is the ability to transmit and receive data from a relatively small satellite dish on Earth and communicate with an orbiting geostationary satellite 22,300 miles above Earth's Equator. In turn, the orbiting satellite transmits (and receives) its information to a single location called the Network Operations Center or NOC (pronounced "knock"). The NOC itself is connected to the Internet (or private network), so all communication made to the Internet must all flow through the NOC.
This is a simple diagram above shows how data moves through the a satellite network.
Data communication via satellite is not much different than someone using a land based data provider, at least from the end-users standpoint. The key to remember is that once the satellite system is configured by the installer, the service acts nearly identically as any other data service and may be configured as such. Those differences will be described later.
There is a location in space where you can place a satellite in orbit so that from the ground, the satellite appears stationary. What is happening is that the satellite is actually orbiting the Earth at the same speed the Earth is rotating. The satellite makes a complete orbit around the Earth in 24 hours, or exactly one day. Geostationary satellites are only located at 22,300 miles directly above the Earth's equator and nowhere else.
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All Geostationary satellites have a name like "Galaxy 18" or "AMC-4"... and they ALSO have a longitude position. If you recall from high school, longitude refers to those imaginary long lines that travel down the Earth for global mapping. There are 360 degrees of longitude readings for Earth (360 degrees is a full circle). If one knows the longitude of a satellite, one knows where the satellite is located in the sky because all Geostationary satellites are always located above the equator (or zero latitude).
To further confuse things, Longitude is divided into two halves with West Hemisphere and East Hemisphere. Orbiting "Slots" for satellites would be from 0° to 180° in the Eastern or Western hemisphere. A satellite orbiting over North and South America may have a Orbital slot of 101 West Longitude (for the Western Hemisphere). A satellite orbiting over Europe and Africa may have the orbital slot of 26° East Longitude. Satellite longitudes help installers locate where to point a satellite dish. It also helps in finding obstacles from an installation location and the satellite.
Make Sense?
Any obstacle, (such as a tree or mountain) will interfere with a satellite signal. It is important to find that there are no obstacles between that installation location and the orbiting satellite and this can be done with a simple little look angle calculator. All that is needed is a current address (anywhere in the world), and the orbital Longitude of the satellite (see above). Plug these two in, and the calculator will give you a compass heading of the satellite, and the degrees up from the horizon it is located. Here is a free look angle calculator from Ground Control.
It takes time for a satellite signal to be sent from your dish to the orbiting satellite back down to Earth, and back to your computer again. This is also called a "Ping Time". The speed of light is 186,000 miles per second and the orbiting satellite is 22,300 miles above earth. Calculated out, satellite latency is roughly ½ of a second, which is not a lot of time, but some applications like real-time gaming don’t like this time delay. It is important to know if Satellite Latency will affect the way you will use the Internet. Ground Control iDirect services have a latency time of approximately 500 milliseconds (0.5 of a second), which half as much as consumer grade service providers.
A MISCONCEPTION ABOUT SATELLITE LATENCY
A common misconception is that latency has an effect on transfer rate. This is not true. A one Megabyte file will transfer just as quick over a 1000Kbps satellite connection as it does over a 1000Kbps terrestrial connection. It just takes the satellite connection less than a second for the file to begin transferring.
CIR is a term often used in the satellite industry. It simply means what the satellite ISP is committed in guaranteeing your lowest speed. Normally CIR is 1:1, which means that you are not sharing your data channel with any other subscriber, and that max speeds are available 100% of the time. CIR should not be confused with Contention Ratios described next.
Contention Ratios are simply the number of subscribers that can share your connection at any given point in time. Contention ratios of consumer satellite Internet services are up to 400 to 1 (written as 400 : 1). Ground Control supports premium access and never has a contention ratio above 20 to 1 (or 20:1). Contention Rations are not CIRs (Committed Information Rates) as speeds are not guaranteed as it is impossible to know if all other subscribers sharing the channel are not simultaneous downloading a data intensive video file, which would slow a connection for all of the users.
The footprint of a satellite shows the location that a satellite dish may be located to communicate with the satellite. Below is the footprint for Galaxy 18 for North America. Also listed is the satellite longitude of each satellite, which can be used to find the look angle of the satellite for any location on the planet using the Satellite Look Angle Calculator.
- Effective Isotropic Radiated Power in the above footprint (Measured in dBW decibel watts), the numbers in red represent the signal strength from the satellite onto the Earth. The higher the dBW, the greater the signal strength. If you have a region with a low dBW level, you may have to use a larger satellite dish in order to receive the signal.
Besides the dish (also called the reflector) what makes up a satellite system is the BUC (pronounced "buck") which is simply the transmitter, and the LNB receiver. Both require a high performance coax cable connected to the indoor Satellite router. BUC's come in different wattages. The higher the wattage, the greater the satellite system can perform in both speed and in poor environmental conditions. Consumer systems normally use a 1 watt BUC. Ground Control uses a 4 watt BUC with most systems.
Satellite communications are radio transmission in the Ku Band of the electromagnetic spectrum. The Ku Band is the same band that police officers use for their radar detectors.
Ku Band satellite dishes transmit between a frequency of 14000 to 14500 MHz.
They receive a frequency range between 11700 to 12750 MHz. Other common Satellite bands are C-Band and KA-Band.
Most all of Ground Control services use the iDirect satellite router. This is the where the coax cables from the satellite dish connect to inside a building, and where a LAN (Local Area Network) can connect to the Internet. Note the Ethernet port on the back of the modem.
Click here for more information on iDirect services from Ground Control.
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