Slashdot Mirror
Open Spectrum: Free the Airwaves
akb writes: "Most of the RF spectrum in use is licensed for exclusive use. What do we get? Inefficient use through spectrum hoarding, political finagling to abuse the regulatory system to gain competitive advantage and access to the airwaves for only a few players. A good article over at CNET picks up on the example of 802.11b in using spread spectrum technology and unlicensed bands and proposes that model be applied to the rest of the spectrum. For the hardcore check out NYU law professor Yochai Benkler's writings, particularly this article (pdf) and Durga Satapathy's papers for the tech end of things."
Licensed airwaves is a good thing. It ensures that frequencies remain useable and don't obstruct other frequencies. If anyone could broadcast on any frequency, the airwaves would be useless due to noise.
Maybe more work needs to go into reforming the regulation policies instead of developing free-for-alls.
tcd004
Fear the box office of Harry Potter!
While this may seem like an unfair govermental restriction, radio frequencies are not an unlimited resource, like, say, bandwidth, at least not at the present time. There are bands that are available for unrestricted use, just as there are bands that are not usable by just anyone. I do think the regulatory bodies need to keep a better handle on the usage and they need to be able to reclaim bands that are not being put to the best use, though this is quite difficult in practice (for example, digital TV is mandated to be put in place over the next several years, but one string attached to the new frequencies given to existing TV stations was that they give up their current frequencies once they switch over).
Specifically, I recall a post here on slashdot about someone's 2.4ghz phone interfered with their pr0n surfing.
Low-power FM was touted to be a great thing for free speech. It was to open up very low-power community FM transmitters, provided (of course) that they didn't interfere with any existing broadcast signal. This would have given voices to community groups, schools, churches, outreach organizations, etc.
There was broad political and popular support for it--but (you know what's coming) the major radio broadcasters lobbied like sons of bitches to have it turned down, using a lame excuse of interference and degradation of signal. Eventually, if I remember correct, LPFM was killed as a last-minute amendment to a bill, an amendment bought by lobbyists no doubt representing Clear Channel Communications and the other bigwigs that bring us the same pap we hear on every FM station in this country.
Don't let big corporations continue to buy up all the bandwidth and hold us hostage with it. We need to get LPFM back on track. Hell, support your local pirate radio station by just listening. You'll be seeing the effect that LPFM should be bringing us and you'll actually hear differing viewpoints, and--dare I say it?--interesting programming.
Karma: Excellent Birds (mostly as a result of listening to Laurie Anderson)
If there was no control of the airwaves then we will have device manufacturers using whatever frequencies they wish. Then the question of interference comes up. What if Verizon and MCI tried to grab the same frequency to market their latest wireless service in the same location? And what if that same frequency was in use by someone else's device? Who would be the final arbiter in these situations?
Just as each computer needs a unique address (let's leave NAT out of this) to successfully transmit and receive their data; radio transmitters must use specific frequencies, power levels and operating times to avoid interferience (the operating times make the spectrum allocations work like dymanic IP).
So someone has to retain control of the spectrum "for the public interest". That's why we human beings create organizations.
Chris
Corporations have been eyeing the amateur radio bands for years. Here are these chunks of bandwidth that are licensed for public use in some very prime locations of the electromagnetic spectrum, all the way from 1.8MHz up to the GHz range. The FCC would just LOVE to auction off the ham radio portions of the spectrum and make millions off of it. Indeed, with waning interest in ham radio, the FCC will be under heavy pressure to free up that spectrum. It'll probably start out with switching them over to "shared use", but once they have their feet in the door, a few years down the road the ham bands will start disappearing. This is just another case of big money having more political influence than the public interest.
I have 802.11b and an 2.4GHz video sending unit. Both are useless when the other is on. I don't think we are all ready to replace everything we have with new technology that shares the spectrum.
If you look at the history of Radio broadcasting, the entire purpose of government regulation of frequency allocations was give interference-free access to the most desirable bands to commercial broadcasters, while forcing non-commercial users who used radio for personal communication or experimentation (the ancestors of modern amateur radio operators) into less desirable frequencies (and then, when those were proven to be useful by the efforts of the amateurs, taking much of that bandwidth away from the public, also).
But now regulation clearly could serve the opposite purpose. After all, if all regulations were eliminated, and everybody were allowed to transmit wherever they like, the big corporate interests (cellphone companies, broadcasters, etc.) would probably be able to effectively claim everything, since they could run higher-power transmitters and more of them than any individual could hope to. If there is to be any kind of non-commercial use of RF, it clearly needs exclusive bandwidth protected by the FCC (as hams, CB users, GPRS/PRS, wireless networks, etc. already have).
Of course regulation as it stands serves the opposite purpose...making as much money as possible auctioning off public spectrum to cellphone companies, etc. But that does not mean that its elimination would solve the problem of the commercialization of public spectrum.
"(Man) tries to live his own life as if he were telling a story. But you have to choose: live or tell." --Sartre
Currently, if a terrorist wanted to block a wireless service (say, television or 802.11b), he would use a transmitter that is easy to locate through triangulation, and only focuses on one particular service. If, however, spectrum is shared amongst many services, that terrorist could take out all of those services and it would be almost impossible to tell which transmitter was his, and which belonged to legitimate users.
How do they "take it out". While certainly they could render services useless in a certain specific geographic area by turning up the power, to do so on a wider basis would require more power which would make them real obvious. I don't really see how a change to more spread spectrum would make a terrorists job easier.
This sig has been temporarily disconnected or is no longer in service
> If, however, spectrum is shared amongst many services, that terrorist could take out all of those services [...]
:) )
Sorry, but doesn't spread spectrum modulation get rid of jamming?
Isn't that the reason why the military uses it?
AFAIK, jamming, sufficiently broad spectrum provided, requires a several magnitude more powerful signal than the signal to be jammed.
( Well, if a terrorist wanted to block a wireless service like 802.11b or Bluetooth, he just switches on his microwave.
"Between strong and weak, between rich and poor [...], it is freedom which oppresses and the law which sets free"
And the sad thing is that the amateur radio community itself is largely to blame for this. All of these years continuing to drag their feet on licensing simplification, removal of extraneous licensing requirements like morse code knowledge, and continuing to protect bandwidth for ancient modes while limiting bandwidth for newer modes, has allowed the community to turn into a small group of old farts, waiting to die. It's a shame you guys couldn't see the value of growing your ranks vs. keeping your sacred Advanced licenses and your private frequency reserves. But elitism always tries to preserve its advantage. Adapt or die, baby. Auction 'em off, I say - and good riddance...
P.S. The anti-government wackos who seemed to be the more vocal inhabitants of the ham bands didn't help endear you to the powers-that-be, either. This is something that the tech community should probably keep in mind when using that new shared communication medium called the Internet.
That is all.
Bingo!
It's been a number of years since I was involved in this sort of work (so my memory may be a bit fuzzy) but this is an old problem. I was part of a group of engineers that were developing software to predict the problems that proposed FM transmitters might have on instrument landing system receivers. If you look at the frequency spectrum allocations you'd say that there shouldn't be any problem. Different frequency ranges so no problem. Right? Wrong. The landing system receiver receives all the freuqncies that the antenna picks up. Some of those FM transmission frequencies combine in the receiver's front end to generate harmonics that are in the landing system frequency band. Some ILS receivers are better than others at rejecting these but the point is that they're there and they affect the S/N (adversely) and degrade the landing system's performance. Not something you want happening. I recall some of the flight tests where other people were collecting real data to confirm out models. In one case, where the technicians had tapped into the guts of the ILS receiver, they could actually hear the audio from a nearby radio station. Similar concerns about interference of the ILS signals had to do with cable systems. You think your local cable TV provider is ensuring that all the connections on the poles aren't leaking RF energy?
And, if memory serves, lowering the S/N in a spread spectrum has an adverse effect on signal acquisition and tracking. Won't it be fun when everyone in the neighborhood has a spread-spectrum connection to the internet and you find that it performs like a dialup connection.
And I just love law professors who spout views on technology policies without having the necessary technical background. Just about as much as I enjoy professional politicians doing the same thing. There are technical reasons why the spectrum is/was carved up into protected bands. The trouble with politicians (and law professors who probably want to be politicians) is that they're mainly concerned with the economic aspects of spectrum allocation. And, IMHO, that's dangerous.
CUR ALLOC 20195.....5804M
The separation of channels by frequency has two special properties that help with this problem:
1. There are no common physical processes that change frequency much between the transmitter and receiver (Doppler and changing refraction effects are generally small).
2. It is possible to get very large channel separation with frequency-selective filters.
You give up these special properties with broadband schemes. Time-division and code-division separation of channels are particularly sensitive to multipath propagation, a ubiquitous property of radio. While multipath can produce fading and distortion in narrowband transmission, it cannot cause one channel to spill into others.