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Discussion in 'Electronic Basics' started by New², Sep 5, 2004.

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  1. New²

    New² Guest

    Hello,
    I'm lokking for a wifi (or other) solution to be used with microcontrollers,
    and wich is able to transmit data (+ voice optionnaly) for distance up to
    3km.
    Thanks.
     
  2. If you need 3 km range, government regulation will come into play, because
    any signal that can be heard reliably at 3 km can cause some interference at
    30 or even 300 km, and there is a finite range of frequencies available.

    I suggest a cellular (mobile) telephone.
     
  3. Guest

  4. New²

    New² Guest

    Hey,
    Thanks for your reply.
    I read some of datasheets, moste of disadvantages are :
    1- Some of them uses chanels already in use by my embedded application.
    2- The protocol used in not secured.
    2- Modules are too big to put them inside my embedded application.
    3- Small rate.
    I need to explain more my aplication.
    I'm working on PaintBall (electronic) application, something like CS game.
    Each player is able to speak to a separate player in his team or to admin
    via a voice server. Modules that i'm looking for will be able to
    send/receive data/sound(voice) in an area of about 3Km² (minimal is 1Km²) in
    a secure way, with a less of power consumption.
    If anny one have a seggestion, dont hesitate to make it here.
    Thanks for your help.
     
  5. 3 square km, or 3 km x 3 km? Not the same.

    If you want a range of 3 km, radio regulation is definitely involved.
     
  6. hamilton

    hamilton Guest

    Sub-space radios have not been invented yet.

    Time to come back to the real world.

    Is a backpack or fanny-pack too big for this application ?

    You might want to check out mesh networks.
    This sounds like a good application for mesh.

    Good luck
     
  7. Tim Auton

    Tim Auton Guest

    So you want suggestions which don't use channels you have not
    specified. I don't think anyone who reads this group can read minds.
    How big is too big?
    Is there anything you don't want? :)

    I suggest mobile (cellular) phones. GSM is hard to hack, cheap to buy
    and does data and voice. Or do you want small, secure, powerful,
    adaptable *and* cheap to run?


    Tim
     
  8. Dingo

    Dingo Guest

    how about a uniden 40 channel CB radio. Each team just uses a separate
    channel, and another for the "admin"

    BTW in this real world paintball CS why do you need to spk with the "admin",
    I mean, asking him to turn gravity off isn't going to do much. And he can't
    take a screenshot of wallhackers because I don't think there will be too
    many IRL :)
     
  9. new²

    new² Guest

    Hey,
    lol, sorry, i haven't gave a good explanation about what i'm looking for.
    Well i will give you a better idea about this work.

    1- My first version :

    The game contain weapons and waistcoats.
    1-1 : Each weapon uses a laser module, a 433Mhz radio module to
    communication with the waistcoat and few photodiodes (Players can shoot
    opponent player's gun).
    1-2 : waistcoat : this one use a bluetooth module to communicate with a
    PC (PDA, Pocket PC ... ), a 433Mhz RF module, its also equiped with two
    belt photodiodes (to read the laser information).

    The system works fine, but only in dark rooms (only soft light), i need
    to find better solutions to ensure the game working outside in daylight
    conditions (* The project have no comercial purpose, it's only for fun
    and it will be published for all PB lovers)

    Annother problem is the use of two different modules & protocol (BT &
    Simple RF comm), BT comm is limited two short ranges.

    The last problem i have is that the BT is very greedy (I'm using TDK
    blue2i modules), so i cant make more then 1 hour every game.

    So, why dont i use a single module to ensure the communication of every
    weapon with its waistcoat in one side, and each waistcoat with the PC
    (PDA ...) in the other side.

    The BT is used to initialize the game (Giving the player name, rank,
    weapon kind ... ) and to get the score from each player.

    Like i explained above, i need to make all that myself (I'm not an
    electronic engineer i'm just a computer engineer) so if you have some
    good experience using lazer modules, the uses of photodiodes in a
    daylight conditions you will realy help me to make progress.

    GSM is a good sollution, i dont know why i dont thaught about it, so i
    want "small, secure, powerful (not important lol), adaptable *and*
    cheap" modules to use them with 8, 16 microcontrollers.

    Thanks.

     
  10. Tim Auton

    Tim Auton Guest

    You want filters on the "hit sensors" which match the frequency of the
    lasers (but the narrower the passband of an optical filter the more it
    costs...), if you don't have them already. You also want some kind of
    modulation scheme. TV remotes should provide some inspiration for
    modulation, encoding and compensating for background light levels -
    that application has long since solved most of the problems associated
    with using light to transmit data in variable conditions. Remember
    that the laser "shots" can carry useful information (you got shot by x
    with y weapon causing z damage), if you aren't using them that way
    already.
    By the sound of it the long-range comms is in irregular short bursts,
    so GSM-based might well be feasible. GPRS would be better and cheaper
    - you get charged by data not time, so you can keep the connection
    open and send packets as required without your bill ticking over the
    whole time. Either way, you should consider what data is time-critical
    and how best to optimise your comm links (local RF, long range RF and
    laser shots) for minimal power consumption and cost. For example, do
    you need scores centrally within a second or will once a minute do?

    I guess from playing commercial laser-tag (Quasar and Laser Quest in
    the UK, no idea if they are more widespread or what other names they
    may go under) that their kit primarily uses the laser shots to carry
    hit information and this information is collected centrally when you
    "recharge" (4 hits or out of ammo and you have to go to a "pod" to
    recharge).


    Tim
     
  11. new²

    new² Guest

    You want filters on the "hit sensors" which match the frequency of the
    I thaught about taking the output from your transimpedance amplifier,
    pass it through a low pass filter and take this signal via an
    appropriate resistor to the summing junction of the transimpedance
    stage, i need to make many tests. As i said above, i wont to make many
    targets for the shooter on each waistcoat. In this case i have two
    configurations :
    1-Making a strip containing many Photodiodes in parallel (Hard to do,
    need a relatively high reverse biase ...)
    2-Making a separate targets (needs many I/O from the µC).
    What do you think about the two solutions ?
    Yes, i tested LaserQuest here in france, the principle is the same here.
    Frankly, i dont enjoyed playing it. I hope to use the game outside, in
    forests for exemple, so no more playing in a close rooms. I tried to do
    that with some of my old schools friends and we found it realy cool
    (sorry, i know that i'm out of the charter);
    Well, I will look for (cheap, small ....) GSM/GPRS embedded modules,
    dont hesitate if you have anny reference of GPRS modules application
    note (used with microcontrollers ... google is not my friend these time).

    Thanks to you and to all who tried to help me.
     
  12. new²

    new² Guest

    I thaught about taking the output from your transimpedance amplifier,
    The best paper i found, talking about photodiodes concepts :
    http://users.bestweb.net/~hobbs/frontends/frontends.pdf
     
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