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Unlimited Airwaves
Dan Gillmor has an article concerning the notion of scarcity of the airwaves, which has long been a testament of faith at the FCC. Recent advances in technology may render that testament false.
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Let's watch our semantics here: Breakthroughs in technology would render the testament obsolete. Rendering the testament false implies an admission that the testament was made while ignoring the technological realities. That isn't the case here.
Kevin Fox
While radio waves may not interfere with one-another directly the way sound waves do, what would happen to radio astronomy if we opened up every possible frequency to exploitation? Is it even remotely possible that's what the FCC bureaucrats are considering, and not simply their own necks?
As an aside: the Internet should have made the TelCos obsolete years ago; but it hasn't happened yet. I wouldn't hold my breath on newer radio technology making old radio obsolete anytime in the next ten years, at least.
!#@%*)anks for hanging up the phone, dear.
So, like so many other computer/data related things, it will amount to how well new equipment would be able to sort through the overlapping radio transmissions to find the one you actually want to capture and decode.
Essentially, current radio tuners are serial, in that they lock onto a single frequency and attenuate all others down. Reed's suggestion is basically to receive many frequencies in parallel and toss them out as you decode them and they prove to not be the one you want?
Sounds good. It would make security through adaptive modulation interesting.
Screw it up??
I seemed to have answered my own question, the article i was refering to was the Ultra Wide Band. Additionally, this article seemed interesting.
-dk
While it is true that the signal-processing capability has expanded to the point where it is technically feasible to pack the spectrum more tightly, the premise fails to address either the economic or political feasibility. How many people would be interested in having two hundred more stations in the FM band if it meant that they had to rip out their existing car stereo and replace it with a $500 (low end) software-controlled radio to listen to them, and if they didn't, all they'd get on their stereo was a random hash of noise because their old radio can't separate the stations?
Look at how effectively HDTV has replaced the existing television broadcasts, for example. Unless you can replace all the hardware in use on a spectrum band at the same time, you're faced with the choice of retaining backward compatibility -- which defeats the purpose of the upgrade -- or cutting off the people who don't want or can't upgrade.
For specific and short-range purposes, such as wireless LANs, it may be practical to require a complete end-to-end replacement, but there are large parts of the EM spectrum that are currently in use for which the entrenched interests will lobby strongly against any disruption
There are not an unlimited number of channels, though there are more now than when the FCC was created.
Modern signalling often reuses bandwith by dividing a channel into accesses* on some other dimension (code-division, time-division, etc, spatial-division, etc). But those divisions are limited within their own scope in ways similar to the bandwidth limits of radio-frequency division, and should be regulated in exactly the same way to prevent overlap and interference.
--Blair
* - A channel is a communications connection medium. An access is an individual division of a parameter differentiating channels. E.g., channel 538 could use frequency access 7, time access 4, code accesses 3-9, and so on.
This is one of the reasons Morse code is still so popular with amateur radio enthusiasts - you can send extremely narrow band signals that allow you to communicate fairly quickly. If someone is really good at it, they can communicate almost as fast as speech, over a channel a few *tens of Hertz* wide.
- If you use better technology (low power, repeaters, signal extraction) then you can fit more information into the same bandwidth.
- You could always use more bandwidth.
- Private industry is better at cooperating than the government is a regulation.
At no point does he really try and dispute Shannon, there is a finite limit to the information that can be transmitted, he just thinks we should be smarter at approaching that theoretical limit. He does the usual job of trying to confuse the issue and make it more complicated than it actually is, but when you get down to it, its fairly obvious.Now I'd tend to agree that we could do with being smarter. But to say that the commercial world is going to make systems that all work nicely together is just plain ignoring realities. Look at the 802.11 / Bluetooth cockup - in reality the aim will be the fast buck and market share. If you can do that by riding roughshod over the competition, so much the better.
In the end you need to engineer a balance between the short term and long term perspectives. I'd agree that its wrong at the moment, but that is a call to shake up the regulations and those that create them, not to throw out all long term thought in an orgy of competing, incompatible systems.
Maybe we could start by allocating bandwidth to particular purposes on a lease term basis. Once you reach the end of your term, you have to show that continuing to allow you that bandwidth is the optimum use for the next lease period, if not, then no bandwidth.
Maybe then we would have faster evolution, and even revolution, in the use of the EM spectrum.
After looking over the lecture slides a few links in, the authour seems to just be saying that congestion (and hence spectrum scarcity) will be a non-issue if we just switch to point-to-point transciever schemes instead of broadcast schemes (either by using cells and a backbone or by clever coding).
This is great, and would indeed increase bandwidth to silly levels... except for the fact that implementing a pervasive point-to-point network with high local bandwidth and low leakage is a PITA of vast proportions.
Summary: Good idea, and it'll certainly see greater use in the future, but it's not "unlimited airwaves" by a long shot.
That's an understandable perception and theoretically will work. Consider this enlightenment and not a flame.
Current FM radio modulates the signal above and below the designated carrier frequency. Therefore a 20Khz signal (peak of human hearing) will modulate a 95.3MHz carrier between 95.28 and 95.32MHz. IIRC the full 40Khz deviation accounts for both channels of a stereo broadcast.
There's additional use for Broadcast radio. I forget where I saw it, but I believe there is an offset from the designated frequency to place a mono only 20Khz band away from the stereo part of the transmission for mono FM radios to pick up properly. This may however be an outdated use of the extra bandwidth.
Additional bandwidth can be used for other data/audio signals to be carried independent of the main broadcast for Broadcast FM plus 'padding' between stations.
Hello? FCC...this really is a no-brainer.
This article comes across like a sci-fi movie, very aloof. The writer paraphrases and quotes from what another guy supposedly said, with no indication of technical facts or other groups or individuals that agree. I have no reason to believe the author and subject are credible, making it hard to trust the article. I'm not the most knowledgable on the FCC's policies, but I don't tend to believe this "evangalist" in general.
However technically speaking, there are some points that sound feasible and are likely true. I would expect that the FCC does inhibit inventors and small companies that have good ideas. Their licensing fees and other policies do make startup "disruptive technologies" difficult, which is exactly what the established companies that already have spectrum want. However some areas of the spectrum (i.e. 2.4GHz, etc) are open, and he fails to address the collision problems that exist in those areas. I think we are now beginning to see hardware in the free spectrums that is capable of dealing with very noisy environments, but in my eyes that equipment is still in it's infancy. (If someone knows more on that please reply to this post on this subject..)
I would say once these technologies are proven, the FCC should listen, but in the meantime there is a LOT of equipment that isn't capable of dealing with this and could become rather useless if the spectrum is opened up. Seems like a logical approach, before changing the regulation system. Prove your point, man! Gimme some examples.
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This is an example of the Paradox of the Best Network:
cpeterso
It's sometimes called M/S (mid/side), so we can express it like this:
M=L+R, S=L-R when transmitting.
L=M+S, R=M-L
Clear as mud, right?
Not only that, but if everyone uses highly directional antennas for both transmission and reception, then pretty much the amount of bandwidth scales linearly with the number of users
Why not take it a step futher, and enclose the signal in a sort of waveguide, with a central wire and a copper braid to protect from the signal leaking out? You could just run these "simul-axial waveguides" from transceiver to transceiver.
Just think, in the future, we may be able to modulate light and send it down a similar enclosed waveguide, for miles at a time!
I've had enough abrasive sigs. Kittens are cute and fuzzy.
Reed's quote about "network operation increasing capacity" obscures an important loss -- the loss of the anonymous listener. It seems that for this technology to work, receivers are going to have to be independently addressable, broadcasting your listening or viewing choices to the public. How's that grab you?
The anonymous listener is fundamental to democracy. Imagine a world where you fear to stay on a given channel too long, for fear that someone is going to associate you with the views being expressed. This is the kind of thing that we should be steering away from with new technologies, not toward.
Couple this with the fact that there's not exactly a lack of spectrum in the first place: 90% of the channels on your UHF dial are sitting there doing nothing right now because the FCC and Congress prefer THAT to leasing them to nonprofit organizations at a reduced rate.
Like most of our current "technological" problems, what's broken isn't electronic but human.
He who refuses to do arithmetic is doomed to talk nonsense.
I recommend that you get hold of the ARRL handbook from your local library, or indeed the RSGB book if you're in the UK. These are the standard works on amateur radio, and explain all these things far better than I can....
So, the simple packet-addressing scheme won't work for two-way communication. As for one-way communication, there's no need to "label" the recipient of a broadcast; radio is inherently broadcast, so everyone can hear everything anyway.
Why cant we just use higher and higer frequencies? 2GHz full? Use 20GHz? Or 50GHz? Or a googlehertz?
You hit the nail on the head right there. Check out my employer's website, since that is the crux of what we are doing today. Actually, Fox News just did a story on us, which should go national soon. I'm the one running the computer in the video, and yes I'm busy surfing Slashdot ;)
Basically, instead of transmitting at high power to a base station, the transciever finds the path that takes the least amount of power. By transmitting at lower power, you get better spectrum reuse in a given area. One conventional cell becomes thousands of picocells. It really doesnt make sense to try to run a packet switched protocol like IP over circut switched networks like CDMA, et al.
This guy does have the right idea, but I think some people are reading the article the wrong way. He isn't calling for deregulation, just more bands for people to experiment in, like the ISM band.
If they can use aplitude modulation and frequency modulation to send signals, why don't they also use polarity modulation and get one more channel?
Since it's free, PM could be reserved for digital devices.
___
It's the end of my comment as I know it and I feel fine.
Umm, what Amateur Radio are you dealing with? The license I hold does allow me to experiment with new techniques. For example PSK-31 was invented in 199\8 or 1999 and is widespread. Yes, there are some limits, for example, you can't use more bandwidth then a voice channel on HF for new modes, but that's just common sense. Up above 3GHz, you're pretty much open to anything you want, including spread spectrum. You can do SS on everything above 70cm. If it's currently not allowed, the FCC does grant 6 month at a time experiment permits. If it works, the FCC will allow it. For example, see the ARRL's experiments in the 60m band.
--Josh
There are exactly 42,935,718 letter sized sheets in a square mile.