What actually happens when I connect to my phone to my bluetooth speaker? I’ve always just assumed it’s some frequency emitted, but how does the frequency get emitted? What is the actual mechanism, And how does my phone know where to shoot that frequency?
Does it send out a constant omnidirectional pulse? Or does it establish a target after an initial omnidirectional pulse to find the speakers location, then switching to some honed in direction? Because that would explain the degradation in sound quality when I move my phone quickly.
Is it a vibration of the air in its varying amplitude and frequency that gets picked up by the speaker, and sent to some decoding mechanism that relates the frequency into sounds? What physically vibrates the air (if that’s whats happening), and if so, how can wireless signals be transmitted over such long distances, satellites for example?
Is it just down to it being so tiny and high energy? Is there a little arm inside the devices that flaps so quickly and forcefully that it can push little atoms into my speaker?
In: Technology
Think of a radio transmitter like a light bulb. If you flash the light on and off (or wiggle the power) you can use a predetermined set of flashes to mean a number, a letter or anything else you could imagine.
Like light, radio can be reflected and focused a bit like the reflector in the end of a torch, but for things like Bluetooth it’s usually omnidirectional.
Just like light passes through some objects (glass etc) radio passes through walls and most nonmetallic things.
Short answer: electromagnetism.
Longer answer: Your phone has an antenna built in, which is basically one (open) end of a circuit. By applying a changing voltage on it the electrons in the antenna are force to vibrate at the same frequency. Since a moving charge always creates a magnetic field that is sent out through the air until it hits another, receiving, antenna, where the changing magnetic field induces the electrons to move, which creates a detectable voltage.
For bluetooth, the phone network, … this is usually omidirectional. You can do directional antennas, but those are usually fixed installations or rarely moved (think satellite dishes).
You can do a small experiment to see the effect of electromagnetism: get a small lighbulb (eg. an oven light), some length of wire, and a medium to strong magnet. Coil up the wire (at least 10 turns, more is better) and connect it to the terminals of the lamp. Then quickly move the magnet over the coil, as close & quickly as possible. You should be able to get the bumb to flash. If not, increase the number of turns in the coil or get a stronger magnet.
Edith says thanks for the silver!
It’s sent in the same manner as a traditional radio or television transmission. Apply power to a transmitting aerial, where the power is varied according to the contained signal, and a suitable receiving aerial picks it up.
It doesn’t move the air, this takes place in what’s referred to as the electro-magnetic spectrum.
Imagine Morse code being sent via a radio.
Modern wireless communication isn’t any different, there’s just no human listening in. The machines are sending signals to each other to communicate.
Instead of Morse code, it’s binary code. The only way it’s dissimilar is that many many more digits are being sent than if you were listening to Morse code.
1 megabit wireless speeds would be a million 0s or 1s per second. Gigabit Ethernet cables can carry a billion per second. It’s Morse code but faster, so we can send more interesting data.
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