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Discussion Starter · #1 ·
What is the maximum number of HD channels that can be broadcast over cable? My cable system (Comcast of Nashville) recently added 5 HD channels (2 HBO, 1 Showtime, ABC local, CBS local). I have heard they plan to add add other local channels when they begin HD broadcasts. They are using the Motorola DCT-5100 STB. Is the limiting factor this box or the bandwidth of the cable?
 

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The limiting factor..seems to me..is the number of HD channels (stations) your local cable company can receive and get a 'deal' with. At least, this will be the limiting factor the next several years.
 

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Quote:
Originally posted by Greg_Smith
What is the maximum number of HD channels that can be broadcast over cable?
As many as the bandwidth of the particular cable system will allow.




Quote:
Is the limiting factor this box or the bandwidth of the cable?
Neither. It's a matter of how they decide to use the bandwidth they have.


There are hundreds of standard digital channels a cableco could carry and each cableco has different system bandwidth capacity. Thus, there is no correct answer to your question beyond saying that there is enough bandwidth to carry all the existing HDTV channels available, even on the most bandwidth limited cableco, assuming they reduce the number of standard channels they carry.
 

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My Time Warner system has about 860+ MHz bandwidth. But about 600 MHz of this is occupied by about 100 of the older analog channels. These same channels, for those with digital converters, are duplicated in ~60 MHz using MPEG-2 digital compression. So if cable systems can cover the huge expense of switching their subscribers from analog (or no) converters to digital there's a huge slice of spectrum available for HDTV. Two to four HD sources fit each 6 MHz cable slot occupied by a single analog channel; about 10 digital (non-HD) sources fit within the same bandwidth. Eliminating standard cable amplifiers restricted to about 1-GHz bandwidth from cable systems and substituting fiber optics would provide virtually unlimited bandwidth. Also, using video-on-demand (VOD) technology, letting you 'call up' programs from head-end hard-disk servers, can be substituted for cablecasting all programming simultaneously to all subscribers. If VOD becomes excessive in some areas, bandwidth can be boosted in only those areas by subdividing the fiber links. (Much as cell phone subscriber spectrum can be boosted by subdividing geographic cells.) -- John
 

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Discussion Starter · #5 ·
Ken,


I guess I should rephrase my question. On the typical existing cable systems (ie. Comcast Nashville), with the typical existing analog channels (~100), what is the range of number of HD channels they can broadcast? There must to be real world examples for this limitation.
 

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While there is a technical limit to the number of HD broadcasts, it depends on what else the cable company is using it's bandwith for.


Right now, the limiting factor is available HD programming and not really bandwidth.


Are any local Nashville stations broadcasting HD over the air that are not available on cable? This is the first source of HD programming.


HBO and Showtime each have HD versions of their primary channel.


DirectTV has an exclusive contract for HDNet, so this channel is not available to cable operators.


Finally, Discovery TV has a single HD channel, for which they charge a hefty monthly fee, usually passed on to the end user at about $5 per month. While they are adding new programming, their existing hours of HD shows is rather limited, and there is much repitition. I think that Discovery HD is available on Dish Network (satellite), and one or two cable systems.


In the next six months, the amount of HD programming available to cable systems will increase dramatically. There will be three HD channels available from Mark Cuban (HDNet). ESPN will begin HD broadcasts. Comcast Sportsnet will begin HD broadcasts of basketball, hockey, and baseball games in the Philadelphia/Baltimore/Washington markets. I think that Cinemax is also going to introduce a HD channel.


It remains to be seen how many of these new channels will be added to your system, and what, if any, the cable companies will charge.


Joe
 

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Greg,

Let's assume that your Comcast system is similar to John Mason's TWC system, and that there are 125 "digital" channels (numbers >100) using 75 MHz, plus local phone service & high speed internet service using 25 MHz. This would leave about 100 MHz free bandwidth, or about 17 6 MHz slots. If 256QAM permits 2-4 HD channels per 6 MHz slot, then such a system could handle between 34 & 68 HD channels. If your system is like my local AT&T/Comcast setup, with no analog channels in the 76-94 range, there might be over 200 MHz free bandwidth, and thus double this HD channel estimate. This is just a wild guess in an effort to provide some hard numbers that you wanted. As the analog channels are eliminated or reduced in the transition to digital TV, the HD capacity will be much greater. So cable companies are in pretty decent shape for HDTV. The DBS industry isn't so fortunate. With the failed merger, I would be surprised if DirecTV is able to expand their present 3 HD channels much beyond 10, and that's assuming they can get 2 on each transponder, which hasn't worked very well for them so far.
 

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Don't forget that in many areas, the cable also carries high speed internet service. It's actually a small bandwidth user, approx 12 MHz for up/downstream channels, but that's the equivalent of several 1080i feeds.


Gerald C
 

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Thanks, Gerald. I will make some adjustments.
 

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Cable, especially in markets where the network is new (like Nashville) is in great shape to become the prime way to get HD. OTA reception is a pain in the butt and satelite companies have to deploy *massively* expensive satelites to get more bandwidth.


I'm pretty confident that as the rest of the local channels get their act together Comcast Nashville is going to carry them.
 

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TWC in So. Calif offers 7 HD channels (CBS, ABC, NBC, FOX, PBS, HBO, and SHOW). They say that their limitation is a business arrangement, not technical to get more HD channels. I'm sure there is a limit as to how much bandwidth digital cable can offer simultaneously, but the the real issues becomes the economics.


For now, there is a limitation on who offers content that is ready to broadcasting in HD. We have a couple more local stations broadcasting in HD after 8pm (namely WB and UPN, plus another local channel). But they don't have an arrangement with the cable company to broadcast in SD and in HD. In the future, I think its a matter of business. What is the right allocation for a cable company to offer content in SD or HD, since HD takes up a lot more bandwidth. TWC is also currently pushing a lot more VOD. Right now, they boast the "most" HD channels at 7 and this is more than Dish and DirecTV, but less than what is available OTA. I think they have a lot more bandwidth to offer more HD and VOD, but they are going to see how many more subscribers they can get first with the current lineup before spending too much more for HD content.


BTW - I already started asking them for more HD for WB and UPN. I think everyone should ask for more HD content.
 

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I'll revise my estimate downward on DirecTV's HDTV capacity, because they have just placed SD channels 450-457 on Tp 12 of Sat C. This leaves only Tp 10 of Sat C available for HD, which may be only one channel unless they can resolve the problems they had when they tried HBOH & HDNet on a single transponder. We D* HDTV subscribers are probably less than 1% of their total, so they probably won't miss us very much when we are forced to defect to cable. I'm beginning to wish AT&T/Comcast had won the new 5-year NFL Sunday Ticket contract.
 

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TWC in So. Calif. has printed a full page ad in the L.A. Times many times comparing their service to Dish Network. They are obviously concerned.


In one of the many items in the ad, they compare their 7 channels of HD to Dish's 4. Their ad is incorrect. It they want to consider their local channels then they they need to consider that dish has the local CBS channel on their satellite bringing Dish's total HD channels to 5 (Disc, PPV, HBO, Sho, KCBS). It you consider the Dish channels plus the OTA available then a Dish subscriber has 9 available HD channels, as I do (The previous plus NBC, WB. ABC, PBS).


Rick R
 
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