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Why Everything Wireless Is 2.4 GHz

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Re: Why Everything Wireless Is 2.4 GHz

#21

Post by Confusion »

CamperBob wrote: post #9
flatulent1 wrote: post #5

Earlier quoted context omitted.

I'm surprised the article didn't mention that a ham band partly overlaps the 2.4 GHz WiFi frequencies. In theory at least, anyone operating WiFi gear isn't allowed to interfere with licensed services, including hams. Also, our unlicensed WiFi gear must accept any interference including that which "may cause undesired operation"... from anything, including the neighbors WiFi. (see FCC notice in U.S. WiFi product manua…

Microwave ovens getting water molecules so excited at 2.4 GHz ties in with WiFi performance. It's a tidbit the head tech at a local wireless ISP didn't even know... 2.4 GHz WiFi is particularly prone to fading in fog/rain because water absorbs energy so efficiently at that frequency. No, no, no, no, no. http://earth.esa.int/applications/data_util/SARDOCS/_icons/c...

Well, that's not very helpful, because he's not talking about the standard atmosphere, but about a particularly humid atmosphere.

Re: Why Everything Wireless Is 2.4 GHz

#22

Post by yread »

mfukar wrote: post #20
flatulent1 wrote: post #11

Earlier quoted context omitted.

I wonder what level of humidity that 2 dB per kilometer figure is for? Is that typical or worst case? At 20 kilometers (about 12.4 miles), a distance this ISP is trying to serve some customers at, that 2 db becomes 40db. Overcoming an additional 40 db loss would require increasing the power by a factor of 10,000 times. They're using amplifiers and directional antennas but the fade margin is nowhere near 40 db. And th…

Are we still talking about WiFi? The one with coverage limited in fractions of a kilometer? Achieving 20 km coverage radius (or even targeted coverage) sounds like a sisyphean task to me.

I dont know how they do it but the longest range wifi link is 382km[1]. And 10 km with good directional antennas is not that special, really.

[1] http://www.slideshare.net/1ereposition/long-distance-wifi-tr...

Re: Why Everything Wireless Is 2.4 GHz

#23

Post by muon »

mathias_10gen wrote: post #13

They didn't really cover the important question of why modern wifi still uses 2.4GHz rather than the much wider 5GHz spectrum. Anyone living in a crowded apartment building owes it to themselves to get 5GHz routers so avoid interference with their neighbors' wifi. For some reason its getting harder to find 5GHz access points and most online stores don't let you search by frequency band.

5GHz opened up pretty recently. This along with high of cost of making a 5GHz radio and wider acceptance of 802.11ng is reason for Wifi still sticking to 2.4 ISM band.

Re: Why Everything Wireless Is 2.4 GHz

#25

Post by gcb »

moultano wrote: post #15

Imagine what crazy technology we'd have if more spectrum was available for free-for-all access. Generally I think the FCC does a reasonable job, but I really doubt FM radio is really the best use of that huge swath of beautiful spectrum. They should think about pulling out little regions of spectra normally used for other things and let the market try to do things with them without restriction. They might end up too…

> Imagine what crazy technology we'd have if more spectrum was available for free-for-all access.

Well, FCC only regulates the U.S., right?

what happens in countries where there's more bands available? i remember a router that allowed me to select twice more wifi channels if i mention i was in japan...

Re: Why Everything Wireless Is 2.4 GHz

#26

Post by gcb »

gcb wrote: post #25
moultano wrote: post #15

Imagine what crazy technology we'd have if more spectrum was available for free-for-all access. Generally I think the FCC does a reasonable job, but I really doubt FM radio is really the best use of that huge swath of beautiful spectrum. They should think about pulling out little regions of spectra normally used for other things and let the market try to do things with them without restriction. They might end up too…

> Imagine what crazy technology we'd have if more spectrum was available for free-for-all access. Well, FCC only regulates the U.S., right? what happens in countries where there's more bands available? i remember a router that allowed me to select twice more wifi channels if i mention i was in japan...

btw, one thing that wouldn't happen is me having to move the Wii away from the home theater with wireless back speakers >:

Re: Why Everything Wireless Is 2.4 GHz

#27

Post by notauser »

moultano wrote: post #15

Imagine what crazy technology we'd have if more spectrum was available for free-for-all access. Generally I think the FCC does a reasonable job, but I really doubt FM radio is really the best use of that huge swath of beautiful spectrum. They should think about pulling out little regions of spectra normally used for other things and let the market try to do things with them without restriction. They might end up too…

The nice thing about 2.4ghz is that it's pretty well attenuated by walls.

That sounds like a disadvantage... but it does let you cram a lot of transmitters into a city. If everyone had a 102Mhz transmitter the resulting network would be like a class room full of five year old boys who each had their own megaphone.

Re: Why Everything Wireless Is 2.4 GHz

#28

Post by notauser »

gcb wrote: post #25
moultano wrote: post #15

Imagine what crazy technology we'd have if more spectrum was available for free-for-all access. Generally I think the FCC does a reasonable job, but I really doubt FM radio is really the best use of that huge swath of beautiful spectrum. They should think about pulling out little regions of spectra normally used for other things and let the market try to do things with them without restriction. They might end up too…

> Imagine what crazy technology we'd have if more spectrum was available for free-for-all access. Well, FCC only regulates the U.S., right? what happens in countries where there's more bands available? i remember a router that allowed me to select twice more wifi channels if i mention i was in japan...

3 extra. 1-11 (US) 1-13 (Europe) 1-14 (Japan).

American MacBook Pros (used to?) come locked to 1-11 with no way to change that, which really sucked if you ever traveled anywhere.

Re: Why Everything Wireless Is 2.4 GHz

#30

Post by rxever »

"A 900-MHz system will be more easily able to broadcast through a multifloor house, but a 2.4-GHz system will have a longer range (if unobstructed)" - isn't it so that lower frequencies can penetrate longer distances without obstructions? And higher frequencies are better in short distances? If they get interupted they can easily replace the "damaged" data with new ones since it's high frequence(ability to transver more information in the same time).
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