macamana satelit tv ASTRO berfungsi yA????

chiKenliTeL

How Satellite TV Works  
by Karim Nice and Tom Harris

When satellite television first hit the market, home dishes were expensive metal units that took up a huge chunk of yard space. In these early years, only the most die-hard TV fans would go through all the hassle and expense of putting in their own dish. Satellite TV was a lot more difficult than broadcast and cable TV.

Today, you see compact satellite dishes perched on rooftops all over the United States. Drive through rural areas beyond the reach of the cable companies and you'll find dishes on just about every house. The major satellite television companies are bringing in more customers every day with the lure of movies, sporting events and news from around the world.

In this article, we'll find out what satellite television is all about, from TV station to TV set.

The Broadcast TV Problem


Photo courtesy DirecTV

Conceptually, satellite television is a lot like broadcast television. It's a wireless system for delivering television programming directly to a viewer's house. Both broadcast television and satellite stations transmit programming via a radio signal (see How Radio Works for information about radio broadcasting).

Broadcast stations use a powerful antenna to transmit radio waves to the surrounding area. Viewers can pick up the signal with a much smaller antenna. The main limitation of broadcast television is range. The radio signals used to broadcast television shoot out from the broadcast antenna in a straight line. In order to receive these signals, you have to be in the direct "line of sight" of the antenna. Small obstacles like trees or small buildings aren't a problem; but a big obstacle, such as the Earth, will reflect these radio waves.

If the Earth were perfectly flat, you could pick up broadcast television thousands of miles from the source. But because the planet is curved, it eventually breaks the signal's line of site. The other problem with broadcast television is that the signal is often distorted even in the viewing area. To get a perfectly clear signal like you find on cable, you have to be pretty close to the broadcast antenna without too many obstacles in the way.

The Satellite TV Solution
Satellite television solves the problems of range and distortion by transmitting broadcast signals from satellites orbiting the Earth. Since satellites are high in the sky, there are a lot more customers in the line of site. Satellite television systems transmit and receive radio signals using specialized antennas called satellite dishes.



Satellites are higher in the sky than TV antennas, so they have a much larger "line of sight" range.


The television satellites are all in geosynchronous orbit, meaning that they stay in one place in the sky relative to the Earth. Each satellite is launched into space at about 7,000 mph (11,000 kph), reaching approximately 22,200 miles (35,700 km) above the Earth. At this speed and altitude, the satellite will revolve around the planet once every 24 hours -- the same period of time it takes the Earth to make one full rotation. In other words, the satellite keeps pace with our moving planet exactly. This way, you only have to direct the dish at the satellite once, and from then on it picks up the signal without adjustment, at least when everything works right. (See How Satellites Work for more information on satellite orbits.)

At the core, this is all there is to satellite television. But as we'll see in the next section, there are several important steps between the original programming source and your television.

sedondon

Mcm mana Astro berfungsi?
Mula2 kena register dulu, pastu dia akan kasi decoder dan piring, dan sudah sedia utk berfungsi...............

padlie

tak boleh lagi sebab hujan lebat dan kilat dan guruh masih sabung-menyabung...

padlie

Originally posted by chiKenliTeL at 25-2-2007 11:12 PM
Each satellite is launched into space at about 7,000 mph (11,000 kph),reaching approximately 22,200 miles (35,700 km) above the Earth.

Baru perasan la... Apasal slow sangat? sepatutnya laju lagi...

chiKenliTeL

well...
speed means money
cutting edge technology means money bro

do you have that money ?~!~~

padlie

escape velocity for earth is 11.2 km/s (40320 km/h). nothing can go to space if it can't go faster than this.
satellites in low earth orbit (LEO) orbiting earth at about 7 km/s (25200 km/h). in GEO, it is few time faster than LEO.

that's why I said it is slow

geForceFX

Aiseh... Satelit MEASAT tu lembik tul ke?? Hujan jer dah takda Signal kat ASTRO aku.!! kalo time time tengah nengok filem hebat hampeh la..

padlie

Satelit tu tak lembik.. Mana-mana satelit komunikasi yang guna Ku-Band memang akan alami masalah bila cuaca tak elok... Ku-Band boleh guna antena kecik (sebesar antena astro sekarang).

Nak elok, kena guna C-Band.. Tapi antena kena besar..

Measat cover dua band ni