HOW DOES SATELLITE TV WORKS?
To understand satellite TV board casting properly we first have some basic knowledge about the parts of the satellite. How satellite moves.
The earth revolves around the sun in an electrical orbit. The earth also turn its own axis. The rotation of the earth is not perpendicular to the orbit surface but it is slightly inclined.
For satellite TV to work satellite should no more gravity of house. This means satellite should move the same speed of the earth. This means it takes 24 ms to take one cycle.
Let’s work out the force balancing equation of gravitational and centrifugal forces using the speed information.
We can see the orbital radius required to achieve non violate motion condition for satellite exactly 42164 KM. this orbit is known as the Geostationary orbit.
The satellite used for TV purpose should be packed in the geostationary orbit.
The power supply reqired for the satellite comes from the solar panel.
If the satellite is not facing the sun for battery pack helps to continue its operation. It is interesting to known satellites have small energies called THRUSTER.
The gravitational field experienced by satellite is not uniform due to irregularity of our surface and presence of the moon and sun. the thruster produce very minute amount of force to the orientation and position of the satellite cracked.
The most important part of the satellite for communication purpose is the transponder. The transponder receives the signals from the base at one frequency and amplifies the power of the signals and remove any noise and transmit back to the earth at different frequency.
The uplink frequency is always higher than the downlink frequency. For D2H the Ku band frequency is generally used.
The Ku band frequency has a good power which allows smaller size receives antenna. In past C band signals has a lower energy used for TV communications, that’s why huge antennas were used in older days. However Ku band signals are affected by rain. Scientist have come over this issue improvements in satellite technology.
Lets see some basic information how 100s of TV channels reached to our home by satellite TV technology.
Consider this case of TV channel
They have video production facility and keep on producing constant viewing 24*7 we called them program source.
This channel needs to available at same time at satellite TV broadcasting its networks. We called them DBS providers. To achieves this beam their signal to transponder in the geostationary orbit.
It should be noted before sending video signals the program source and advertisement is at suitable points and this is first source of the income for the channel. Now this signal commonly available at one point. Any DBS provider collects signals from many such channels from many program source. At the broadcast center they club all these contest together and do video formatting like MPEG compression, standardization of bit rate and encryption of the signal.
After that DBS provider beems the signal to the rented transponder in a satellite. DBS provider rents the many transponder to transmit huge amount of data. This way 300-400 channels on available on the single DBS provider satellite. Now the last phase in signal transmission is the transmission to the end user.
The end user has to angle the antenna towards the DBS provider satellite.
There are different DBS provider for different angle dishes even dishes are in same location this is because the different providers may be using different satellites for transmitting the signals.
Signals received by our dishes are encrypted to prevent privacy only dedicated card in setup box is able to decrypted back.
Do you know live events watching on your satellite TV are actually delayed by a few seconds. The signal leaving from the broadcast center trace a huge distance to satellites before reaches you. Even though signal frames at a speed of light huge distance cause a delay of 0.5 seconds. Moreover line broadcast may add specific profanity delay on the top of the normal delay.
Compare between internet video and satellite TV
Both of the TV and internet technology transit data in digital format as 0s and 1s.
Why there is no buffering on the TV and way in the you see in Facebook or you-tube videos.
Satellite TV broadcast offers as only 300-400 channels or video streams and the user has to select one channel from their collection. But in internet demands of the each user very different there are millions of videos to choose from. This means the volume of traffic handled TV broadcast is no were close to the level of internet traffic and there is a huge level of traffic in the internet. Which sometimes cause traffic conjunction.