Shirky on Spectrum Ownership 184
scubacuda writes "When engineering assumptions change, shouldn't the laws that govern technology reflect those changing assumptions? Perhaps Clay Shirky puts it best: 'Things like shoes, cars, and houses are all property. Property is excludable -- it is easy to prevent others from using it -- and rival -- meaning that one person's use of it will interfere with another person's use of it. Spectrum has neither characteristic. Spectrum is purely descriptive -- a frequency is just a particular number of waves a second -- so no one can own a particular frequency of spectrum in the same way no one can own a particular color of light. Instead, when an organization 'owns' spectrum, what they really have is a contract guaranteeing Federal prosecution if someone else broadcasts on their frequency in their area. The regulatory costs of forcing spectrum to emulate property are enormous, but worthwhile so long as it leads to better use of spectrum than other methods can. That used to be true. No longer.'"
keep it pithy (Score:3, Funny)
spectrum (Score:3, Interesting)
Doesn't this happen, though? People complain a lot about their microwaves and cordless phones screwing up their WIFI, for example. Or am I missing something?
Re:spectrum (Score:3, Informative)
Re:spectrum (Score:2)
The property model may be a better way to manage the resource. And Economist makes a good point for it.
Re:spectrum (Score:2)
Re:spectrum (Score:4, Interesting)
For example, when you use these bits of spectrum, you have serious power limits -- generally less than one watt. Which is probably the only reason they're useful at all, because if it wasn't for this, you'd have people with 1 kW WiFi amplifiers :)
(Note that the ham bands do overlap with the 2.4 gHz region, so by going under the ham rules, a ham operator CAN use a lot more power in that section. But most hams are quite considerate about not interfering with other people, even when they don't legally have to be. For the record, I'm AD5RH, but I've not tried any 2.4 gHz ham stuff. Yet.)
As for the microwave, there's a tiny bit of spectrum allocated for things like this, with few restrictions beyond 1) not emitting so much RF to be dangerous and 2) not emitting RF outside this band beyond a certain small amount. It's meant for `trash' signals, like that emitted by microwave ovens and some medical equipment. In theory, your microwave's signal should stay within the spectrum allocated to it, but the rules do allow it to radiate outside it a little bit, and that's probably what you see. Also, a strong signal (especially on a nearby frequency will `desense' a receiver), reducing it's sensitivity -- you might be seeing that too, even if the microwave is staying perfectly within it's little chunk of bandwidth.
Re:spectrum (Score:2)
I've thought about this. Have you heard of any hams who've experimented with signal propagation on 2.4GHz using the full-strength (relatively) power we have available
Re:spectrum (Score:2)
Yes. The local ARES group has done some stuff with it, at least experimenting with setting up high power WiFi links between local hospitals. Compared to the 1200 bps packet that they usually do, it would be a whole lot faster. I don't know what kind of results they've gotten, however.
However, many possible uses of high power WiFi are basically shot do
Re:spectrum (Score:2)
if it wasn't for this, you'd have people with 1 kW WiFi amplifiers
A 1kW WiFi amplifier would probably put one in the running for a Darwin award. It would work on one's surroundings like a microwave oven, just not quite as fast ;-)
73 DE KC2IDF.
Re:spectrum (Score:2)
Standing in front of microwave dishes to stay warm is nothing new (at least not up north where it actually gets cold.) It's not smart, but people do it.
I've got a friend who tore open a microwave oven and removed all the shielding, so it's now a 700 watt microwave projector. I'm not sure what he does with it (he jokes about killing WiFi
Re:spectrum (Score:2)
Spectrum is excludable and rival (Score:3, Informative)
Wrong, at least in part. If I broadcast on a spectrum being used by another, it can interfere. And by interfering, I can exclude others from using it.
However, this may be purely semantics on my part, since one depends on the other.
(tig)
Re:Spectrum is excludable and rival (Score:4, Insightful)
That's the reason for regulation of the radio spectrum. (Score:5 insightful)
A critical point that Shirky and countless others fail's to graps is that the reasons unlicensed spectrum works are:
1) The frequency band in use does not support long distance propagation (i.e. ionspheric reflection) - hence interference is a local problem.
2) The FCC and equivalent regulatory bodies limit the transmit power (and often effective radiated power).
There is a simple method for minimizing interference - use directional antennas with the narrowest possible beamwidth (some of this can be done electronically) for both transmit and receive - and lowest power needed for communication. Unfortunately, most wi-fi users use omnidirectional antennas.
I've also had w-a-y too much experience with interference with poorly designed consumer electronics and similar problems to think that the FCC and related organizations are obsolete. Sure, the state of the art equipment is less susceptible than previous generations of equipment, but I strongly doubt that the typical consumer will anything close to state of the art. To prove my point on the latter - look at all of the problems on the internet due to viruses, worms and the ilk that propagate through Winoze boxes...
Re:Spectrum is excludable and rival (Score:2)
First, I'm not sure the FCC is obsolete, but their regulations should loosen up. They should always be loose enough that consumer level techn that's more than a certain amount below average will have problems. Otherwise, there will be no incentive for it to get better. Having the spectrum be more free is in all of our best interests in the long run.
Also, this reply [slashdot.org] addresses some of your other points.
No More ugly colors (Score:5, Informative)
Same story, better colors.
sad, sad times (Score:2, Insightful)
Hey, that's my color! (Score:2)
The Orange is Mine (Score:4, Interesting)
Wrong. At least some big corporations would disagree with this statement. As a matter of fact we (figuratively) pay taxes to educate business people who dispute who actually owns a color [bbc.co.uk]...
Re:The Orange is Mine (Score:2, Interesting)
the issue under discussion there isnt really can one own a color, the article is misleading in that respect.
the issue in that case is that the company Orange is claiming that "its rival having a similar logo to its own will cause confusion among its customers and damage its business.". This is a very different claim from saying it owns the color orange. The issue that easyMobile and Orange are fighting over is no different from any other case involvi
Re:The Orange is Mine (Score:2)
Your formulation is correct but, IMO, a lousy interpretation of the article allows someone to say that the companies are fighting for the right to own the color. The author of the article did the same "mistake" when choosing a title for his article...
Ownership of Light (Score:5, Informative)
You can "own" colors, no problem.
See this short article [colormatters.com] explaining how the courts have favoured/denied color trademarking.
I believe Coke owns their colour of red, IBM blue, KPN (Dutch Telco) green, etc.
As long as the color is not indicative of "function" (ie. isn't associated with a particular "message", ie. blue is cold, red is hot, green is environmental, etc), you have a shot at getting it trademarked.
When trademarked, competitors in your marketspace/mindshare can't use that same colour.
Which means you effectively "own" the wavelength of light that is that colour!
Re:Ownership of Light (Score:2)
Re:Ownership of Light (Score:3, Informative)
Remember... there are an infinite number of ways of representing yellow. One way is to have a pure yellow light source. The other way is to have one red light source, one green, that excite the red and green receptors in our eyes with the same ratio that the yellow light source does.
Thus, a COLOUR is trademarked, not an arrangement of wavelengths of light.
(Yes, this means th
Full of sound and fury, signifying nothing (Score:3, Interesting)
Now there does exist quite a bit of licensed spectrum in the lower bands that isn't being used everywhere, but it is in some places. Exactly how to utilize those in some places and not others in an open market is a tough question.
No longer? (Score:2, Insightful)
Re:No longer? (Score:2)
Yes. Namely, the bigger company will switch it's cell phones to a new frequency and start up a radio station that just happens to transmit elevator music on their competitors frequency with mor
Property (Score:4, Interesting)
As many
PS - just for the record, I'm not American, I'm Dutch.
Re:Property (Score:5, Interesting)
Why is that "obvious"? Capitalism as an ideology has been widely discredited worldwide (although the media doesn't reflect that) through its end results in practice (colonialism and its aftermath, slavery and its aftermath, increasing rich/poor divide, pollution, inappropriate technological solutions, human suffering, mindless work) as opposed to claims in theory, see for example: Millionaire Wannabes [conceptualguerilla.com]. If Capitalism worked, we'd all be using Smalltalk or Lisp (developed thirty years ago) instead of Java and XML.
Money (in terms of Federal Reserve Notes) and loans (in terms of usury with interest and a fractional reserve banking system) are also equally problematical. In fact, the American Revolution was fought mainly over the right for the colonies to print their own paper money (a fact long forgotten or suppressed). See: The World's Alternative Trading Network [xat.org] for some more details. Or google on "Fractional Reserve". Alan Greenspan isn't busy setting interest rates to help everyone out -- he is trying to be an optimum parasite to get the most blood out of everyone he can by balancing drawing blood (interest) against how big the economy is.
Corporations? They are the biggest marauders around in many ways. Why should they have more than human rights in the USA? Effectively their charters are no longer revoked and if they commit a crime they just get fined and maybe some employees (disposable cells, like your skin cells) go to prison, while nothing about the corporation really changes. Why should investors have limited liability? If people support a bad cause, shouldn't they too go to jail? It is happening now with people who supposedly support "terrorism", so why should corporate investors get a free pass when they support pollution, habitat destruction, sweatshop practices, employee boredom, and so on?
In fact, the whole notion of "Work" underlying all that stuff is itself bogus. For alternatives to capitalism, consider: Buddhist Economics [schumachersociety.org] or: The End of Work [deoxy.org]. From that last: "Curiously --- maybe not --- all the old ideologies are conservative because they believe in work. Some of them, like Marxism and most brands of anarchism, believe in work all the more fiercely because they believe in so little else. Liberals say we should end employment discrimination. I say we should end employment. Conservatives support right-to-work laws. Following Karl Marx's wayward son-in-law Paul Lafargue I support the right to be lazy. Leftists favor full employment. Like the surrealists--except that I'm not kidding--I favor full unemployment. Trotskyists agitate for permanent revolution. I agitate for permanent revelry. But if all the ideologues (as they do) advocate work--and not only because they plan to make other people do theirs--they are strangely reluctant to say so. They will carry on endlessly about wages, hours, working conditions, exploitation, productivity, profitability. They'll gladly talk about anything but work itself. These experts who offer to do our thinking for us rarely share their conclusions about work, for all its saliency in the lives of all of us. Among themselves they quibble over the details. Unions and management agree that we ought to sell the time of our lives in exchange for survival, although they haggle over the price. Marxists think we should be bossed by bureaucrats. Libertarians think we should be bossed by businessmen. Feminists don't care which form bossing takes so long as the bosses are women. Clearly these ideology-mongers have serious differences over how to divvy up the spoils of power. Just as clearly, none of them have any objection to power as such and
Re:Property (Score:2, Interesting)
Part of the problem is that thanks to the Cold War, most Americas think that capitalism is the One True Way... Our Way Or The Highway... We Are Right So Everyone Else Is Wrong. In reality, capitalism is most certainly NOT the most efficient economical model! And, anybody who says so (like I just did) tends to be labeled "unamerican" or "communist". I'm NOT advocating Communism, I think that sucks too. But I think that our curr
Re:Property (Score:2)
Re:Property (Score:2)
Re:Property (Score:2)
FYI, Java's Swing is derived from VisualWorks Smalltalk (and designed by people hired away from the related company at the time). Sun actually tried to license VisualWorks for their settop box project (which Oak, Java's precursor was developed for); ParcPlace would not provide what Sun thought a reasonable lic
Re:Property (Score:2)
In case he's not, well, he's a idiot. Here's a good one:
"Why should investors have limited liability? If people support a bad cause, shouldn't they too go to jail? It is happening now with people who supposedly support "terrorism", so why should corporate investors get a free pass when they support pollution, habitat destruction, sweatshop practices, employee boredom, and so on?"
The
Re:Property (Score:2)
Your Slashdot handle of "MoralHazard" suggests this way to look at it: limited liability for investors, no flow through bankruptcy for investors, and no criminal liability for investors, all create a "moral hazard" allowing investors to do less than proper dilligence and provide less than complete oversight for their investments. If equity investors' personal butts were on the line for each investment, one could hope investors would ensure corporate behavior met higher moral standards
Re:Property (Score:2)
"LIMITED CORPORATE LIABILITY" HAS NO RELATION TO CRIMINAL OR CIVIL LIABILITY FOR A CORPORATION'S BEHAVIOR!!! It is an expression that ONLY relates bankruptcy and responsibility for debts.
Dude, this isn't personal--I have a very specific beef with you because you keep ranting on about how vile corporations are, but you don't seem t
Re:Property (Score:2)
So it is strange you then call me an anarchist.
Read the linked article (if you dare to allow your worldview to be challenged a teensy bit) and you will see answers to the issues you raise.
And if you poke at the issue of money or conventional economics even the tiniest bit, you will see it is now widely agree
Re:Property (Score:2)
Why? That 5% could be organized in any way from forced labor to volunteers to ration-unit-based (money-based) capitalism.
The article I linked to by Black (as well as the Buddhist Economics one by Schumacher) makes clear that even without automation much that 5% could be made much more enriching experiences by rethinking how it is d
Re:Property (Score:2)
Re:Property (Score:2)
Deja vu... (Score:2, Insightful)
Re:Deja vu... (Score:2)
Re:Deja vu... (Score:2)
Well, that rather proves the point. If I have a fish, I have it. If I give it to you, I don't have it anymore. If you steal it, I don't have it anymore. Hence, there is a very natural idea to physical property.
Contrast this with intellectual property. If I give it to you, I still have it. You can give it to others and I still have it. The only
2.4GHz WIFI is good, but... ? (Score:2, Offtopic)
Re:2.4GHz WIFI is good, but... ? (Score:2)
Smoked what now? (Score:3, Insightful)
I'm a big fan of Clay, but what precisely was he smokign when he wrote this? Spectrum is both excludable and rival. Exclusion, as applied to spectrum, can be equivocated with "jamming." Rival is known simply as "interference."
Perhaps his argument is that over range both characteristics (excludability and rivalry) of spectrum diminish, unlike with physical property. But spectrum is absolutely property, by both definitions.
Should spectrum be free? Don't know. Don't care. But let's not jumpstart the debate by twisting core characteristics of property.
Re:Smoked what now? (Score:2)
Use transmitter power control (mentioned in the article), smart processing in the receiver (mentioned in the article), and adaptive beamforming antenna systems (not mentioned in the article), and you get lots of reuse.
Re:Smoked what now? (Score:2)
I always like pushing these things into the visual EM spectrum because that's where both the sending and receiving technologies are much more sophisticated than any artifacts we've created.
So, the fact that I can create something that flashes, say, blue in a random pattern that makes it nearly impossible to tell how blue something really is means that blue is excludable? Or does this mean that I would be hunted down and forced to turn off my blue flashing device in most situations outside of nightclubs?
I
Spectrum as Property (or not) (Score:3, Insightful)
- Neil Wehneman
*****
Lawrence Lessig [lessig.org] spends a not insignificant amount of time on the concept of spectrum in 2001's The Future of Ideas.
Quoting him from page 233 (emphasis in original)...
"Here again, an idea about property is doing all the work - but this time the idea is at its most attenuated. We don't yet have a full property regime for allocating and controlling spectrum. Yet we are still being driven to embrace this single view. We are racing to deny the opportunity for balance, pushed (as we always are) by those who have the least to gain from a world of balance. The possibility of a commons at the physical layer is ignored; even the chance to experiment with the commons is denied. Instead, policy makers on the Right and the Left race to embrace a system of perfect control.
So strong is this idea of property, so unbalanced is our understanding of its tradition, that we embrace it fully, without limitation, even when it doesn't yet exist, and even when the asset being assigned a property right is not - like the wires of AT&T's cable or the creative genius behind Disney's Mickey Mouse - something anyone has created. We are racing to assign property rights in the air, because we can't imagine that balance could do better."
Buy it new [the-future-of-ideas.com], buy it used [ebay.com], or get it from the library. But if you have interest in spectrum you should definitely read this book.
Here's Why (Score:2, Insightful)
any color you like (Score:4, Interesting)
Traditional antennae are "1 dimensional" in their tuned band: a signal is either present or not (to a degree, in an amplitude of power) at any given moment. So the world looks either like a wash of, say, "green", or is completely dark - no edges or other features, which appear only in dimensions. A phased array is like a video sensor area- as signals of a tuned color arrive from a single origin in space, at slightly different times to slightly different points in the array, the same color can be sensed as emanating from different "spots". Human eyes use lenses to assign different arrival times/points to different retinal detector cells, while phased array antennae can use use the actual timing differences.
These new arrays allow a single color to be used by different transmitters, separated by the exclusive positions we're familiar withj in our daily lives: each thing is in only one place at a time. So phased array antennae are even more sophisticated than spread spectrum codecs, or the FCC: using the properties of space and light, there's no need to "register" or negotiate colors. Each color can be used by anyone, so long as their position is exclusive of everyone else. As that condition comes free with physical existence, we're freed from the limits of one-dimensional, low-fidelity sensors, and archaic monopoly administrators like the FCC, as well.
Re:any color you like (Score:2)
My short answer: in no way. And the introduction of phased arrays does give benefits, but in no way reduce the need for spectrum planning.
Re:any color you like (Score:2)
Re:any color you like (Score:2)
The benefit from the phased arrays are mainly that they are more compact than a set of dish antennas, and that they are electronically steerable, that is, you can choose the direction electronically instead of mechanically rotating an antenna.
Re:any color you like (Score:4, Informative)
It's like asking "what's the difference between a metal rod and a VHF mast"? For all but trolling purposes, the difference is that a VHF mast is a special metal rod, more practically useable for tuning VHF signals than any old metal rod. It's useful for DIY to understand that this gear isn't magic, and basically pretty simple. It's also useful for fellow DIY'ers to cooperate for better results, rather than picking semantic fights.
Re:any color you like (Score:2)
What I suggested was not a phased array of parabolic dishes, but one parabolic dish, on a servo-controlled gimbal. This has the same properties of being able to follow a certain transmitter in spatial space, without using any phased-array technology.
Phased arrays is in engineering language a specific technology where the signals from two or more separate antennas
Re:any color you like (Score:2)
Re:any color you like (Score:2)
Phased arrays are not fundamnetally different from other directional antennas, such as parabolic dishes. And I will uphold that position until you show me how they are different.
F
Re:any color you like (Score:2)
There is one other benfit, and that may be what Doc Ruby was trying to get across, that the phased array is capable of multiple simulatneous "beams".
Phased array antennas have been around for a long time - AM broadcasters have been using them since the 30's (if not
Re:any color you like (Score:2)
Re:any color you like (Score:2)
Re:any color you like (Score:2)
Re:any color you like (Score:2)
Re:any color you like (Score:2)
Re:any color you like (Score:2)
I'm going to go out on a limb here and try and interprete it. If I understand you right, you're talking about using a phased array to differentiate amungst various signals all on the same freq, and signal processing equipment to pull a specific signal out of the noise.
I think that's what you're trying to get
Re:any color you like (Score:2)
Re:any color you like (Score:2)
While I agree that a sophisticated phased array setup for a base station would help with the current issues, it's not an all-in-wonder solution. While it would be great for differentiating between laptops in opposite corners of a room, t
I don't understand why (Score:2)
I'd also like to see how eliminating the FCC would solve anything. Even if TV bands and specifications were decided by a consortium, they'd also have to be arbitrary on who can transmit where. If anyone can decide their frequency, then it is who is willing to pump out the most watts wins, which is expensive
Re:I don't understand why (Score:2)
There are new technologies out there that will let a radio listen on a frequency and selectively mask out the stuff it doesn't want to hear. It's
A question of commons? (Score:2)
Spectrum is intangible the way the physical space is intangible. They exist, but they are not easily quantifiable. Yet we all depend on their availabiltiy in one way or another. Waves passing from one point to another can have all manner of implications: who has access to them, are they interfering with anyone else's use (or enjoyment), etc. So maybe, when we talk about things like spectrum ownership, it's not ownership per se, but a limited right to exclusive utilization.
I don't have a problem with regula
Are regulatory costs really "enormous"? (Score:3, Interesting)
I'm not a fan of regulation, and the article makes good points, and it's true that the budget of the FCC is about $280 million/year. [broadcastengineering.com] However, compared to the total annual income of the radio, television, and other industries that use spectrum, is the FCC's budget really that large a percentage?
Re:Are regulatory costs really "enormous"? (Score:2)
2.4ghz isn't exactly unrestricted (Score:3, Insightful)
However keep in mind that just because 2.4ghz is unlicensed, it is not unrestricted. If I went on the balcony of my downtown condo and put a 500dBm wifi AP with a 10dbi omni antenna, it would wreak havoc (and get me in trouble with the fcc).
For another example, imagine unlicensed wireless internet over AM radio spectrum. Yeah you could surf the web from 10 miles away from your house, but your signal would be destroyed from interference from everybody else's.
Now, I'm all for opening up as much spectrum as makes sense provided that the wavelenth is short enough to not blow through buildings etc, and provided the FCC restricts transmission strengths enough to not create anarchy.
I don't get it. (Score:2)
I don't support licensing of colors for the same reason.
Multiplexing Radio (Score:2)
Why don't we multiplex radio broadcasts the way we can multiplex fiber optics.
As I understand fiber optics multiplexing the idea is to split the light by the underlying frequency of the light. In a really simple example we might split the red and green light. Now each of these red and green channels gives us a function I(t) or intensity as a function of time which can be both freq
Re:Multiplexing Radio (Score:2)
We do. Ever hear of channels? Wavelength division multiplexing is nothing more than channelization (as in radio/TV) done at optical frequencies. Instead of channels being 10 kHz wide (AM), 200 kHz (FM) or 6 MHz (TV), the channels are ten's to hundred's of GHz wide.
Go find a copy of the ARRL Handbook and read up the chapter on modulation - you obviously aren't comprehending the basics of modulation.
Re:Multiplexing Radio (Score:2)
The question is basically the following. Why can't we take a laser that produces pure green light and then modulate it's intensity as a function of time. That is why must the frequency of
Re:Multiplexing Radio (Score:2)
Second, remember the trig identity cos(at)cos(bt) = 1/2(cos((a+b)t) + cos((a-b)t).
Thirdly, remember Heisenberg. If you know the photon's frequency exactly, then you have no knowledge of the position (which implies no knowledge of time of arrival). Modulation puts constraints on time, hence position, which then p
Whoops! (Score:2)
10 million users * one hundred dollars = ONE billion.
He was making a valid point but he botched the math.
-
Free market and private property (Score:2)
Headline (Score:2)
When I read that, my first thought was thet I never owned a Spectrum, but I do have to Sinclair QLs in the attic.
Re:All property is theft (Score:2)
Re:All property is theft (Score:2)
Also, that does not back up your argument. I could tell you to go read Marx/Engles, and that proves nothing.
I hate democracy, go read Plato!
I like democracy, go read Mill!
I hate capitalism, go read Marx/Engles!
I like capitalism, go read Ayn Rand!
I hate life, read Camus!
Re:All property is theft (Score:3, Insightful)
Amen. When will liberals stop trying to put regulations on everything. After all, we need our liberty. If I want to have my factory outputting mercury into a river upstream of a city, why should there be environment regulations to stop me? I think I'll pay my works 0.05/hour and never install safety systems. I just need to stop those regulations from the Department of Labor.
I agree on property rights too. What is it with a
Re:Excuse me? (Score:2)
All that intro, and then you thorw that in there? No reason, no reference, no link, just that? I was all ready to read about WHY and HOW, but you didn't bother with that.
That's how zealots have arguments.
Windows sucks! Linux rules! Your mom uses a Mac!
Re:How does frequency really work? (phycics questi (Score:2)
Actually, yes. Like nearly 100 years of development within radio transmission technology. Ordinary QAM modulation is more or less what you describe: to send independent information in the phase and the amplitude regime.
And there are problems with UWB and collisions. And the addition of UWB or CDMA only adds the complexity of assigning codes to transmitters, and does not remove the frequency planning part. If you do not suggest putting a stop to a lot of scientific applic
Re:How does frequency really work? (phycics questi (Score:2)
In other words it has always been described to me as a signal of 'fixed frequency' the amplitude of that frequency is adjusted. I always had taken this to mean that it was a fixed frequency only in approximation. So for instance you could send an AM signal through power lines just using voltage (and not sending radio waves
Re:How does frequency really work? (phycics questi (Score:2)
Perhaps my initial post didn't explain things well enough. For contrast think of a sound wave which can be completly described given pressure as a function of time. As I understand it QAM works by setting P(t)=s_1(t)*sin((w+s_2(t))*t) or similar. Where s_1(t) and s_2(t) are
Re:How does frequency really work? (phycics questi (Score:2)
He isn't completely off base. QAM uses a combination of phase and amplitude to encode information.
A key point about QAM - in order to detect the extra information, you need a better signal-to-noise ratio than with a simpler form of modulation (you get some of it from a narrower bandwidth). There are no magical modulation schemes that will get you past the limit set by Nyquist and Shannon.
If I wanted to take out a CDMA base station (at least for receive) it would
Re:How does frequency really work? (phycics questi (Score:2)
The important point to understand here is that there are really two frequencies in question here. There is frequency_photon and frequency_signal.
To put things another way you could use QAM modulation on a signal composed of pure green (single frequency light). We can encode the intensity of recieved green light by the function I(t)=A(t)*sin( (w+deltaF(t))*t). The term A(t) modulates the amplitude of the signal, deltaF modulates the frequency of the signal but th
Re:How does frequency really work? (phycics questi (Score:2)
Re:How does frequency really work? (phycics questi (Score:2)
From what I've read, "turbo-codes" are capable of getting within 0.5dB of the Shannon limit.
While radio propagation is indeed done with photons, they are of such low energy that radio can be treated as a continuum. If you want to get down and dirty about photons, then you will run nto Heisenberg's indeterminancy principle (the original German term
Re:How does frequency really work? (phycics questi (Score:2)
QAM on wikipedia [wikipedia.org]
Note the following in the wikipedia explanation "What this actually means is that the amplitude and the phase of the carrier wave are simultaneously changed according to the information you want to transmit."
QAM can transmit more information than simple AM or phase modulation because it modulates phase and amplitude of the carrier, not
Re:How does frequency really work? (phycics questi (Score:2)
For those of you who don't want to read farther I believe what I am proposing is essentially using multiplex
Re:How does frequency really work? (phycics questi (Score:2)
I think I can guess your resoning in the parent, and I think you make a mistake. If we take your example with the green photons, A(t) is the amplitude of the signal, i.e. the number of incoming photons per second. But if all the photons are exactly the same kind of green, then F(t) is fixed and can not transmit any information. Because if we change F(t), then we will chang
Re:How does frequency really work? (phycics questi (Score:2)
As I understand it one can still do frequency modulation on something simple like sound waves. Is this wrong?
My understanding is that sound waves can be frequency modulated using something like the equation I gave before. Namely, P(t) is the air pressure as a function of time so to frequency modulate this we just set
P(t)=sin ( (w+FM(t))*t)
However, if we can do this we can do the same thing with the pressure of green
Re:How does frequency really work? (phycics questi (Score:2)
Re:How does frequency really work? (phycics questi (Score:2, Informative)
When things were analog, it was simply a matter of pumping out enough noise or frequency-matched garble to confuse radar sets and other RF-based equipment.
HARM missiles home in on frequencies *and* location (obviously), and will fly to last-received location, in case a clever radar/radio operator figures he's about ready to be bombed and scoots out of the area, well, the antenna set is likely to get hit.
With digital radio sets, the goal is to try and pump out enough broadband
Re:FCC ? (Score:4, Interesting)
BZZZZT!! The water absorption frequency is up around 21 GHz and the liquid absorption line is REALLY broad. I have seen a large industrial "microwave oven" running at 916 MHz - so there is nothing magical about 2.4 GHz.
The reason that 2.4 GHz is widely used is that most countries have agreed on the use for ISM (Industrial, Scientific, Medical). Other users of the frequency must tolerate interference from these sources, which makes it undesirable for licensed services.
Re:FCC ? (Score:2)
Without reading the article - I would guess that "optimality" is more of a good compromise - penetration gets better at lower frequencies (reason for using 916 MHz in the "industrial microwave oven") and being able to "brown" the foods by surface heating. Another reason is smaller nodes in the standing waves inside the oven cavity.
Heck, I remembering reading an article from an early 1970's issue of QST about a resonant cavity made with a ga
Re:More Interesting Questions For You Today (Score:2)
LMFAO
the slashdot hit squad is now on its way to your door.....