Making Room for HDTV


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SatelliteGuys Regular
Original poster
Supporting Founder
Sep 8, 2003
Owasso, OK
from CED magazine Web site.

I have heard lots of people talking about how Cable is going to take away from Satellite because they have more bandwidth. But this artical says to me that cable is going to have challenges also because of bandwidth. From what i understand of this artical, cable will have to take away bits from SD broadcast to make room for HD channels. Might be time to buy stock in the StatMux businesses.

What do you guys think?
The problem that Cable has is that they carry a large number of analog channels. Each of the analog channels takes up the room of 2 HDTV channels. Cable might have to drop down the number of analog stations to make room for the HDTV channels. This causes issues with subs that would now need a box to recieve these channels.
I thought it was the other way around, that HD took up a bit more space than analog does, or maybe that just pertains to the digital signal that Dish and Direct bring down and is different when it comes to analog.

I also thought I heard that cable had plenty of bandwidth especially with some new technology coming out to bring about plenty of HD.
HD takes up about 6x the space of a DIGITAL standard definition channel. An ANALOG standard definition channel takes up 6MHZ of cable spectrum. An HDTV digital channel takes up about 3MHZ worth of cable bandwidth. A standard definition digital station takes up about 1/2 MHZ of spectrum.

Cable has a good path to the subscriber (all on wire (or fiber)), so unlike OTA HDTV or DBS can really turn up the data rate with 256QAM. Remember with DBS you have to focus in on a 200 watt light bulb 24000 miles away, and with OTA you have 50+ miles of terrain between you and the tower (you might be closer but they need to get the signal to all the people out on the edge). Cable most likely has Fiber to within a few hundred feet of your location, then a nice big wire to your house.

Cable Gets 38Mbit/Sec in 6MHZ
OTA gets 19Mbit/sec in 6MHZ
DBS gets 12Mbit/sec in 6MHZ 8PSK
DBS gets 9Mbit/sec in 6MHZ QPSK

The above all approximate
So it looks like DBS still needs to get some new technology to get more Mbit per second in 6MHZ seeing that they only have a third of the Mbit per second in 6MHZ than what cable does.
If you study information theory, Shannon's theory will tell you that DBS can not get to the point that cable can in terms of Mbps per MHz of bandwidth. This has to do with signal-to-noise ratio.

This does not mean that DBS can't compete with cable. They do have some room to improve both Mbps/MHz and compression technology. They also have the ability to spot beam signals from their multiple orbital locations.

Cable companies would like to go completely digital, getting rid of their analog channels. As mentioned above each analog channels 6MHz of bandwidth can be used for approx. 10 SD channels or 2 HD channels (using MPEG2 compession). My local Comcast transmits about 70 analog channels. That's a lot of bandwidth. Their hesitation is that lots of people do not want a set top box (my grandparents) and it will take some cash to upgrade the systems for full digital. But it will happen, it's only a matter of time. When they do, they should have no problem with adding lots of HD channels (and not overcompressing them).

For more info read:

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