| Backbone | a LAN or WAN that interconnects intermediate systems; a high speed series of connections which form a major pathway within a network; the part of a network that handles the major part of the traffic |
| Backhaul | a terrestrial communications channel linking an earth station to a local network or population centre |
| Backoff | the reduction of input power to an HPA so that the amplifier operates in a more linear region |
| Backplane | the main bus that carries data within a device, often synonymous with motherboard |
| Band pass filter | a circuit or device which allows frequencies in a desired band through but which attenuates signals of higher and lower frequencies |
| Bandwidth | the amount of frequency space occupied by a signal |
| Baseband | the raw audio, video or digital signal before coding and modulation onto a carrier, or after decoding and demodulation |
| Basic cable | channels received by cable subscribers at no extra charge, usually supported by advertising and small per-subscriber fees paid by cable operators |
| Basic Rate Interface | an international standard switched digital interface (a form of ISDN) offering two 64 kb/s B channels and a 16 kb/s D channel to carry voice, data or video signals |
| Baud | rate of data transmission based on the number of signal elements or symbols transmitted per second |
| B channel | in ISDN, a full duplex 64 kb/s channel for sending data |
| Beacon | a low power carrier transmitted by a satellite which often carries telemetry |
| Beam | the concentrated pencil of radiation produced by an antenna |
| Beamwidth | the angular width of an antenna beam; usually the 3 dB beam width at which the antenna gain is 3 dB below that on the boresight |
| Bearer channel | a channel from which a user derives multiple channels |
| Bent pipe | term used to describe a transponder which only amplifies and frequency converts a signal, but does not perform any other processing such as regeneration |
| Big LEO | low earth orbit satellite for voice and data communications |
| Binary Coded Decimal (BCD) | an encoding scheme in which each decimal digit is encoded as a 4 bit binary word |
| Binary Synchronous Communications (BSC) | a byte controlled communications protocol using control characters and synchronised binary coded data transmissions between stations |
| Bird | slang expression for a satellite |
| Bisync | character oriented data link protocol for half duplex applications; typically used in mainframe applications |
| Bit error rate | the rate at which errors occur in the transmission of data over a particular channel |
| Bit rate | the speed of a digital transmission, expressed in bits per second |
| Bit stuffing | atechnique in which a 0 bit is inserted in a transmitted data stream to ensure that six 1 bits never appear consecutively |
| Blanking interval | the period in a television signal between the end of one picture frame and the start of the next |
| Block | a group of consecutive words or characters handled as a unit |
| Block check character | a character used for error correction, calculated by a transmission verification algorithm and normally added to the end of a block |
| Block down converter | a unit, which is normally located at the antenna feed behind the LNB, which converts the received frequency down to L band (approx 1 GHz) |
| Boresight | the direction along the principal axis of an antenna; usually the direction of maximum gain |
| Bouquet | a group of TV channels marketed by the same organisation and which can be decoded by a single smart card; the channels though, may originate from different broadcasters |
| Break | a transmission interruption, usually initiated by a controlled terminal, to allow it to interrupt the controlling computer |
| Broadband | high data rate, usually taken to mean higher than 64 kb/s or 2 Mb/s, though there is no generally accepted definition |
| Broadcast | the transmission of a signal to all terminals in a service area/network or the signal itself |
| Broadcast storm | multiple simultaneous broadcasts that can absorb available network capacity and can cause network time-outs |
| Buffer | area in a device for the temporary storage of data in transit; can accommodate differences in processing speeds between devices by storing data blocks until they are ready to be processed by a slower device |
| Bundling | the practice of offering several services as a package |
| Business TV | private use of television within an organisation to keep staff up to date with new product releases, events and company news |
| Bypass | the use of transmission facilities other than those of the local telephone company network |
| Byte | a group of bits used to make a discrete unit of information; a byte usually consists of 8 bits and represents a character |
