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Satellite Glossary

AGC:

Automatic Gain Control. The signal strength of the received signal. ...more>

Antenna gain dBi:

The gain of a directional antenna is compared to an omni-directional (or isotropic) antenna....more>

AZ Azimuth:

The azimuth is the horizontal angle from true north in a clockwise direction , or bearing of the satellite from the antenna . ...more>

BUC:

Block Up Converter is the transmitter of the antenna system. It converts the IF frequencies up to RF frequencies and amplifies the signal for transmission by the antenna....more>

C-Band (4-8 GHz):

Satellite C-band usually transmits around 6 GHz and receives around 4 GHz. It uses large (2.4- 3.7 meter) antennas. These are the large white domes that you see on top of the cruise ships and commercial vessels....more>

CDMA- Code Division Multiple Access:

CDMA- Code Division Multiple Access works much the same as TDMA for sharing the circuit, except that instead of allocating timeslots for each burst of information, everyone just talks at the same time. Due to special coding, each listener listens only to his own data messages and ignores the rest. It is like several songs being sung in the same room at the same time, but we can still tune out the others and follow just one of the songs at a time....more>

CIR - Committed Information Rate:

(Pronounced C - I - R  like "Sea Eye Are")...more>

Circular Polarization (US/Canada/Caribbean):

Satellite TV in the Americas uses circular polarization. Instead of transmitting the signal in a vertical or horizontal plane, they somehow manage to send the signal out in a spiral pattern, separating the signals in a left hand spiral or a right hand spiral. This allows them to reuse the same frequencies on the both the Left Hand Circular Pol (LHCP) and the Right Hand Circular Pol (RHCP) on the same satellite, resulting in twice the number of channels....more>

dBW and dBm:

Decibels can also express absolute values by referencing one of the power values like a Watt or milliWatt. ...more>

Downlink:

Link from the satellite to the ground station...more>

EIRP or dBW on a satellite footprint map.:

The dBW EIRP lines that you see on a satellite coverage footprint map indicate the downlink signal strength that you can expect to receive at that spot on the map....more>

EIRP or E.I.R.P.:

Effective Isotropic Radiated Power which is the effective power radiated  from a directional antenna compared to a theoretical isotropical (omnidirectional) antenna. ...more>

ESV- Earth Station aboard Vessel:

A FCC term  used in regulations, describing VSAT terminals aboard vessels...more>

GEO - Geostationary Earth Orbit:

In order to order to overcome Earth's gravity, and remain stationary in the sky, synchronized with the rotation of the earth, geostationary satellites must maintain an orbit  of 22,300 miles (37,000Km) above the equator, spaced just 2 degrees apart, and  often even less. This results in the satellite orbiting the earth at exactly the same rate that the earth revolves, thus appearing to the observer to be stationary in the sky. ...more>

LNB Low Noise Block DownConverter:

The LNB is the radio receiver of a satellite antenna system. Depending on the type of feed, the LNB is installed either in front of, or behind the dish. It receives high frequency radio signals from the satellite and converts them to, more easily managed, intermediate frequencies....more>

M2M:

...more>

MegaBytes MB and Megabits Mb:

It is important to differentiate between Bytes and bits. There are 8 bits in a byte. ...more>

MIR - Maximum Information Rate:

(Pronounced M - I - R   like "Em Eye Are")...more>

Noise Temperature:

The small amount of noise produced by a C-Band LNA or LNB is called Noise Temperature even though for our practical purposes this has little to do with temperature. C- Band uses Noise temperature but Ku and Ka-band LNBs are usually rated by Noise Figure in dBs, rather than Noise temperature....more>

Parabolic dish:

The parabolic dish focuses the weak signals from the satellite to the center of the feed....more>

PCMA - Paired Carrier Multiple Access:

...more>

REL: Relative Azimuth :

Relative azimuth is the bearing of the satellte referenced from the bow of the vessel, in a clockwise direction. This is computed considering the ship's heading and the Azimuth. ...more>

Satellite Latency:

The time delay between data leaving the satellite and reaching the ground network and vice versa....more>

SCPC - Dedicated, One-on-one circuits:

Single Carrier Per Channel circuits provide a dedicated channel between ship and shore where the full bandwidth is always on and available to you alone, whether you are using it or not. ...more>

SCPC - Single Carrier Per Channel:

SCPC - Dedicated, One-on-one satellite circuits. ...more>

TDM -Time Division Multiplexing:

Not to be confused with TDMA, Time-division multiplexing  is a type of digital multiplexing in which two or more signals are transferred  simultaneously as sub-channels in one communication channel, but are physically taking turns on the channel. ...more>

TDMA - Time Division Multiple Access::

TDMA is the common form of securely sharing bandwidth, where each second or millisecond is sliced up into microseconds and shared between several users. This is timeshare in the sky except that you are not buying a week or two per year, but rather a few milliseconds every second. While you are downloading your Internet, or speaking on the phone, you don't even realize that there are several other users doing the same thing on the same satellite link. When there are fewer people using the link, there is more bandwidth available for you, and when there are more people, you will have a bit less. ...more>

VSAT - Very Small Aperture Terminal:

VSAT- ALWAYS ON - FIXED PRICE. Technically, all parabollic dish satellite terminals less than 3.8 m could be called Very Small Aperture Terminals, or VSATs, but the term VSAT generally refers to  transmit/receive (TX/RX) satellite terminals used for two way, data and voice traffic, like internet and telephone. A VSAT service is typically billed on a monthly contract, rather than by the minute, or by the megabyte like Inmarsat satcoms.  ...more>

VSAT - Very Small Aperture Terminal:

ALWAYS ON - FIXED PRICE. Technically, all parabollic dish satellite terminals less than 3.8 m could be called Very Small Aperture Terminals, or VSATs, but the term VSAT generally refers to  transmit/receive (TX/RX) satellite terminals used for two way, data and voice traffic, like internet and telephone. The term "small" compares to the huge 25 meter Standard A  teleport antennas....more>