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Number
10/100BASE-T	This combines the 10BASE-T and 100BASE-TX Ethernet standards into a single term. 100BASE-TX is a general term referring to a group of fast Ethernet standards used for transmission over twisted-pair cables, etc. 10BASE-T is another Ethernet standard. Both 10BASE-T and 100BASE-TX are used to link equipment in a star-configured LAN via a hub. 10BASE-T can be used to transmit data at up to 10Mbps over a maximum distance of 100 meters, while 100BASE-TX is capable of data transmission at 100Mbps over the same distance. 100BASE-TX equipment is usually compatible with 10BASE-T, so it is possible for them to coexist on a single network.
2-Tone (Two-Tone)	This refers to two-tone squelch. This function employs a sequential transmission of 2 audible tones for user selection, enabling the receiver to hear an alert tone. It can also be used for group calling.
4-Level FSK modulation	Frequency Shift Keying (FSK) is a modulation method by which the instantaneous frequency of a carrier is discretely changed according to a digital code. For example, with 2-level FSK, bit 0 changes the carrier frequency to -Δf, while bit 1 changes the carrier frequency to +Δf. With 4-level FSK, codes 00, 01, 10 and 11 indicate frequency shifts of +Δf, +3Δf, -Δf and -3Δf. Using 4 values instead of 2, 4-level FSK allows for double the data rate; alternatively, it is possible to send the same amount of data using half the bandwidth. Since FSK modulation has a constant envelope, the effects of amplitude shift are reduced and a non-linear Class C amplifier can be used.

A
ACC	Abbreviation for Accessory.
Air Interface	Protocol specifying connection and transmission methods between radio units in a digital mobile radio system.
AMBE+2™	AMBE™ is an abbreviation for Advanced Multi-Band Excitation, an audio compression technology developed by Digital Voice Systems, Inc. (DVSI). This technology maintains audio quality over a narrower transmission bandwidth than linear-predictive encoding systems, and copes well with transmission errors and noise. AMBE+2™ is the latest version of AMBE™.
ANI	Automatic Number Identification. This identifies the transmitting radio and is used in two-way selective calling.
AUX	Abbreviation for Auxiliary port. A terminal for connecting a peripheral device.
AVL	Automatic Vehicle Location. A system or service using a radio terminal and a vehicle-mounted GPS device that enables owners to prevent vehicle theft or locate stolen vehicles. It can also provide trip information for bus and other transport service passengers, and increase operational efficiency for trucking companies.

B
BER	Bit Error Rate. This measures the error bits in a received bit stream over a given period.

C
Class-C Power Amplifier	A power amplifier employing Class C electronics. Power amplifier circuits (output stages) are classified as A, B, AB or C. Class A, B, and AB are linear amplifiers, while Class C can be categorized as non-linear. Class C amplifiers conduct less than 50% of the input signal and the distortion at the output is high, yet high efficiencies (up to 90%) are possible. Class C amps thus have advantages in efficiency and cost performance when compared to Class A, B and AB, which are used for digital wireless communications.
Clone	To copy user programmable data – such as frequency, ID, signal and scan information – from one radio to another.
Conventional Mode	A communications method whereby the user selects the appropriate channel for a call, since a control device to assign a traffic channel is not available. In Direct Mode Operation mobile radios communicate with each other directly, while in Repeater Operation they communicate via a repeater.
CTCSS	Continuous Tone-Coded Squelch System. A circuit that adds continuous tones to the transmitted signal to enable the other party to screen out unwanted signals and receive only the desired station. This is common for business radio systems as it allows multiple transceivers to use the same radio frequency. Equivalent to Kenwood's proprietary QT (Quiet tone) system.
CW	Continuous Wave. Morse code is created by switching a continuous wave on and off.

D
DB25	Refers to 25-pin cables and plugs.
DCS	Digital Coded Squelch. While CTCSS modulates a carrier with a continuous tone signal, DCS uses a continuous NRZ data stream. Equivalent to Kenwood's proprietary DQT (Digital Quiet Talk) system.
DQT	Digital Quiet Talk. DQT has 512 codes (from 000 to 777 in octal notation) but 86 code sets are actually used. Since DQT uses FSK modulation with binary data, it is more complex than QT and is incompatible with QT.
DSP	Digital Signal Processor. A microprocessor specialized for audio, signaling, error correction and vocoder data. It can relieve the CPU of some of the signal processing load.
DTMF	Dual Tone Multiple Frequency. Tones are emulated by pressing the 0-9, * and # keys. This is different from CTCSS, since it operates in the audio range and cannot be transmitted simultaneously with voice audio.
Duplex	A communications method for simultaneous transmission and reception using two separate frequencies.

E
EIA	Electronic Industries Alliance.
ESN	Electronic Serial Number, a unique number assigned to individual radio units for identification purposes.
Ethernet	A family of frame-based computer networking technologies for LANs, standardized as IEEE 802.3. Originally proposed by Xerox and DEC (now part of Hewlett-Packard).

F
FDMA	Frequency Division Multiple Access. A channel access method in which a radio system shares spectrum by assigning different frequencies to multiple users.
FEC	Forward Error Correction. A transmitter adds redundancy data to information data prior to transmission so the receiver can detect and correct errors in the received data.
FleetSync®	FleetSync® is the generic name for Kenwood's proprietary message communications system that utilizes MSK (Minimum Shift Keying) signaling. FleetSync® allows the user to identify individual transceivers as well as send and receive text messages. FleetSync® also supports serial communications, allowing the user to connect a computer or other external device to the transceiver. FleetSync® provides diverse messaging functions not possible with conventional voice communications, and it supports a wide variety of operating environments.
FM	Frequency Modulation, a technique for modulating an analog signal. The information is transmitted by modulating the frequency. FM offers better sound quality with less noise than AM, although FM requires more bandwidth and is therefore not very efficient.
FPU	Field Programming Unit, programming software for loading various settings into radio unit.
Fringe Area	Boundary of the coverage area of a transmitter in which signals are weakened and distorted.

G
GPS	Global Positioning System. Developed by the United States military, GPS technology uses signals from about 30 satellites to provide accurate information about one's position on the Earth. The latitude, longitude and altitude of the receiver can be determined with an accuracy ranging from twenty meters or more to just a few centimeters.

I
I/O	Input-Output.
IMBE™	Improved Multi-Band Excitation, an audio compression technology developed by Digital Voice Systems, Inc. (DVSI).
Intrinsically Safe (IS)	Explosion-proof specifications, required for transceivers used in such places as coal mines or oil refineries, where the risk of triggering an explosion is high.
IP (1)	Internet Protocol. The protocol used for data transmission across the Internet. IP forms the foundation of the Internet, and hence plays a major role in Internet activity.
IP (2)	International Protection. IEC standard IEC60529 (Degrees of protection provided by enclosures) specifies the level of protection from intrusion by body parts, foreign materials or liquids into electrical equipment enclosures. 'IP' is followed by a number indicating the level of protection. The first digit describes the degree of protection from foreign materials, and the second from liquids. For example, in the case of IP 54, '5' indicates that the device is dust resistant, though there should be no harmful effects if a small amount of dust enters the enclosure, while '4' indicates that there will be no harmful effects if a small amount of water is splashed on the equipment from any direction. In the case of IP 55, the second '5' indicates that water sprayed directly from a nozzle onto the device enclosure from any direction will have no harmful effects.
IPSec	Internet Protocol Security. IP packet encoding standards for encrypted communications across the internet.

L
LAN	Local Area Network. A network set up within a building which connects devices such as computers and printers, for data transfer via twisted-pair coaxial or optical fiber.
LCD	Liquid Crystal Display.
LED	Light Emitting Diode. A type of semiconductor element that emits light when an electrical current passes through it. The three basic colors are red, blue and green, and in combination these can be used to produce a range of other colors including white, making it easy to reproduce full color images. A wide viewing angle is possible.
LTR®	Logic Trunked Radio. A trunked radio system developed in the late 1970s by the E. F. Johnson Company.

M
MIL-STD	Military Standard. Such standards are defined by the United States Department of Defense for product procurement.
Mission-Critical	A key business mainframe system that operates 24/7, or other systems that cannot be turned off without impacting normal business operations are referred to as "mission-critical."
MSK	Minimum Shift Keying. A kind of FSK modulation in which the minimum possible carrier frequency shift is set for each data bit.
Multi-site	A system that has multiple sites connected via a network.

N
NEXEDGE®	NEXEDGE® is the trade name for Kenwood's digital radio systems using the NXDN® digital air interface.
NRZ	Non-Return-to-Zero encoding.
NXDN®	NXDN® is the name of the digital air interface protocol and trademark of JVC KENWOOD Corporation and ICOM Inc. It is comprised of a digital radio communications protocol using 4-Level FSK (4LFSK) modulation capable of operating on 12.5 and 6.25 kHz channel bandwidths. NXDN® access methodology is classified as FDMA (Frequency Division Multiple Access).

O
OCXO	Oven-Controlled Crystal Oscillator. A highly stable oven-type crystal oscillator in which internal temperature fluctuations are kept to a minimum to ensure precise transmit performance.

P
PF	Programmable Function Key. Such keys are assigned functions with an FPU.
PTT ID	A generic term for an ANI-like system used in two-way radio systems. It provides identification of the transmitting radio over the air, and is commonly employed in Selective calling/signaling systems, usually in commercial and public safety radio systems.
Push-to-Talk	Abbreviated as PTT. A simplex or half-duplex communications service, where it is only possible to talk while the transmit button is pushed down.

Q
QT	Quiet Talk. Kenwood's proprietary CTCSS system using EIA tones. This enables the user to call groups or individuals on a single frequency.

R
RAN	Radio Access Number. With NXDN® this digital signaling ensures smooth communication among groups using the same channel. Used in the same way as analog signaling with QT/DQT.
RF	Radio Frequency. Refers to the frequency of the radio waves or electrical signals used as a carrier for wireless communications.
ROI	Return on Investment, a figure that expresses the operational profits returned from a particular investment.
RSSI	Received Signal Strength Indicator. A circuit incorporated into a receiver that indicates the strength of a received signal.

S
Scan	To sequentially receive on specific channels stored in memory, in order to search for a valid transmission.
Simplex	Communication in one direction at one time. Therefore, simplex communication on the same frequency must alternate between transmission and reception.
SINAD	Signal to Noise And Distortion. A standardized value used to measure the sensitivity of an FM receiver. Measured in dB (decibels).
Site	A term to describe an aggregate of repeaters in a system.

T
TDMA	Time Division Multiple Access. A channel access method whereby a radio system assigns users different time slots on the same frequency. One frequency can thus be shared by multiple stations.
Trunking	A "trunk" is a communications channel between two points, and "trunking" refers to automatically sharing trunks. A radio system with this capability is a "trunked system," a concept analogous to the way phone lines are switched by an exchange. Traffic channels in a repeater site are thus automatically distributed. Since the controller in a trunked system identifies available repeaters and assigns them to users, a trunked system improves the operation rate of repeaters and offers more spectral efficiency than a conventional system.
Turnkey	A configuration aid rendering complicated initialization settings unnecessary.

U
UHF	Ultra High Frequency. The UHF band is defined as 300MHz~3GHz. UHF waves are not reflected by the ionosphere and propagation loss is larger than it is for VHF. UHF waves are mainly used for line-of-sight or short-distance communications. Since the wavelength is short, a small antenna is sufficient for mobile radios.
USB	Universal Serial Bus. A standard routing system for connecting computers and peripheral equipment.

V
VHF	Very High Frequency. The VHF band is defined as 30MHz~300MHz. VHF waves are not reflected by the ionosphere most of the time, and propagation loss is comparatively large. VHF is used mainly for line-of-sight communications.
Vocoder	A type of audio compression technology. Vocoder systems analyze the human voice and can generate an "artificial" voice. This dramatically reduces the amount of information needed to store speech, from a complete audio recording to a series of numbers.
VOX	Voice Operated X. With a two-way radio, this is a circuit that automatically activates the transmitter when the user speaks, enabling hands-free switching between transmission and reception. The 'X' indicates the particular device or circuit for voice operation.
VPN	Virtual Private Network. A service that creates a discreet virtual network over a public network. This is useful for connecting important bases within a corporation while avoiding the cost of installing a private network. Data encoding and certification systems ensure confidentiality by lowering security risk from leakage, signal interference and interception.

W
WAN	Wide Area Network. A network designed for data communications between computers that are separated geographically, such as those in a company headquarters and its branches.