Glossary - B
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Back Channel - A back channel is a term that applies to asymmetric data connections. It is the slower of the two data paths, or directions, in the connection. Often times, as with ADSL and 56Kbps modems, the back channel is transmitted over the same set of wires or other media as the larger of the two data paths. In other cases, such as with satellite downlinks and some cable modem systems that use a modem and the telephone system to carry the back channel, the data is returned via a different transmission media.
Back Porch - That portion of the composite picture signal which lies between the trailing edge of the horizontal sync pulse and the trailing edge of the corresponding blanking pulse.
Backbone - Part of a network used as the primary path for transmitting between network segments. Also, high-speed line or series of connections that forms amajor pathway within a network.
Background Noise - In an amplifier or other device that draws current, there is always some noise output in addition to the desired signal.
Bandwidth - (1) A measure of spectrum (frequency) use or capacity. For instance, a voice transmission by telephone requires a bandwidth of about 3000 cycles per second (3KHz). A TV channel occupies a bandwidth of 6 million cycles per second (6MHz). Cable system bandwidth occupies 50 to 300 MHz on the electromagnetic spectrum. (2) Measure of capacity of a transmission channel, or the difference between the highest and lowest frequency levels. Information-carrying capacity of a communication channel. The amount of transmission capacity possessed by a system or a specific location in a system.
Base station - Also called cell station. A radio transceiver (transmitter/ receiver) that uses processing hardware/software and an antenna array to control and relay voice and data signals between the central office of a telephone network, or the internet transport provider, and the remote subscriber unit (fixed or mobile) or internet appliance; it connects wireless users to a phone network, or to an internet service provider.
Basic Cable - The basic program services distributed by a cable system for a basic monthly fee. These include one or more local broadcast stations, distant broadcast stations, non-pay networks and local origination programming.
Baud Rate - The measure of the speed of transmission of a digital code.
Binder - In telecommunications lexicon, a binder is a grouping of wires inside a common sheath. The common two pair telephone cable you can buy at hardware stores for household wiring jobs (black, yellow, green, and red wires) is a two pair binder. Binders can hold almost any number of wires. Thick telephone company trunk binders may hold 250 pairs. Neighborhood streets generally have 20, 50 or even 100 pair telephone binders supplying “dialtone” to the neighborhood. Within a house, two pair binders are very common. Modern office building often fun 4, 6, or 8 pair cables to each desktop to provide telephone and computer network connections.
Bit - (1) An abbreviation of binary digit. A bit can be one of the two binary characters, either a 1 or 0. (2) A unit of information. One bit of information is sufficient to specify one of two equally likely possibilities.
Bit Error Rate (BER) - The fraction of bits transmitted that are received incorrectly.
Bit Rate - The rate of a binary-coded transmission which is the number of bits per second.
Bits per Second (b/s) - Digital information rate expressed in the number of binary information units transmitted per second. Typically, a data channel is described as having a stated bit rate and a stated expected error rate.
Blanking (Picture) - The portion of the composite video signal whose instantaneous amplitude makes the vertical and horizontal retrace invisible.
Block Tilt - A method of setting the output levels of all low-band channels at a given number of dB lower than high-band channels.
Bonding - Telecommunications shorthand for Bandwidth on Demand Interoperability Group. A method for combining two ISDN B Channels into a single logical 128Kbps connections. Used most often for video conferencing and emulating a standard analog modem connection.
Bookmarks - A specific marked point in a Web document that allows quick access for returning to that point. When you want to easily return to a Web page, create a bookmark for it. This term is usually used by Netscape—Microsoft Internet Explorer calls these favorites.
Bridger Amplifier - Trunk amplifiers serve not only to boost the signal and pass it along, but also to provide branching lines, called feeders, for distribution of the signals to subscribers. The bridger amplifier is housed in the same case as the trunk amplifier. It taps the trunk at about +20 dBmV and splits the signal into 2 to 4 feeder lines.
Broadband - A transmission medium which allows transmission of voice, data, and video simultaneously at rates of 1.544Mbps or higher. Broadband transmission media generally can carry multiple channels—each at a different frequency or specific time slot.
Broadband Communications System - Frequently used as a synonym for cable television. It can describe any system capable of delivering wide-band channels and services.
Broadband Modulation - The transfer of information by a radio signal requires a certain minimum amount of spectrum space. This minimum depends on the rate at which this information is conveyed. Sometimes called wideband modulation.
Broadband Network Bridge - More commonly known as a Cable Modem, a broadband network bridge is a device that “bridges” radio-wave-like signals sent over cable TV wiring to standard Ethernet LAN connections, which you can plug into a computer’s Ethernet network card.
Broadcaster’s Service Area - Geographical area encompassed by a station’s signal.
Broadcasting - The dissemination of any form of radio electric communications by means of Hertzian waves intended to be received by the public. Transmission of over-the-air signals for public use.
Broadcast - A broadcast is a service that is delivered to all customers. Each customer may select a particular broadcast channel out of many.
Broadcast Addresses - A predefined destination address that denotes the set of all service access points.
Broadcast Application - A broadcast application is an application running on a set-top converter that is loaded through in-band information, inserted either at the headend or by a content provider further upstream.
Broadcast Control Channel - The channel, broadcast continually from the base station, that contains telemetry, identification and configuration data.
Broadcast File System (BFS) - A broadcast file system is a data carousel system by which application data can be stored on an application server and transmitted frequently to the set-top converters for application use.
Browser - A program used to graphically display HTML documents from the World Wide Web or other sources. Newer versions of most browsers can also display video clips and animations, play sound and interactive games. The two most popular browsers are Microsoft Internet Explorer and Netscape Communicator.
Business-to-Business (B-to-B) - Used to describe an e-commerce site used to facilitate business between two separate businesses.
Business-to-Consumer (B-to-C) - Used to describe an e-commerce site used to facilitate business between a business and a consumer.
Byte - A unit of data measurement made up of eight bits, short for binary term. One byte can represent a character such as a letter, number, or punctuation mark. Large groups of bytes (megabytes and gigabytes) are typical units of measurement for things such as RAM and hard drive size.
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