About Satellite TV
Satellite TV Basics
A satellite is an object that orbits around another object in space. The satellites that concern us transmit television directly to the consumer. These satellites require a special orbit, so a little information about orbits is a good place to start in understanding satellite television basics.
The time it takes for a satellite to complete an orbit depends upon its distance from the object that it orbits. The moon is a natural satellite that is 238,328 miles from Earth. It takes 27.32 days for the moon to complete one orbit of the Earth. The space shuttle operates in a low Earth orbit. The shuttle orbits less than 200 miles to about 350 miles above the Earth. The average time for the space shuttle to complete an orbit around the Earth is about 90 minutes. The moon takes longer to complete an orbit of the Earth because it is much further from the Earth than is the space shuttle. The type of orbit that is required of the satellites that transmit television signals to the Earth lies between these two extremes.
In order for a satellite to be used for television transmission, it must "hang" over one spot above the Earth. The types of orbits described so far would require a receiving dish that is constantly moving, in order to keep up with the transmitting satellite. Satellite television satellites are in a geosynchronous orbit that exactly matches the speed that the Earth spins. When a satellite is in a geosynchronous orbit, the satellite appears to be stationary when viewed from the ground. In order to accomplish a geosynchronous orbit, a satellite must be directly over the equator and about 22,300 miles from the Earth. This area around the Earth is often called the Clarke Belt. Satellites maintain proper positioning in the Clarke Belt with onboard fuel. Ground stations constantly monitor these satellites and make any adjustments that are necessary.
The television signals transmitted by a satellite are quite different from the television or radio signals that are broadcast over the air. The particulars of a satellite TV signal are beyond the scope of this small article, but there are some basics that you should know. Satellite TV is transmitted by microwaves. Microwaves don't behave like the lower frequency radio waves of off-air television or radio, which can bounce off obstructions, clouds, and the ground. Microwaves are strictly line of sight. In order for a satellite dish to receive a signal, there can be no obstruction between the transmitting satellite and the receiving satellite dish. The very first thing that a prospective dish owner should do is perform a site survey in order to ensure that there are no obstructions blocking the satellite(s) of interest. Because microwaves are highly directional, the satellite dish and associated components must be properly aligned.
Satellite television in the USA is divided into two major types. The first major type is TVRO. TVRO satellite systems have a large dish which is movable. The movable dish enables a TVRO system to view programs on the many satellites that are positioned in the Clarke Belt. TVRO satellite systems are also called BUD, Big Dish, C-Band, and Full View satellite TV. Just remember that if the dish is large (usually 6 - 12 feet across) and it moves, it is a TVRO satellite system. To find out more about TVRO satellite systems go to TVRO Basics.
The second major type of satellite TV is DBS. DBS systems have a small dish (18 inches to 3 feet across) that does not move. In the US there are currently 3 types of DBS satellite systems. Each DBS system requires it's own special receiving equipment and has it's own programming line up. The 3 types of DBS systems are DSS, DISH Network, and Primestar. The receiving equipment for the DSS system is currently being manufactured by 11 companies and the DISH Network receiving hardware is being made by 2 companies. All Primestar equipment is made by Primestar only. To find out more about DBS satellite systems go to DBS basics.
The first satellite television systems for the consumer were TVRO (TeleVision Receive Only) satellite systems. TVRO started sprouting up all over the U.S. in the late 1970s and early 1980s. TVRO satellite systems are characterized by big dishes that are usually 6-12 feet across. TVRO systems receive television signals from C-Band satellites. A C-Band satellite has 24 channels (transponders) on each satellite. There are over 20 C-Band satellites that may be received in the continental United States. A TVRO satellite system must have a movable dish in order to access the signals from so many satellites. Even though most of the press and most of the advertising that you now see involves the small dish DBS systems, TVRO is still alive and well.
Other words are often used to describe a TVRO system. Some of these words are Big Dish TV, Full view, C Band Satellite TV, and BUD (Big Ugly Dish).
The biggest variety of programming in satellite television is available through TVRO. Cable TV programming is available to the TVRO owner, along with programming that is usually not available to cable TV subscribers. There are two types of TVRO satellite channels.
The first type of TVRO satellite channels are called scrambled or subscription services. In order to view these scrambled channels you will need two things. Number one is a piece of electronic hardware called a descrambler. In most modern satellite receivers the descrambler lives inside the receiver and is sold as part of the receiver. The descrambler has a metal plate over it and can be removed by simply sliding it out. Be sure that you unplug the receiver from the wall socket before you remove or replace the descrambler from its slot in the receiver. The second thing you will need to view scrambled channels is to buy a subscription to the channels of your choice. A subscription is just a phone call away. There are many companies that handle satellite TV subscriptions. Each company will have a variety of program packages designed for your viewing preferences. You can find out about the programming companies from one of the satellite TV magazines or from the advertisements that may appear when you go to a satellite channel that is blanked out because you don't have a subscription. When you call the programming company the picture will usually pop on the screen while you are talking. It's easy!
In addition to scrambled satellite TV channels, TVRO has a big variety of free channels available. The variety of channels includes news, educational, foreign language programming, music, old movies, and many other unusual programs. These free channels are called in the clear or unscrambled channels. Some of these free channels are regularly scheduled programs, such as Classic Arts Showcase, other free channels are known as feeds. Feeds can be scheduled or unscheduled programs. Feeds are used by networks or other programming providers to beam shows, events, or news to their affiliates. When these programs are beamed unscrambled, TVRO viewers can pick them up. For instance, if a game is being played in Atlanta Georgia and a TV station in L.A. is carrying that game, a TVRO system can pick the game up, provided the signal is not scrambled. There is a huge wealth of programs, available to the TVRO owner, that are broadcast unscrambled. News feeds are a favorite of mine. News feeds may be used by network or other program providers to beam reports out in the field to their central location. Some news feeds are used by their program providers live, others are fed to their central location where they are edited for a later program. Unedited news feeds can be very interesting.
If you enjoy radio you can tune in MANY radio stations from all over North America. The variety of music available for free with a TVRO system is truly amazing.
The TVRO owner can upgrade a regular C band TVRO system in order to add the capability of picking up Ku band signals. From Ku band satellites, the TVRO system can pick up additional free feeds and free programming. There are also scrambled signals on Ku band, but most of what the TVRO system can view on Ku band is free. People that are into sports and news feeds are some of Ku band's biggest fans.
Ku band satellite signals are at a higher frequency than C-band. Most modern satellite receivers have the ability to receive Ku band signals. The only upgrade that is required is in the modification of some of the outside electronics at the dish. The upgrade involves the feed and LNB, which are above the center of the dish, usually under a plastic cover.
DBS stands for Direct Broadcast Satellite. DBS is broadcast by medium and high powered satellites operating in the microwave Ku band. These high powered, high frequency satellites make it possible for the signals to be picked up on a small dish. Digital compression makes it possible to have many channels on a single satellite. The current DBS systems that are operating in the USA are DSS, DISH Network, and Primestar. The DSS and DISH Network systems both have 18 inch satellite dishes. Primestar has a 3 foot satellite dish. One of the big advantages of DBS systems is that the small dish does not have to move.
All current DBS systems in the U.S. have nothing but scrambled channels and require descrambling with their own special receivers. For example a DSS system can't pick up Primestar, DISH Network, or TVRO signals. A Primestar system can't pick up DSS, DISH Network, or TVRO signals. The consumer can only receive programs intended for their type of satellite TV system.