How does a TV tuner work?

How do Tv tuner cards work?

• I am looking to buy a tv tuner card, but i need to know first whether i will only get the channels I receive from my TV provider, will i have to pay any fees for service, and also will it work independently from my set top box (will it show the channel which is on the box or if 2 different channels can be viewed at the same time), if they do not work independently of each other. Thank you in advance.

• Answer:

  TV tuner cards either sample an analogue signal and covert it a compressed digital video stream like mpeg2 or sample and analogue signal and compare it against a code table of analogue waveforms and convert it into binary code and then to its respective decoder....either MPEG-1 or MPEG2 or MPEG4/AVC/H.264 thus outputting a digital stream. Basically, one analogue waveform is analogue video that needs to be sample and encoded into a digital stream (this is called analogue) The other is an analogue waveform that is directly representant of that digital stream and just needs to be converted using a known table to binary. (this is known as digital) The standards for some common digital signals are: DVB-T (terrestrial digital signals) DVB-S/S2/S2+Turbo (satellite digital signals) DVB-C (cable digital signals) Each operate at a different frequency range and different signal modulations. Sometime the binary code is encrypted, and no known header can be found. This requires a decryption of somesort. This is called a CAM. You can get DVB-C cards with CAM slots. These CAM slots take a small pcmia card that has the encryption standard on it and a smart card reader to authorize the viewing of your purchased channels. Cable has CableCard cams and smart cards, and the cable company is require to provide it by law. Directv has NDS VideoGuard or an illegal variant of NDS Videoguard (NDS is actually suing directv). DTV will probably NOT provide you with a cam and a smart card because we live in a capitalist country. Dish Network and Globecast use nagravision which require hardware from NagraStar and a smart card. DN and GC will not provide you with a cam/smart card because we live in a capitalist country. CAMs can be emulated to receive unauthorized programming, but it is illegal and cannot be discussed. If you lived in Germany or Brazil, you can easily obtain a cam and a smart card to receive authorized satellite programming on a compliant DVB-S/S2/S2+Turbo PCI Card.