• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 32
  • 10
  • Tagged with
  • 42
  • 8
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Architecture for a remote diagnosis system used in heavy-duty vehicles

Björkman, Anders January 2008 (has links)
<p>The diagnosis system of a Scania vehicle is an indispensable tool for workshop personnel and engineers in their work. Today Scania has a system for fetching diagnostic information from field test vehicles remotely and store them in a database, so called remote diagnosis. This saves the engineers much time by not having to visit every vehicle. The system uses a Windows based on-board PC in the vehicle called an Interactor. The Interactor has a telematic unit for communication with Scanias Fleet Management System and the CAN-bus in the vehicle. In the next generation of the Interactor, its telematic unit is to be replaced by a Linux based telematic unit called the Communicator 200 (C200). The purpose of this master project is to create a new architecture for a remote diagnosis system that uses the new telematic unit Communicator 200.</p><p><br />The thesis gives an analysis of the current remote diagnosis system used at Scania and proposes an architecture for a new generation remote diagnosis system using the C200. Also a system for demonstrating how to perform remote diagnosis over the C200 has been built. The thesis describes the operation and how the demonstration system was implemented.</p>
22

Positionering i GSM-nätverk

Persson, Patrik January 2007 (has links)
Merparten av de kommersiella system för mobilkommunikation som finns och byggs i världen idag bygger fortfarande på GSM, antalet abbonnenter är över 2 miljarder. För att utöka funktionaliteten med mobila terminaler har det forskats på att införa positionering i GSM-nätverk. Tjänster som använder abbonnentens positionsinformation kallas Location Based Service och de ger möjlighet att utöka funktionaliteten och spara användaren av tjänsten arbete. Rapporten beskriver olika tekniker för positionering och slutsatsen att CGI-TA är den teknik som positioneringen ska byggas på. Denna teknik finns tillgänglig hos de svenska operatörerna idag och för att kommunicera med dem används Mobile Location Protocol 3.0.0. Implementation av positioneringen realiserades i en J2EE-miljö i form av en WebLogic Server 8.1 med hjälp av Enterprise Java Beans och Java Connector Architecture. Prototypen verifierades med hjälp av en emulator till Ericsson Mobile Positioning System som klarar av att hantera Mobile Location Protocol 3.0.0.
23

Synchronization of POTS Systems Connected over Ethernet

Lindblad, Jonatan January 2005 (has links)
<p>POTS (Plain Old Telephony Service) systems have traditionally been connected via synchronous connections. When installing new nodes in the telephone network, they may sometimes be connected via packet networks such as Ethernet. Ethernet is an asynchronous network which means that nodes connected to the network don’t have access to the same clock frequency if it is not provided in some other way. If two nodes have different clock frequency, the receiver’s buffer will eventually overflow or starve. While not being a severe problem for telephony, devices used for data transmission, e.g. modems and fax will not be able to function properly. To avoid this it is necessary to synchronize the nodes.</p><p>This thesis investigates methods to synchronize nodes connected over Ethernet by simulating them in Matlab. The simulations show that under certain circumstances it is possible to produce a clock signal conforming to relevant standards.</p>
24

Industrial Ethernet and new possibilities - Simplifying function tests of industrial devices

Norén, Henrik January 2010 (has links)
<p>What do you do if you are implementing a new fieldbus protocol in your embed- ded industrial system and want to test it? This was the question that a group of engineers at ABB Corporate Research was asking themselves. Normally, the easiest way would probably be to buy a matching device supporting the same protocol and hook it up to the system. You might also need some equipment to listen in on the traffic between the two, so you’d need to buy that too.</p><p>But what if you are working with a limited budget? Or what if this protocol is fairly new, and matching devices are hard to find? Or what if you want to test cases that can’t normally be achieved with normal usage?</p><p>Normally, with traditional fieldbus standards, this could be complicated. You would probably need an additional sample of your new system, with some cus- tom made test code, and use this to test the original system. This is not a bad method, but this report will give an example of the new possibilities that comes with the new Ethernet base fieldbus standards emerging on the market today. It will highlight the possibility to create a test tool for your industrial system to use on a standard PC.</p><p>”Why?” you might ask. The report suggests that this solution is cheap, fast and flexible. First of all, no special hardware was needed, which had a posi- tive impact on cost. The only thing used was a PC and some standard office equipment.</p><p>Second, once the test tool was created, new test cases was really fast and easy to make. The test tool was designed to function as a general framework for creating dynamic test sequences based on Ethernet.</p><p>Third, the tool is flexible enough to test a lot of different cases, even cases not allowed by the standard. It made it possible to test cases that would have required the use of several samples of test system simultaneously to work. Also, because Ethernet is such a well known standard, there are a lot of existing software tools at your disposal. For example, free software for capturing and analyzing the test results was used during the tests. Furthermore, since the test tool was designed to be easily extendable to handle more protocols, it is even more flexible and useable for future similar problems.</p>
25

Turbo Equalization for HSPA / Turboutjämning för HSPA

Konuskan, Cagatay January 2010 (has links)
<p>New high quality mobile telecommunication services are offered everyday and the demand for higher data rates is continuously increasing. To maximize the uplink throughput in HSPA when transmission is propagated through a dispersive channel causing self-interference, equalizers are used. One interesting solution, where the equalizer and decoder exchange information in an iterative way, for improving the equalizer performance is Turbo equalization.</p><p>In this thesis a literature survey has been performed on Turbo equalization methods and a chosen method has been implemented for the uplink HSPA standard to evaluate the performance in heavily dispersive channels. The selected algorithm has been adapted for multiple receiving antennas, oversampled processing and HARQ retransmissions. The results derived from the computer based link simulations show that the implemented algorithm provide a gain of approximately 0.5 dB when performing up to 7 Turbo equalization iterations. Gains up to 1 dB have been obtained by disabling power control, not using retransmission combining and utilizing a single receiver antenna. The algorithm has also been evaluated considering alternative dispersive channels, Log-MAP decoding, different code rates, number of Turbo equalization iterations and number of Turbo decoding iterations.</p><p>The simulation results do not motivate a real implementation of the chosen algorithm considering the increased computational complexity and small gain achieved in a full featured receiver system. Further studies are needed before concluding the HSPA uplink Turbo equalization approach.</p>
26

Data Transmission over Speech Coded Voice Channels / Datatransmission över Talkodade Kanaler

Tyrberg, Andreas January 2006 (has links)
<p>The voice channel in mobile communication systems have high priority and are almost always available. By using the voice channel also for data transmissions it is possible to get the same availability as for voice calls. But due to speech codecs in the voice channel, regular modems can not be used and special techniques are needed to transmit data.</p><p>This thesis presents methods to transmit data over the voice channel in a GSM, UMTS or TETRA network. The focus has been on robust data transmission rather than high data bit rates. Approaches are introduced which improve the reliability for transmissions even for systems with low rate speech codecs and channels with some distortion.</p><p>The results of the thesis are suggestions of symbol patterns and ways to create and adapt symbols for specific application and channel conditions to achieve the desired goal for the application.</p>
27

Dynamisk simulering med hjälp av RPS-beräkningar för radiovågors utbredning i urban miljö

Fors, Karina January 2006 (has links)
<p>Militära insatser i urban miljö kommer troligen att öka alltmer. Detta kräver soldater till fots eftersom dessa lättare kan förflytta sig via och mellan byggnader. Varje deltagande soldat kommer att behöva egen radioutrustning. Då stadsmiljö är ett relativt outforskat område vad gäller militär radiokommunikation är det viktigt att öka förståelsen för radiovågors utbredning i stadsmiljö. Härtill har institutionen för Informationsöverföring på FOI köpt in programmet Radiowave Propagation Simulator (RPS). RPS används i det här examensarbetet för att genomföra en beräkning för ett statiskt scenario, och till beräkningen infoga påverkan från sändares och</p><p>mottagares mobilitet. Detta utförs genom att rumsligt extrapolera kanalens impulssvar till att gälla i andra positioner än de ursprungligen var beräknade för. Kanalens impulssvar blir då modifierat så att impulssvarets utbredningsvägar får nya fördröjningstider och dess komplexa signal får ny fas.</p><p>Metoden, som har tagits fram i det här arbetet, för den rumsliga extrapoleringen har implementerats och utvärderats för ett litet scenario. Det extrapolerade resultatet har sedan jämförts med beräknade resultat från RPS. Analysen visade att metoden ger ett tillförlitligt resultat. Ett annat syfte med examensarbetet har varit att visa hur forskningsresultat (från radiokanalen) kan användas effektivare för att ge högre kvalité på forskningsresultat, både på länk- och på nätnivå.</p>
28

Investigation and implementation of the OMA BCAST Service Interaction Function

Lundkvist, Karl-Johan January 2007 (has links)
<p>This thesis is a study of a new specification for end user interactivity developed by the Open Mobile Alliance, the specification is called OMA BCAST Service Interaction Function. The specification is one part of the OMA BCAST Service Enabler, which enables service delivery to mobile devices, where the most common service is mobile television. The Service Interaction Function enables end user interactivity related to a service, this could be a poll about the current television program or a chat where every message is presented to the users that are watching the same channel.</p><p>The specification is still of draft version and the scope of this thesis has been to investigate the Service Interaction Function and implement a PC prototype.</p>
29

Turbo Equalization for HSPA / Turboutjämning för HSPA

Konuskan, Cagatay January 2010 (has links)
New high quality mobile telecommunication services are offered everyday and the demand for higher data rates is continuously increasing. To maximize the uplink throughput in HSPA when transmission is propagated through a dispersive channel causing self-interference, equalizers are used. One interesting solution, where the equalizer and decoder exchange information in an iterative way, for improving the equalizer performance is Turbo equalization. In this thesis a literature survey has been performed on Turbo equalization methods and a chosen method has been implemented for the uplink HSPA standard to evaluate the performance in heavily dispersive channels. The selected algorithm has been adapted for multiple receiving antennas, oversampled processing and HARQ retransmissions. The results derived from the computer based link simulations show that the implemented algorithm provide a gain of approximately 0.5 dB when performing up to 7 Turbo equalization iterations. Gains up to 1 dB have been obtained by disabling power control, not using retransmission combining and utilizing a single receiver antenna. The algorithm has also been evaluated considering alternative dispersive channels, Log-MAP decoding, different code rates, number of Turbo equalization iterations and number of Turbo decoding iterations. The simulation results do not motivate a real implementation of the chosen algorithm considering the increased computational complexity and small gain achieved in a full featured receiver system. Further studies are needed before concluding the HSPA uplink Turbo equalization approach.
30

Synchronization of POTS Systems Connected over Ethernet

Lindblad, Jonatan January 2005 (has links)
POTS (Plain Old Telephony Service) systems have traditionally been connected via synchronous connections. When installing new nodes in the telephone network, they may sometimes be connected via packet networks such as Ethernet. Ethernet is an asynchronous network which means that nodes connected to the network don’t have access to the same clock frequency if it is not provided in some other way. If two nodes have different clock frequency, the receiver’s buffer will eventually overflow or starve. While not being a severe problem for telephony, devices used for data transmission, e.g. modems and fax will not be able to function properly. To avoid this it is necessary to synchronize the nodes. This thesis investigates methods to synchronize nodes connected over Ethernet by simulating them in Matlab. The simulations show that under certain circumstances it is possible to produce a clock signal conforming to relevant standards.

Page generated in 0.0924 seconds