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Starting an electronics project

Discussion in 'Hobby Electronics' started by John Lam, Sep 9, 2003.

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  1. John Lam

    John Lam Guest

    This is my first time in a newsgroup and i am surprised how wide the subject
    of electronics can be. i am an electronics engineering student, now in my
    second year at Multimedia University. I am doing a project to create a
    wireless device. This project requires us to send voice data and other
    instructions to a computer.

    So far what we have learned in lectures are theories and experiments
    conducted are just to test the theories. Therefore, me and my group members
    have embarked on a project to gain some practical knowledge on how to create
    circuits and hopefully be able to understand deeper about the workings of
    electronic devices.

    Therefore, i would like help on how to put a step forward to achieving our
    objective. I am at a lost of where to start. We have referred to materials
    on wireless communication and due to our only shallow knowledge of
    electronics, we are going nowhere.

    Any feedback would be very much appreciated. Hopefully, I would be able to
    gain some knowledge in this interesting field and also gain some friends
    through the same interest.

    Sincerely,
    John Lam
     
  2. Hi,

    We did something similar. Yours sounds pretty broad at the moment- how far
    does it have to transmit? Is it line of sight? What commands do you have to
    send? Does it have to be radio? Have you been allocated a frequency band?

    If it is line of sight, and close, i would send using Infra red- its a lot
    easier than stuffing around with radio stuff. You'll have to convert your
    signal to digital at the microphone end using an analougue digital
    converter. Probably the easiest thing to use is a microcontroller with an
    A-D, and a UART. That way you can input the signal into the serial pot of
    the computer at the other end without any real problems.

    If you have to use radio, then I would make all efforts to send your
    information in analougue rather than digital- It is easier to get working. I
    would also recommend, over a short distance to use AM rather than FM- again
    it is a lot less stuffing around to get working with reasonable quality.

    The core of a transmitter is an oscillator- and this is where it is probably
    best to start. Depending what frequency you want to transmit at the best two
    options is a crystsal oscillator- supplieses a very stable frequency with
    relative ease (look up colpitts crystal oscillator). This is good for HF
    frequencies (i.e: 1-10M HZ). If you needs to go higher, you may need to use
    Phase locked loop... which I know nothing about. In its simplest form the
    transmitter can just be an oscillator feeding into an amplifier (just a
    simple BJT wil work over a short distance), with a voltage modulator. look
    up "pixie 2" transceiver in google. its a really good basic radio.

    The receiver desing depends a lot on your transmitter design.

    Be creative wqith your computer stuff- if you send in analougu try inputting
    the demodulated signal into the audio input on your sound card- save having
    to do any A-D external to the computer.

    hope this helps a little bit.

    cheers,

    Phil T
     
  3. I assume this would be one-way communication from some sort of hand
    held device with a microphone to the computer via a receiver and the
    serial port?

    Do you have to design the actual wireless part yourself?
    If it's an RF link then there are plenty of RF modules around which
    will do the job for you, as designing the RF stuff yourself might be
    beyond a second year project.
    An infrared link on the other hand would probably be within your
    capabilities.

    Do you have to sample voice data into the PC and do some sort of voice
    recognition?
    Or is it just as simple as a wireless microphone feeding into a sound
    card?

    We'll need some more detail before being able to help much further.

    Regards
    Dave :)
     
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