Understanding digital cable

From LinuxMCE
Revision as of 04:11, 21 January 2009 by Afkpuz (Talk | contribs) (What does it mean for LMCE users?)

Jump to: navigation, search


In the United States, a transition to digital cable is being made on February 17th, 2009. Many people have been giving confusing information about who will need converters and this also affects LMCE's tv recording. Here are the answers that LMCE users will need to know about the switch.


OTA: This is shorthand for "Over the Air". This refers to any tv channels which are broadcast for free. They are over the air in the sense that all you need is an antenna plugged into your tv to access them. There is no need for a subscription to a cable company in order to receive these stations. However, some cable companies provide these channels in their tv line up.

Broadcast Television: This is the another way to say OTA.

A Coax cable: This is the standard tv cable. When going from a wall jack to the tv, you use a coax cable. It's basically an insulated piece of copper wiring with an attachment on the ends to hold it in the plug.

Analog cable: This refers to the type of signal that comes through the coax cable. It is very similar to a radio signal in that multiple channels (or stations) can be carried through the wire on different frequencies. You don't need a wire for each tv station. This is why we use the term "tv tuner". A tuner is able to lock onto different frequencies carried through the coax cable. This is simplified definition. If you have any more details, please add them.

Digital cable: This also refers to the type of signal that comes through a coax cable. But with digital tv, 1s and 0s are sent through the coax cable. Thus, a different type of tuner is required to understand this stream of data.

NTSC: Another name for analog cable

ATSC: Another name for digital cable

Qam: Qam is a format for digital information. Just like there are multiple types of file formats for an audio file, (mp3, wma, ogg, flac, etc) there are formats for digital television. Qam seems to be becoming the standard format in the US. More information is needed here, so please help out.

Encrypted signal: If a piece of data is encrypted, that means that the information is sent in code which only a few people are allowed to know. Cable companies often encrypt their cable signal in order to prevent stealing. If the signal cannot be decrypted, the tv signal is not viewable.

Clear QAM: Clear QAM is basically a television signal in QAM format that is not encrypted. Virtually all of the OTA stations in the U.S.A use this format.

The switch to digital

So what exactly will be happening on February 17th? All OTA stations will be required by federal law to cease broadcasting analog and begin broadcasting digital. That means that the free stations which are tuned using rabbit ears will no longer carry an analog signal. They will carry digital. Thus, a digital tuner will be needed to understand this new stream of data.

However, cable companies are NOT required to change to digital. Hence, comcast customers will not be required to change anything once the February 17th change happens. Comcast will still continue to send analog cable to it's subscribers if they so choose. Here are some common situations and what the outcome will be after February 17th.

Cable subscription: NO, I use an antenna

Does your tv have a digital tuner?: NO

Result: In order to continue watching any television at all, you will need a digital converter. Your antenna will be plugged into the converter box, which will then feed into your tv set.

Cable subscription: Yes, from Comcast (or any other)

Analog or digital subscription?: Analog

Does your tv have a digital tuner?: NO or YES. Doesn't matter either way

Result: Nothing will need to change. Your cable provider will continue providing you with analog tv and your television will be able to understand it. Comcast has specifically said it will continue broadcasting analog.

Cable subscription: Yes, from Comast (or any other)

Analog or digital subscription?: Digital and/or High Def

Does your tv have a digital tuner?: Yes, of course

Result: Nothing will change for you either. You already are using digital, so the change doesn't affect you.

Cable subscription: Yes, from a satellite provider

Analog or digital subscription?: either

Result: Satellite TV will not be affected in anyway by the change to digital.

What does it mean for LMCE users?

First and foremost, it is essential that your tuner first be compatible with LMCE. Before asking the question "Will I be able to record my television?", you must first ask "Will my tuner work at all with LMCE?" For that, please check TV_Cards

Now, onto business. The abilities of your computer's tv tuner will be limited by the type of signal. If you have an analog cable subscription, LMCE will be able to tune every single channel which you enjoy on your normal television. You will need an NTSC capable tuner for your computer.

The problems arise when trying to record digital television. In general, most, if not all cable companies encrypt their digital tv signals. Since they undoubtedly keep their encryption techniques a secret, LMCE will be unable to decrypt those signals. The net result is that digital cable from a provider is unable to be tuned/recorded by LMCE, even when using a digital (ATSC) tuner. The only exception are the free, OTA channels. These channels are not encrypted, thus your ATSC computer tuner will be able to watch these streams. There are work arounds to recording digital subscriptions, but that will be added later as it is very cumbersome and unreliable.