Telecom Dictionary Navigation

Telecom Dictionary - A

Abort - To stop doing something.  Particularly, to exit a software program or stop receiving or sending a message.

Access - (1) (verb) to get use of something, or (2) (noun) refers to a particular level or security clearance of use of something (i.e., one's "access" to the mainframe).

Account - A term that refers to information that a particular telecom system has about you, and typically refers to an ID number or your personal information.

ACK - A character transmitted by a receiver that acknowledges that some particular reception took place.

Acoustic Coupler - This is an acoustic modem that transfers data over phone lines by tones and sounds instead of electronically.  Old-fashion handsets fit into a the modem to transmit information.

Acoustic Modem - This is simply a modem that uses an acoustic coupler.

Adaptive Dialing - A modem will try dialing with tones initially and will then dial in pulse if necessary (i.e., if tone dialing is ignored).

ADC - This stands for Analog-to-Digital Conversion.

ADSL - This stands for Asymmetrical Digital Subscriber Line and is the typical DSL service that connects customers to the internet.  Preexisting channels in telephone lines are used to transmit data to and from the net.

Alias - This is an assumed name with which bulletin board users may post messages.

Altitude - the distance an object appears to be above the horizon. This angle is measured up from the closest point on the horizon.

Ampersand - The character "&", which usually is written to signify "and".

Amplitude Modulation (AM) - The signal carries the desired information content by varying the amplitude or height of the carrier wave.

Amplifier - A device that is used to boost the strength or intensity of an electronic signal.

Analog - Transmitting information that is characterized by continuously variable quantities (such as with AM or FM). This is different from digital transmission, which is characterized by discrete bits of information transmitted in numerical steps.

Analog-to-Digital Conversion (ADC) - Converting analog signals to their digital representation. (DAC represents the reverse translation.)

ANIK - The Canadian domestic satellite system that transmits the CBC's (Canadian Broadcasting Corporation's) network feeds throughout Canada. This system also carries data and long distance voice services throughout Canada.

Anonymous - An unknown author of a software program or message.

ANSI - This stands for American National Standards Institute, which was founded in 1918 and creates voluntary standards for data transmissions, protocols, and high-level languages.

Answer Back - This is a signal sent to a transmitter of information that, in effect, says "I am ready to receive information now."  It can also signify the successful reception of information.

Answer Mode - A modem's condition in which it is ready to receive data.

Answer Supervision - A signal sent to the telephone company's central office that says a call has been connected (primarily used for long-distance phone calls to start the billing time).

Antenna - A device for transmitting and receiving radio waves. Depending on their intended use, antennas could be a single piece of wire, a di-pole, a grid, a helix, a parabolic satellite dish, etc.

Aperture - A cross-sectional area of the part of the antenna that is to be exposed to the received satellite signal.

Apogee - The point in an elliptical satellite orbit which is farthest from the surface of the earth.

Apogee Kick Motor (AKM) - The rocket motor that is fired to deploy the satellite into geostationary orbit.

Append - To add the contents of one thing to that of another.

Archive - This is a backup of a file in compressed or uncompressed form.

Area code - This is a 3-digit number, preceding normal 7-digit telephone numbers, that are used by the telephone company to designate a geographic billing area in the US.

ASCII - This stands for American Standard Code of Information Interchange, and it is a popular code for representing letters, numbers, and punctuation into a digital format.

Asterisk - This is the character "*".

Asynchronous Transmission - This is a method of data transmission that allows characters to be sent irregular intervals.

AT Command - This is the character "@" and usually means "at".

AT&T - American Telegraph and Telephone, the inventors of the first modem.

Attended Mode - This is the mode in which two or more users manually enter commands to send or receive files.

Attenuation - The phenomenon that is the loss in the power of electromagnetic signals between their transmission and receiving points.

Audio Monitor - This is a speaker that is part of the modem and allows you to hear sound on the phone line.  

Auto Answer - This is when a modem, phone, or other device has the capability to automatically set up a connection with an incoming transmission.

Auto Baud  - The ability of a modem to adapt its communication rate if the computer it is communicating with is unable to connect at the requested speed.

Auto Dial - When a phone or other device allows the dialing a one or a few numbers to cause the dialing of a long string of numbers.

Auto Redial - When a phone or modem redials a number if it encounters a busy signal the first time around.

Auto Reply - To send a message immediately upon the reception of one.

Automatic Frequency Control (AFC) - A circuit that can automatically control a signal's frequency.

Automatic Gain Control (AGC) - A circuit that automatically governs the gain of an amplifier so that the output signal level remains essentially constant (even if there are varying input signal levels).

AZ/EL Mount - This is an adjustable antenna mount.

Azimuth - Generally, this is the angular distance along the horizon to the location of the object (measured in degrees). By convention, azimuth is measured from north, rotating towards the east, along the horizon. Regarding satellites specifically, it is the horizontal angle of rotation that a parabolic antenna located on the ground must be rotated through to point towards a specific satellite in space.