BAND PASS FILTER - A circuit or device that allows only a specified range of frequencies to pass from input to output, rejecting all signals at lower or higher frequencies.

BANDWIDTH - The range of frequencies occupied by a signal or allowed by receiving equipment. In other words what a receiver can receive.

BAT - An optional element of SI which provides a means of pointing to associated services on other multiplexes.

B.E.R. - (Bit Error Rate) The chance of an error occurring during a digital satellite transmission.

BIT - A '0' or a '1' - The on/off basis of digital transmission.

BLUETOOTH - In-home radio system for communicating between devices in the same room. It first appeared in mobile phones and linking computers and peripherals wirelessly, but you will soon be using your mobile phone as a remote control for the telly. Bluetooth is going places according to the advocates. The name, incidentally, is that of an ancient Scandinavian king.

BROADBAND - The transmission of digital audio, video or data through a high data-rate system such as satellite, digital cable or ADSL.