How satellite TV works Satellite TV channels are broadcast wirelessly from a base station to television satellites orbiting the Earth on a geosynchronous orbit, meaning that they all stay in specific places in the sky relative to the Earth. The collection of artificial satellites on such orbit is otherwise known as Clarke Belt. The satellites retransmit the channel signals back to Earth, where a customer captures such satellite signals with a satellite system made of at least a satellite antenna, otherwise known as satellite dish, an LNB (Low Noise Block Converter) that hangs off of the arm of the dish, and a satellite receiver to decode and process the signal and send it to a TV.
Satellite signals are nothing more than special radio waves that carry many channels’ digital or analog programming. These waves are reflected off of the parabolic or oval surface of the metallic dish and converge into the LNB, which captures the concentrated signals and sends them to the receiver through a coaxial cable. The satellite receiver converts such signals of different frequencies into viewable TV channels on the TV.
The satellite dish may be either parabolic or oval in form. The major difference between these two different forms is the amount of satellite signals they receive. The parabolic dishes are capable of converging signals to the LNB from only one point in the sky. Thus, they are normally used for receiving satellite TV channels from only one satellite at a time. Oval dishes are capable of converging satellite signals to more than one LNB from multiple points in the sky, and thus can be used to receive satellite TV channels from multiple satellites, depending on how close to one another these satellites are in the geosynchronous orbit.
The satellite receiver is a set-top-box (STB) device similar to the cable box, except that it performs different functions. Its primary function is to receive the signal from the LNB, and transform it into a signal for the TV to display the channels. The satellite signal is basically digital content encoded and compressed by the base station using the MPEG2 standard. This standard allows the base station to send a lot more information (channels) to the satellite and eventually to the customer’s dish antenna than if the signal was not compressed into an MPEG2 stream. The satellite receiver decompresses and decodes the MPEG2 digital content and sends it to the TV to be displayed in NTCS, PAL, or any other TV standard.
The MPEG2 stream that the satellite receiver decodes could have both unscrambled and scrambled channels. The unscrambled channels are viewable for free and are called FTA channels, or Free-To-Air channels. The scrambled channels constitute the subscription channels. In order to view a subscription channel, you’ll need a receiver that accepts a smart card distributed by the channel provider when you subscribe. There are a number of different encryption technologies that the providers use, such as Irdeto, Nagravision, Nagravision 2, Viaccess, Conax, Cryptoworks, Mediaguard, etc. The smart card as well as the receiver would need to be compatible with the technology that is used to encrypt the channel that you’re interested in, in order to view that channel.
Since there are two types of satellite channels that you can view (FTA and subscription channels), then there are also two classes of DVB-S (Digital Video Broadcasting for Satellite) receivers, namely free-to-air receivers and DVB-S receivers that accept smart cards for subscription channels. FTA receivers are useful only for FTA channels; therefore, if you’re interested in viewing any subscription satellite channels, you should not buy an FTA receiver. Instead, you should buy satellite receivers that accept smart cards provided by the channel provider in order to descramble the satellite signal. These receivers are further classified into Common Interface (CI) receivers and Embedded CA (Conditional Access) receivers.
CI receivers have a slot that accepts a Conditional Access Module (CAM), which is basically a PCMCIA module that reads the smart card. The common interface on such receivers is a standard interface, which means that the receiver could be used with different types of CAMs that read different types of smart cards, such as Nagravision, Irdeto, Viaccess, Conax, Cryptoworks, Mediaguard, etc. So, if you were interested in subscribing to a channel that is encrypted with Irdeto technology, then you’d buy an Irdeto CAM that you’d insert into the common interface of the CI receiver. Thus, an Irdeto smart card could be read by the Irdeto CAM and used to unscramble the channel. If later you decide to pay for a Nagravision scrambled channel, you don’t have to buy a separate receiver. Instead, you’d buy a Nagravision CAM and insert it in the same CI slot of the same receiver. Some receivers have more than one CI slot to support different subscription technologies at the same time.
Embedded CA satellite receivers are basically the same as CI satellite receivers except that they may or may not have a CI to plug any CAM into it for reading smart cards. Instead, they have an embedded CAM that is used to read the smart card. Since the CAM is embedded, you could only use such receivers for reading smart cards of a particular scrambling technology. For example, if the channel that you’re interested in subscribing is scrambled using Irdeto technology, then you might want to buy an Embedded Irdeto CA satellite receiver to read Irdeto smart cards. However, you need to understand that if such satellite receiver does not have an additional CI (Common Interface) for any additional CAMs, then you can only watch subscription satellite channels scrambled with Irdeto technology, in addition to the FTA satellite channels.
There are hundreds of FTA (free-to-air) satellite channels being broadcast by many different satellites over North America, and a satellite system made up of an appropriate dish, FTA receiver and an optional motor to point the dish to different satellites would allow you to view them for free. The optional motor is controlled with the same remote control that you use for the FTA receiver. Just make sure that the FTA receiver supports DiSEqC (Digital Satellite Equipment Control) standards. Many more scrambled satellite channels for which you may subscribe individually could be viewed by having the right Embedded CA satellite receiver or the right CI satellite receiver and CAM to plug into it for reading the smart card.
Dish Network and DirectTV are nothing more than providers of DVB-S (Digital Video Broadcast for Satellite) programming that own a number of satellites and provide full service to their customers, including installation and equipment. However, you’ll have to pay monthly for the channels that they provide, with limited choices of which channels you want to pay for and which channels you just don’t want to spend a penny on. Alternatively, you may want to purchase the satellite equipment and install it on your own, or ask a local installer to do it for you. This will allow you to enjoy both FTA channels and any subscription channels that you feel are worth paying for.