How many HD channels can cable support?

[i4tas]

I have noticed that DirecTV is saying they will have more bandwith than cable companies (HD lite or not).

It seems that DishNet has a lot of room, offereing the HD locals.
Cable operates on channels 2-130 or something. Does that mean the best they could do is 128 HD channels in the near future.

Not taking into consideration multicasting hd channels.

Also you would think cable companies would rather get away from the set to box and use the built in one. And then this brings up another question whats going to happen to analog and will cable want to part ways in 2009 or must they.

I really don't know anything about cable and what there plans are for hd, and when exactly there will be 200 or so hd channels.

 

[rad]

This question is almost impossible to answer since each cable system is different as to how much bandwidth their physical plant can handle. Then after that you can get into what modulation they are using, QAM64 or QAM256, have they moved all their analog channels to digital, using MPEG2 or MPEG4, are they using broadband or switched video. The last ROT I knew was that using QAM256 and MPEG2 was 3 HD channels in each 6Mhz channel if that helps.

 

[LonghornXP]

I will try and answer some of these questions but as Rad said it greatly depends on the local cable system plants. First most cable plants are 750Mhz systems that can use QAM256 and the plants that are older than this will soon start to be upgraded to 1Ghz systems over the next couple of years. Now I'm going to tell you different ways they can create bandwidth but that doesn't mean cable companies will deploy these ways.

Switched Digital Video technology. This is a way for a cable company to take any number of channels and only send them down the cable when a customer tunes them in. This is very good for channels that aren't watched by the masses like a local ABC station for example. Today all the channels are sent down the pipe at a specific frequency and of course that pipe only has so much room. So SDV in simple terms can reuse a small amount of that pipe over and over for different lesser watch channels as they are viewed.

Another option is for cable companies to deploy a device called the TerraPix which is a product made by BroadLogic. Each cable company would buy this chip and enclose it into a gateway device. This device would need to be installed on the outside of every customers home that still has a TV connected via analog means (ie jack directly from the wall into the TV). Again not all customers need this just the customers that still want analog. This device is also quite cheap considering the bandwidth savings.

This TerraPix device would allow the cable company to go 100% digital (no analog channels at all) at the plant thus freeing up around 350Mhz of their 650Mhz plant. This would allow hundreds of HD channels worth of bandwidth. This device via the gateway would decode all the old analog channels (now in digital of course) and convert them using the chip into an analog signal and output them into the home. This will allow everything to work exactly the same as before within the home. The benefit of this would be that the picture quality of those analogs would also be much much better and even better the snow issue would be gone too.

I know for a fact that Comcast is testing both SDV and this TerraPix device.

Now many cable companies such as Comcast, Time Warner Cable and Bright House Networks have been upgrading their plants to support OCAP and DCAS. The simple plan for this in the future is to allow a fairly cheap means for electronic devices to have full support of the features of digital cable. First this doesn't require a cablecard either. I will describe this more but think of this as a QAM tuner super charged.

So a TV maker can build their TVs to support OCAP and DCAS and this is the benefit. First everything I will say below can be done just using the coax cable connection directly from the wall into this new TV set.

First if the TV maker doesn't include its own guide it can allow the cable company to download its guide data and the guide software (guide GUI) directly into the TV set. So you could use the same exact guide the cable companies digital box has right on your TV set without using the box. The cable company can load your authorized channel list directly into the TV set thus stopping you from viewing channels you don't subscribe to. As you might guess all available current and future channels will be available to you. Now as this system is a full two-way system this means you can also order PPV movies and have it billed onto your cable bill. Also all On Demand programming can also be viewed on this TV set as well again all without the box. Now of course you must call the cable company to authorize your new TV set "only" if you want to order PPV whether it be On Demand it not and this is for billing reasons as they must add this TV onto your account like they do with a digital box. But if you don't order PPV all other features will work without a phone call including all free or subscription On Demand content.

Now the benefit of this is that Tivo for example can build a DVR with OCAP and DCAS and use their own guide software. This would allow Tivo to provide a dual-tuner HD DVR that unlike the current Series 3 HD Tivo can support PPV and On Demand. This newer Tivo also has the benefit of always being able to tune into the latest channels even if the cable company changes their technology. For example if a cable company ads new channels via switched digital video those new channels cannot be watched on the current Series 3 HD Tivo.

This would also allow Tivo to make SD DVR products that can get all features that current cable company DVR boxes have. I can say that Comcast and Time Warner are the two companies really pushing this hard. Right now Panasonic has a working TV (plasma) that I've seen working in a testing home in Nashua, NH which is the part of the Boston Comcast market which has just finished their OCAP upgrade. It still has some ways to go even for those in markets with OCAP but in about two years I can see all TV sets having this even non HDTV sets.

 

[rcbridge]

This TerraPix device would allow the cable company to go 100% digital (no analog channels at all) at the plant thus freeing up around 350Mhz of their 650Mhz plant. This would allow hundreds of HD channels worth of bandwidth. This device via the gateway would decode all the old analog channels (now in digital of course) and convert them using the chip into an analog signal and output them into the home. This will allow everything to work exactly the same as before within the home. The benefit of this would be that the picture quality of those analogs would also be much much better and even better the snow issue would be gone too.

That sounds like a very interesting method to get rid of the analog channels, if you can say more about it, I am curious, after the device demodulates and returns the signal to baseband does it remodulate all the channels with analog carriers or just one carrier which is selected by the gateway control?
If it does all of the channels do you need a seperate cable for analog only?

 

[i4tas]

Wow, it seems that the cable companies have a lot of work and more complex than just than the OTA switch in 2009.

Seems like cable companies will have enough room for high speed interent and lots of hdtv channels.

The satellite companies in a sense have endless space with multiple satellites but the cable companies will do just fine and i assume the hdtv picture will look better than satellite does (compression).



Thanks for you nice post!

 

[LonghornXP]

That sounds like a very interesting method to get rid of the analog channels, if you can say more about it, I am curious, after the device demodulates and returns the signal to baseband does it remodulate all the channels with analog carriers or just one carrier which is selected by the gateway control?
If it does all of the channels do you need a seperate cable for analog only?

I'm not sure what it does down to the specifics but I will say how I've been told it works. First I've been told that this TerraPix device will act as a head-end via the gateway. This gateway will have software within it that will tell it what channels are on what specific frequencies at the head-end. It will in turn use software to in simple terms create a new head-end channel map. So it will create a channel map that will put all analog channels at their old frequencies like today along with generating a new channel map for all other channels. So if a customer uses a digital box this box will gain two-way communication which this terrapix head-end on a chip instead of the real head-end which will tell the box what channels are available and where they are. This device for the most part is going to act as a full blown head-end as far as mapping channels goes.

Now the only drawback to this device is that it does need power but I've been told and have seen in action my local system passing DC current over coax to power this device using the same cable. This will also be in the future works for their voice modems so that in the future phone service will be self powered without the need for a battery using DC current over coax.

That is the best way I can describe all of this based on what I know but you get the drift. This device has been coined as "the head-end on a chip" and that is for a reason.