Motorised dish installation
There are lots of satellites broadcasting over Europe with lots of TV and radio channels, some channels are free and some scrambled. It is possible to use a fixed dish to receive one satellite, a multi feed dish to receive several satellites or a motorised satellite dish to receive multiple satellites.
Satellites are based in the Clarke belt, so named after Arthur C Clarke who predicted the use of communications satellites in the fixed orbit 24000 miles or so above the equator. Satellites in this belt are termed as geo-stationary due to the fact that they appear fixed in relation to the earth. Satellites are kept in position by on board rocket boosters. Satellites have a limited life because of the low amount of fuel on board. However they are regularly replaced by updated powerful satellites.
The satellites broadcast a beam to earth rather like a torch beam with a powerful signal at the centre getting weaker at the edges. These beams are also known as footprints and all satellite owners publish maps that predict the EIRP or radiated power that determines the size of dish required to receive a signal. Satellites also have multiple beams meaning that some signals are stronger or weaker from the same satellite. Sometime the edge of a beam can have strong signal areas as the fade rate from a beam will vary causing confusion over dish size required in certain areas.
A dish has a view of the satellite belt that is over the equator known as the satellite arc (see image). In the UK the available arc is around 60 degrees East and West of South at an elevation of around 30 degrees at south getting lower at the edges. Most satellites broadcast high in the arc to avoid problems with line of sight. The dish is set up to track the arc so that satellites can be received. The majority of European style receivers have the Disecq protocol that allows control of a disecq dish motor down the same cable as the LNB. Some motors also have the USALS (Universal satellite automatic location system) Protocol that means satellites positions are preset into the memory of the motor for easier installation.
Fitting a motorised dish will depend largely on location and available line of sight to satellites. Using a compass and inclinometer to determine line of sight is one way to check. Many installers use the Satpointer app on iphone to check for line of sight or online see http://www.satpointer.com
One of the most important factors is to ensure that the pole that the dish and motor is installed on is 100% level in all aspects or the motor will never track the arc correctly.
Dishes can be mounted on the wall or ground depending on dish size and line of sight etc. It is best to get your local installer to carry out a survey and give their recommendations.
Once installed receivers will automatically move the dish to the correct satellite after a channel is selected.
Older dish systems used a separate 36v power lead to power motors that used reed switches and optical sensors to memorise dish positions.
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