Sattelite TV DescramblerWhat is a descrambler - Satellite TV basics
If you subscribe to a provider of sattelite TV such as Dish Network, Directv or Sky in the UK then you will have a small box near your TV that is connected to your sattelite dish and TV equipment. This set-top box as it's called, contains the circuitry required to receive sattelite TV from your dish and convert it from an incoming analogue or digital stream into audio and video signals suitable for plugging into your TV.
The set-top box also contains a descrambler. Satellite TV signals from the receiver are fed into the descrambler circuitry where it is unscrambled or decoded into audio and TV signals that we can understand.
Why do we need a satellite TV descrambler?
Not all incoming signals need a descrambler. Sattelite TV is often broadcast in Free To Air (FTA) format, which is not scrambled. Anyone with FTA equipment is able to receive and watch these signals without paying any subscription or pay-per-view costs.
You will need a descrambler when you want to watch premium channels or pay-per-view programmes broadcast by your provider. This is how the broadcasters make their money and stay in business.
Why are sattelite TV broadcasts scrambled?
Satellite TV is scrambled to prevent you from watching the programs that your provider wants you to pay for. They encode the signal and provide you with a key to decode it with. The key is used in conjunction with the descrambler in your set-top box to convert the unwatchable, scrambled signal into nice clear TV audio and video.
How does a descrambler-satellite TV work?
There are two types of television signal transmitted by TV satellites. There are the old, soon to be phased out, analogue services and the newer digital signals that are here to stay. Descrambling analogue TV signals is a lot easier than decoding digital TV signals which is I'm sure, one of the main reasons that the sattelite, cable and terrestrial TV providers are so keen to move to digital.
There is only so much you can do with an analogue TV signal to distort it in a way that it can't be watched and once you've worked out how they distort it it's a relatively simple matter to apply appropriate decoding circuitry to put it back how it started out.
Descrambling digital TV
Digital satellite TV is transmitted as a series of ones and noughts grouped into packets that contain the information necessary to reconstruct the original audio and video streams. Because it's digital you can process the signal with computers and when you have a computer, satellite TV providers can devise scrambling techniques that are extremely difficult to break.
When you pay your satellite TV provider to watch a channel or pay per view program, a programming signal is sent through the satellite up in space down to your set-top box receiver. The computer inside your box then reprograms your viewing card, which acts as a key to decode the signal that you've paid for.
To make things more difficult for anyone to watch the scrambled programs without paying, your viewing card can be tied to the receiver that it was plugged into at the time it was programmed. This prevents you from taking it and using it in another receiver. It also prevents the pirates from reverse engineering your card and duplicating it. They can do that but there wouldn't be any point.
Just to be on the safe side your satellite TV provider is able to reprogram your set-top box periodically to upgrade software and change the descrambler algorithms. So if someone where to work out how to duplicate a paid for subscription and duplicate it the chances are that it would work for a while then become useless as your provider changes their software.
Is it legal to have your own satellite TV descrambler?
Yes it is perfectly legal for you to own your own equipment but if you are going to use it to watch premium channels or pay-per-view then you must inform your sattelite TV provider. When you do that I guess that they will charge you for what you watch.
Can you get scrambled sattelite TV for free?
Yes, it is possible to hack your decoder in such a way that it bypasses your supplier and descrambles the sattelite TV signal for you but I would argue that it isn't worth your trouble. You could end up spending more money and time than if you had simply subscribed to the service and paid the fees legally.
Another informative article on how things work: Personal Video recorders - PVR and DVR