HDTV Forum

Wasn't sure where to put this, but after reading part of the service manual for a Mits DLP, there were pages on Cable Cards. What I found interesting was this description of OOB data and how it relates to channel mapping;

If the set receives an encrypted TS it will ask the CableCARD to unscramble the stream.
The card will only unscramble the TS if it receives the proper authorizations to do so. Those authorizations
are received via Out-of-Band data (OOB). The OOB contains information about authorizations, channel maps and more.

My question are:
1. Is this OOB data on each digital channel or is it on a separate 'Out of Band' channel,
2. If it is on a separate 'channel', is it located below ch. 2, between ch. 7 and ch 22, or in the FM band?
3. If it is one of those, what would a band stop trap do?
4. Would it prevent reception of the unencripted channels altogether?

The reason for the question is this; Many sets have issues with channel mapping where more than one (in the clear) cable channel shows up on the same number. Example 1.1 or channel '0'.
Worse yet, there are many sets (if not all to one extent or another) that have trouble receiving one or more of those same channel numbered stations (ever though they re actually non-encripted) apparently because the tuner gets confused by the poorly written data and/or designed CATV system.

So, by 'blocking' this data solve this problem and remove that silly fictious channel mapping data as to let the sets tuner display the actual channel number ending the confusion?

The OOB data is basically the cable companies internet service line. This is how cable boxes and the head end talk to each other. You must have this for a cable card to work.

If you don't have a cable card then it won't matter what you do with the OOB because the channel number comes from the station you are tuning to and the data the cable company put there for that channel, not the OOB.

Most if not all of these problems are from your cable company, not the display manufacturer. It's such a huge problem that many manufacturers dropped the cable card feature from their line preferring you get a cable box instead.

Clear QAM tuning and your results are only as good as your cable company...

This is how cable boxes and the head end talk to each other. You must have this for a cable card to work.

I understand this, but that isn't a issue. This is only for unencripted (in the clear) channels, no CC provided STB and no CC.

Most if not all of these problems are from your cable company, not the display manufacturer.

I also understand this, but since they won't do anything about it (probably on purpose), I'm looking for a solution on my end. Don't leave out the manufactures. If they would provide the ability of turning off channel mapping in the first place, there would be no need for this discussion.

In your experiance, where have you found this OOB?

Maybe I am missing something... are you using a cable card?

No CC or company supplied STB.

K...

We are back to square one.

As I understand it... For Clear QAM, no cable card, the channel ID is embedded into the actual signal you receive and has little relevance to it's actual location in the frequency spectrum which is also why it can be a royal pain to figure out where these channels are. This is mapped at the head end and has NOTHING to do with the OOB used for cable cards and cable boxes.



Cable companies are sloppy with standards and this caused problems way back when. Recall TV's and VCR's with 3 different cable reception settings? HRC, IRC and standard? The FCC regs on frequency tolerances are very loose on cable compared to broadcast. Eventually manufacturers overcame all this by designing tuners that no longer looked at the correct frequencies but were able to tune to ANY frequency along the way from one channel to another.

Ultimately you are on the cutting and bleeding edge for clear QAM and like way back then, it is what it is and eventually it will all get worked out by one party or the other. Like the old days, you can grit your teeth and get a cable box or grit your teeth and live with how it is.