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Grandstream Networks, Inc. HT-502 User Manual Page 32 of 35
Firmware 1.0.0.39 Last Updated: 03/2007
GLOSSARY OF TERMS
ADSL Asymmetric Digital Subscriber Line: Modems attached to twisted pair copper wiring that transmit
from 1.5 Mbps to 9 Mbps downstream (to the subscriber) and from 16 kbps to 800 kbps upstream,
depending on line distance.
AGC Automatic Gain Control is an electronic
system found in many types of devices. Its purpose is to
control the gain
of a system in order to maintain some measure of performance over a changing range of
real world conditions.
ARP Address Resolution Protocol is a protocol used by the Internet Protocol (IP)
[RFC826], specifically
IPv4, to map IP network addresses
to the hardware addresses used by a data link protocol. The protocol
operates below the network layer as a part of the interface between the OSI network and OSI link layer. It
is used when IPv4 is used over Ethernet
ATA Analogue Telephone Adapter. Covert analogue telephone to be used in data network for VoIP, like
Grandstream HT series products.
CODEC Abbreviation for Coder-Decoder. It's an analog-to-digital (A/D) and digital-to-analog (D/A)
converter for translating the signals from the outside world to digital, and back again.
CNG Comfort Noise Generator, generate artificial background noise
used in radio and wireless
communications to fill the silent
time in a transmission resulting from voice activity detection.
DATAGRAM A data packet carrying its own address information so it can be independently routed from its
source to the destination computer
DECIMATE To discard portions of a signal in order to reduce the amount of information to be encoded or
compressed. Lossy compression algorithms ordinarily decimate while sub-sampling.
DECT Digital Enhanced Cordless Telecommunications: A standard developed by the European
Telecommunication Standard Institute from 1988, governing pan-European digital mobile telephony. DECT
covers wireless PBXs, telepoint, residential cordless telephones, wireless access to the public switched
telephone network, Closed User Groups (CUGs), Local Area Networks, and wireless local loop. The DECT
Common Interface radio standard is a multi-carrier time division multiple access, time division duplex (MC-
TDMA-TDD) radio transmission technique using ten radio frequency channels from 1880 to 1930 MHz,
each divided into 24 time slots of 10ms, and twelve full-duplex accesses per carrier, for a total of 120
possible combinations. A DECT base station (an RFP, Radio Fixed Part) can transmit all 12 possible
accesses (time slots) simultaneously by using different frequencies or using only one frequency. All
signaling information is transmitted from the RFP within a multi-frame (16 frames). Voice signals are
digitally encoded into a 32 Kbit/s signal using Adaptive Differential Pulse Code Modulation.
DNS Short for Domain Name System (or Service or Server), an Internet
service that translates domain
names into IP addresses
DID Direct Inward Dialing. The ability for an outside caller to dial to a PBX extension without going
through an attendant or auto-attendant.
DSP Digital Signal Processor. A specialized CPU used for digital signal processing. Grandstream
products all have DSP chips built inside.
DTMF Dual Tone Multi Frequency. The standard tone-pairs used on telephone terminals for dialing using
in-band signaling. The standards define 16 tone-pairs (0-9, #, * and A-F) although most terminals support
only 12 of them (0-9, * and #).