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Radio transmitter

Discussion in 'General Electronics Discussion' started by Javier Manzano, Nov 27, 2015.

  1. Javier Manzano

    Javier Manzano

    17
    4
    Nov 26, 2015
    Hi guys!

    I'm doing some research on a new project I want to do this Xmas. I was looking forward to developing a radio transmitter and, if it's possible, recieve the signals from my car.

    The issue is I'm not sure which would be the best approach. On the one hand I've seen with a Raspberri Pi it wouldn't be too difficult, but maybe doing the whole circuit design myself would be more fun. In any case, I had several doubts:
    • FM or AM? What's the practical difference for what I want to achieve?
    • I know there are some frequencies that are restricted, is it possible to transmit in a permitted one and sync with the car's radio?
    • What modules should I look to design?
    As I said, I'm not sure how to start with this, so hopefully you guys can help me a bit with the design!
    Thanks a ton! :D:D:D
     
  2. Arouse1973

    Arouse1973 Adam

    5,164
    1,077
    Dec 18, 2013
    Hello
    You can transmit on 433 MHz band and 2.54 GHz and 5.8GHz and 24.125 GHz, there are others. Your best bet is to look for a cheap 433 MHz TX and RX. I have found AM to be better for this sort of thing. Have a look at your local electronics suppliers and see what they have.
    Adam
     
  3. davenn

    davenn Moderator

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    1,713
    Sep 5, 2009
    if he goes for one of these standard products as you suggested
    modulation type is already set and doesn't need to be thought about
     
    Last edited: Nov 28, 2015
  4. Javier Manzano

    Javier Manzano

    17
    4
    Nov 26, 2015
    What's the difference on transmitting in lower frequencies from higher ones?

    Since I was looking forward to doing myself the whole circuit, instead of buying the transmitter already built, a kind of AM transmitter I found was this:
    [​IMG]

    What are the "modules" within this circuit, as in, what do the different parts do? I was hoping to understand the reasons behind it.

    The thing is I would like to transmit within a distance of several kilometers, if that is possible and recieve the signal as "listenable" as possible.
     
  5. Arouse1973

    Arouse1973 Adam

    5,164
    1,077
    Dec 18, 2013
    Hi You have to be careful doing your own circuit. It will have to comply with a standard to make sure you are not transmitting out of band and that the RF power isn't greater than is allowed by the ISM band you choose. I personally would buy an off the shelf module.
    Adam
     
  6. Javier Manzano

    Javier Manzano

    17
    4
    Nov 26, 2015
    Well, certainly that is another possibility. The third one is to use my raspberry. I found this really sexy project (here) that uses python and C to turn the pi into a pretty powerful transmitter.

    One of the things I look forward to if this projects gets somewhere this Christmas is to implement a better version, along with a receiver, to take with me when I go hiking to the mountains with my friends and maybe cover a range of 1-2km. Maybe it's not even viable. I'm doing my research :rolleyes:
     
  7. davenn

    davenn Moderator

    13,168
    1,713
    Sep 5, 2009
    then you will need a higher power transmitter and it will need to be tested for type approval and licenced
    this will cost you lots of money.
    If you decide not to get the testing done by an approved testing company, then get it licenced
    and just put you product on the air then you leave yourself open to prosecution, which could cost you
    everything you own, when you start interfering with legal transmitter / receiver systems


    Do it properly and legally
    use citizens band (CB) radio ( or what ever it's called in Spain or learn for your amateur radio licence
    with which you can then build your own gear legally


    Dave
     
    Arouse1973 likes this.
  8. Javier Manzano

    Javier Manzano

    17
    4
    Nov 26, 2015
    And could I do all that in the CB?
     
  9. davenn

    davenn Moderator

    13,168
    1,713
    Sep 5, 2009
    CB is designed for voice only communications

    if you are wanting to transmit data over a link, then you are back to a specialist system
     
  10. Javier Manzano

    Javier Manzano

    17
    4
    Nov 26, 2015
    Gotcha. Looks like I'll have to be stay happy with a small Tx/Rx to play around at home hahaha
     
    davenn likes this.
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