Designing wireless controllers

Dec 11, 2005 6 Replies
J

I am designing a game that requires three players to wirelessly signal a central unit whether their 'buzz in with the answer' button is pushed. I had great success modifying Radio Shack wireless doorbells because they have three different channels with three different carrier frequencies. Unfortunately, when two players 'buzz in' nearly simultaneously, the signals interfere with each other and I can't properly detect them. I also tried using commercial TV infrared controllers and receivers but, if two players buzz in nearly simultaneously, the signals again interfere and the receiver gets confused. I tried using a Holtek encoder-decoder scheme but, again, if two players buzz in nearly simultaneously, the signals interfere. Any suggestions?



Jeff Schwartz



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C

Use fourier transform to determine which phase is earlier.

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J

Here\'s what I\'d do: I\'d have the handheld units be transmitter-receivers, each with a crystal oscillator and a counter which would start accumulating oscillator clocks as soon as the button was pushed. At the same time, a signal would be sent to the remote receiver (in the control unit) which would cause the remote transmitter to send a signal to all of the handhelds, at once, telling them to stop counting but to hold the count. It would then query each of the handhelds, one at a time, as to what number of clocks its counter had accumulated. After determining which one had accumulated the largest number of clocks (the winner) and lighting the lamp (or whatever) it would send a signal to all of the handhelds which would clear the counters and start another round.
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K

Jeffrey Schwartz wrote in news:XJVmf.23131 $ snipped-for-privacy@fe12.lga:

Are there simple R/C model transmitter/receivers that can be set to channels, and have the outputs fed to "Jeapordy" logic circuits already available on several web sites. I have a 6 position unit that I would like to "cut the wires" and go RF. I just haven't looked yet.

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J

yes typical RC transmitters are operate on separate channels unlike thise doorbels, door openers, and infrared remote controls, which just use coded pulses to diferentiate.

Bye. Jasen

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R

What about Radio Shack fob transmitters? Are they all pretty much at the same frequency? I wonder if it'd be worth it to poke around with retuning a set.

Thanks, Rich

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J

that'd probably require replacing the tuning component (SAW filtter or crystal)

If only three transmitters are needed three of those cheap golf-ball sized radio-controlled toy cars would have the neccesary parts.

Bye. Jasen

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