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Radio Transmitter, question on channels

Discussion in 'General Electronics Discussion' started by BlueBluby, Nov 15, 2013.

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  1. BlueBluby

    BlueBluby

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    Nov 15, 2013
    Hey guys I am trying to build a radio system for a RC Plane because I can't afford a radio :D .
    I haven't managed to understand the 2.4ghz concept that the commercially available ones use.
    But I have managed to understand FM and AM radio communications(phased locked loops, filters etc.).
    What I struggle is a way to transmit multiple inputs over one RF wave. I can have a potentiometer connected to a Voltage Regulated Oscillator that will transmit for example the throttle input. The problem is how to transmit the other inputs.
    I have few ideas.

    To make my communication digital with micro processors at both ends. I will transmit a code that will tell the receiver what to move and a value.( ex. 01(for throttle) 000001(set throttle at 1))

    To have 3 different transmitters, one for each input.(the most inefficient solution in my eyes but the simplest one)

    Last try to explain the problem as simple as possible.
    How can I encode 3 different potentiometer inputs into a radio wave and decode them.

    I am looking for keywords of the technology needed for my solution that i can look up and learn how they work. The best you can guys give me is information on how the 2,4 ghz communication works or a reference to it.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
    2,838
    Jan 21, 2010
    It is hard to imagine it's going to be cheaper to build your own as opposed to buying one, especially when your requirements are pretty generic.

    That being said, I'm sure we have members who will detail how you would have to proceed.
     
  3. BlueBluby

    BlueBluby

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    Nov 15, 2013
    Where is the fun in buying one? And I accept the challenge ;)
     
  4. jpanhalt

    jpanhalt

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    4
    Nov 12, 2013
    You will find all equipment today is highly integrated. But, since you asked, here are some links you may want to look at for information:

    This is to an older, single-chip receiver:: http://pdf.datasheetcatalog.com/datasheet/nationalsemiconductor/DS007912.PDF

    This is that receiver's matching transmitter: http://pdf.datasheetcatalog.com/datasheet/nationalsemiconductor/DS007911.PDF

    There are several such chips on the market. Finally, here is a forum where the interest is DIY model electronics: http://www.rcgroups.com/diy-electronics-199/

    I suspect a search of that forum for receiver and transmitter will get you some threads.

    As at learning tool, you may want to get a very simple, two-channel RC transmitter and receiver to disassemble and study. In the USA, such equipment is only a few dollars. You might also want to study one of the inexpensive, infrared controlled helicopters.

    In a general sense, I think it is fun to read about and understand how such RC systems work. However, I agree completely with the practical advice not to build your own. Not only will it be a long road for you, assuming you have the equipment necessary to layout and tune RF sections, but there are many regulatory hurdles in most countries. Even if the police or military don't get you*, if you happen to "shoot down" someone else's model because your poorly designed, wide-spectrum transmitter caused radio interference, you will be faced with a very angry person and potential financial liability for property damage and personal injury.

    John

    *Remember that today, remotely controlled model aircraft are considered potential terrorist weapons.
     
    Last edited: Nov 15, 2013
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