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Can Cable really offer HDTV?

Discussion in 'Technical Talk (Closed Forum)' started by KingLoop, Mar 12, 2005.

  1. KingLoop

    KingLoop Custom User Title DBSTalk Gold Club

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    I posted a similar comment elsewhere, either I posted it in the wrong place or no one cared to comment.

    Can cable really offer true HD? WOW offers an HD DVR with a buffer that holds 1 hour of HD content and it buffers about 2 hrs of non-HD content. I'm not sure how much room is on the hard drive, Comcast offers an HD DVR that buffers a little over 20 min of HD content and around 45 min of non-HD content. This model holds around 40 hrs on the hard drive for non-HD content and about 20 for HD.

    Now, I'm not a Tech and don't fully understand everything there is to know about HD and bandwidth and compression and everything in that whole field but I do know that with D* and E* the ratio of HD to SD information storage seems to be about 7/1 and with WOW and Comcast it seems to be 2/1. Logic would dictate that satellite HD contains MORE information than cable HD. Is this right? If it is wouldn't satellite be the only logical programming source for someone who made an investment in an HD tv? Unless I'm mistaken, (and if I am I would like to know) D* and E* would be my only real choice when I make the move to HD. Given that, I would hope that E* would hustle up on getting more HD channels and getting this whole M-PEG 4 thing done as well. I would appreciate any feedback from anyone more versed in HD than I.
     
  2. koji68

    koji68 Icon

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    Jun 21, 2004
    Video is transmitted digitally in the MPEG-2 format, the same video compression format as DVD’s. HDTV MPEG-2 however is generally broadcast at data bit rates of up to 19 Mbps (megabits per second) compared to the maximum of 9.8 Mbps of a DVD disk.

    A single satellite transponder can handle 30Mbps of usable data. Usually 2 HD channels are carried per transponder at 15Mbps per channel. Newer satellites have 32 transponders. So you could have up to 64 HD channels per satelite.

    When MPEG4 comes they will get 25 channels per transponder at 1.2Mbps. That is 800 channels per satellite.

    The North American cable plan allows for 5-42MHz for upstream communications and from 52MHz and above for downstream communications. With fiber in the backbone and copper to your house the downstream passband can go up to 750MHz, and they are planning to go up to 860MHz.

    From 52MHz to 500MHz the spectrum is dedicated exclusively to analog NTSC TV channels. Approximately 78 to 80 channels are in this space.

    The rest is used for digital content. With current technology and using 100MHz of passband you can get 1Gpbs for HDTV. This is because you can get an effective 10 bauds per second per Hz. If they use 15Mbps for each channel you can get 66 HD Channels.

    If they convert to all digital, they could get 8Gbps from the total RF passband. This would be 533 HD Channels at 15 Mbps with MPEG2 or 6667 channels at 1.2 Mbps with MPEG4.

    Probably enough. :)
     
  3. SimpleSimon

    SimpleSimon Hall Of Fame

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    Most of what you post sounds reasonable - except for the MPEG-4 1.2M for HDTV.

    I've seen other estimates of the improvement, and it's nowhere near that much.

    As for the 7/1 vs. 2/1 SD/HD ratio, might it be possible that cable isn't overcompressing the freak out of the SD content? :rolleyes:
     
  4. MarkA

    MarkA God Bless America! DBSTalk Gold Club

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    "When MPEG4 comes they will get 25 channels per transponder at 1.2Mbps."

    Lol, NOT a chance. There's the possibility of 25 terrible-looking (lower than S-VHS) channels per transponder with MPEG4

    To the OP's question - cable has far more bandwidth than satellite to play with, especially when they go all digital within the decade.
     
  5. larrystotler

    larrystotler Hall Of Fame DBSTalk Gold Club

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    Let's see......

    Cable runs on standard coax at between 5-860Mhz. This is all cable will ever have available. That's about 850Mhz.............

    DBS sats have 768Mhz available and FSS sats have 864Mhz available per sat. Now, we know that E* only have part of the 119 and 110, but this gives them, at 24Mhz per trans, 1200Mhz with just those 2 sats. The have all of the 105 and 121, as well as the 148/157. This gives them 1728Mhz on the 105/121 and 1536Mhz on the 148/157. This is not counting the 61.5, the 72.5 and all the other stas, including D* new Ka band sats, which we don't have the specs for yet. Now, granted that with the use of spotbeams, the full conus availability is lessened, but I don't see how cable can have more bandwidth than sat....
     
  6. RAD

    RAD Well-Known Member

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    Dripping...
    But then a 850Mhz cable plant doesn't need to provide LIL channel coverage into over >100 markets now do they? Looking at Lynsat, 110 and 119 have only 33 transponders for CONUS coverage, the others are spot beams, that's 792Mhz of bandwidth. 105 is all LIL and 121 has a few transponders that are LIL's. Now if E* had all those for national channels thet yep they would be able to kick cable's a** in bandwidth department. If the FCC and D*/E* would get their act together and share the job of providing LIL coverage look at all the additional bandwidth they'd have to work with.
     
  7. SimpleSimon

    SimpleSimon Hall Of Fame

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    What RAD said. :)

    There is an obstacle to sharing LiL or anything else right now, though. D* and E* using different encoding schemes. I doubt either would be willing to try upgrading their boxes to fit the other - if that's even possible.

    However, MPEG-4 just might solve that problem permanently. Lessee, there's 100+ "cable" channels right? Share just those and both sides get back 5 CONUS transponders each.
     
  8. KingLoop

    KingLoop Custom User Title DBSTalk Gold Club

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    Mar 3, 2005
    Ultimately, Do you think that a cable company can deliver the same HD picture quality as D* and E*?
     
  9. MarkA

    MarkA God Bless America! DBSTalk Gold Club

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    Absolutely - a cable company has far, far more resources (effective bandwidth) available. They need to dump the analog channels, which should happen within the decade (Motorola has a really cheap digital only low-low-low end digital box available now which makes this far more feasible)

    "Now, granted that with the use of spotbeams, the full conus availability is lessened, but I don't see how cable can have more bandwidth than sat"

    Not more physical bandwidth, that was a misstatement. More effective bandwidth at the end of the day. Satellite has to use QPSK or 8PSK encoding with a high level of FEC (forward error correction). Cable uses 64QAM and 256QAM with less FEC.
     
  10. larrystotler

    larrystotler Hall Of Fame DBSTalk Gold Club

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    The real question will be if these new Digital TVs with the ATCS tuner will work properly with the digital cable systems without having ot have a box. IF this is the case, the all the cust would need is a new TV with ATSC. However, cable is not know for their ability to make things simple.
     
  11. RAD

    RAD Well-Known Member

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    Dripping...
    Coworker at work has a new Panny plasma with the cable card and he get's all the cable channels, including the HD one's that he's subscribed to. It did take a couple of weeks to get the cable folks to get it working, he was the first one on their system to try it.
     
  12. MarkA

    MarkA God Bless America! DBSTalk Gold Club

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    A normal 8VSB ATSC tuner is useless for cable, but most also support clear QAM and cablecard QAM. I firmly expect to see the current analog channels as clear QAM within the decade - and very affordable clear QAM boxes available to users. No different from the early days of analog cable.
     
  13. larrystotler

    larrystotler Hall Of Fame DBSTalk Gold Club

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    We've had some serious issues with Adelphia getting the cable cards to work with the Big Screens we sell. I'm just amazed at how people are like " I bought THIS TV so I don't have to have a BOX!" I mean come one, what are they gonna do when the cablecard is replaced since it is about useless? Geez.
     
  14. stonecold

    stonecold Banned User

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    Feb 20, 2004
    Comcast of South West Floridas HD looks over compressed even compared to dish networks standards.
     

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