Dial-Up Definitions

ACD (Analog to Digital Converter) A device that converts an analog waveform to a digital waveform
AM (Amplitude Modulation) A method of storing information in the magnitude of a waveform
Bandwidth Frequency range that extends form the lowest to the highest possible frequencies, a larger bandwidth allows for higher date throughput
Bit A single binary digit
bps (Bit per Second) A measure of data speed
BRI (Basic Rate Interface) A type of ISDN that is sent on 2 or 4 wires and has (2) B-Channels at 64Kbps each, and one D-Channels at 16bps
CCITT The International Telephone & Telegraph Consultative Committee, that is a subsection of the ITU, whose recommendations are followed more closely in Europe that North America
Client Modem Modem that resides in your home that connects your computer to the analog telephone line
CO (Central Office) The location where the (2) wires (Tip & Ring) from your house are terminated (i.e. connected to electronic equipment)
CODEC COder/DECoder, Converts analog to digital and digital analog
DAA (Data Access Arrangement) A circuit utilize by the modem to interface the telephone line the to the CODEC
DAC ( Digital to Analog Converter) A device that converts a digital waveform to an analog waveform
dB (Decibel) Unit and Scale used for measuring amplitude of one signal to another signal, dB = 10*Log(P1/P2)
Digital Pad An attenuator that comes most commonly in 3dB and 6dB values, used in the network to reduce amplitudes, these pads negatively effect V.90
DP (Dial Pulse) Pulses that a rotary telephone generates in making a call
DSP (Digital Signal Processor) A Micro Processor that is dedicated to calculating the complex mathematics to process digital waveforms
DTMF Dual Tone Multi-Frequency, is the technique by using two simultaneous tones to represent digits - Touch Tone
E1 A (4) wire European Telco Standard that carries data at 2.048 Mbps
EMI Electromagnetic Interface
FCC USA Federal Communication Commission
Harmonic Distortions Due to non-linearity’s in the communication channel that produces harmonics (integer multiples) of the original signal
Hybrid A circuit that makes the transformation from a 2 wire transmission to a 4 wire and also the reverse
Hz (Hertz) Measure of frequency, Cycles per Second
ISDN (Integrated Service Digital Network) Telephone service that is based two digital channels
ISP (Internet Service Provider) The organization that connects individuals to the World Wide Web (www)
ITU International Telecommunications Union; the standards agency that set the V90 modem standard in Geneva on Feb 6, 1998
K56flex A open 56K standard developed by Rockwell and Lucent that is being eclipsed by V.90
Kbps (Thousand Bit per Second) A measure of data speed
KHz (Kilo-Hertz) Thousand Cycles per Second
LAN Local Area Network
Local Loop The analog telephone line that runs from your house to your local CO
MAC Media Access Controller
Mbps (Million Bit per Second) A measure of data speed
MHz (Mega-Hertz) Million Cycles per Second
Modem MOdulate/DEModulate, Interface device between the telephone line and the local computer
Multiplexer A device that integrates serial digital waveforms into a single channel by partitioning the inputted data into segments and combining them together into a bitstream
PBX (Private Branch Exchange) Private Telephone system that many companies use for there internal telephone service
PCM (Pulse Coded Modulation) A digital waveform that stores data in a modulated pulse, this technique is used by V.90
Port An interface on a computer that is used to connect a peripheral device such as a modem
POTS Plain Old Telephone Service, analog telephone line
PRI Primary Rate Access of 23 B-Channels (64Kbps each) with 1D-Channel (16Kbps) that operates at T1 data rates
PSTN Public Service Telephone Network
Quantization The process that ADC use to convert Analog to Digital
Quantization Error The error that occurs when an analog waveform that can be any value in an infinite range is converted to a digital value that is at finite discrete levels
Ring One of the wires that make up the local loop, Ring is the connected ring on the jack that was used when operators use to switch the calls. Also the term for the energy on a POTS line that allows the telephone to ring
RJ-11 Telephone connector used in the USA for connecting to Tip and Ring
Robbed Bit Signaling An older technique used by the telephone companies on T1 lines that use digital transmission. The technique is to take the least significant bit use it to control functions such a Dial Tone, Ring, Busy Answer and etc. This signaling method negatively effects V.90 by reducing the data rate.
Server Modem Modem that resides at the remote server and is usually connected to digital lines
Shannon’s Theorem Defines the relationship between the maximum throughput in any given channel to the presence of noise
SNR (Signal to Noise Ratio) A measurement of Signal Power divided by the Noise Power, measured in dB’s
Symbol Is a representation of a group of bits into a signal waveform
T1 A (4) wire USA Telco Standard that carries data at 1.544 Mbps
Telco Telephone Company
Tip One of the wires that makes up the local loop, Tip is the end of the jack that was used when operators use to switch the calls
V.80 A synchronous connection between a modem and PC to allow PC to adjust the flow of video data during a point to point H.324 video call
V.90 The international 56K analog modem standard
V.PCM A pre-standard reference to Pulse Coded Modulation, used as a working name before V.90 was named
WAN (Wide Area Network) The POTS, ISDN, T1 and ext. that are used to connect to distance locations
X2 A proprietary USR/3-Com Standard that is being eclipsed by V.90
XDSL Digital Subscriber Line where the "X" denotes for the many forms of the technology, XDSL is an asymmetric transmission that is capable of data transfers theoretically of up to 52 Mbps