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Monday, March 21, 2011


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Paul Templeton

Thank you.
That was very informative.


Depends on the system, old/small systems may only be 450Mhz. The newest/highest capacity cable plants are 1Ghz (1000Mhz) and 1.2GHz is a possible future technology.

An analog tv channel takes 6Mhz of that line so theoretically you could see anywhere from 75 to 166 raw analog video channels.

Each one of those 6Mhz analog channels can carry 6-10 SD digital video channels or 3-5 HD channels depending on the compression technology available.

A 6Mhz channel could also carry a 38Megabit docsis internet downstream channel. Upstream is always harder to do, so that 6Mhz upstream channel would provide at best 27Megabit upstream.

DOCSIS 3 brings channel bonding into play with the same raw numbers for each channel. So that cisco test at max capacity (72 Down, 60 Up) would max out at 2736 Megabit (2.7Gigabit) down and 1620 Megabit (1.6Gigabit) up and would utilize 800Mhz of bandwidth, leaving 200Mhz for video on the biggest cable plants deployed today.

These are all best case numbers, line loss, damage to the coax and radio interference would decrease the number of usable 6Mhz channels.

https://en.wikipedia.org/wiki/North_American_cable_television_frequencies and https://en.wikipedia.org/wiki/DOCSIS provide the details behind these numbers.

Paul Templeton

This may be a dumb question but how many channels can a single coaxial cable carry?

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