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New Lighting Technology To Wipe Out Wi-Fi Access?
Richard Evans writes "Focus on Broadband Wireless Internet Access has an article
[cached by google ]
on the potentially catastrophic interference to Communications Users Of The 2.4 GHz Band e.g. Wi-Fi, DECT and Bluetooth by a new lighting technology called RF Lighting."
The website it cites: Link is *still* blank at least a year after it was cited.
The article also goes into very little detail as to *why* this new lighting technology will be either popular nor necessary. It's vaguely referred to as "very high efficiency."
Summary: Call us when you have real news.
That's why 2.4 GHz will rapidy become unreliable for wireless LANs.
Luckily, 5 GHz wireless LAN products (802.11a) are now becoming available (called WiFi-5, I believe). Since they
do not use the 2.4 GHz frequency range, they will not be affected by this issue.
http://www.fusionlighting.com/technology.htm
Read the article:
Eventually the FCC decided to offer a Faustian bargain: Industry could use the existing ISM spectrum if they adhered to certain technical limitations with no expectation of protection.
In other words, as long as you stay within the 2.4 GHz spectrum, you can do what ever you want, as long as you didn't expect to be protected from interference from other devices.
Bluetooth and 802.11B have already violently clashed in this space already. I have seen it myself - with a 802.11B card in one PCMCIA slot, as soon as I turn on a bluetooth card in the other slot, my average ping time on the 802.11B goes up considerably.
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The company I used to work for did the very first large scale (non-test) installation of their lighting products in the US. It sounded like an awesome product. It would provide MORE light for LESS power with LESS maintenance.
:)
We installed a HUGE area with this stuff (took many months to do the install). A year later we ended up yanking every bit of it out. Why? Well, there were SEVERAL technical problems with these things that they hadn't worked out. The short version of how they work is that they irradiate a glove with some sulfur in it with microwaves and turn it into a glowing plasma. Well, that stuff is a bit hot, so you have to continuously rotate the 'bulb' This rotational part breaks, so the light breaks.. the reflectors can't stand the heat, etc.
so don't worry.. they are in bankruptcy...
This looks like a niche product. It's not even clear that Fusion Lighting is still in business. Their web site is essentially defunct. Their web site used to have some nice pictures of glass bulbs and more info, but now, it's just a starter page.
The really stupid part about that is eventually 5 GHz will have the exact same problem.
Read the article more carefully. It states a section in the 5 GHz range reserved for communication devices only.
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- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
Yeah, those were the promises. I really wish it would have worked out better. a few details of the problems:
#1 - the BULBS might last 11.4 years, but the magnetron that shoots the microwaves into the bulb, and the motor that turns both the fan (that cools) and the bulb (to prevent the plasma from burning through the glass of the bulb) burn out VERY fast. 1st generation units had 50% of the magnetrons burn out within 6 months. We were told this was due to the power supplies. 2nd gen units seemed much more solid in the power department.
#2 - the fan motor / bulb turner would break/no longer rotate. It didn't appear to us that they had a high enough quality motor on these... a large percentage of them would break within 3-6 months. If the motor stops turning that bulb it goes POOF when the plasma burns through.
#3 - the light is NOT white. it is kinda green.. pretty noticibly green actually. People do not seem to like greenish light. Most of us are used to either a yellowish or blueish tint. We had several people complain of feeling sick.. Dunno why green light would do it, but it didn't make our customer happy.
#4 - the high temps that these units achieve lead to a break down in both the reflectors and in plastics used to feed the light into useful places. We replaced many lights with one of these units (like a 5 to 1 ratio maybe) and then used a plastic tube as a 'light pipe' to deliver the light where it was needed. The material in the reflector would either a) degrade, or b) get deposited on the plastic tube due to the high temps. Also the plastic joins on the tubes would degrade seriously in a short (months) time frame. Maintenance costs were incredibly high.
In short: great idea, bad implementation. I have no doubt that if the engineering of these untis was higher (with the subsequently higher cost) that these would work. But then these already pricey (very) units would not be able to compete with existing technologies (like metal halide).
Crow
You obviously don't know much either. Incandescent and flourescent lighting both "flicker" because they are powered by alternating current. Incandescent lights work by heating a wire so hot it glows white (that's what "incandescent" means). Flourescent lights work by using high voltage to excite a gas. That gas emits UV light which strikes phosphor compounds on the inside surface of the tube. These compounds emit visible light when struck by UV (they "flouresce," hence "flourescent").
Whether or not flicker is visible depends on the "persistence" of the phosphors and the cooling rate of the incandescent wire. They all flicker. The flicker is a result of the alternating current. Of course, you can use DC to make an incandescent bulb work. You can't do that with flourescent lights because AC is required to keep high voltage coming out of a transformer (transformers only work with changing magnetic fields - put DC into them and you only get output voltage when DC comes on and again when it shuts off).
I'm not an RF expert, but I'll tell you why I personally don't worry. The 2.4GHz band was set aside as an ISM band precisely because it is very well absorbed by water. Which is how a microwave oven works. The several hundred watts of microwaves emitted inside of the oven will bounce off the metal walls until they get absorbed by something. Usually this is your food. Or more accurately, the water in the food. Which is why it heats it up so well.
You don't want to be around the output of a microwave oven for precisely the same reason you don't want to stick your hand on the stove when it's on. You'll get burnt, plain and simple. With microwaves, you could actually get burnt on the inside. Most internal organs don't like extra heat. Witness how little of a fever you have to have before it becomes life threatening.
Now, back to wireless devices. The power output of your typical 802.11b device is between 30mW and 100mW. A typical microwave oven will produce up to 1000W of power. 10,000 times the power of your wireless card. Can the output of your wireless card or phone heat up your head? Of course. Will it heat it up enough to matter? Not likely.
I've found the description at PhysicsClassroom to be useful for explaining light. Now, it's geared toward high school students, and as such is not strictly accurate (most notably, light is a transverse wave, whereas the picture seems to imply that it is longitudinal), but at the least it answers the often asked question of "why does light only travel at c in a vacuum". It's a good site overall, I'd definately recommend it.
Effectively, a particle in quantum physics is a cohesive bundle of energy. We measure the mass of that energy in "electron-volts" (eV), which you can think of as a electron-level volt-meter. It's similar to measuring the voltage of a battery; we can't directly see how much charge is in a battery, but we can see how hard it pushes / pulls a test charge. Likewise, we can't see how big a proton or electron or up-quark is, but we can see how it affects other particilars of similar size (e.g. an electron as a reference point). Due to the massive deviances in particular masses, it's hard to know for sure if a photon is truely massless (even though it carry's energy). post-modern quantum physics speculates that photons, neutrino's, and even gravitons have mass. (Yes, this does imply that gravity has a weight of it's own. More precisely, the emision of the force of gravity adds weight to the space between two particles.)
The substance of the particle is subject to debate. String theorists believe (if I'm not mistaken), that all particles are made of strings of something (which we'll never know), and that those strings wrap around space (which we also can't know it's consistency)- warping it and being stretched by it.
Another point of view is that of Ether, which we tend to hold on to, since quntum physics is so similar to our percieved world that it would be a shame that such patterns could not be known to persist at different scales. One theory that I like is called
Aethero-kinematics. It's based on the idea that tiny hard balls (perfectly elastic, like steel) bounce about in different patterns (mostly vortexs, like in a drain). All energy is in the form of the kinetic energy present from these bouncing balls. The cohesion allows for quantum particles. The augmentation / contraction of mass (via Einsteins special relativity) is explained away the same as Mach-theory (where an the air-resistance increases exponentially as you exceed the speed of sound). The "speed of light" is merely the average velocity of the balls. The explained reason why we can't perceive relative motion against the ether of space is that earth is not moving with respect to the ether about it; nothing does. Motion is only ever a small fraction of a difference in speed from it's surrounding ether. Lastly, the concept of experimentally determined transverse nature of light is nicely explained away in Aethero-kinematics in common sence ways. (having to do with the probability distribution of collisions of particles in an ideal gass)
Modern quantum physics simply ignores the what's and hows of particles, and simply says they exist with certained measured properties.. That's it, that's all, that's ugly. Because of this, I tend to look at models like the above (so long as they fit the experimental data) as a way of putting my mind at ease. The problem is that until the theory's demonstrate validity, we can't take the analogies they present (ideal gas, or strings) too far in extrapolation / interpolation.
As for waves (also questioned in this thread): a wave is a regular periodic fluxuation. Longitudal waves are like a wripple in a violin string or cresting waves on the ocean. If you just look at a single water molecule, however, you'll see that it doesn't move forward, but instead up and down (just like a boat). You could also look at a police-car flashing light. The color of the light slowly fluxuates from red to blue and back again in a definite period. If you took a cardboard box and punched a hole through it, you'd see on a wall the color fluxuation. If you look more closely, the fluxuation is merely caused by a rotation of two light bulbs. Photonic transverse waves are the fluxuation of the state of the photon from electric to magnetic (hense the phrase, electro-magnetic). An electron sitting still has only an electric field (which applies force to other adjacent electric objects (pretty much anything but a neutron; and even it, if you break it down into quarks). When an electron moves in a circle, it applies a strange perpendicular force which only affects other spining electrons. You can understand that it's different than charge because two electrons are attracted to each other when they counter-rotate (or rotate, I forget which). It turns out that rotation has nothing to do with it; it's the motion of the electrons (but the math gets harder). So here are two completely independent characteristics of a charged particle. As it turns out the transmission of photons accounts for both activities, so the photon is both a messenger particle for magnetic fields and charged-fields (electric-fields). Since a photon must always travel at the speed of light (relative to it's medium), it should be apparent that it works within a magnetic context (e.g. charge in motion). It seems that the photon fluxuates between the two in a sinusoidal pattern with respect to time (independent of it's physical motion). The "frequency" of the photon is the speed at which it oscilates a full transition between electric and magnetic. Such a periodic transverse wave-pattern has many astonishing properties. Most notibly that the same beam of photons when reflecting back apon itself can have interference patterns; namely that the waves can cancel each other out (or amplify one another). The best example of this is to take a beam of monochromatic polarized light and send it through a cardboard box with two slits on it. On the other side of the box, you should see a periodic pattern of light and dark spots.
I'm not a physisist, but I am an electrical engineer, so I have more than a lay understanding of the principles.
-Michael
-Michael
Here's your requested correction.
: users.ox.ac.uk/~jsw/Schroedinger.html+schroedinger %27s+cat&hl=en
Schroedinger's cat test is a little more sadistic than that.
You have a box you can't see into. Inside the box you place a vial of deadly poison that will produce instant death if it's broken. Close to the vial you position a hammer that's cocked. It can go off and break the vial at any time.
After you stick the cat in the box, you close it up. What follows is an incredibly simplified base for Quantum physics.
At any time, the hammer is both cocked and uncocked, the vial both broken and unbroken, the cat both alive and dead. None of the objects are in a definite state until you take a measurement, in which case you determine all three.
The nature of light is similar. It is both a particle and a wave, depending on how you measure it. In most experiments, researchers focus upon either light's particle aspects (by counting photons, for instance) or wave aspects (by measuring an interference between electromagnetic fields, to cite a simple example). Hence the dual nature of light and the relation to Schroedinger's cat experiment.
A good page with further explanation is cached at google here http://216.239.35.100/search?q=cache:fbyF8_1R6_4C