电信专业英英词典B-1

（单词翻译:单击）

　　B-Mac - This is a method of transmitting and scrambling¹ television signals; the are time-multiplexed with a digital burst that contains digitized sound, video synchronizing², authorization³, or information.

　　Backdoor - A way of getting into a guarded system without using the required password.

　　Backlog⁴ - The amount of work in process in the factory; it is usually expressed in terms of sales (sales backlog) or satellites (satellite backlog).

　　Backslash - This is the character "\".

　　Backspace - This is the command that causes the cursor on your screen to move back one space, and it can or cannot delete characters.

　　Band Pass Filter - A circuit that will allow signals within a desired frequency band to pass through but prohibits signals outside this frequency band from penetrating⁵.

　　Bandwidth - The range of frequencies, expressed in hertz (Hz), that can pass over a given transmission channel (thus, determining the rate at which information can be transmitted). In satellite based systems a larger bandwidth of 17.5 to 72 MHz is used to spread the television signal; this helps to prevent interference.

　　Baseband - The basic direct output signal, which is in an intermediate frequency base and is obtained directly from a television camera, satellite TV receiver, or video recorder.

　　Baud - The rate of data transmission; it is based on the number of signal elements transmitted in a second. The term comes from the scientist J. M. E. Baudot.

　　BBS - This is an acronym⁶ for Bulletin Board Systems, which typically allow users to leave messages for other users.

　　Beacon⁷ - Relatively⁸ low-power carrier transmitted by a satellite, allowing the controlling engineers on Earth to monitor telemetry data or track the satellite.

　　Beamwidth - The angle or conical shape of the beam that the antenna⁹ projects. Since larger antennas¹⁰ have narrower beamwidths, they can pinpoint¹¹ satellites in space or in dense¹² traffic areas on the earth with more precision.

　　Bell 103 - This is an AT&T specification¹³ for a modem¹⁴ at speeds of up to 300 bps (bits per second). This is the most common standard for modems¹⁵ in PCs.

　　Bell 201 - The AT&T standard for 2400 bps modems.

　　Bell 202 - The AT&T standard for 1800 bps modems.

　　Bell 208 - The AT&T standard for 4800 bps modems.

　　Bell 209 - The AT&T standard for 9800 bps modems.

　　Bipropellant - Propellants are the fuel used in satellite propulsion systems. Bipropellant means that two fuels are used.

　　BISYNC - This refers to bisynchronous transmission.