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Thread: Alfa setup

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  1. #1
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    Default Alfa setup

    There are multiple versions of the alfa.
    On one version the alfa needed 2 usb ports to power the device?
    Is this the same as the Y cable from a previous thread?

    I have a long range stationary setup in planning.
    dish/grid antenna->alfa->PoE hub->UTP down tower and into house.
    UTP->PoE injector+ethernet-USB converter.

    Some of the points in this setup are hazy to me.
    Does such a hub/switch/router exist?-I found one for verizon wireless USB cards
    Would chipset for the hub would be important when interfacing with BT?
    Or would BT see through the Hub into the alfa?
    Will the PoE blow up my USB host interface in the laptop/PC?

    It seems I am making this more complicated than it should be but sitting on top of a tower with my laptop surfing the internet does not sound right.

    I could sit my laptop on the tower and share the internet connection with the builtin ethernet adapter, but then Ive dedicated a laptop to a sky burial.

    Help is appreciated.

  2. #2
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    Default

    I am at a loss as to what you are trying to do...

    Are you trying to put a laptop on a tower for better reception?

    Are you trying to put an antenna on a tower for better line of sight?



    JT

  3. #3
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    Default

    well yes and yes, sort of.

    I am putting the antenna on the tower for better LOS.
    The prospect of putting the laptop on the tower is the alternative to the PoE cable solution, so that I dont have to run a coax into the house and lose dbm

  4. #4
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    seems kind of foolish in my book. Isn't your wireless router in your flat/apartment/house?

    Or are you trying to circumvent your works router by streaming from your house internet to your work, provided you live close enough?

    If the later, there are far better methods of doing that.


    JT

  5. #5
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    Perhaps Im not explaining myself properly.
    There is no wireless router near my laptop.

    I live in the woods.
    I am setting up a network with a friend to play Halo3 over system link.
    He lives 5-10 miles away.
    So Im setting up a point to point.

    I have included the alfa in the plan just to throw in BT3 functionality, otherwise Id just use an access point.

  6. #6
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    An interesting question, albeit not really related to backtrack.

    If you both have Alfa's, you could set them up with parabolic dishes (be it either the popular cardboard windsurfer parabolic reflector, something you stole out of your mom's kitchen, or a full blown dish). Point them right (a good laser could be a great asset here), and enjoy

  7. #7
    Just burned his ISO imported_RaderCad's Avatar
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    Talking Not legal in any country.

    Quote Originally Posted by xxXen0xx View Post
    Perhaps Im not explaining myself properly.
    There is no wireless router near my laptop.

    I live in the woods.
    I am setting up a network with a friend to play Halo3 over system link.
    He lives 5-10 miles away.
    So Im setting up a point to point.

    I have included the Alfa in the plan just to throw in BT3 functionality, otherwise Id just use an access point.
    Well here is some information but probably not any help.

    To get that kind of range you may have to go to a Yagi antenna, to use the highly directional Yagi antenna you will need a direct line of sight to the other point. No obstructions! The alpha is rated at 1/2 Watt (500 milliwatts) this gives you a 27dBm gain from your Alpha and possibility 24dBi from a Yagi (there may be higher gain antennas out there.) Now the problem is this may be already way over the legal maximum for the USA but I am not worried about that, you might have to be. The range at 11 mb/s goes something like this. 27dBm will give a guaranteed 11 mb/s connection at 450 meters (clear air no obstructions). Now for every 6dBm(i) added you double the range (clear air no obstructions.) So with the 24dBi gain Yagi you have 4 sixes or 900 meters, 1800 meters 3600 meters and 7200 meters is the final answer for the described rig, or something like 4.47 miles (clear air no obstructions, get the hint yet?) To get out further you will need more of an amplifier and / or more of an antenna gain.

    Since the antenna gain is topped out you will have to go with a different type of wifi adapter and a larger amplifier between it and the antenna, 4 watts is 6 dBm more than the alpha. Now you are in the highly illegal area of microwave radio. You will also need to be very careful as you are getting into some very harmful microwave cooking power. The first described rig, Yagi and Alpha 51dBm, is already over 125 Watts (Do not stand in front of the antenna when it is transmitting.) Try looking up dBm to watt conversion tables or calculators to see what I mean. The scale for dBm to power flattens out very quickly over 40dBm in fact from 46dBm to 47dBm it takes 10 Watts for that one dBm. For instance if you wanted to double the range of the 51dBm rig you would have to add another 6dB for 57dBm total. How you would do that is find a 4 Watt signal transmitter booster and signal receiver booster. You will need to amplify the incoming signal as much as the outgoing signal. Unless your friend matches your rig then the out will be good enough. Now you are over 500Watts of total combined power and out to about 9 miles (clear air no obstructions).

    The problem is, if you are in the USA, you can't purchase these amplifiers unless you are a licensed radio operator (I think an amateur license will do.) You may want to settle on another type of radio rig for this setup, one not quite so expensive, dangerous, or illegal. It could be a bad sign if there are cooked squirrels and birds at the bottom of your antenna pole.

    I think it would be cheaper to just move closer to your friend. Or just drive when you want to play games together.......

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