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from the we'll-all-watch-your-latest-YouTube-video dept.
UHF takes up the space between 400 and 700 megahertz on the wireless spectrum [Ed: Technically, it's defined as being from 300Mhz to 3Ghz]. [At these frequencies] its signals can carry for miles and more easily penetrate walls and trees than the higher frequencies used for most wireless routers. Despite this and the growing demand for wireless data, TV broadcasters continue to maintain preferential access to the UHF spectrum, even as the percentage of Americans relying on over-the-air signals for TV programming has begun to dip into the single digits in recent years.
The Federal Communications Commission allows for data to be transmitted over open UHF channels not claimed by a TV broadcaster, but urban areas where the need for more Wi-Fi options is greatest are also the least likely to have unclaimed UHF frequencies.
Knightly and Rice graduate student Xu Zhang designed a new solution to allow for transmitting wireless data over UHF channels during TV broadcasts over those same channels called WATCH (for "Wi-Fi in Active TV Channels") and were granted permission from the FCC to test it on the Rice campus last year. The basic idea behind the system is to actively monitor nearby TVs that are tuned into a local UHF video signal and to use advanced and efficient signal-canceling technology to send wireless data over the same channel without interference between the data and video transmissions.
Perhaps this is a candidate for open access to the Internet that this and other forums have been kicking around the past few years.
Original Submission
(Score: 2, Interesting) by Anonymous Coward on Friday July 17 2015, @03:08AM
My limited knowledge of data transmission over radio prevents me from knowing if this is a problem, but...
What is the capacity of these frequencies compared to higher frequencies? My crude understanding is that data density increases with frequency, so low frequency means low data transmission rates. Is it linear? Does 600 MHz have one quarter the bandwidth of 2.4 GHz? Would the equivalent of WiFi g drop from 54 Mbps to 13.5 Mbps? Wouldn't these frequencies cause a lot of nerds to whine?
(Score: 0) by Anonymous Coward on Friday July 17 2015, @04:56AM
What matters is the width of the channel, not so much where the channel sits. Higher channels more naturally lend themselves to wider spacing though.
(Score: 2) by captain normal on Friday July 17 2015, @06:06AM
Plus isn't this basically encryption over airwaves? How is this different from what we discussed a couple of days ago: https://soylentnews.org/article.pl?sid=15/07/13/2210241 [soylentnews.org]
Everyone is entitled to his own opinion, but not to his own facts"- --Daniel Patrick Moynihan--
(Score: 1) by pyg on Friday July 17 2015, @03:21PM
IIRC FCC part 97 (amateur radio/ham) requires data transmissions to be limited to 100 KHz wide and 56 Kbps on frequencies below 928.0 MHz. So yes. Also below 28 MHz, limited to 300 bps, 28-54 MHz 1200 bps, 144-148 MHz 19.6 Kbps.
This of course is not what is technically possible with spread spectrum and ultra wide band but current FCC limits on amateur radio.
Re: Amateur Radio. Honestly I'm not sure what limits bandwidth except for at lower frequencies there is just less of it. In the 2 meter band (popular VHF band 144-148 MHz) there is 1.9 MHz of bandwith for data/voice. At 80 meters there is only 100 KHz for data and 400 KHz for voice. When you get into microwave frequencies there are literally GHz of bandwidth available. Some of the most interesting stuff right now, IMO, is happening in microwave transmissions.
Also I've seen some "nerds" with a great fist top digital for throughput with CW on lower HF and they where smiling, but my first networked computer was with a 300 Kbps dialup modem so I guess I still have low standards.
(Score: 1) by pyg on Friday July 17 2015, @03:41PM
For reference 802.11a-n channels are 20-40 MHz wide so if you took 400-700 MHz and used it like 802.11n you could fit 7-14 channels... also you would have a lot of pissed off hams who just lost their precious 30 MHz of 70 cm band.