Library items tagged: networks

Broadband networks

Anonymous
Tuesday, January 10, 2012 - 16:46
introduction
Videoconferencing
networks
Computers connected to the Internet via a modem and telephone line are limited to a data rate of around 56Kbit/s. Broadband connections using ADSL (Asymmetric Digital Subscriber Line) technology achieve rates from 512Kbit/s up to around 16 Mbit/s. The speed of both these connections will however depend on the amount of data traffic currently on the network and as the name “Asymmetric” implies, the download and upload speeds differ. Generally data can be downloaded approximately twice as fast as it can be uploaded, which for domestic users is convenient.
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IP and ISDN CODECs

Anonymous
Tuesday, January 10, 2012 - 16:46
introduction
Videoconferencing
networks
As has been previously mentioned, a CODEC is necessary to enable the sound and vision signals to be converted and then transmitted from the local site. Another CODEC is also required at the remote site to convert the digital signals back into sound and vision signals for the audience. The method of transmission for IP and ISDN are different and so require different CODECs.
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ISDN

Anonymous
Tuesday, January 10, 2012 - 16:44
introduction
Videoconferencing
networks
Before the Internet achieved its present ubiquitous state and reached every school the telephone network offered its own digital communication via telephone lines. Termed ISDN (Integrated Services Digital Network), this uses the existing telephone infrastructure to carry digital signals. Offered by telecommunications providers it is available in many parts of the world. The service is accessed through dial up in the same way as a telephone, so the network does not have to be dedicated between the videoconference centres.
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The Internet

Anonymous
Tuesday, January 10, 2012 - 16:43
Videoconferencing
introduction
networks
All schools now have access to the World Wide Web via the Internet. This technology uses a common method of transmitting and receiving data called IP or Internet Protocol standard to ensure information passes flawlessly between networks. The success of the WWW could not have been achieved without this single ubiquitous standard. A disadvantage of IP transmission is that because all data traffic e.g. e-mails, WWW downloads or videoconferencing has to share the same pipes, they all have to compete for the available space or bandwidth.
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