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Analysis of Speech Signals in VoIP Transferred Over a Network Channel
Báňa, Josef
The article examines the impact of VoIP transmission channel characteristics on speech parameters. It seeks ways of emulating properties of a selected VoIP transmission channel and creating a network emulation environment. Several scripts have been created in the Matlab development environment and used to modify and divide a continuous recording into parts identical to the original speeches, before passing through the transmission channel. Subsequently a database of speech recordings is created, as affected by selected characteristics - jitter, bandwidth, loss. Within these databases, symptoms are sought as the most evident characteristics of the transmission channel. Using correlation, symptoms are selected that are best suited for automated determination of the properties of transmission channel characteristics such as jitter, loss and bandwidth.
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VoIP in Jabber Client
Kulička, Vojtěch ; Veselý, Vladimír (referee) ; Mlích, Jozef (advisor)
Práce se zabývá možnostmi implementace VoIP do existujícího XMPP programu se sdílenou tabulí. Analyzuje možnosti využití současných technologií pro podporu VoIP. Cílem je nahrazení stávajících komunikačních knihoven klienta za telepathy. Dále také přidání VoIP.
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Implementation of quality of service in a converged network
Zvolenský, Daniel ; Kovář, Petr (referee) ; Škorpil, Vladislav (advisor)
The point of this work is the creation of IP network with a proper topology, in Network Simulator version 2, where voice packet stream with recommended compresion by G.723 standard and real-time video by H.263 standard will be simulated. Theoretical part of this work consists of convergence of nets with an implementation of Quality of Services description. In practical part of this work is identification with bacis commands in program Network Simulator 2, which make possible simulation of network behaviour.
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Detection of VoIP Applications in Network Statistics
Havelka, Ondřej ; Tobola, Jiří (referee) ; Žádník, Martin (advisor)
VoIP applications allow us fast and cheap communication over the internet. Due to the massive expansion of these applications in last few years, there is growth of VoIP traffic, which is needed to distinguish from other traffic. Detection of VoIP applications is related to data monitoring and network traffic classification. The work focuses on detection of these applications: GTalk, ICQ, Skype, WLM a Yahoo. There are presented two detection techniques. First of them is based on behavior of VoIP applications. This technique uses the statistical characteristics of network flows as packet frequency and packet size. The second method is based on searching for patterns in packet contents. These packets carry voice data using protocol RTP. Both techniques were experimentally verified and the results are presented in the work.
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SIP client with advanced features
Šacl, Vojtěch ; Číka, Petr (referee) ; Zukal, Martin (advisor)
The main objective of this thesis is the design and implementation of client software, which will be able to conduct text and video communication over an IP based network. The client application is supposed to run from a web page without the need of any additional software. The first part describes possible technologies suitable for the development of such an application. After that follows a brief description of the selected technology with emphasis on SIP protocol. The thesis also includes a brief description of characteristics of libraries that were considered for implementation into the application. The proposed solution consists of the description of the graphic environment and behavior of the application. The developed application is tested in different situations in the last part of the thesis.
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Project of VoIP exchange for commercial usage
František, Jiří ; Hanák, Pavel (referee) ; Janovič, Filip (advisor)
The aim of this thesis is create VOIP central based on Asterisk with billing system A2Billing. First of all is describe process of instalation programing instrument and provisioning pbx for local and outgoing calls. Short describe to billing of calls and praktical show of completely setting of system are follows. Administrator and user web based interface is described to. At the end of thesis is shown different technology of VOIP phones which was use in thesis. Setting of this phones is briefly described.
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Communication systems based on IP telephony
Zimek, Josef ; Kapoun, Vladimír (referee) ; Herman, Ivo (advisor)
My master’s thesis is focused on designing and creating communication network, which provides communication between two independent networks through encrypted tunnel. My solution is based on routers formed by older personal computers with FreeBSD like a operating system. Between routers is created static encrypted tunnel by using IPSec protocol. Voice services provides packet oriented exchange Asterisk with support of signaling protocol SIP. This solution can be used eg. for connecting remote branch to headquarters of company and then can branch utilize shrared resources. To headquarters can connect also remote workers from their home. In this case are used SSL certificates to authentication of user. This scenario is very required today.
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Special application of VoIP
Lembard, Tomáš ; Šebesta, Jan (referee) ; Fuchs, Michal (advisor)
The aim of this master's thesis is suggestion and following realization of voice transmission over the local network equipment and a description of used circuits and solutions in terms of hardware and software. This thesis deals with digitization of low-frequency signals, the structure of IP and UDP protocols, implementation of TCP/IP stack cIPS
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QoS assurance in wireless networks
Dvořák, Filip ; Vychodil, Petr (referee) ; Vymazal, Michal (advisor)
The bachelor´s work deals with wireless network WiFi and describes basic standards and their supplements. This work is divided into two parts - theoretical and practical. The first part of the work is applied to theoretic description of the best known standards IEEE 802.11 and detailed description of standard 802.11e. The second part of the work takes an interest in proposal and influence of service Wireless Multimedia in wireless network both in real world and in simulation program Opnet Modeler. Obtained results of the measurement are described and summarized in the conclusion.
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Proprietary VoIP protocols of PBX manufacturers
Bělík, David ; Daněček, Vít (referee) ; Šilhavý, Pavel (advisor)
This thesis focuses on the analysis of proprietary Voice over IP protocols. The first part describes the principles and VoIP technology types. The next section describes proprietary protocols Panasonic IP-PT from Panasonic Corporation and Siemens CorNet-IP from Siemens Corporation. Protocols which are being used in these systems are listed here. Further there is being described the process of registration of terminals to central province. Subsequently calling process and particular terminal functions including packet analysis are being decoded in detail. In conclusion H.323 and MGCP protocols are being compared.
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