Hambergler

I use a cable provider for internet and cable TV. If I had 10 HDTVs running HD content at about 55 Mbit/s* each. Would the current networks be able to handle it? What if everybody in my neighborhood was also running the same scheme?



*Got that number from wiki. Don't know if it's correct.
http://en.wikipedia.org/wiki/Megabit_per_second

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loyalguard

I'm a little over my head here so those more knowledgeable please correct me, but, I don't think this is problematic.

The biggest factor in the bandwidth capacity is how big of a frequency range is allocated to the cable system. Digital cable usually transmit between 552-864 Mhz. This allows between 33-52 6-Mhz channels transmitted simultaneously (These aren't "TV" channels). Each 6-Mhz channel can carry two 19.39 Mbit/s transport streams. Each stream carries a HD "TV" channel. If you look a little further down in the wikipedia entry you posted, using Comcast as an example, I don't think more than 20 Mbit/s is being used per HD channel right now. So, the cable coming into your house can carry 400-600 HD channels each at 19.39 Mbit/s.

I hope this makes sense, and again, please correct me if I am wrong.

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|TG| LoyalGuard

Hambergler

Ok, so if an HD channel uses 20 Mbit/s compressed. Can the line carry 200Mbit/s if I had 10 HDTVs going at the same time?

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Satertek

If I understand correctly, it wouldn't matter how many HDTV's are connected to the line, as they all recieve the same input signal (unlike a normal network connection where the signal is completely different going out each line depending on what is requested).

It would be the same concept as putting 10 FM radios (or HDTV's receiving over-the-air signal) in a room, they all receive the same signal, so there isn't any limit to how many can get it at the same time.

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loyalguard

Satertek-

BTW, my 400-600 calculation above if off...I miscalculated.

Here is another breakdown:

The standard frequency allocation for digital cable is Between 552 Mhz and 750 MHz. This enough bandwidth to transmit 33 6-MHz channels and each of these transmission channels can carry two HDTV streams. Each stream is a program to watch. So, the coaxial cable entering your house is carrying (or is capable of carrying depending on your cable provider) 66 HDTV programs simultaneously. (33 6-Mhz Channels * 2 HDTV streams per 6-Mhz channel). So, if you have 10 HD Televisions running at the same time, each one is tuning in to 1 of the 66 HDTV programs already coming in. You could have 66 tv's and so could everyone other customer because they are all getting 66 channels coming into their homes, each TVis only picking one out at a time.

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|TG| LoyalGuard

icky

On satellite and digital cable transmissions, the pipe carries ALL available channels all the time and you are just "tuning" to one of them. So if you had the capacity to manipulate the flood of data, you could theoretically tune into them all at once.

Edit: I should have read the thread first. What he said --^

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