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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.
UHF would be great for wireless internet, especially in rural areas. The "wave" would be able to travel farther than it does using 2.4Ghz or 5.8Ghz technology.
Off-hand I know that UHF TV (approx. 440MHz I believe) is usually city wide in coverage, but remember analog TV is far more accepting of data errors (no error correction, no retransmissions) than digital data needs to be.
Also UHF TV still follows the 1-directional broadcast methology. That means, one powerful transmitter (~10-100kW I think) and an antenna at one high location, e.g. hilltop.
For wireless networking, you need bidirectional transmission, longer antennas (17cm versus 3mm if I have my math right), and because the signals transmit further you need frequency coorditation (i.e. licensing) from the FCC to prevent interference if you also want higher power station, over 100 milliwatts.
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.
Nobody is claiming TV is a right, just that the use of the spectrum should be in the public interest, since it is a shared resource, and as such, really needs to be regulated, or it won't work.
Same as the water we drink and the air we breathe, and the food we eat.
They did this a generation ago w. channel 1 (there is no lnger any channel 1, because that's been given over to other services). UHF was supposed to supplant VHF, but it didn't because the higher frequencies required only allowed for line-of-sight transmission, whereas the lower-frequency VHF signal can be bounced off the ionosphere, giving a greater coverage area. Superstations then boosted their signal output to get more viewers, higher revenue. This doesn't work w. UHF, b/c of the aformentioned relative transparency of the ionosphere to UHF signals.
Besides, let's not forget that most of the excuses/uses for grabbing the VHF channels will be just more of the same old shit, anyway.
I live just 1/2 mile to the end of the cable line. Time Warner keeps saying that any time now they will run cable to my house. Therefore I get TV from satellite. However, I must get local channels over the air because of copyright violations between the local channel affiliates that are in the area and the ones that are broadcast over satellite.
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.