I thought they were called guard bands
i've never heard of guard bands being called white spaces before
Why did the FCC give a failing grade to a controversial Microsoft prototype that sends high-speed Internet signals over unused television airwaves? It was broken. At least, that's the word from Microsoft. As we reported earlier today, on July 31 the Federal Communications Commission released an 85-page report saying that …
that while google wants to buy a few channels for it's own use, microsoft is trying to use every channel that it finds free. For channels that are not operating 7/24 that means once they turn off their signal for just a short time, could they find their channel used by someone else when they try to go back online? What if someone turns on a wireless microphone while its channel is used by some intelligent device? If i promise to stop using it when I detect external activity, could I also use the mobile phone or satellite tv frequencies? Or the emergency service frequencies maybe? (with the promise to intelligently turn off my signal if i detect a distress call, so i won't interfere with rescuers) This just looks like a way to legalize deregulated long range tv broadcast stations. Imho they should just buy frequencies for their own use or use free for all frequencies, like 2.4 Ghz.
As a radio amateur, I have watched in horror as the computer industry has played with radio frequencies, both within and outside the "box" with precious little regard for the consequences, except to itself. "Electronic smog" is now so pervasive that whole frequency bands are now useless to low power signals, especially in built up areas. Frequency bands that used to provide good reliable low power communication around the world!
It really would be a good idea if the computer industry employed some RF Communications Engineers and practitioners to understand the consequences of its intentions. Equally it would be an excellent idea if they didn't ride roughshod over everyone else who might be "in the way". But then we are talking of Microsoft, and they didn't get to where they are today by being considerate of the needs of anyone but Microsoft, did they.
The outcome that I expect? Microsoft will be given permission to proceed with this device, which will perform exactly as the "defective" device did, and that the US government will use it as a further lever to remove all analogue TV from the spectrum. [Now why they would want to do that is a whole new thread!]
I don't think they are talking about guard bands. Instead, channels where no analogue television signal is being broadcast (which will increase with the switch over to digital broadcasting).
I'd assume that the existing guard bands would be left in silent, so if Microsoft's prototype worked as intended it shouldn't produce any more interference than two adjacent television channels.
James: the technology will basically work by listen before transmit, which will inevitably include guards bands...
There's a couple of fundamental flaws here of course. Where a device is listening (and subsequently transmitting) is not where other devices are listening. Add on that that people may have noticed TV aerials tend to be quite big, meaning they have quite a lot of gain, and that there is no real (from an electronics perspective) limit on the receiver size for a TV (OK I know DMB & DVB-H...) meaning you'd expect them to be a bit more sensitive than a mobile or portable device. Add to that that there is no incentive for device manufacturers to mass produce within spec...if one of two prototypes which must have been tested within an inch of its life (Microsoft aren't so dumb as to ship untested kit to the government) failed what can we expect to happen in future.
This is a horrible idea, as horrible as UWB.
"The outcome that I expect? Microsoft will be given permission to proceed with this device, which will perform exactly as the "defective" device did, and that the US government will use it as a further lever to remove all analogue TV from the spectrum."
Duh? That's already on the slate. By Feb 2009, analogue TV in the US is already supposed to be completely phased out. Learn to read, mmkay?
@ The Article:
Let me fix that quote for you...
"Microsoft is playing Russian Roulette with America's access to interference free TV reception. OH NOES!!! They'll have to go outside!!!"
How does this device know that a frequency is clear? All TV stations outside the range of Microsoft's tiny antenna get trampled?
Well, it's a good thing MS isn't an evil monopoly that crushes all competition and then locks people into paying for low quality products. I might be worried that this new wireless device is a scam to destroy over-the-air broadcasts and force MS IPTV as a new standard.
The whole idea is that "if I cant hear anything, then it is OK to shout as loud as I want", and as some have already commented, that is a real problem in practice.
Not only will these devices have much smaller antennas than typical TV systems, but they could be in an area (e.g. street level) where they can't get a signal, but another antenna (e.g. roof level) can. In this case they trash a perfectly good working system without knowing it.
As pointed out before, and the same applies to UWB (which will trash lots of the lower microwave band to any sensitive space related work), but the government of the USA (and elsewhere) care not. All that matters is money, and the likes of Intel and Microsoft can usually do as they please. By time the complaints are heard it is too late.
If such a system is deployed and causes problems, how do you recal it? The users are unlikely to know or care about the concequenses.
Have they made it mandatory to receive an authenticated "frequency range OK" messages at regular intervals from some central management unit to make sure they go silent if there is a problem? I doubt it...
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