RF or IR?

Discussion in 'The Projects Forum' started by Binxinator, Mar 24, 2008.

  1. Binxinator

    Thread Starter New Member

    Mar 24, 2008
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    0
    I'm trying to create a pitching/sensor pad that can tell the difference between two or more balls being thrown into it. I want the pad to be able to tell if ball A hits it or Ball B.

    What would be the best way at approaching this problem? Is RFID the best way? Since I'm only using two balls would I need to use high tech rfid chips inside the ball? Or is there another type of "simple" rf solution?

    I was thinking if the first ball had a small rf transmitter in it that just was set frequency A the sensor pad could be set to look for that frequency only and then when A comes close to it the sensor would know it. Same with ball B it would be set to another frequency and so on...

    Or does it make sense to use some type of IR sensor that can detect ball A or B, but then how would it know the difference between the two balls?

    Any ideas?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Any sensing dealing with light sensing is going to be affected by changes in the reflecting/absorbing qualities of the ball's surface. If this is an outdoor setup, then IR may not be a good way to go.

    It might be possible to use a scheme something like a metal detector. A circuit runs as an oscillator, with an antenna as part of the frequency control. If one ball had a core that would change the oscillator frequency as it passed the antenna, then it would be possible to distinguish it from the other ball.

    Add to that another means of sensing a ball - striking a pad, blocking a light path - and you can tell the difference between ball A and ball B.
     
  3. Binxinator

    Thread Starter New Member

    Mar 24, 2008
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    What if the ball had a core made of some type of metal (tbd) that when placed near an RF antenna the metal would cause interference and that could be detected by some type of circuit?
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    Yes, that would work. That's the way a metal detector works.
     
  5. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
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    The metal detector idea seems good. They use a commercial unit here that does all the work and feeds a voltage to a PIC. I've seen beat frequency oscillator ones that you should be able to rectify the audio, filter it and ensure the DC level is compatible with your ADC or divide it down.

    http://forums.basicmicro.net/ShowPost.aspx?PostID=173
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Doesn't Binxinator want to tell which ball hits first? If one ball has metal in it and the other doesn't, then how do you tell when the other hits? If they both have metal, how do you tell the difference? Whatever the contest is, I don't think it would be fair to have one ball metal filled and the other not. John
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    That's in my first reply - "Add to that another means of sensing a ball - striking a pad, blocking a light path - and you can tell the difference between ball A and ball B."
     
  8. DC_Kid

    Distinguished Member

    Feb 25, 2008
    638
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    the trend is very very small rfid chips. they get encoded before use, etc, and the other side can read them as they come in, etc.
     
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