Glossary

ADSL

Abbreviation of Asymmetric Digital Subscriber Line. ADSL is one kind of broadband line. It relies on the conventional copper wires of telephone lines but supports transmission of large amounts of data by using the high- frequency bandwidth separate from audio signals. The upstream rate of communication (for data sent from the user’s terminal) is slower than the downstream rate (sent from the provider to the user’s terminal), hence the description “asymmetric”. Transmission speeds vary depending on the contracted service.

Broadband

General name for communication lines that use a broad frequency bandwidth for sending and receiving large amounts of video or audio data at high speed. Currently, ADSL, CATV, FTTH and other systems are identified as broadband.

Broadband router

For Internet connections through ADSL or a cable TV line, devices called ADSL modems or cable modems are used. However, for Internet access from multiple terminals connected at once, a broadband router is used.

DHCP

Abbreviation of Dynamic Host Configuration Protocol. A system for automatically allocating configuration data required for an Internet connection.

DLNA

Abbreviation of Digital Living Network Alliance. The DLNA is a nonprofit organization that establishes design guidelines for digital content shared over networks.

For details, see http://www.dlna.org/.

Ethernet

A method of networking computers in a Local Area Network (LAN). Developed by Xerox Corporation, Ethernet has become a very popular means of creating LANs.

Internet

A communication network linking computers around the world. The Internet supports many services, including email and search engines. This system cannot connect directly to the internet.

IP address

IP addresses usually comprise four groups of up to three digits each, separated by a period (such as 192.168.239.1). All devices on a network must have an IP address.

ISP

An Internet service provider. Called as an “Internet Service Provider (ISP)”. Companies that provide a connection to the Internet.

LAN

Abbreviation of Local Area Network.

LAN is a general name for networks set up for communication among devices including computers, printers, and fax machines in relatively small areas such as offices or buildings.

Router

A device that bridges networks, converting the protocols and addresses of each network. Recently, dial-up routers for connecting to ISDN lines and broadband routers for ADSL and CATV networks have been introduced. The term “router” by itself may refer to any of these devices.

Sampling frequency

When audio sources are converted from analog to digital data, they must be changed into numbers (digitized). This process is called sampling, and the sampling frequency refers to the number of times per second that the signals are measured for the recording.

Music CDs are sampled at 44,100 times per second, so the sampling frequency is expressed as 44.1 kHz. Generally, the higher the sampling frequency, the higher the fidelity of the recording.

Subnet mask

Part of an IP address that identifies the subnet, a smaller group on the network.

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