Understanding broadband basics: Satellite internet technology
If you’ve looked at the FCC National Broadband Map recently, you’ve probably seen that your address has access to satellite internet availability, labeled as either “GSO” for geostationary orbit or “NGSO” for nongeostationary orbit.
But what is geostationary and nongeostationary orbit satellite internet, and what are the differences?
What is satellite internet?
Satellite internet is a type of wireless data transmission. A dish mounted high on a building sends a signal to satellites orbiting the Earth, the satellites broadcast the signal to base stations on the ground, and then the process is reversed to transmit data signals back to the user. Without a clear line of sight between the building-mounted dish and the satellites, the signal will be blocked, so the dish needs to be placed where it will be free from obstructions like buildings and foliage. Unfortunately, inclement weather can also block the signal.
There are a few primary types of satellite internet technology for residential service, categorized by the type of orbit: low Earth orbit, geosynchronous orbit, and geostationary orbit.
Low Earth orbit
Low Earth orbit (LEO) internet involves satellites in nongeostationary orbit. Examples of LEO satellite internet providers include OneWeb and SpaceX’s Starlink.
As the name implies, satellites in LEO are positioned close to the planet’s surface (112 to 1,242 miles), which means the signal has less distance to travel, resulting in lower latency — the time it takes to send data and receive a response (e.g., the delay between clicking on a link and the link beginning to load).
However, LEO satellites orbit the Earth in 90 to 120 minutes, so the connection has to jump from one satellite to the next as the satellites move across the sky and disappear from view, and a constellation of satellites is needed to provide continuous coverage. Users might notice lag when the receiving dish transitions between satellites.
Upload speeds for LEO satellite internet are slower than download speeds, which can negatively affect activities that benefit from faster speeds, like gaming and video conferencing. For instance, participating in a video call over a slow connection might mean that even if you do not notice a problem, other callers may complain that your audio and video are choppy and garbled.
LEO satellites can also be distinguished from other types based on their observable movement across the sky.
Geosynchronous and geostationary orbit
Geostationary orbit is a type of geosynchronous orbit. Geosynchronous satellites orbit the Earth at the same rate as the Earth’s rotation. Because the satellites also orbit the planet in the same direction that the Earth rotates, they are synchronized.
Satellites in geostationary orbit are positioned directly above the equator and appear unmoving, or “stationary,” in the sky to an observer on the ground. While all geostationary satellites are geosynchronous, not all geosynchronous satellites are geostationary.
These satellites are positioned at a higher altitude (22,236 miles) than LEO satellites, so the signal has a longer distance to travel, resulting in higher latency and slower speeds. However, the receiving dish does not need to track the satellite across the sky or transition the connection from one satellite to another, eliminating the associated lag time that LEO satellite customers experience when their receiver transitions to a new satellite.
Internet service providers can achieve stable coverage for a large geographic area via three satellites (to compensate for the curvature of the Earth), rather than a constellation. Geostationary satellites can cover locations within a 70-degree span of latitude above or below the equator, but not farther north or south.
Examples include HughesNet and ViaSat, labeled as GSO on the National Broadband Map.
Applications of satellite internet
Satellite internet is unlikely to ever replace traditional wireline internet technology like fiber optic because fiber provides faster, more consistent symmetrical speeds that can scale up as demand increases.
However, satellites can fill the gaps where wireline internet isn’t available, such as in remote locations, on airplanes, or at sea. This type of internet technology can also be used as a redundant link in case wireline broadband stops working or is damaged, such as during a natural disaster.
Future applications include collaborations between terrestrial wireless providers and satellite internet companies to offer text messaging, email, and, potentially, voice services in areas with no existing mobile cellular service.
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What questions do you have about satellite internet? What other broadband basics would you like to read about?
