Black Box 5000 manual Glossary

Glossary

one bit, as in quadrature amplitude modulation, the baud rate is smaller than bps.

BCC, block check character — A character added to the end of a transmission block for the purpose of error detection.

BERT — Acronym for Bit Error Rate Tester.

bit — Contraction of binary digit. This is the smallest unit of information and the basic unit in digital data communications. A bit can have a value of zero or one (mark or space in data- communications terminology).

block — The part of a stacking connector that is mounted on the top side of a module.

bps, bits per second — A standard for measuring the rate of data; the number of bits passing a specific point each second.

break or <break> — A spacing condition that exists longer than one character time. Break is often used by a receiving terminal to interrupt the sending device’s transmission, to request a disconnection, or to terminate a computer process.

bridge — Equipment connecting two similar local area networks (LANs).

broadcast — The transmission of a message intended for general reception rather than for a specific station.

buffer — Temporary data storage area to absorb the difference in transfer rates between two devices, or to collect data for more efficient block transferral.

busyout — A configuration option in the voice module that is used to place the voice channel into the busy state, effectively disabling the channel.

byte — A collection of bits operated upon as a unit. Most bytes in data communications are 8 bits long, and most characters sets use one byte per character. The capacity of storage devices (such as RAM) is frequently given in bytes or in kilobytes (1KB=1024 bytes).

call inhibit — A configuration option that prevents

the voice/fax channel from calling another voice/fax channel.

carrier — A continuous signal which is modulated

with a second, information-carrying signal.

carrier frequency — The frequency of the wave (carrier) that is being modulated to transmit signals.

CCITT, Consultative Committee for International Telegraph and Telephone — This committee

makes international communications recommendations to participating members. These are frequently adopted and made standards by national organizations. The CCITT develops recommendations that pertain to interfacing, modems, and data networks. Membership includes various scientific and trade associations, as well as governmental and private companies. It is a part of the International Telecommunications Union (a United Nations treaty organization) in Geneva.

CCM, Communications Control Module — The CCM is the six-channel base module which comes with the Multiserver. With the exception of the 56K CSU/DSU module, all interconnect and mux links are configured through the CCM. The CCM also houses the CommPak cartridge. The CCM provides control of composite and channel communication.

CD, carrier detect — A control signal that indicates that the local modem is receiving a signal from the remote modem.

CEM, Channel Expansion Module — A data channel expansion module, increasing channel capacity by 6 or 12 channels, depending on the module chosen.

central office — The building where common carriers terminate customer circuits and where the switching equipment that interconnects those circuits is located.

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