Glossary

10BaseT

Ethernet standard using twisted pair cabling (such as CAT5). Supports a maximum data rate of 10 Mbps.

100BaseT

Fast Ethernet standard using twisted pair cabling (such as CAT5). Supports a maximum data rate of 100 Mbps.

802.11

Wireless network communications standard commonly used in LANs.

ACU

Antenna Control Unit.

AGC

Automatic Gain Control. Function that automatically boosts the gain of a received signal, as required, to maintain a constant output level. Indicates RF level.

Analog Phone

Standard telephone, also referred to as POTS (Plain Old Telephone Service). Voice signals are converted into electrical pulses by modulating a carrier signal.

AZ

Azimuth angle. Horizontal direction in which the antenna points.

bps

Bits per second.

BUC

Block Up-Converter. Device that converts the intermediate frequency signal from the modem to a Ku-band frequency and amplifies it for transmission.

Bulletin Board

Communications from the hub to all terminals within its network.

Cache

A web browser's local storage of visited web pages and other Internet files, allowing that information to be accessed more quickly on subsequent visits.

CAT5

Category of twisted pair cable with a maximum data rate of 1,000 Mbps.

Channel

Frequency (between 2.4-2.5 GHz) used for Wi-Fi communications. To communicate via a wireless connection, both router and host must be set to the same channel. There are 11 channels to choose from, allowing users to prevent interference between multiple wireless networks.

Chassis

The outside enclosure of an electronic device.

Client

A computer application that accesses resources held by a server.

Cloud

“The cloud” refers to the accessibility of software applications and data storage services through a web browser.

CRMA

Code Reuse Multiple Access (CRMA) protocol is a variant of CDMA, which is widely used in cellular communications. Using this protocol, multiple vessels share bandwidth for ship-to-shore transmissions to the satellite. Unlike TDMA, vessels don’t need to wait their turn to transmit. They can immediately transmit in bursts at the same time as other vessels and at the fastest data rate available, significantly reducing delays.

Crossover Cable

Cable in which the pins are reversed from one end to the other. Used for connecting two computers back-to-back without using an Ethernet hub.

Data Rate

Speed at which a communications path can transfer information, normally measured in bits per second (bps).

dB

Decibel. Ratio of one power level to another.

DHCP

Dynamic Host Configuration Protocol. IP protocol that allows a server to automatically assign IP addressing information to a computer or device on the network.

DNS

Domain Name Service. IP service that translates domain names (such as “www.kvh.com”) into IP addresses (such as “63.105.58.10”).

Downlink

Communication path from the satellite to the antenna.

DVB

Digital Video Broadcasting project. Global standard of digital broadcasts.

Es/No

Ratio of Energy-per-symbol to Noise power spectral density, indicating the general quality of a received signal.

EIRP

Effective Isotropic Radiated Power, measured in dBW.

EL

Elevation angle. Vertical direction in which the antenna points.

Encryption

As it applies to Wi-Fi, encoding of a wireless signal to protect it from unauthorized reception.

Ethernet

Network communications standard adopted by most LANs. Communicates via twisted pair cable at one of three maximum data rates: (1) Standard - 10 Mbps, (2) Fast - 100 Mbps, and (3) Gigabit - 1 Gbps (1,000 Mbps).

Firewall

Security mechanism that protects a network from unauthorized access.

Floating Ground

Dangerous condition in which the chassis ground of an electrical device differs from ship’s ground. This difference can measure well over 100 volts, risking damage to the equipment and electric shock, potentially resulting in death. A floating ground can be prevented by ensuring proper grounding of the device to ship’s ground.

Footprint

Coverage area of a satellite.

Forward Link

Communication path from the satellite hub to the user terminal. Another term for “Downlink.”

Frequency

Number of cycles per second of a radio wave, measured in Hertz (Hz).

GPRS

General Packet Radio Service. High-speed wireless data communications standard.

GPS

Global Positioning System. Network of satellites that allow anyone with a GPS device to accurately fix their position on Earth.

Gyro

A device that precisely senses and measures motion in a single axis, such as elevation or azimuth.

Host

Any computer connected to a network.

HTTP

HyperText Transfer Protocol. The primary protocol for the World Wide Web.

Hub

Earth station that links the satellite network to the terrestrial network.

ICM

Integrated CommBox Modem.

IF

Intermediate Frequency. As it applies to TracPhone V7-IP, L-band output of an LNB, or input to a BUC.

IMAP

Internet Message Access Protocol. Email protocol by which a client retrieves user-selected messages that are stored on a remote mail server. Messages are saved on the server until the user deletes them.

Internet

Global network connecting a vast number of networks and computers.

IP Address

Unique network identifier assigned to a single computer or device on a network. Consists of four eight-bit numbers, each between 0 and 255 (for example, “195.172.7.2”).

Kbps

Kilobits (1,000 bits) per second.

Ku-band

Range of frequencies from 10.7 GHz to 18 GHz.

LAN

Local Area Network. A relatively small group of computers and devices linked together within close proximity to each other and usually on the same IP network.

L-band

Range of frequencies from 950 MHz to 2150 MHz.

LNB

Low Noise Block down-converter. Device that converts and amplifies a Ku-band satellite signal into an intermediate frequency (IF) L-band signal.

MAC Address

Media Access Control Address. Unique six-byte hardware identifier assigned to every network interface card (NIC). Used in most LAN configurations to ensure the correct addressing of data to specific hosts.

Mbps

Megabits (1,000,000 bits) per second.

Modem

Modulator-demodulator. Translates digital signals into analog signals and vice-versa.

MTA

Multimedia Terminal Adapter. Device that converts analog telephone signals into digital Voice over IP (VoIP) signals.

Network

A group of computers and devices (such as printers) linked together.

Network Operations Center (NOC)

Station that maintains and manages a telecommunications network.

NIC

Network Interface Card. Expansion or built-in circuit card that provides a computer with network communication capabilities.

NMEA 0183 Talker

Marine electronic device, such as a gyrocompass, that transmits data messages that comply with the NMEA 0183 standard. Data is transmitted serially at 4800 baud over a pair of wires (A and B).

Packet

Part of a data message transmitted over a network. Also contains the address of the destination for routing purposes. (Data messages are divided into packets, sent over a network, then reassembled in the correct order at the destination.)

PCI

Peripheral Component Interconnect. Bus standard that supports high-speed connections between computers and peripheral devices.

PCMCIA

Personal Computer Memory Card International Association. Organization that establishes standards for PC cards, credit card-sized memory or input/output devices, primarily used in laptops.

Ping

Software utility used to check a network connection. Sends a test packet to the designated address and reports how long it takes to receive a response.

Polarization

Orientation of a satellite signal. Circular polarization, which has a “corkscrew” propagation path, consists of left-hand (LHCP) and right-hand (RHCP) signals. Linear polarization consists of vertical and horizontal signals offset by 90 degrees.

POP3

Post Office Protocol. Email protocol by which a client retrieves all available messages from a remote mail server and saves them locally. Messages are normally deleted from the server upon download.

Protocol

Standard that establishes strict rules for how data is communicated over a network.

Proxy

A server that controls client access to another server.

PSTN

Public Switched Telephone Network. Worldwide telephone network carrying analog voice signals.

Return Link

Communication path from the antenna to the satellite. Another term for “Uplink.”

RF

Radio Frequency.

RJ45

Registered Jack 45. Eight-wire network cable connector for LANs. Similar to a telephone jack.

Router

Device that connects multiple IP networks. For each data packet it receives that is destined for another IP network, determines the best path to reach its destination.

RSSI

Receive Signal Strength Indicator. Indicates the strength of the received satellite signal.

RX

Receive.

SIP

Session Initiation Protocol. Protocol for routing VoIP calls.

Skew

Adjustment angle to orient an LNB with a linearly polarized satellite signal.

Spread Spectrum

A type of communication method by which the information signal energy is spread over a frequency band much wider than the minimum bandwidth required for transmitting the information. The resulting low power level across the full bandwidth does not interfere with neighboring satellites, so the width of the transmitted beam is not as critical as it is with traditional VSAT antennas.

SSID

Service Set Identifier. Unique identifier shared by all computers and devices on a single wireless network.

Straight-through Cable

Cable in which the pins at one end match the pins at the other end.

Subnet

Subdivision of a network based on IP address. For example, with a subnet mask of “255.255.255.0,” all computers and devices assigned an IP address starting with “195.172.8” belong to one subnet (there are 255 possible). An IP address starting with “195.172.9” designates a different subnet.

Subnet Mask

Divides the latter portion of an IP address into subnet and host designations. For example, in a regular class B network, the first two numbers in an IP address define the network ID while the last two numbers define the host ID (the individual computer or device on that network). A subnet mask changes the format of these last two numbers by designating the third number as the subnet ID and designating the last number as the host ID (the computer or device within that subnet).

SW   

Software.

Switch

Device that connects two segments of a LAN. Routes data from one segment to another based on the MAC address of the destination.

TCP/IP

Transmission Control Protocol/Internet Protocol. Two communications protocols for the Internet. IP handles the delivery of data packets over the Internet; TCP ensures that all data packets are successfully delivered and assembled in the proper order.

Transponder

Component of a satellite that receives radio transmissions from Earth, amplifies them, and retransmits them back to Earth on a different frequency.

Twisted Pair

Cable type consisting of multiple pairs of cable in which two wires are spiraled together to reduce electromagnetic noise. Can be either shielded (STP) or unshielded (UTP). Used extensively in LANs and telephone networks.

TX

Transmit.

URL

Uniform Resource Locator. Address of a web page or file on the World Wide Web. Consists of three parts: (1) protocol (such as “http”), (2) IP address or domain name (such as “www.kvh.com”), and (3) name of the web page or file to be retrieved from that address (such as “index.html”).

USB

Universal Serial Bus. Bus standard for connecting peripheral devices to a computer. Supports a data rate of 12 Mbps.

UTP

Unshielded Twisted Pair. Cable consisting of four twisted pairs (8 wires), usually terminated by RJ45 connectors. Commonly used in LANs.

VoIP

Voice over Internet Protocol. Allows telephone conversations to be routed via the Internet.

VSAT

Very Small Aperture (< 3 m) Terminal. Communications system in which multiple users connect via satellite to a single land-based hub, which handles the routing of all network traffic.

WAN

Wide Area Network. A group of computers, devices, and possibly LANs, linked together over a large geographic area.

WAP

Wireless Access Point. Device that links computers wirelessly to a LAN. To communicate with the WAP, each computer needs a properly configured wireless network card.

WEP

Wired Equivalent Privacy. Security mechanism for wireless networks. Encrypts data to protect it from unauthorized interception.

Wi-Fi

Wireless Fidelity. Refers to an 802.11 wireless network.

WINS Resolution

Windows Internet Naming Service Resolution. Organizes the names of all Windows computers in a network with their respective IP addresses. Similar function to DNS.

Wireless Network Card

PCI or PCMCIA card that provides a computer with wireless access to a LAN via a WAP.

WPA2

Wi-Fi Protected Access. Security mechanism for wireless networks. Encrypts data to protect it from unauthorized interception. More secure than WEP.

XAZ

Cross-azimuth angle. Angle at which the antenna’s RF feed assembly rotates to maintain the proper skew angle while tracking the satellite.