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Thread: Wireless Range

  1. #61
    Senior Member Thorn's Avatar
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    Quote Originally Posted by ShadowKill View Post
    Oh no, I understand fully brother, I was speaking on behalf of those less informed and too shy/nervous/whatever to speak up.
    Yeah, I understood why you asked. In the same vein, I give the KISS answer, but just quoted you for the sake of continuity.
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  2. #62
    Senior Member ShadowKill's Avatar
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    Quote Originally Posted by Thorn View Post
    Yeah, I understood why you asked. In the same vein, I give the KISS answer, but just quoted you for the sake of continuity.
    Oh continuity, the bane of many an auditee.... Speaking of which, I need to update my continuity binder, thanks



    "The goal of every man should be to continue living even after he can no longer draw breath."

    ~ShadowKill

  3. #63

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    Quote Originally Posted by Nokii View Post
    I'll add that there is one more thing. MIMO.

    MIMO enhances NLOS (Non-line-of-sight) propagation and cancels reflections.
    Good to mention MIMO, but that's not a necessary part of a radio link budget ("the Prez" covered the basic parts nicely in the original post). MIMO more of an "extra feature"...and remember it must be on both receiving and transmitting sides to work. If your laptop card has MIMO, but not the Access Point, it won't work. And may not always be needed (ex: in LOS links MIMO won't really give any additional benefit)

    MIMO isn't required in 802.11g, but has been used in some proprietary equipment, not just to increase the range, but thruput as well since they use it to transmit/receive on 2 channels instead of just one (ie: jumping from the standard 54Mbps to 108Mbps). With 802.11n MIMO will be standard. MIMO is also being incorporated in furute releases of HSPA and is used in WiMAX.


    PS- WiFi has also had a built in feature to help overcome multi-path propogation losses since it was officially released in 1999 called OFDM.

    http://www.radioraiders.com/wlan-datarates.html

    Since wifi channels are quite large (20Mhz) it can take advantage of that wide bandwidth by breaking the signal down and spreading the signal over the full 20Mhz. This makes it less prone to multipath fading compared to narrowband signals (like say GSM which transmits in 200khz channels).
    The link budget is not a problem, we intend on splitting the bill...

  4. #64
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    I was only going of what I know about radio waves with regard to FM transmission, I figured it might apply to wifi too - obviously not. Don't be too harsh, I'm only trying to add to the discusion.

  5. #65
    Senior Member Thorn's Avatar
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    Quote Originally Posted by madferret View Post
    I was only going of what I know about radio waves with regard to FM transmission, I figured it might apply to wifi too - obviously not.
    It doesn't apply to FM either. The fact that it was based upon your experience with pirate radio though, doesn't surprise me. Based on my experience, what the average pirate radio moron don't know about RF could fill several books. The real shame is that there isn't a bounty on such 'pirates'.

    Quote Originally Posted by madferret View Post
    Don't be too harsh, I'm only trying to add to the discusion.
    SLK001's answer wasn't harsh. SLK001 was just stating the truth. I was being harsh above, and I admit it.

    Quote Originally Posted by madferret View Post
    I'm only trying to add to the discusion.
    You probably shouldn't add to a technical discussion if you don't know the technology. While you at least understand wavelengths, you might want to learn more on antenna design. I would suggest the ARRL Antenna Book as a good starting place.
    Thorn
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  6. #66
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    Quote Originally Posted by Thorn View Post
    You probably shouldn't add to a technical discussion if you don't know the technology. While you at least understand wavelengths, you might want to learn more on antenna design. I would suggest the ARRL Antenna Book as a good starting place.
    Point taken.

  7. #67
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    Quote Originally Posted by madferret View Post
    Lots of great info on antennas here guys but I've found out the hard way during a brief stint in pirate radio that to get the best signal strength (ie. best propagation) you need to make sure that your aerial is at least 1 wave length off the ground and should be 1 wavelength long.

    Since 802.11 is 2.4 GHZ and wavelength = speed of light / frequency

    Wavelength = 299,792,458 / 2,400,000,000 = 0.12491352416666666 meters

    12.49 cm = 4.9 inches

    So if you want best results from your antennas make sure they're at least 4.9 inches away from the walls or desktop they're sat on (how many of us have them sat in a corner?) and ideally they should be 4.9 inches long.

    Of course since each wifi channel has a slightly different frequency we could tailor an antenna to a channel:

    ch1: 2.412
    ch2: 2.417
    ch3: 2.422
    ch4: 2.427
    ch5: 2.432
    ch6: 2.437
    ch7: 2.442
    ch8: 2.447
    ch9: 2.452
    ch10: 2.457
    ch11: 2.462
    ch12: 2.467
    ch13: 2.472
    ch14: 2.484

    Though I think we'd only be talking about a milimeter or so probably not worth it .
    I can't say that all the info you gave is correct, some of it might be. For example the height of the antenna to the ground.

    http://en.wikipedia.org/wiki/Fresnel_zone
    Aquillar> hey, you guys ever play kmem russian roulette?
    Agnostos> I don't believe I have. care to explain the details?
    Aquillar> dd if=/dev/urandom of=/dev/kmem bs=1 count=1 seek=$RANDOM
    Aquillar> keep executing until system crashes
    Aquillar> person that crashes system has to buy beer
    Agnostos> lol
    Agnostos> I wonder if I can sneak that into a server startup script here.

  8. #68
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    Default Hawking == landfill

    Quote Originally Posted by -=Xploitz=- View Post
    I spent $80 USD on a device called a "WiFi Signal Booster" made by Hawking Technology. IMO..this thing is a complete piece of shit and a waste of money.
    In my experience, every piece of Hawking Technology hardware has been a complete piece of shit and a waste of money.

    When something comes with a 30 or 90 day warranty, you know it's crap.

    This is the garbage that local big-box stores sell with rebates that let you get a router for $1. Then they hose you for the setup charge, which of course you have to pay again when your POS router dies in 6 months.

    Seen it with many customers, and I've got a lot of them to swear off Hawking crap.

    Didn't think I'd have to convince you.......

  9. #69
    Just burned his ISO Dimus's Avatar
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    Talking Wifi Signal boost with a can..

    I used a baby formula can and cut a small hole big enough for the USB wifi card to fit into. Pushed it in like 70 percent of the way and connected the Cable extention or whatever you wanna call it and BAMM! I got 20 percent increase in signal.. Pretty sweet.. It's posted all over the internet so its nothing new..
    +Dimus+

  10. #70
    My life is this forum Barry's Avatar
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    Quote Originally Posted by Dimus View Post
    I used a baby formula can and cut a small hole big enough for the USB wifi card to fit into. Pushed it in like 70 percent of the way and connected the Cable extention or whatever you wanna call it and BAMM! I got 20 percent increase in signal.. Pretty sweet.. It's posted all over the internet so its nothing new..
    Tetra Brik?
    Of course, if you really wanted to have some fun, go to Wal-Mart late at night and ask the greeter if they could help you find trashbags, roll of carpet, rope, quicklime, clorox and a shovel. See if they give you any strange looks. --Streaker69

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