Near Field Wireless Audio Output

Discussion in 'General Electronics Chat' started by Bradley Burnham, Apr 10, 2018.

  1. Bradley Burnham

    Thread Starter New Member

    Apr 10, 2018
    You know how GSM cell phones make normal audio speakers "blip-blip-buzz" when they are near by? This is just an example.

    Is there a way I can modulate audio (not cellular audio) so that I may aim a type of analog magnetic modulator at any speaker, and it will amplify the audio that I give it, without being directly connected to the speaker? What terms am I looking for? I assume this would be a type of modulated electromagnetic pulse and probably violate all kinds of part 15 regulations, but still be interesting theory.

    I'd love to be able to talk to the person in their car next to me by sending audio straight to their speakers :D It would be like a PA system that can be made directional

    Thanks in advance for any thoughts ;)
    Last edited: Apr 10, 2018
  2. BobTPH

    Senior Member

    Jun 5, 2013
    Use a digital communication protocol to communicate with the driver next to you, like everyone else does. The middle finger works best.

    Bradley Burnham and nsaspook like this.
  3. MisterBill2

    Distinguished Member

    Jan 23, 2018
    Quite probably there is not enough electrical power available in your car to create a signal strong enough to do what you ask. AND, if you could do it, the transmission would be seriously illegal, at least in most countries.
    A mobile sound system that delivers several hundred watts of audio might be able to gain somebodies attention, they use them to play really bad "music" in the Detroit Michigan area.
  4. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    The cell phone or other source of interference is not affecting the speaker, because the speaker impedance is way too low to be overpowered by a radiated field, especially if the speaker is connected to an audio amp output (usually a near-zero ohm impedance across the speaker terminals). You phone is radiating interference into the *input* of the audio amplifier, a much higher impedance point. Well-designed equipment, and *all* car audio devices, have RF filter circuits at the inputs to prevent this exact thing from working.

    2 feet away from the car radio is a 20 watt spark-gap radio transmitter (the ignition system). If the radio can't hear that, I doubt that it will hear something farther away.

    Last edited: Apr 11, 2018
  5. Bradley Burnham

    Thread Starter New Member

    Apr 10, 2018
    Great points. bummer. thanks for the comments.