B

[This is preliminary documentation and subject to change.]

back channel

The segment of a two-way communications system that flows from the consumer back to the content provider, or to a system component, to provide feedback.

backbone

The top level in a hierarchical network.

bandwidth

Literally, the frequency range of an electromagnetic signal, measured in hertz (cycles per second). The term has come to refer more generally to the capacity of a channel to carry information, as measured in data transferred per second. Transfer of digital data, for example, is measured in bits per second.

bandwidth reservation

The process of setting aside bandwidth on a specific broadcast channel for a specific data transmission. A content server application reserves bandwidth on a Microsoft Multicast Router by calling the msbdnReserveBandwidth function. This function forwards the request to a bandwidth reservation server. The server returns a unique reservation identifier if the bandwidth can be reserved. See also IP multicast address assignment.

baseband

Describes transmissions using the entire spectrum as one channel. Alternatively, baseband describes a communication system in which only one signal is carried at any time. An example of the latter is S-video or a composite video signal that is not modulated to a particular television channel. See also broadband.

baud

Number of bits per second, a measure of data-transmission speed. Baud was originally used to measure the transmission speed of telegraph equipment but now most commonly measures modem speed. The measurement is named after the French engineer and telegrapher Jean Maurice-Emile Baudot.

broadband

Describes high-frequency transmissions over coaxial cable or optical fibers, involving sending several data streams simultaneously. Broadband is also sometimes used to describe high-speed networks in general. See also baseband.

broadcast

In general terms, a transmission sent simultaneously to more than one recipient. In Internet terminology, a transmission sent to a single address to be forwarded to many recipients. In practice, Internet broadcasts only function on local networks, because routers do not forward them. Broadcast Architecture uses a refinement of this Internet technique known as multicast, in which routers forward transmissions. In multicast, each transmission is assigned its own Internet Protocol (IP) multicast address, allowing clients to filter incoming data for specific packets of interest at the network interface card.

Broadcast Architecture

The Microsoft computer software and hardware design that enables personal computers to serve as clients of broadband digital and analog broadcast networks.

Broadcast Architecture subsystems

The functional parts that make up Broadcast Architecture. These include the Broadcast and Data Receiver subsystem, the Data Services subsystem, the Video and Display subsystem, the User Interface subsystem, and the Television Client Services subsystem. For more information, see the Broadcast Client Architecture section of the Broadcast Architecture Programmer's Reference.

broadcast client

A versatile personal computer that can receive and display broadband digital and analog broadcasts, blending television with new forms of information and entertainment. Broadcast client programming can include television, audio, World Wide Web pages, and computer data content.

Broadcast Cryptography API

Broadcast Architecture functions that help CryptoAPI decrypt content using encryption keys.

broadcast data encoder

A hardware subsystem provided by an independent hardware vendor that encodes data for broadcast, for example pay-per-view shows that only subscribers may watch. A broadcast data encoder receives data streams from the Microsoft Multicast Router through a virtual interface.

broadcast receiver card

A printed circuit board or adapter that can be plugged into a computer to receive and process broadcast signals, such as television or other broadcast data. One type of broadcast receiver card is a satellite receiver card. Another is an analog television tuner card.

broadcast server

A computer that sends broadcast programming across a broadcast channel to broadcast clients, in some cases forwarding data over the Microsoft Multicast Router. The programming sent can include television, audio, World Wide Web pages, and digital data such as stock prices, multimedia magazines, and computer software.

Broadcast Architecture transport

A Broadcast Architecture component that manages broadcast data received through a broadcast receiver card. The Broadcast Architecture transport binds to the Broadcast Architecture NIC miniports, which control and retrieve data in formats such as MPEG, audio, Microsoft Broadcast Data Network (MSBDN), or any arbitrary format.