B

	B Channel
	A 56Kbps or 64-kbps channel that carries user data on a line using ISDN D-channel signalling.
	B-Mac
	A method of transmitting and scrambling television signals. In such transmissions MAC (Multiplexed Analogue Component) signals are time-multiplexed with a digital burst containing digitised sound, video synchronizing, authorization, and information.
	Bandwidth
	Bandwidth is the data capacity of a service, measured in thousands of bits per second (kbps) or millions of bits per second (Mbps). In videoconferencing systems a larger bandwidth is used to spread or "dither" the signal in order to prevent interference.
	Baseband
	The basic direct output signal in an intermediate frequency based obtained directly from a television camera, videoconference television receiver, or video tape recorder. Baseband signals can be viewed only on studio monitors. To display the baseband signal on a conventional television set a "modulator" is required to convert the baseband signal to one of the VHF or UHF television channels, which the television set, can be tuned to receive.
	Bit Error Rate
	The percentage of received bits in error compared to the total number of bits received. A bit error rate of 10-6 means that there is an average of one error per million bits.
	bps (bits per second)
	A unit of measurement of the speed of data transmission and thus of bandwidth. Actually a nested acronym, meaning binary digits per second.
	BRI (Basic Rate Interface)
	One of two ISDN subscriber "interfaces" in ISDN. 2 voice (B) channels at 64 kbps channels and 1 data signal (D) channel at 16 kbps. The B-channels are for voice, video, and data. The D-channel is for signalling between telephone company switches and for carrying ISDN user-network messages.
	Bridge
	In videoconferencing vernacular, a bridge connects three or more conference sites so that they can simultaneously pass data, voice, or video. Videoconferencing bridges are often called MCU's - multipoint conferencing units. (See router).
	Broadband
	A way of transmitting large amounts of data, voice, and video that is greater than telephony networks. In ISDN, broadband channels support rates above the primary rate (1.544 Mbps or 2.048 Mbps). (See wideband and narrowband)
	Business Television
	Corporate communications tool involving video transmissions of information via videoconference. Common uses of business television are for meetings, product introductions and training.