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Putting the TV Broadcast Spectrum to Better Use?
KoshClassic asks: "Recently, on the NPR show All Things Considered, an interview was broadcast with Thomas Hazlett, formerly the chief economist of the FCC. Although short on details, Mr. Hazlett raises the point that, with the high penetration rate of cable / satellite TV into American homes, broadcasting television over the air has (or soon will) become superfulous and that this portion of the radio spectrum could be better utilized for other purposes. What do Slashdot readers think of this idea and, for those who agree, what alternative uses of the broadcast spectrum would you like to see?"
I think the airwaves are still good for HD content (cable company here doesn't throw any our way). Over the air hdtv is still a reason to use the airwaves.
For my money, we're already heading in the right direction with the switch to digital broadcasting, since that change involves moving all of the TV broadcasters up to UHF. The big VHF give-back is, IMHO, the important part. There are 12 channels of VHF TV. At 6 MHz each, that's 72 MHz of space, or more than a quarter of the available VHF spectrum. VHF is prime real estate that could be much better used than for a fixed-point broadcasting service (most TV receivers don't move).
The larger point, however, is that networks of terrestrial broadcast stations are already obsolete. Back before widespread adoption of cable, it was the only option. But now, having NBC programming come out of a few hundred transmitters scattered across the US is wasteful, given that just about everyone gets TV programming from a satellite (directly or indirectly from their cable company). NBC, CBS, ABC, Fox and PBS should each have a single channel on that satellite, just like Comedy Central, and the local broadcasters should use their bandwidth to serve local needs. It's just common sense.
Erm. No. You've got that completely wrong.
It was decided years ago that digital TV broadcasts (whether HD or not; that hadn't been decided at that point) would occupy the same slices of spectrum we used for analog broadcasts: 6 MHz channels. So a single HD channel occupies the same amount of spectrum as a single analog channel. Which is why HD has to be so highly compressed for broadcast. (HD starts out at over 1.3 Gbps, and gets MPEGged down to 19 Mbps.)
The 6X figure comes in when you start talking about subchannels. Inside a 6 MHz channel, you can broadcast as many subchannels as you want, dividing up the channel's bandwidth among them. A SD broadcast can be squeezed down to about 3 Mbps (1 MHz) and still look acceptable, so you can put 6 SD subchannels inside a single digital broadcast channel.
This is not HDTV, however. In order for a broadcast to be called HDTV, it has to have a vertical resolution of at least 1,000 lines. (That's the ATSC's definition.) Broadcasting SD digitially is not the same as HD.
There's a company based in Saskatoon, where I am, which manufactures wireless internet connectivity products that emulate cable. So, basically, you plug a cable modem into it, and as far as the modem is concerned it's connected to Coax all the way to the central office. Currently the units they sell cost about $400 CAD each... but they can sell a unit that does the same thing to people in India that costs only $50 CAD, because they can use the TV spectrum there.
An ISP can provide wireless internet in a radius of 20 miles with the technology... they can set up a whole ISP in a day in India for under $2000... can't do that in North America, of course.