Broadcasters fight hard against public use of blank spectrum
However, there's plenty of room for use of that whitespace in WiFi-style devices that are smart enough to know where they are and adjust their use of spectrum accordingly. The tiny sliver of spectrum given over to WiFi (and other unlicensed uses) at 2.4GHz has generated untold billions in economic activity and public good.
Nevertheless, the broadcasters -- who are squatting on all this beachfront spectrum that actually belongs to the public -- are pulling out all the stops to prevent anyone from lighting up this unused spectrum and doing anything useful with it. For example, rural communities could use their local whitespace frequencies to provide "fixed wireless" links to homes and businesses where no DSL or cable-modems reach.
The broadcasters argue that we dirty unlicensed users of spectrum will surely spoil their lovely groomed golf-course of sitcom reruns, sporting events, and reality TV, and the mere possibility of a single bit of interference is too much to countenance, no matter how great the potential rewards.
And who are we to disagree? After all, we only own this spectrum that we've loaned to them.
White spaces are blank spots in the TV lineup where no stations transmit; they vary in number and location around the country, but even major markets have open slots. Tech companies and digital rights groups have been pushing hard at the FCC to make these white spaces available for broadband access. While the FCC has already approved the idea of fixed transmitters, the more contentious issue is whether millions of consumers should be allowed to install mobile, unlicensed transmitters in homes and businesses.Link. TThe WIA represents companies like Google, Philips, and Microsoft that are trying to build the devices in question, so it's no surprise that Corbett is bullish on the possibilities, dismissive of interference complaints, and given to talking of white spaces as a crucial battleground. But she's not the only one.
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I seem to remember that as part of the deal for tv stations getting their chunk of spectrum, they had to provide a public service. Part of that was the news and the rest was public service messages (like anti-drug commercials), community event announcements, and some other things. How much of a public service are these stations providing now?
screw broadcast television. Really. I see less and less point for it in its past and present form. They show no signs of learning whatsoever.
To my understanding, the concern is less by the N.A.B. about interference with their broadcast signals, but rather concern from the entertainment industry as a whole with interference with their wireless communication devices.
This issue has been somewhat well explained in the Ars forums.
In essence, any high quality wireless audio product, from the wireless mic at your church or from last week's conference, to the wireless in-ear-monitors used by your favorite mid to large band uses these whitespaces.
(I have a small bias in this as a live sound engineer, and thus work with devices that would be made obsolete by the usage of this whitespace. Already it is difficult to fit in. And yes, the entertainment industry does have the momentum here having used wireless devices for these purposes since the 70s, and in this frequency range since the late 80's or so. That said, the entire live entertainment industry does depend on them, from the top all the way to the college where I do theater as a student, to high schools)
Seems to me like the entertainment industry should be using standards, rather than simply grabbing the whitespaces. If they chose to use these with any regulation or controls, then they're going to have to suck it in.
Why don't they use WiFi?
For the record, some of this could have been avoided if we had gone with non-high def TV.
Traditional analog TV really does need a buttload of whitespace around it, no foolin'. A TV signal is about 6Mhz wide to fit in all those gradations from light to dark, plus AM audio. To give you some idea how big 6Mhz is, the entire FM radio band fits between TV channels 6 and 7!*
So you have to keep that band pretty "clean" or you get a nasty picture, since the receivers have to be made really sensitive to pick out even moderate amounts of detail. Due to a quirk of physics, the filters that prevent TV stations from splattering outside their 6Mhz bands are big, (physically large), very expensive, and impossible to tune much outside the frequency they were built for.
So for most of the prior existence of TV, it was just plain dumb to let expensive, sensitive, and somewhat delicate TV transmitters be required to accommodate other stuff. Now, if you just wanted ordinary-def digital TV...well, that you could pack in a lot tighter. But the broadcasters already had 6Mhz allotments, and you know the rest.
The real problem with "white space" devices, is that they have to work correctly every single time, or risk screwing up something actually fairly important - like emergency communication frequencies, radio astronomy, or ... wifi. That means a standard of engineering better than your typical generic video card that comes out of the discount electronics factories overseas.
*for example, if you were willing to do away with TV that lands on channels 2-6, you could have another 1200 FM stations! [Slightly oversimplified, due to boundary issues, desired channel interleave, etc. A better back of the envelope sketch would be 600. But still!]
AS I understand it (and I certainly could be wrong), the issue is unused spectrum in certain areas. As Cory described it, SF may have a broadcaster on channel 2, and San Jose will not, as the two signals would "clobber" each other.
Given that, the real issue is (IMHO) that while the policy is sound (licensed transmitters shouldn't interfere with each other), each transmitter is over-powered. Let's make up some numbers to illustrate my point:
If a TV station transmits 50,000 Watts on channel two, and that signal carries, say 50 miles, the nearest station that can broadcast on channel two will likely be well over 100 miles away (maybe 150 miles, based on where applicants choose to place their transmitters). That would leave a fifty mile swath of land with no signal on channel two.
It is also a long held policy of the FCC that an unlicensed use may not interfere with a licensed operator. Any device of any significant output level (a signal stronger than say could cover half a city block) that transmits on channel two would cause interference with anyone trying to watch channel two. Typically this isn't a problem, as few people try to tune in brodcast TV at concerts and other live events, and the signal isn;t that strong, people use directional antennas on their TVs, etc.
I think the broadcasters are right - permitting unlicensed use of the frequencies they are licensed to use will put them in the position of having to monitor for interefence and determine who is to blame.
As to the point raised by #4, Cronan:
As I understand it, FCC regulations Part 15 allow the use of nearly any frequency if the part meets certain emission standards (less than 100 mW output, not designed to coause interference to a licensed service, etc.). The use of "whitespace" makes perfect sense, since the transmitters are typically so low powered that their signals travel in the concert hall/room they are in, and comply with Part 15 (not intended to jam channel two, and they most likely have a means for changing freq. if they are found to interfere).
Ken
If they keep us to 2.4 GHz, then they only have to monitor 2.4GHz.
The National Ass. of Broadcasters
did you type "National Ass." on purpose?
Perhaps they should have left us some public space in the first place. We just finished following a tense big for new spectrum. If we need room for personal devices, why are we selling all of the remaining spectrum to big companies? Set some aside and let consumer-level devices use it.
Since the FCC does have a policy of not allowing low-class devices to interfere with higher-class devices, it makes sense to keep those different classes on different frequencies.
While it makes sense, in terms of efficiency, to use whitespaces for consumer devices, it's only becoming necessary because the FCC is too busy selling public spectrum in exclusive contracts to large corporations. If they would just leave some room aside for everybody to use, this wouldn't be an issue.
I want to see unlicensed use of "white space". This spectrum is great for penetrating buildings and providing wide-area coverage. The innovation that's taken off in the 2.4Ghz ISM band is something that U.S. spectrum policy should be working to foster.
My issue: I don't have a lot of time to research this issue, but I really, really want to help. Who should I be giving money to? Who should I be writing to?
I'm happy to get the word out, and to contribute funds. What I don't have, and I suspect others don't either, is a lot of spare time to read up on who the players are and how to get involved.
To my mind, the "good guys" are the people out there fighting for free public use of this spectrum. Who *are* the good guys? How can I help them?
The problem with the FCC's regulations against unlicensed devices interfering with licensed services is twofold.
First, unlicensed devices are not traceable to the individuals using them, hence it is difficult to identify the source of interference without going into the field with receiving equipment to triangulate on the device's location in order to actually find it, and hence its operator. Except in the case of ongoing, continuous interference, this isn't likely to be possible. Unlicensed portable devices are likely to be difficult or impossible to locate if they cause interference.
Second, the FCC seems no longer well-equipped to conduct investigations into interference complaints. Consider that U.S. Coast Guard vessels off the coast of Maine are frequently finding marine radio channels unusable due to truck drivers - illegally - using marine radios and powerful amplifiers in preference to the CB radios they used to use - also usually illegally. The FCC told the Coast Guard that they haven't the ability to police such a problem. If maritime emergencies have to take a back seat to trucker chit-chat, what chance does a DTV viewer have of getting the FCC to investigate their interference complaints?
A problem exists in how - or how well - a device determines it is operating on a truly vacant channel. Unless it can accurately determine that a nearby TV viewer using a rooftop antenna can or cannot be receiving a DTV signal on that channel, it can't use the channel without risking interfering.
Consider that the device doesn't have the same height or antenna gain as the DTV viewer's system, so it can easily construe a channel as vacant and start broadcasting a signal that may be enough to interfere with what had been perfect DTV reception in a fringe area. The ability to get clear reception even in weak signal areas is one of DTV's real advantages, but an unlicensed device that doesn't accurately determine channel usage could deprive a viewer of their DTV signal.
All of this supposes that a DTV viewer experiencing reception problems due to white space device interference could actually determine that to be the cause. Since the effect would be either sporadic or total loss of the TV signal with no hint that it's because of a nearby white space device, the viewer is left to guess at the cause.
Some might call the TV station to complain, only to be told - correctly - that everything is normal there; most will give up and change the channel.
REVENG's suggestion that these devices have their own frequencies is the simplest solution - but until unlicensed device users are able to pay through the nose for their own chunk of spectrum, I'm not expecting to see it happen. It's all about the sale of spectrum.
Something to remember, analog colour TV signals consume huge amounts of spectrum. Each station runs around 6 megahertz.
What would be the problem with this space if it were considered federal property? Companies using it could then lease the land, or it could be allocated with grants.
Topics:
* Open Spectrum
* Cognitive radio
* Software-defined radio (SDR)
Key people:
* David Weinberger (author of Everything is Miscellaneous)
* David P. Reed (of Reed's law fame)
* Larry Lessig (founded Creative Commons)
* Eric Blossom (spearheading GNU Radio software)
* Matt Ettus (spearheading the Universal Software Radio Peripheral (USRP) hardware)
See also:
* Motorolla / Google whitespace prototype
* White Spaces Coalition
* Wireless Innovation Alliance
* Radio Reference wiki
* Prometheus Radio
@11
is that still true? You still need a detector van festooned with antennae creeping around and triangulating fixes? I would have thought by now some software solution existed that worked backwards from multiple points where interference was reported.
"The National Ass. of Broadcasters"
I see what you did there.
Hey Cory, nice article! It's been an ongoing issue. The government loves spectrum! no need for investment and can sell it and resell it as much as they want for huge profits! I'm sure this isn't going to be the last time we are going to hear about it.
Here's an article about the battling over white space spectrum. A little bit of history, and then some conflicting topics.