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The Myth of Radio Spectrum Interference
Selanit writes "Just came across a fascinating article on Salon about a technologist who claims that there is no such thing as "interference" in the radio spectrum. He argues that interference is a symptom of inadequate equipment, not a fact of nature, and that with improved transceivers we could open the spectrum up to high-quality broadcasts by anyone. Reference is made to the GNU Radio Project. Neat stuff." We've posted other stories about this. I wonder if the "color" meme will catch on.
If Reed is right, nearly a century of government policy on how to best administer the airwaves needs to be reconfigured, from the bottom up.
Based on the power that Television companies hold, does anybody really think this is going to happen? We have a hard enough time with the record labels, now they want to go up against people like NBC?
Great idea. Unfortunatly, it would never happen without serious reform within the Gov itself.
Not that I don't like making waves, but one step at a time.
Just my humble opinion,
SirLantos
The flying hamster of DOOM rains coconuts on your pitiful city.
This article is complete bunk. Yes, its true that radio frequencies are like colors. So imagine this scenario: you are receiving signals from someone who is using 'green'. They are flashing a huge green light, and you can pick up the pulses they are sending by being bathed in the green light. Now someone else comes along and also starts flashing a huge green light. You can't read the signal any more, because there are now two huge green lights bathing you with their signals. How can you tell which pulse is coming from which light? You can't! That's interference.
All is Number -Pythagoras.
Radio's basic signal function defined in software? Sure, "Maximize your bandwidth with our new RadioBooster!!!" (at the cost of your neighbors).
While this guy might have a point - the current FCC policies on RF spectrum might be a bit outdated, I would be careful with deregulation here.
Large radio broadcasters love to claim this when there is a threat of a new station being added in their market. Not because there is a possibility of interference if the frequencies are close - they're scared of competition.
Well made and tuned equipment can eliminate any chance of interference and allow for more radio stations within an area. However, organizations like NAB (www.nab,org) and now, the FCC stonewall any attempts to open up the airwaves. At one time, there was a proposal to allow low power broadcasters to operate, unlicensed, if they could prove they weren't interferring and accept the interference from other channels. It was approved but still puts the "little guy" at a disadvantage: http://www.fcc.gov/mb/audio/lpfm/.
If there ever was an "ol' boy network", it's broadcasting. If you want to broadcast legally, you're looking at dropping half a million in legal and license fees alone before you buy your first piece of equipment.
Sit back and relax as Windows 98 installs on your computer.
Reed's article is based on the observation that Maxwell's Equations are linear (for most materials) and that, therefore the waves pass through each other without modification (again, unless you're in pretty exotic environments --- early universe, etc.) The problem with interference arises because of imperfect spectral content and non ideal antenna response for both transmitters and receivers. Interference is like being at a party: There are a lot of people talking, and your ears hear in all directions, so you have to be near the person you're trying to talk to.
... the reason that it works is that your eyes have very fine angular sensitivity (high quality antennas) compared to your ears.
For a variation on this theme, there's an interesting moment in a movie (Frankie and Johnnie?) where there's a terrific racket in a diner, impossible to understand anything, but a cook and a clerk are communicating easily --- by sign language. Consider also those occasional TV images of the Wall Street pit traders flinging gang signs at each other
Spectral purity and antenna quality limitations can be overcome --- by money. You can build higher quality receivers and transmitters, bigger antenna installations but it costs money and space in fairly unavoidable ways.
Reed is also wrong from a regulatory level. It's not just the FCC that you'd have to work with, but the ITU. Those pesky radio waves have this interesting habit of leaking over borders on the ground, and pretty much everywhere down here from satellites.
There are pretty good reasons to pick on modern broadcasting: crappy content, media concentration --- but "broadcasting" is not one of them. Those great big transmitters permit the use of very dumb receivers with poor sensitivy. The very simplicity and asymmetry of broadcast provides tremendous economic and technical appeal, and I'd be amazed if it ever went away.
Far more interesting is the glacial progress of DTV in broadcast.
with improved transceivers we could open the spectrum up to high-quality broadcasts by anyone
While this is *techniclly* correct, On could also say that A knife could be built that can cut a loaf of bread into infinite pieces, if we could design it to cut sub-elementary particles. Why are we not making knives that can do this? Because the technology isn't there, and if it was it would probably be cost prohibitive.
There are many concepts that, if tweaked to the current technology, could be greatly improved. However, keeping old technology also has it's merits: Firstly, it's proven technology so all quicks are known or resolved; New technology undoubtedly has more problems. Even the threat that new technology has more problems, people will not use it. Also, changing to a new kind of technology require huge investments. New technology has to be pretty profitable if it is to overcome the investments made in the old one.
This principle is part of human nature: People get used to some kind of technology/ideas and stick to it. Even when these concepts stop to be meaningful. I refer to the Querty-effect: Old typewriters had little pins with letters on them which hit an ink-soaked ribbon and presses it onto the paper. To prevent these pins from hitting eachother (which happened a lot), the qwerty keyboard was invented. The most abundant letters in English were as far apart as possible to prevent collisions. But a computer doen's have pins, so why do we still use a qwerty keybaord?
But also think of buttons in programmes: You press buttons in real life, why show them on a screen and press them with a virtual hand (the mouse cursor)? There are many more examples; the radio/TV frequency story if Mr. Reed being one of them.
The problem usually isn't the technology, it's the ideas that need to be changed. But sometimes technology improvements do get through, e.g. the DVD is nothing than an up-to date CD. MP3-player replacing the old walkman. Telefones replacing the telegraph.
Things change, ideas change. Some want to accellerate it, some want to slow it down. In the end, things just change at the rate they do and, as harsh as it sounds, there's nothing you can do about it. It just takes a little time...
aspect of this article are total bunk. However, I do think we should rethink our spectrum.
High quality broadcasts for everyone is a pipe dream. Want to know how that works out? Check out our Citizens Band. Not pretty at all.
I am in the process of getting an amateur radio license again. HAMs do more with less spectrum than just about anybody. Doing this has made me rethink spectrum allocations and how they are wasted. The amateur bands have very reasonable band plans that allow for a number of uses and work well.
Our primary problem with spectrum use is the band planning, not the avaliable resource. (Which is limited no matter what this guy says.)
Commercial and military uses basically get what they ask for and they ask for everything they can.
Comes back to this really. We live in a competitive culture. We have given companies the same rights we have. They are better competetors than we are.
We lose.
Our fault.
Blogging because I can...
You will need:
- A sheet of college-ruled paper
- A green marker
- A copy of Moby Dick
Open up the Moby Dick to the first page. Then, with the marker, start transcribing the text onto the sheet of paper -- "call me Ishmael" and all. When you run out of space, don't get more paper -- instead, just go back to the top of the sheet, and overwrite the text that's already there. When you are done with the entire Moby Dick, mail the sheet to Mr. Reed.Since there is no such thing as color spectrum interference, Mr. Reed should be able to read the entire Moby Dick just from the one sheet of paper.
This revolutionary discovery will surely eliminate waste, and save our rainforests... If only the paper-making companies didn't want to keep it under wraps !
>|<*:=
YOU CAN'T TRANSMIT AN ARBITRARILY LARGE AMOUNT OF DATA/SECOND ON A FINITE AMOUNT OF BANDWIDTH
You mean through an information channel of finite bandwidth.
However radio paths exist in a 3D environment, which can multiply the number of channels of finite bandwidth. Reed's point is really about mesh networks and using spatial diversity receivers to create more "pipes" (i.e. channels) through the air at the same frequency.
In his concepts, mesh networked receivers can even work together to untangle interfered signals. It doesn't lead to infinite information capacity, but it sure is higher than what most radio spectrum is used for today.
Reed really shouldn't say that there isn't interference...it is that interference as physicists know it is a useful and constructive tool (as in holograms), unless your radio architecture is stupid (i.e. uni-frequency, uni-source broadcast).