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Discussion Starter · #1 ·
I've been following a CableCard / SetTobBox discussion in the plasma/lcd forum , and I'd like to make sure I understand what I'm reading. Can someone help me fill in the blanks, please.


Seems to me we have 4 signal attributes:

- Resolution: SD / HD

- Analog / Digital: A / D

- Delivery: OTA / Cbl / Satellite

- Scrambledness (sorry): S / U


Technically I think SD is digital only, but I mean any 480i signal. I'm also going to ignore Satellite, because I know nothing and it's not my interest.


Then we have 4 'gizmos' (sorry to get technical) to receive them:

- NTSC Tuner

- ATSC Tuner

- QAM Tuner (? or decoder?)

- Descrambler

The first three gizmos can live in a TV or a STB. The Descrambler lives in a STB or a Cable Card, and must be activated by your friendly cable co.


How am I doing so far? Please let me know what I'm missing.


Assuming there's no such thing as Scrambled Analogue or HD Analogue or Scrambled OTA, we get 8 possible signal types. For each of these I've guessed what gizmos are needed:
Code:
Code:
SD-A-OTA-U  -->  NTSC
SD-A-CBL-U  -->  NTSC
SD-D-OTA-U  -->  ATSC
SD-D-CBL-U  -->  ATSC & QAM
SD-D-CBL-S  -->  ATSC & QAM & Descrambler
HD-D-OTA-U  -->  ATSC
HD-D-CBL-U  -->  ATSC & QAM
HD-D-CBL-S  -->  ATSC & QAM & Descrambler
...or in words: All Analogue requires NTSC; Digital requires ATSC. Digital Cable requires QAM in addition. If it's scrambled, you'll also need a Descrambler.


Am I close? Can you help me understand this?


Thanks... Perry.
 

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Well, scrambled analog did exist, and may still exist in some cable systems that have not been updated, but they're on their way out.


OTA and cable HD are both ATSC, but they are different kinds of ATSC. QAM is part of ATSC, aurthorized for cable use. OTA uses 8VSB (or something like that). also part of ATSC. Digital SD cable as it currently exists may be ATSC, but I've never thought about it.


You referred to satellite delivery, then left it out. Assuming you mean D* and Dish, it's all digital and can all be scrambled (but not all is). SD tuners get SD, HD satellite tuners get SD and HD. It is not transmitted via ATSC, but the digital stream out of the STB is the same as the digital stream from a cable STB, other considerations aside.


Satellite delivery can provide Digital Dolby with sd picture, but I don't know if digital cable does that or can do that.


Cablecard does not support PPV, as a cable STB will.
 

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Quote:
Originally Posted by PerryU
I've been following a CableCard / SetTobBox discussion in the plasma/lcd forum , and I'd like to make sure I understand what I'm reading. Can someone help me fill in the blanks, please.


-
Perhaps this will help :) (from resmagonline.com):


"The thing to remember is that there are three types of tuners, excluding those required for satellite, which is a different subject altogether. “NTSC†tuners are used to receive the standard analog over-the-air and analog cable channels we’ve all been watching for the last fifty years. “ATSC†tuning allows a set to tune to those same frequencies, but when it “sees†a DTV or HDTV signal, it is able to receive, demodulate and decode it. This gets you the local, over-the-air HD signals, but not anything from a cable hook-up. The key there is to look for sets that have “QAM†tuners built-in. That lets the set deal with digital cable signals. Remember that a QAM tuner alone, without a CableCard, will only allow reception of “in the clear†digital cable channels, and there aren’t many of those. To receive the “pay†channels or “tiered†premium channels you will need to still resort to the use of an external cable STB unless the set has a CableCard slot. "


Here's the link (caution: its a long article): :)

http://resmagonline.com/articles/pub...icle_435.shtml
 

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Quote:
Originally Posted by vstone
I don't think the phase 1 cablecards support PPV.
You are proabably correct, I quote from an old (July'04) article that clarifies the terms... :)
 

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Quote:
Originally Posted by vstone
I don't think the phase 1 cablecards support PPV.
By "pay" channels I think the article meant HBO/Showtime/Cinemax, etc., not PPV.

At least that is how I saw it...



BTW Perry, I think SD stands for "Standard Definition", and does not usually refer to a digital signal, but rather an analog one.
 

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NTSC = National Television System Committee. Existing US analog TV. 480i (Joke: Never Twice the Same Color)
http://www.ntsc-tv.com/


ATSC = Advanced Television Systems Committee, developers of the US digital TV system.
http://www.atsc.org/


DTV = Digital TV. Including all 18 of the ATSC digital TV formats, including the commonly used SDTV, EDTV, HDTV.


SDTV = Standard Digital TV, 480i


EDTV = Enhanced Digital TV, 480p


HDTV = High Definition TV, 720p & 1080i


QAM = Quadrature amplitude modulation. Modulation system use by cable to get DTV into consumers homes.
http://en.wikipedia.org/wiki/Quadrat...ude_modulation


8VSB = 8-level vestigial sideband modulation. Over-the-air modulation system used for DTV reception.
http://en.wikipedia.org/wiki/8VSB
http://www.broadcast.net/~sbe1/8vsb/8vsb.htm

Quote:
...or in words: All Analogue requires NTSC; Digital requires ATSC. Digital Cable requires QAM in addition.
Pretty much.


To receive DTV over-the-air (OTA), you need a DTV tuner & antenna. A select few also have a QAM tuner.


To receive cable DTV, you need one of the following:

A cable set-top-box (STB), for any/all cable DTV. None have a DTV tuner.

A QAM tuner, for unscrambled cable channels. All have a DTV tuner.

A CableCARD tuner, which incorporates QAM with conditional access for all authorised cable DTV & digital cable channels. No PPV is possible at this time. All have a DTV tuner.


To receive satellite (DBS) DTV, you need a HD DBS tuner specific to the DBS provider you want to subscribe to, either Dish Network or DirecTV. All have a DTV tuner.


Some HDTV's have a DTV tuner built in. Some HDTV's have a DTV & QAM tuner built in. Some HDTV's have a CableCARD tuner built in. None of the current HDTV's have a DBS tuner built in. Outboard STB's of many varieties are available.


Whew.
 

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Discussion Starter · #8 ·
Wow... phenomenal response. Thanks very much, folks; exactly the info I was seeking.


Ken, one question. You said:
Quote:
To receive cable DTV, you need one of the following:

A cable set-top-box (STB), for any/all cable DTV. None have a DTV tuner.

A QAM tuner, for unscrambled cable channels. All have a DTV tuner.

A CableCARD tuner, which incorporates QAM with conditional access for all authorised cable DTV & digital cable channels. No PPV is possible at this time. All have a DTV tuner.
I currently have an SD digital cable STB, that lets me tune any of my subscribed digital channels, as well as any unscrambled digital and analogue channels. Also supports PPV and VOD. That sounds to me like "A cable set-top-box (STB)" but with a DTV/QAM tuner. Is this right? (The box is a Moto DCT2500.)


Thanks again... Perry.
 

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Quote:
Originally Posted by PerryU
I currently have an SD digital cable STB, that lets me tune any of my subscribed digital channels, as well as any unscrambled digital and analogue channels. Also supports PPV and VOD. That sounds to me like "A cable set-top-box (STB)" but with a DTV/QAM tuner. Is this right? (The box is a Moto DCT2500.)
Close, but no cigar. The 2500 is a standard digital cable STB, and will receive analog cable, and standard digital cable via QAM, but no DTV. Remember, none of the cable STB's will do over-the-air DTV.


I should have more specific with my reply, regarding the cable STB's, in that for cable DTV, you need a cable HD STB, which does analog cable, standard digital cable, and cable DTV. No NTSC or OTA DTV.
 

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Discussion Starter · #10 ·
Uh... so what you're referring to as "standard digital cable" is not one of the 18 ATSC DTV standards, like SDTV? Obviously I know it won't receive HDTV, but it sounds like you're saying there are 2 kinds of 480i digital cable: "standard digital cable" and SDTV, which requires a DTV tuner, which presumably receives all the ATSC standards, including HDTV.


Is that closer? Sorry if I'm being dense.
 

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Quote:
Originally Posted by PerryU
Uh... so what you're referring to as "standard digital cable" is not one of the 18 ATSC DTV standards, like SDTV?
Correct, standard digital cable is not ATSC.




Quote:
Obviously I know it won't receive HDTV, but it sounds like you're saying there are 2 kinds of 480i digital cable: "standard digital cable" and SDTV....
Correct.




Quote:
....which requires a DTV tuner, which presumably receives all the ATSC standards, including HDTV.
Almost. In reference to cable STB's, a HD cable STB will receive any SDTV/EDTV/HDTV that a local DTV station broadcasts and the cableco carries. But the cable HD STB is not a DTV STB, in the sense that it gets the DTV via QAM, and not over-the-air DTV.
 

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Quote:
Originally Posted by Ken H
A CableCARD tuner, which incorporates QAM with conditional access for all authorised cable DTV & digital cable channels. No PPV is possible at this time.
You can't actually order PPV from the CableCard device.


However, my local cable system (and apparantly most cable systems) support ordering PPV via phone or web for viewing on your CableCard device.
 

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Quote:
Originally Posted by Ken H
NTSC = Joke: Never Twice the Same Color
Ken,


Good one.


Seriously though, one thing a layman like me finds hard to understand is why the studios/cable companies seem to be stingy in providing more better quality content.


It would appear that it would be easier to upgrade the transmissions at the source (MPEG2?) and transmit more as ATSC (8VSB/QAM) rather than have the end user struggle and try to improve life with expensive electronic equipment.


Is this due to bandwidth or some other monstrous technical barrier?


p.s. I second PerryU that yours was a phenomenal posting.
 

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Qam is not HD. It is a form of compression i.e 64qam,256qam also note there is BPSK and QPSK with the last being used for cable modem's along with 64qam.


Bob
 

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Quote:
Originally Posted by ybsane
Qam is not HD. It is a form of compression i.e 64qam,256qam also note there is BPSK and QPSK with the last being used for cable modem's along with 64qam.


Bob
QAM is not HD, but HD over cable is sent via QAM,


Since QAM is part of the ATSC spec (or so I've read), QAM is part of ATSC. Since the ATSC spec includes some SD formats, SD digital transmissions over cable may very well comply with the ATSC spec.


Since digital TV is really not well defined, I would say that digital cable SD could be classified as digital TV whether or not it is actually ATSC, but that's omly opinion.
 

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"Since QAM is part of the ATSC spec (or so I've read), QAM is part of ATSC. Since the ATSC spec includes some SD formats, SD digital transmissions over cable may very well comply with the ATSC spec"


Your confused? ATSC is a format of SD and HDTV; QAM is a compression of signal sent over analog channel i.e. NTSC 6mhz channel carrier.


We send Music Choice over an analog 6mhz NTSC signal via a 256QAM compression and it has nothing to do with ATSC or HDTV, same goes for the downstream and upstream of a DOCSIS cable modem.


Bob
 

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Quote:
Originally Posted by vstone
Since QAM is part of the ATSC spec (or so I've read), QAM is part of ATSC. Since the ATSC spec includes some SD formats, SD digital transmissions over cable may very well comply with the ATSC spec.
ATSC originally called for 16VSB for cable DTV, and although I haven't read the entire standards paper, I don't believe QAM is part of ATSC. To be clear, digital cable is not the same as Digital Television, as defined by ATSC.


What QAM is, is the delivery method for DTV on cable.



Quote:
Since digital TV is really not well defined...
Actually, digital TV is very well defined. A better way to think about it, is to say it's not well implemented at this point in time.


Remember that we've grown used to seeing relatively flawless analog TV, developed over decades. DTV only went on the air in 1998, so it's still a work in progress.
 

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Quote:
Originally Posted by dt_dc
You can't actually order PPV from the CableCard device.


However, my local cable system (and apparantly most cable systems) support ordering PPV via phone or web for viewing on your CableCard device.
As always, thanks for the correction.
 

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Quote:
Originally Posted by Geo05
Seriously though, one thing a layman like me finds hard to understand is why the studios/cable companies seem to be stingy in providing more better quality content.


It would appear that it would be easier to upgrade the transmissions at the source (MPEG2?) and transmit more as ATSC (8VSB/QAM) rather than have the end user struggle and try to improve life with expensive electronic equipment.


Is this due to bandwidth or some other monstrous technical barrier?
The barrier is money.


For HDTV, a completely unique, and much more expensive signal path must exist, from initial image and sound acquisition to the end user location. HD providers have to shoulder the entire cost (unless they find a sponsor) because HDTV produces no revenue. The analog broadcast pays all the bills. One of the more recent developments that helps to offset the cost of HDTV, is that broadcasters have started unified SD/HD production. They spend the additional funds to do HD, and downconvert for the SD production.
 

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Quote:
Originally Posted by Ken H
The barrier is money.


For HDTV, a completely unique, and much more expensive signal path must exist, from initial image and sound acquisition to the end user location. HD providers have to shoulder the entire cost (unless they find a sponsor) because HDTV produces no revenue. The analog broadcast pays all the bills. One of the more recent developments that helps to offset the cost of HDTV, is that broadcasters have started unified SD/HD production. They spend the additional funds to do HD, and downconvert for the SD production.
KenH,


Is this one of the big reasons why the cable co's fear AT&T and other phone companies from getting into the cable business because they have monster manpower, revenue(they can absorb the cost), and a new distribution system in the works currently(fiber optics)?


It would seem that cable's biggest fear is not satellite(although current commercials from cable co's. display just the opposite POV. That may be the case NOW, but not in the futre) co's, but from the telephone co's for above mentioned reasons.
 
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