Satellite TV Reception 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 383,551 Kilometres 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 322 Km to about 563 Km 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 35888 Km 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 Australia is divided into two major types. The first major type is TVRO (Television Receive Only ). TVRO satellite systems have a large dish which is normally movable. This 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 C-Band. Just remember that if the dish is large (usually 2 to 4 metres across) and it can be moving, it is a TVRO satellite system.
The second major type of satellite TV is DBS. DBS systems have a small dish (60 Cm to 90 Cm across generally) that does not move. In the Australia there are Four main users of DBS satellite systems, these are all pay TV operators ( Foxtel, Austar, Select TV & Aurora out back services) while there are more smaller services as well some encrypted . Each DBS system requires it's own special receiving equipment and has it's own programming line up.
TVRO ( Television Receive Only )
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 2 to 4 metres across. TVRO systems receive television signals from C-Band satellites. A C-Band satellite has 24 channels (transponders) on each satellite. There are more than six C-Band satellites that may be received on the Australian mainland. 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 such as C Band Satellite TV.
There is a variety of programming on satellite television that is available through TVRO.
The first type of TVRO satellite channels are called scrambled or subscription services. In order to view these scrambled channels you will need a decoder and a smartcard and buy a subscription to the channels of your choice. A subscription maybe 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 channels available by looking at the available programming on LYNGSAT web site. When you have the right equipment and call the programming company to subscribe 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, 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 at times beamed unscrambled, TVRO viewers can pick them up. For instance, if a game is being played in Perth and a TV station in Sydney 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 TVRO owners, which are sometimes broadcast unscrambled. News feeds are a favourite. 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.
The TVRO owner can not usually upgrade a regular C band TVRO system in order to add the capability of picking up Ku band signals. The Ku band signal is much higher in frequency and the mesh dish is not ideal for this signal. There are also scrambled signals on Ku band, Ku band satellite signals are at a higher frequency than C-band, typically 12 GHz apposed to 4 GHz on C band. Most modern satellite receivers have the ability to receive Ku band signals. The only upgrade that is required if this would be possible is in the modification of some of the outside electronics at the dish. The upgrade involves the feed and LNB, which are above the centre 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 Australia are Foxtel, Austar, Select TV and Aurora. Commonly they all use a 60Cm offset satellite dish in the most powerful reception areas this can increase to one metre in some parts of the continent. One of the big advantages of DBS systems is that the small dish does not have to move.
All current DBS systems in Australia have mainly scrambled channels and require descrambling with their own special receivers and smart card. The consumer can only receive programs intended for their subscribed of satellite TV system.
Satellite Dish Installation Guide for a Offset KU Band Dish
Satellite Dish InstallationSatellite TV is one of the growing forms of entertainment whether you are travelling on the road in your caravan or are a home user. The choice we have is constantly growing.
The choice includes free to air programs such as Optus Aurora, which has ABC and SBS available to everyone along with a selection of regional commercial stations which are available to travellers, outback homesteads and locations which cannot receive TV by a regular antenna, known as black spots. Along with the free to air channels we have a choice of pay services such as Foxtel, Austar and the latest entrant in the market being Selectv.
This guide will explain the steps involved in installing & aligning your satellite dish for TV reception.