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WiFi, Light Bulbs, And The FCC
JFMulder writes "According to Cringely, 802.11 WiFi wireless networking is going to get in lot of troubles when Fushion Lightning starts marketting low-power light blubs which causes interferences with Wifi signals. Read about it at I, Cringely. Supposedly the new kind of light bulb is a real electricity saver and can wreck havoc to wireless networks in a half a mile radius. So what would you prefer? Wireless networks or low cost light bulbs all around the country to save more and more on electricity?" Update: 06/13 03:52 GMT by M : Cringely confused the FHSS-or-DSSS 802.11 standard with the DSSS-only 802.11b standard, but the general warning about the potential for interference is certainly troubling.
This was posted -- what, two or three weeks ago? Come on guys!
The old story even had a poster who mentioned that he'd used the lighting technology Cringley mentioned, and it's nowhere NEAR primetime, so it won't be causing probs for several years, if ever.
LED's are not cheaper right now if you look at them in terms of lumens per dollar. They are also not very bright. You cannot use LED's as the headlights on your car, for instance. As the prices continue to drop, there will be more and more uses, but the technology needs to develop more high-power, high-output LED's in order to take over the place of incandescent and halogen bulbs.
My other first post is car post.
er,
Don't Wi-Fi cards output in the 20-100 milliwatt range usually? I'd presume that these lights only produce a minor amount of 2.4ghz of output or the FCC'd be all over them. The 2.4Ghz band *is* regulated still - there are limits on power output etc.
Anyway, it all depends on how it is distributed across the 2.4Ghz spectrum - I presume it's peaked being RF excitation, which normally means you're aiming for a narrow energy state in your gas. So, a single 500khz-wide peak with all output power going into it ain't going to hurt too much.
But the other extreme is also true - a few watts of energy, dispersed across the entire 2.4Ghz range will just wind up being a low-level noise.
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
Please read the article before you guys get all "the story sucks" -- XM radio uses this frequency band as well;
WiFi i can't care less -- 802.11a is already making headways, by the time any kind of remotely user base of the light bulbs are established, i would have (as i assume a large portion of the rest of y'all) moved onto 5.8Ghz; or drop the speed down to 2Mbps; -- DSL is only 1.5 anyway -- and if i was really gonna move that much file -- i would just pull a cable temporarily or start the transfer and get some coffee -- either way i do not see it being a big problem for WiFi.
on the other hand, i don't see the feasibility of XM radios getting an upgrade... so if these bulbs do get popular, it means XM would work everywhere except the cities. ha!
so if they are really that troublesome, we will be seeing the company getting squashed in no time; there are too much $$ at stake for XM;
My life in the land of the rising sun.
Wind is cheaper than nuclear, actually. But best case, wind can't supply more than maybe 50% of current needs, and it has other problems. Solar looks like the up and coming thing, expect to see prices fall below nuclear over the coming decade. It too has problems though, and so nuclear is still a good idea. If nothing else, nuclear power plants work even during calm, overcast days. :-) But it's too expensive to supply all our power, and unlike wind and solar, doesn't look to be getting cheaper.
Also, with breeder reactors, you're not going to run out of fuel, ever (more or less).
You're right that nuclear waste storage is more or less a non-issue though. Just stick is somewhere. Yeah, it'll leak. But so what? We've got plenty of room (note for the geographically impaired: this isn't sarcasm).
It takes very little signal power to disrupt radio communications.
.01% of its power - that would be half a milliwatt. Assume the leak is an isotropic radiator (radiates equally in all directions). So you have .5 mW (= -6 dBm) into a 0 dBi radiating antenna. Your wireless card is about +30 dBm into a +3dBi antenna - so you would have -6 dBm interference vs. +33 dBm ERP for the wireless transmitter, assuming they were both at the same place. That wouldn't be a problem.
In radio, you measure signal power in dBm (decibels referenced to 1 mW). A typical narrowband FM receiver, like a cell phone, has a sensitivity of about -120 dBm - in other words, if the phone is getting -120 dBm at the antenna port it will just barely work. -120 dBm is one 10E-12 of 1 milliwatt - or one thousandth of a picowatt.
For a wireless LAN card, I think they usually want to see about -76 dBm for a good link - that's 10E-7.6 of a milliwatt being received, or about a twentieth of a nanowatt.
Let's say the lamp is a 5 watt lamp (and from what I understand most of these lights are more like 100 watts excitation energy - these aren't your floor lamp!) Let's say the lamp leaks
Now, if the lamp is anything like the microwave pumped lamps I used to work with, you are talking about 500 watts or more of excitation energy - that's +20 dB. If the lamp leaks 1% of its signal (still small enough to have no real effect on the light output) that would be another +20 dB of leakage. You now have taken the lamp from -6 dBm ERP to +34 dBm - and you are now just as "loud" as the network card.
Also, these lamps are pumped by magnetron tubes, same as your microwave oven. These aren't nice, single-frequency sources - they spatter over a fair chunk of the band. So you cannot modulate them and use them as network nodes, and you cannot easily skip over the frequencies they use - they don't just impair one channel of a frequency hopping system, the impair many channels.
However, I have to wonder how the efficency of these lamps compares to the new LEDs on the market - it may be a moot point.
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