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FCC Rule Cuts Bandwidth For 72-Mile 802.11b
sonamchauhan writes "This Computerworld article reported a 72-mile 802.11b wireless link (discussed in
this Slashdot story). Now a Computerworld followup story is reporting the link power has been reduced by 75% to comply with FCC regulations for the 2.4-GHz band -- reducing the link's throughput from 1 Mbps to 300 Kbps. The owner is reported saying that: "any violation of the power limits was unintentional and resulted from the fact that the personnel working [on it] primarily have expertise in computers and not radio technology.""
I can't write a comment, I'm leaving for CompUSA to buy all remaining 802.11b transmitters + receivers!
So set up two more of them, and multiplex. Bingo! 1MBit.
FCC regulations exist for a reason, folks.
Cretin - a powerful and flexible CD reencoder
Its pretty easy to go over the maximum power output, which I believe is two watts. Assuming certain combinations of high-gain antennae and an amplifiers, there is no helping blowing past the FCC regs.
To find out if you are over, you need to calculate to total db of gain you have, and convert that to watts.
geogeek
To all the people that flamed me in the previous story for pointing out they were likely violating FCC regs, bite me.
People just couldn't fathom that college professors might not know what they are doing. Credentialism at it's worst.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
Everytime there's a story about 802.11b I wind up posting this link which provides a lucid explanation of the FCC rules in order to correct wrong information.
For that type of data, I would imagine that the reduced bandwidth will be just fine.
Sex - Find It
These guys manage to create a 72-mile wireless link, truly an impressive feat, and do it with mostly computer guys? I'm not exactly certain, but it seems to me like they would have contacted a radio engineer at some point during the construction to assist them. Continuing with this hypothesis, shouldn't the radio engineer know the FCC guidelines and at least mention them so they wouldn't have to adjust the power?
You zap the moderators with a wand of humor! The moderators resist!
300Kbps free transmission for 72 miles is fine in my book.
cat
Why is building your own transmitter ilegal?
It's not. Operating it in certain ways is illegal though.
Who decided that any government "owns" the radio spectrum?
The people own the radio spectrum, the government is "the people". At least in theory.
Who gives this organization such power to control the "airwaves"?
Consent of the people.
If anyone could transmit at any power anywhere on the spectrum, no one would be able to use any non-microwave frequency. One guy with one poorly designed transmitter can easily obliterate several frequencies at once, rendering them all unusable, on a nearly worldwide scale.
I suggest you listen in on CB frequencies for a while at night to see what sort of thing lack of regulation would bring to the spectrum as a whole.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
300Kbps should be enough for anyone
Building your own transmitter is perfectly legal, and kinda fun. However, turning it on and broadcasting above the LPFM limits is illegal because you're interfering with someone else's transmission.
The reason these rules exist (at least theoretically) are to prevent any and every organization from building hundred-thousand watt transmitters (or more!) and broadcasting their message willy-nilly... such as the KKK, NAMBLA, the RIAA, Coca-cola, etc. In order to get a license to broadcast, broadcasters must show signifigant community need, they have to have a local point-of-presence for the public to come in to see them, they must maintain public records, they must broadcast community interest messages (ads for local businesses, PSAs, etc.)
These rules have been enforced a little bit loosely lately, but that's starting to step up - the FCCs enforcement budget was drastically increased this past year.
Stop and consider what would happen, though, if the FCC didn't exist - companies would start broadcasting their advertisements non-stop, and if a competitor tries to broadcast theirs, the first one simply brings up the power on his transmitter and jams the other one out. Pirates (who, of course would not be pirates if there was no FCC) wouldn't have a chance, as there would be so much radio being broadcast that there wouldn't be anywhere they could find to put in a low power transmitter (and before you think about a high power one, keep in mind how expensive they are). After a short time of this, people would stop listening to the radio, stop watching TV, etc. There would be no reason to do so, as there would be nothing of entertainment or educational value. Radio and television would then die out.
In essence, your question is very much the same as saying "why is carrying a gun around illegal? Who decided that any government could make laws telling me I can't carry a gun? Who gives them such power to enforce 'laws'?" The reason why is that it would be disruptive to society otherwise - that's why the FCC is there.
We may not like 'em, but they're much better than the alternative.
-T
The FCC doesn't pass regulations for no good reason. , so as long as folks use after-market antennas and no one files any complaints, the FCC isn't looking to imply cut back on allowable bandwidth. Wide bandwidth spectrum can be used by many users for diffeent reasons. For example, in urban areas, some of the users may be hospitals utilizing heart monitors.
The government doesn't "own" the radio spectrum; it regulates it.
In theory, the government's power to control the "airwaves" was granted by the people, by way of their elected representatives--you and me, that is (or in this case, our parents and grandparents). In practice, of course, giving and taking power from the government is much more complicated and frustrating.
The reasons for having a regulatory body for the radio spectrum should be obvious. The best reason I can think of offhand is airplanes. Airplanes rely heavily on communication via radio waves for safe and accurate travel. If there is no regulation (which might be though of as standards + enforcement), then no airplane can know with any certainty any of the important information:
What band to use to communicate with air traffic control?
What band to use to communicate with guidance beacons?
What band to use to communicate in an emergency?
Assuming you've got a good idea of which band to use, how can you guarantee that any of these bands will be available?
Will the guidance beacon band be overridden by a nearby private transmitter?
Will pranksters or malefactors transmit false traffic control instructions over the air traffic control band?
Will high-powered transmissions from nearby (unregulated) transmitters inadvertently disrupt the plane's avionics during takeoff or landing?
Without standards that everybody agrees on, and without proper enforcement of these standards, air travel would involve crashing planes into buildings on a regular basis. And that's just one of the many reasons why regulation is a good thing.
Transmittors who think that regulation is an "opt-in" thing, and that they're somehow entitled to ignore it if they want to, ruin it for everybody else. Every use of the radio spectrum that you enjoy in your daily life is made possible by regulation. It's why your cellphone doesn't pick up Mexican radio stations. It's why your radio-dispatched taxi arrives on time to pick you up. It's why your satellite TV gives you a clear image, without static from nearby 802.11b nodes.
Nobody "owns" the radio spectrum, but we all use it. Regulation helps make sure that it remains useful. You and I probably agree that the regulations aren't always beneficial to citizens, but ignoring them won't make things any better for anyone.
If none of this is obvious to you, then how can we possibly trust you to voluntarily play nice with others? And if we can't trust you to play nice, then we're left with two options: abandon any hope of ever using the radio spectrum for anything at all, or else enforce the standards and keep the spoilers out of the spectrum.
Which option would you vote for?
Any sufficiently well-organized community is indistinguishable from Government.
And I gotta get down to 7-11 before they outlaw pringles cans!
The owner is reported saying that: "any violation of the power limits was unintentional and resulted from the fact that the personnel working [on it] primarily have expertise in computers and not radio technology." That says it all. A bunch of computer people playing with RF; no knowledge of Part 15 rules, no concept of RF. Really, if the FCC is going to assign new frequencies for wireless networking, we owe it to ourselves to become acquainted with the technology and the rules thereof. The last thing that anyone needs is to turn 802.11 into another RF wasteland like CB radio.
And I gotta get down to 7-11 before they outlaw pringles cans!
Pringles can antennas are already illegal. They are unapproved by the FCC. I still can't believe that the FCC is unwilling to free up some space in the spectrum. If they could make just one 1-gigahertz wide band in the 10-50 ghz range unlicensed, that would really expand the opportunities for wifi. (That frequency would make it hard to transmit between rooms in houses. The 2.4 ghz is better for that. But it would have no problem going a mile or two over the air with enough power, provided there isn't any fog or anything.)
If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth.
DSL is limited in the United States due to concerns that the signal will bleed over in legacy telco equipment, thereby rendering many older phone systems obsolete. The baby bells wanted to push this regulatory measure through to enable her to make all equipment, even older Phone systems, work with the extra measure of having DSL on the line.
:) (Two DSL lines channel bonded together through a netopia router)
Keep in mind that most DSL equipment actually operates several thousand hertz higher than what you can physically hear.
It is quite all right though, as I worked for a DSL acompany, I got to test equipment. Imagine pure internet joy at 3 MB up and down with a class C of Public IP's
Blah Blah Blah.
In the US, the 2.390-2.450 allocation belongs to radio amateurs, who are using at least some of it to receive to weak signals from the AO-40 amateur radio satellite. Owners of unlicenced (Part 15) devices are requred to cease operation immediately if they are causing interference to licenced users, even if their equipment is unmodified, within power limits and type-accepted.
Signals at this frequency are highly directional, and if you interefere with an amatuer satellite operator, you can expect to hear from them. They know who to talk to at FCC about enforcement, too.
-=Maggie Leber=-
I thought this was pretty ridiculous when I first read it, so I did some research and read up on the part 15 and part 97 regs... but you're right, if you have a radio license, part 15 regs don't apply to you, and part 97's do. And you could, theoretically at least, crank the power at the transmitter up to 100W. One thing stopping you is part 97 section 313(a): An amateur station must use the minimum transmitter power necessary to carry out the desired communications. 100W is only perfectly legal if that is how much you need. I'm pretty sure if you work the numbers you could show that no two line of sight points within 50km of the surface of the earth would require that much power.
So even with a license, they would probably have to keep the power down to 250mW unless they could show they needed more than 300kbps. The FCC is far less lenient with licensed radio operators than amateurs and cranking the power up well above the minimum necessary could result in your licensed being revoked.
Also to fall under part 97, while transmitting you must have a control operator manning the equipment, or if you have an automatically controlled station your bandwidth limitation is 500Hz (I'm not sure that is even possible with 2.4GHz).
Education is a better safeguard of liberty than a standing army.
Edward Everett (1794 - 1865)