• cmhe@lemmy.world
    link
    fedilink
    English
    arrow-up
    5
    arrow-down
    1
    ·
    edit-2
    3 days ago

    These radio telescopes don’t transmit anything at all, they listen to radio waves coming from the cosmos. Much like a normal telescope doesn’t transmit light.

    If you invert the flow of the electrons, a receiver becomes a transmitter.

    Speakers can become bad microphones and vice versa. Pretty sure that a radio telescope is a very bad transmitter for human music, but it could be possible with some changes…

    • stevestevesteve@lemmy.world
      link
      fedilink
      English
      arrow-up
      7
      ·
      3 days ago

      if you invert the flow of electrons, a receiver becomes a transmitter

      Ehh not really. That’s kind of like saying if you invert the flow of photons, your eyes work as flashlights.

      “It could be possible with some changes” the changes would amount to removing the receiver and replacing it with a transmitter. In this specific case I’m not sure if a transmitter already exists at this antenna and it’s definitely possible one does, but that’s not a guarantee at all

      • cmhe@lemmy.world
        link
        fedilink
        English
        arrow-up
        6
        ·
        edit-2
        2 days ago

        There is no such big differences between a light emitting (LED) and a light receiving diode (photodiode), they are just the reverse of each other. In fact photodiodes can even emit light, but very inefficiently. Same in reverse, LEDs can also detect light, just badly.

        It seems like most efficient energy conversion methods can be used in both directions.

        • stevestevesteve@lemmy.world
          link
          fedilink
          English
          arrow-up
          1
          ·
          21 hours ago

          An LED (or photodiode used as one) is a fairly simplistic device compared to an assembled receiver / transmitter. Just like you can burn gasoline in a car but you can’t push a car to turn the engine to make gasoline - it’s a complex system that really only works one way.

          • cmhe@lemmy.world
            link
            fedilink
            English
            arrow-up
            1
            arrow-down
            1
            ·
            19 hours ago

            Nothing gets burned or otherwise destroyed when receiving EM radiation via a dish and converted it into electricity via a receiver.

            Sure, the amplification stage of the process likely works only one way, and should be replaced in order to send something.

            The one way process of burning oil to generate heat seems much more primitive than the energy conversion offered by a diode, TBH.

            You can push or tow an electric car and charge their batteries. Because electric motors are also generators.

            Even with your simplistic fossil fuel car in your example the alternator within can also be used as a motor.

            • stevestevesteve@lemmy.world
              link
              fedilink
              English
              arrow-up
              1
              ·
              13 hours ago

              Even with your simplistic fossil fuel car in your example the alternator within can also be used as a motor.

              Not by “simply reversing the flow” it can’t. You’d need to remove and replace many components, just like the example of changing an Rx to Tx system

        • Strykker@programming.dev
          link
          fedilink
          English
          arrow-up
          1
          ·
          1 day ago

          Yes, but you would blow out most of the amplification circuitry in a radio telescope reciver if you tried to use it for broadcast at any kind of power.