Satellite Basics – Glossary Terms

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Have you ever wondered what your satellite technician was saying? Were they using really technical jargon that you didn’t understand? Use this glossary about Satellite Basics Terms to understand what they were saying. And don’t worry we have attached a PDF so that you can download this and use it wherever you are.

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Satellite Basics – Term Glossary


Advanced Encryption Standard is an encryption standard comprised of three blocks of ciphers AES‐128, AES‐192, and AES‐256


Adaptive Coding and Modulation uses an algorithm to dynamically change the coding and modulation scheme based on atmospheric conditions and network configurations


Amplitude and Phase Shift Key is a modulation scheme that changes the amplitude and phase of the carrier wave

Analog transmission

Transmission of information using a continuous signal that varies based on amplitude, phase, or other proportion


Equipment that typically transmits and receives electromagnetic waves, usually referred to as the satellite dish


A measure of the percentage of time that a link is operational. A desirable availability is often referred to as “five 9s” or up 99.999% of the time.


Block Up Converter. Used for uplink satellite transmission that converts a band from a lower frequency to a higher frequency


A range of frequencies within a spectrum, expressed in Hertz. Can also be the data transfer rate or throughput expressed in bits per second


Border Gateway Protocol is a core routing protocol of the Internet

Bit Rate

Speed of transmission measured in bits per second (bps)


Binary Phase Key Shifting is a modulation scheme that uses two phases separated 180 degrees


Sending a single transmission to multiple sites that are capable of receiving the signal


Code Division Multiple Access is a radio communication technology that uses channel access method


Frequency band with uplink 5.925‐6.425 GHz, downlink 3.7‐4.2 GHz. The C band is primarily used for voice and data communications as well as backhauling

Cellular Backhaul

Transmission of cellular voice and data signals, typically from a base station to a remote site

Carrier to Noise Ratio (C/N)

The ratio of the received carrier power and the noise power in a given bandwidth, expressed in dB. This figure is directly related to G/T and S/N. Typically in a signal, the higher the C/N, the better the quality

 Circular Polarization

Refers to a method of transmitting signals from a satellite. On some satellites, both right‐hand rotating and left‐hand rotating signals can be transmitted simultaneously on the same frequency; thereby doubling the capacity of the satellite to carry communications channels


Footprint or the area on the earth’s surface that is covered by a satellite’s transmission beam dBW. The ratio of the power to one Watt expressed in decibels. Typically, the E.I.R.P of satellite beams are measured in dBW


Decibel – A logarithmic measure of a transmission signal’s power such that every 3rd ordinal number increase in measure represents a two-fold increase in strength. i.e. A dB level of 23 is twice that of a dB level of 20. A dB level of 203 is twice that of a dB level of 200.


Decibel Watts, the ratio of the power output to one Watt expressed in decibels. Typically, the E.I.R.P. of satellite beams are measured in dBW.


Deterministic Time Division Multiple Access – iDirect’s patented access technology that provides simultaneous access to shared upstream channels using dynamically assigned time slots


The time it takes for a signal to go from the sending station through the satellite to the receiving station. This transmission delay for a single hop satellite connection is very close to 240 ms

Double Hop

Transmission of information from one terminal to another terminal in two stages, first from a remote site VSAT up to the satellite to the network hub or from the network hub up to the satellite then to another remote site


Transmission of a signal from the satellite to the earth. In a network it is typically referred to the link between a network hub over the satellite to a remote site


Digital Video Broadcasting – Satellite – Second Generation is the enhanced version of the DVB‐S satellite broadband transmission standard and has forward error correction and modulation specifications

Earth station

Ground equipment that transmits and receives electromagnetic waves, also referred to as an antenna


Effective Isotropic Radiated Power. This term describes the strength of the satellite signal in dBW and is a result of the transponder output power and the gain of the satellite transmit antenna


World Region including Europe, Middle East and Africa


iDirect’s next‐generation product line of routers, line cards, and iDX software, all built on the DVB‐S2 standard with Adaptive Coding and Modulation (ACM)


Frequency Division Multiple Access. It is a channel access method that allocates each application or user a different frequency bands


Forward Error Correction. It is the system for error control that has the sender include redundant data so, errors can be detected and corrected at the receiver

FIPS 1402

Federal Information Processing Standard Publication 140‐2 is a U.S. government computer security standard that accredits cryptography modules


The area on the earth’s surface that is covered by a satellite’s transmission beam


A measure of amplification expressed in dB


Geostationary Earth Orbit satellites orbit at 35,786 km (22,282 mi) above the equator in the same direction and speed as the earth rotates on its axis, making them appear as fixed in the sky


Global System for Mobile communications is a standard for digital wireless communications to mobile phones


Group Quality of Service is iDirect’s bandwidth allocation and prioritization algorithm that allows for countless possibilities of quality of service levels, bandwidth management and traffic prioritization


A figure of merit of an antenna and low noise amplifier combination expressed in dB. “G” is the gain of the system and “T” is the noise temperature. The higher the G/T, the better the system

Guard Band

Transmission carriers are separated on a transponder by spacing them several kilohertz apart. This unused space serves to prevent the adjacent transmission carriers from interfering with each other


Host Network Operator is a network operator who leases out hub space to smaller service providers


Hyper Text Transfer Protocol is an application level protocol used to request and transfer objects across the web


Satellite network equipment that controls the satellite bandwidth allocation, often located at a teleport. It usually consists of a chassis and other equipment connected to terrestrial networks


Indoor Unit is network equipment typically located inside a building that consists of a modem and router (or hub if it inside a teleport) connected to the corporate LAN or terrestrial infrastructure


Internet Protocol is a protocol used for data communication across a packet switched network. Typically used with TCP, a higher-level protocol


International Organization for Standardization is a standard setting body composed of multiple national standards organizations


Internet Service Provider is a company that offers Internet access to customers


International Telecommunication Union is a United Nations organization helping governments and private organizations coordinate global telecommunications usage


Transmission of a signal to the satellite. In a network it is typically referred to as the transmission from the remote router to a satellite to a hub


Same as inbound, some people just say inroute instead.


iDirect’s product line of routers and line cards, built on iDirect’s proprietary implementation of the TDM protocol

Ka Band

Frequency band with uplink 26.5‐40GHz; downlink 18‐20 GHZ, this band is primarily used for two‐way consumer broadband


Kilobits per second. Refers to transmission speed of 1,024 bits per second

Ku Band

Frequency band with uplink 14 GHz; downlink 10.9‐12.75 GHz, with more powerful transmission from the satellite more susceptible to rain fade than C‐Band


Local Area Network is a computer network that covers a small physical area

Low Noise Amplifier (LNA)

This is the preamplifier between the antenna and the earth station receiver. For maximum effectiveness, it must be located as near the antenna as possible, and is usually attached directly to the antenna receive port

Low Noise Block Downconverter (LNB)

A combination Low Noise Amplifier and downconverter built into one device attached to the feed. It is used for the downlink satellite transmission by converting a band from a higher frequency to a lower frequency


Frequency band from 1 to 2 GHz, this band is the result of the down‐conversion of the received downlink satellite signal from the LNB


Low Density Parity Check is a forward error correction code that is currently the most efficient scheme, used with DVB‐S2


Low Earth Orbit satellites orbit from 160‐2000km above the earth and take approximately 1.5 hrs for a full orbit and only cover a portion of the earth’s surface


MEO satellites are located above LEO and below GEO satellites and typically travel in an elliptical orbit over the North and South Pole or in an equatorial orbit

Mesh network

Topology whereby a remote VSAT location communicates with another remote location without routing through the hub


Multiple‐Frequency Time Division Multiple‐Access is a broadband access method where different data streams are put into different slots that are separated by both frequency and time


A piece of network equipment containing a modulator and demodulator for receiving or transmitting satellite signals.


The encoding of a carrier wave by amplitude or frequency or phase


A device which modulates a carrier


Multicast is a subset of broadcast whereby the signal can be sent to many sites within a defined group, but not necessarily to all sites in that group


Sending multiple signals or streams of information on a carrier simultaneously transmitting on a single signal


Network Operations Center is a centralized location where control over operation of a network is managed and monitored


Network Management System is the hardware and software that monitors and controls a satellite network


An Outdoor Unit is the equipment located outside of a building close to the satellite dish or antenna and typically includes, a low noise block converter (LNB), and a block‐up‐converter (BUC)


Transmission of a signal from the satellite to an antenna. In a network it is typically referred to as the transmission from the hub to a satellite to a remote router


A Private Branch Exchange is a telephone exchange that connects a private enterprise or organization to the public switched telephone network


The Paired Carrier Multiple Access (PCMA) Hub Canceller is a satellite signal canceller that maximizes the capacity of satellite networks by using ViaSat’s patented PCMA technology to reduce satellite bandwidth as much as 50 percent


A technique used by satellite operators to reuse the satellite transponder frequencies when transmitting these signals to Earth. Two methods are possible: linear and circular. To successfully receive and decode these signals on earth, the antenna must be outfitted with a properly polarized linear or circular feedhorn to select the signals as desired


Phase Shift Key is a digital modulation scheme that changes the phase of the carrier wave


Public Switched Telephone Network is an international network for public circuit‐switched voice telephony


Quality of Service provides priority and guarantees a certain level of network response time and other performance factors for each application and user


Quadrature Phase Key Shifting is a modulation scheme that uses four phases

Rain Fade

Decrease of satellite signal strength due to rainfall. This occurs typically at Ku Band frequencies due to its increased sensitivity to noise temperature


Radio Frequency is the electromagnetic frequencies for wireless transmission that is above the audio range and below infrared light


Routing Information Protocol is a dynamic routing protocol used in local area and wide area networks


A device connected to the modem and the antenna on one side and the computers and other LAN devices on the other side. It forwards IP packets based on network layer information and enables applications such as VoIP, Video and data


Real Time Traffic Management is an iDirect feature set that is designed to enable high‐quality transmission of voice applications that are less tolerant to delay or jitter that can occur on satellite links


Communications satellites orbit the earth and transmit and receive radio signals from earth stations


Supervisory Control and Data Acquisition is the system that monitors and controls industrial or facility based remote devices

SingleChannelPerCarrier (SCPC)

A satellite access method that dedicates one channel to each remote site, sometime used for very high capacity links. See also TDMA

Signal to Noise Ratio (S/N)

The ratio of the signal power and noise power. The higher the number the better the quality

Single hop

Transmission of information from one remote site to another antenna. Typically, it describes the path between two remote stations in a mesh network. Single hop occurs when transmission is passed from one remote directly to another mote without having to go to the hub (double hop)


Satellite news gathering typically done from a transportable unit (truck or mobile entity) to transmit video and voice feeds back to the studios

Spot Beam

A spot beam is a satellite signal that covers a concentrated geographic area so only antennas in that area will receive the signal

Spread Spectrum

Eliminates adjacent satellite interference by spreading the signal over the available bandwidth to enable extremely small antennas or phased array antennas in mobile operations

Star network

Topology whereby a remote VSAT location communicates with another remote location by routing through the hub


Transmission Control Protocol is a core Internet protocol that is a higher-level protocol often combined with IP.


Time Division Multiple Access is channel access method that allows applications or users to share the same frequency by dividing the full bandwidth into specific timeslots


Receives outbound signal at the satellite and amplifies the signal before retransmitting it to an earth station


Transmission Security secures VSAT transmissions with encryption to prevent from interception and exploitation


Transmission of a signal from the remote router to a satellite to a hub


Virtual LAN is a group of hosts that simulates a LAN although they are not located locally on the same network switch


Virtual Network Operators lease hub space from HNOs while keeping complete control of their network and their remotes. iDirect offers this capability by assigning each VNO operator its own line cards and NMS servers and protocol processors. The VNO commissions, controls and operates its remote sites in the proprietary network as if it owns a physical hub


Very Small Aperture Terminal is an antenna that is typically less than 3 meters in diameter


Wide Area Network is a computer network that covers a broad area that connects multiple remote locations.


Wideband Global Satcom is a satellite communication system used by the U.S. Department of Defense


Frequency band with uplink 7.9‐ 8.4 GHz, downlink 7.25 – 7.75 GHz, this band is primarily used for military communications and Wideband Global Satcom (WGS) systems



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