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FCC Will Test Internet Over TV Airwaves, Again
Weather Storm writes "According to MSNBC.com, the FCC will try again to test prototypes on Jan. 24 for transmitting high-speed Internet service over unused television airwaves. The devices were developed by Microsoft and Motorola, among other corporate partners, and will be tested in laboratory and real-world conditions for three months. 'Last year, a high-technology coalition — which included Microsoft, Google Inc., Dell Inc., Hewlett-Packard Co., Intel Corp. among others — submitted prototypes they said could transmit broadband Internet service over unlicensed and unused TV spectrum, known as "white spaces." Television broadcasters and the wireless microphone industry say such devices could interfere with programming. The Initial prototype testing failed last July because the devices did not reliably detect and avoid TV programming signals and could have caused interference. If the tests are successful this time and the devices are approved, the coalition plans to introduce commercial devices for sale after the digital television transition in February 2009.'"
TV broadcasts use a fairly wide frequency band. Just define one small part that is restricted to just TV, and make sure there is no signal on that portion, then use the rest. Of course, you have to recheck periodically, as there may still be some stations that go off the air at night, and you would need to stop using that frequency when they come back on.
Can you even imagine handling TV signal detection in an are like the Northeast Corridor? Anywhere from Richmond, VA to Portland, ME there are so friggin many channels that when you include out-of-DMA channels there simply is no real white space.
Understand that a channel in the eastern US can be reasonably expected to be detectable up to 100 miles away. For example, I live in central Pennsylvania, and even without atmospheric effects with a decent antenna I can get channels from eastern Ohio.
Point being that the device is going to pick up a lot of channels. Also, since it is presumed to be mobile, that device will have to shift channels.
Channel-shifting is where the real nightmare occurs, especially in cities. With path interference, you have total signal dead zones that are three feet away from strong signal. The device could pick a channel, celebrate and start transmitting right into a zone where there would be perfect TV reception and never be able to detect it because of a dead zone.
Trying to avoid this sort of interference in a practical application is impossible.
I scream. You scream. I assume that means we're both acquainted with the problem. We proceed.
A lot of companies in rural areas won't bother running what really amounts to the last mile of lines needed for DSL and cable. The reason is simple -- they will never recover the cost of running the line.
Presently, asynchronous satellite service is the only rural high speed internet available.
A ground-based synchronous wireless system circumvents some of that trouble, but the TV signals are sitting in the only bandwidth useful for reaching down into valleys. The truth is, VHF channels 7 and 8 are the plum spots. They have great range. They are at a low enough freqeuncy that they curve with the shape of the earth, while being high enough that they don't just suck in nearby electrical interference.
TV sits in the coveted spot.
I scream. You scream. I assume that means we're both acquainted with the problem. We proceed.