will be examined, which can be of two types: systematic fluctuations, main cause of divergence from the “real” time and the “real” frequency in the long term (days or years) and the random fluctuations, observed in the short term (fractions of second or minutes). For the oscillator random fluctuations a mathematical model will be introduced, in order to have a simulation method of the oscillator behavior. The model is different and more complex than the well-known additive gaussian noise frequently assumed in telecommunications. Finally some oscillator types on the market will be presented with a comparison between the performances declared by the manufacturers. In the second part of the thesis (chapters V – VII) the operation of a multilateration system studied by the Radarlab at Tor Vergata University in Rome together with Selex-Sistemi Integrati company, which has realized it, will be described; the system has been successfully deployed at Milano Malpensa for the airport surveillance. In particular the study that led to the selection of the oscillator for the system stations will be reported and the synchronization procedure designed to maintain a common time reference will be described. Besides an innovative multilateration architecture will be presented which allows the extension of surveillance, in addition to aircrafts, also to vehicles moving on airport surface (ground surveillance), with reduced update costs. Finally a multilateration architecture for aircrafts surveillance in wider areas (WAM, Wide Area MLAT) such as en route and airport approach areas will be presented, an application whom many manufacturers are looking at with interest, as an alternative to classic radar systems.
Cavallini, A. (2009). Modelli statistici degli orologi e problemi di sincronizzazione nei sistemi di sorveglianza cooperativa distribuita.
Modelli statistici degli orologi e problemi di sincronizzazione nei sistemi di sorveglianza cooperativa distribuita
2009-08-03
Abstract
The choice of a stable time reference common to all the components of a distributed system (i.e. made up by stations or sensors placed in different sites), is a topic which applies to several telecommunication and electronic problems. In a distributed system, in fact, it is fundamental that all elements have a unique time reference so that they can exchange data in unambiguous way and for a possible subsequent data elaboration. In this work a distributed system, the multilateration (in short MLAT) will be considered, with particular attention to the generation of a common time reference and to the keeping of synchronization between the different elements. In a MLAT system the ground stations receive Mode S signals (reply/squitter) from transponders installed on board the cooperative targets (en route aircrafts, aircrafts and vehicles on airport surface) and determine the position of targets using the TDOA (Time Difference of Arrival) technique. In the first part of the thesis (chapters I – IV) the aspects related to the generation of a stable time reference by a local oscillator will be investigated. In particular the fluctuations of a generic oscillator will be examined, which can be of two types: systematic fluctuations, main cause of divergence from the “real” time and the “real” frequency in the long term (days or years) and the random fluctuations, observed in the short term (fractions of second or minutes). For the oscillator random fluctuations a mathematical model will be introduced, in order to have a simulation method of the oscillator behavior. The model is different and more complex than the well-known additive gaussian noise frequently assumed in telecommunications. Finally some oscillator types on the market will be presented with a comparison between the performances declared by the manufacturers. In the second part of the thesis (chapters V – VII) the operation of a multilateration system studied by the Radarlab at Tor Vergata University in Rome together with Selex-Sistemi Integrati company, which has realized it, will be described; the system has been successfully deployed at Milano Malpensa for the airport surveillance. In particular the study that led to the selection of the oscillator for the system stations will be reported and the synchronization procedure designed to maintain a common time reference will be described. Besides an innovative multilateration architecture will be presented which allows the extension of surveillance, in addition to aircrafts, also to vehicles moving on airport surface (ground surveillance), with reduced update costs. Finally a multilateration architecture for aircrafts surveillance in wider areas (WAM, Wide Area MLAT) such as en route and airport approach areas will be presented, an application whom many manufacturers are looking at with interest, as an alternative to classic radar systems.Campo DC | Valore | Lingua |
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dc.authority.academicField2000 | Settore SECS-S/02 - STATISTICA PER LA RICERCA SPERIMENTALE E TECNOLOGICA | en |
dc.authority.advisor | Accardi, Luigi | it |
dc.authority.people | Cavallini, Alessio | - |
dc.cilea.antefix | yes | it |
dc.collection.id.s | e291c0df-b2ad-cddb-e053-3a05fe0aa144 | * |
dc.collection.name | 07 - Tesi di dottorato | * |
dc.coverage.academicyear | A.A. 2006/2007 | en |
dc.date.accessioned | 2009-08-03T09:29:06Z | it |
dc.date.available | 2009-08-03T09:29:06Z | it |
dc.date.issued | 2009-08-03T09:29:06Z | it |
dc.description.abstracteng | The choice of a stable time reference common to all the components of a distributed system (i.e. made up by stations or sensors placed in different sites), is a topic which applies to several telecommunication and electronic problems. In a distributed system, in fact, it is fundamental that all elements have a unique time reference so that they can exchange data in unambiguous way and for a possible subsequent data elaboration. In this work a distributed system, the multilateration (in short MLAT) will be considered, with particular attention to the generation of a common time reference and to the keeping of synchronization between the different elements. In a MLAT system the ground stations receive Mode S signals (reply/squitter) from transponders installed on board the cooperative targets (en route aircrafts, aircrafts and vehicles on airport surface) and determine the position of targets using the TDOA (Time Difference of Arrival) technique. In the first part of the thesis (chapters I – IV) the aspects related to the generation of a stable time reference by a local oscillator will be investigated. In particular the fluctuations of a generic oscillator will be examined, which can be of two types: systematic fluctuations, main cause of divergence from the “real” time and the “real” frequency in the long term (days or years) and the random fluctuations, observed in the short term (fractions of second or minutes). For the oscillator random fluctuations a mathematical model will be introduced, in order to have a simulation method of the oscillator behavior. The model is different and more complex than the well-known additive gaussian noise frequently assumed in telecommunications. Finally some oscillator types on the market will be presented with a comparison between the performances declared by the manufacturers. In the second part of the thesis (chapters V – VII) the operation of a multilateration system studied by the Radarlab at Tor Vergata University in Rome together with Selex-Sistemi Integrati company, which has realized it, will be described; the system has been successfully deployed at Milano Malpensa for the airport surveillance. In particular the study that led to the selection of the oscillator for the system stations will be reported and the synchronization procedure designed to maintain a common time reference will be described. Besides an innovative multilateration architecture will be presented which allows the extension of surveillance, in addition to aircrafts, also to vehicles moving on airport surface (ground surveillance), with reduced update costs. Finally a multilateration architecture for aircrafts surveillance in wider areas (WAM, Wide Area MLAT) such as en route and airport approach areas will be presented, an application whom many manufacturers are looking at with interest, as an alternative to classic radar systems. | en |
dc.description.abstracteng | La scelta di un riferimento temporale stabile e comune a tutte le componenti di un sistema distribuito (costituito cioè da stazioni o sensori dislocati in siti differenti), è una tematica che trova applicazione in diversi campi delle telecomunicazioni e dell’elettronica. Per un sistema distribuito è, infatti, fondamentale che tutti gli elementi abbiano un riferimento temporale unico in modo da potersi scambiare dati in maniera univoca e per un’eventuale successiva elaborazione dati. In questo lavoro verrà considerato un sistema distribuito, la multilaterazione (in breve MLAT), con particolare attenzione per le tematiche relative alla generazione di un riferimento temporale comune ed al mantenimento della sincronizzazione tra i diversi elementi. In un sistema MLAT le stazioni a terra ricevono segnali di Modo S (repliche/squitter) dai transponder installati a bordo di bersagli cooperativi (aerei in rotta, aerei e veicoli sulla superficie aeroportuale) e ne determinano la posizione usando la tecnica TDOA (Time Difference of Arrival). Nella prima parte della tesi (cap I - IV) saranno approfonditi gli aspetti legati alla generazione di un riferimento temporale stabile, tramite un oscillatore locale. In particolare saranno esaminate le fluttuazioni di un generico oscillatore, che possono essere di due tipi: fluttuazioni sistematiche, principali cause di divergenza dal “vero” tempo e dalla “vera” frequenza nel lungo periodo (giorni od anni), e fluttuazioni “random”, osservate sul breve periodo (frazioni di secondo o minuti). Per le fluttuazioni “random” dell’oscillatore verrà introdotto un modellizzo matematico, allo scopo di avere un metodo di simulazione del comportamento di un oscillatore. I modelli sono diversi e più complessi del ben noto rumore gaussiano additivo spesso ipotizzato nelle telecomunicazioni. Infine saranno presentate alcune tipologie di oscillatori in commercio con un confronto tra le prestazioni dichiarate dai produttori. Nella seconda parte della tesi (cap V - VII) sarà descritto il funzionamento di un sistema di multilaterazione studiato dal Radarlab dell’Università di Roma Tor Vergata insieme alla società Selex-Sistemi Integrati, che lo ha realizzato; il sistema è impiegato con successo per la sorveglianza in ambito aeroportuale presso Milano Malpensa. In particolare verrà riportato lo studio che ha condotto alla scelta degli oscillatori per le stazioni del sistema e verrà descritta la procedura di sincronizzazione ideata per mantenere un riferimento temporale comune. Inoltre sarà presentata un’innovativa architettura di multilaterazione che permette di estendere la sorveglianza, in aggiunta agli aeromobili, anche ai veicoli che si muovono sulla superficie aeroportuale (sorveglianza terrestre), con costi di aggiornamento ridotti. Infine verrà presentata un’architettura di multilaterazione per la sorveglianza degli aeromobili su aree più vaste (WAM, Wide Area MLAT), come le aree di rotta e di approccio all’aeroporto, un’applicazione cui molti operatori del settore stanno guardando con interesse, in alternativa ai classici sistemi radar. | en |
dc.description.allpeople | Cavallini, Alessio | it |
dc.description.allpeopleoriginal | Cavallini, Alessio | it |
dc.description.doctschool | Probabilità, informazione e comunicazione quantistica | en |
dc.description.fulltext | restricted | en |
dc.format.extent | 2364093 bytes | it |
dc.format.mimetype | application/pdf | it |
dc.identifier.citation | Cavallini, A. (2009). Modelli statistici degli orologi e problemi di sincronizzazione nei sistemi di sorveglianza cooperativa distribuita. | en |
dc.identifier.uri | http://hdl.handle.net/2108/968 | it |
dc.identifier.uri | http://hdl.handle.net/http://hdl.handle.net/2108/968 | - |
dc.language.iso | it | en |
dc.publisher.country | Italy | - |
dc.publisher.name | Università degli Studi di Roma "Tor Vergata" | - |
dc.subject.keywordseng | oscillatore | en |
dc.subject.keywordseng | stabilità | en |
dc.subject.keywordseng | sincronizzazione | en |
dc.subject.keywordseng | sorveglianza cooperativa distribuita (multilaterazione) | en |
dc.subject.keywordseng | sistemi di sorveglianza terrestre | en |
dc.subject.keywordseng | sistemi di sorveglianza aerea (WAM) | en |
dc.subject.singlekeyword | oscillatore | * |
dc.subject.singlekeyword | stabilità | * |
dc.subject.singlekeyword | sincronizzazione | * |
dc.subject.singlekeyword | sorveglianza cooperativa distribuita (multilaterazione) | * |
dc.subject.singlekeyword | sistemi di sorveglianza terrestre | * |
dc.subject.singlekeyword | sistemi di sorveglianza aerea (WAM) | * |
dc.title | Modelli statistici degli orologi e problemi di sincronizzazione nei sistemi di sorveglianza cooperativa distribuita | en |
dc.type | Tesi di dottorato | - |
dc.type.driver | info:eu-repo/semantics/doctoralThesis | - |
dc.type.full | Pubblicazioni::07 - Tesi di dottorato | it |
iris.orcid.lastModifiedDate | 2023/07/26 13:04:44 | * |
iris.orcid.lastModifiedMillisecond | 1690369484936 | * |
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