how does wireless communications work

93 viewsOtherTechnology

I want to understand what actually happens when some data is sent over a particular frequency/channel. My understanding is that to send data on a particular channel, a ripple is created in the medium with the corresponding frequency. Not sure how the receiver accepts the info from the channel.

In: Technology

3 Answers

Anonymous 0 Comments

Think of morse code. its just a light blinking on and off. the frequency/color of the light is the channel. If you arent looking when the message is sent, it is lost.

to get a different channel you just use a colored filter to only see a specific channel.

same for wireless, its just the light is a frequency you cant see that thinks most materials are transparent, and the filter is electronic, and its not morse code, its binary code.

there is no medium, light doesnt need one.

Anonymous 0 Comments

Imagine you have two floating fishing bobbers on lines. One you hold and one your friend holds a few feet away. Your friend (the “Receiver”) keeps his bobber in the water and it’s just sitting there.

You plunk your bobber into the water (you are the “transmitter”) and it creates a ripple. Plunking your bobber in requires energy (your muscles) and that energy transforms into a ripple in the water that spreads out and away from your bobber.

A moment later the ripple has traveled and reaches your friend’s bobber, causing it to go up and down as it follows the small wave. The key is realize that the path of your friend’s bobber going up and down is determined by the water wave, which was determined by your original plunk input.

So what’s really be ‘sent’ is energy, you provide energy into your plunk, the plunk energy creates a water wave which travels and lifts/bobs your friend’s bobber. If your friend could “feel” or “read” their bobber’s path they could work backwards to your original signal.

In this metaphor your bobber is actually electrons in a special kind of wire called an “antenna”, energy from devices battery or wall outlet goes into the electron making it jiggle (that’s creating the plunk) This bit gets sciency but an electron has an electric charge and jiggling it creates a magnetic field which pulses into what we call an Electromagnetic Wave. So jiggling an electron creates this kind of wave just like your bobber creates a water wave.

On the opposite side, your friend’s bobber is also an antenna wire which is filled with electrons. The electromagnetic wave, like the water wave, hits the electrons and makes them jiggle, creating an electric current in the receiving device. Somehow, the receiver has a circuit that can “read” the current (either digitally with computer chips, or using analog components like an old radio or telegraph).

If you can visualize it, the size of the bobber is important to the water wave it can feel, you need the right pairing of a bobber and water wave to “Read” it properly, way to big or too small and it won’t react properly. Similarly, your receiving antenna needs to be “tuned” to the right size to read the signal. This is why we have radio stations and “dial in” the specific station we want, we’re adjusting our “bobber size” to read the right wave.

Modern devices kind of do this do, but a lot of it is computerized automatically now, this is how “pairing” bluetooth devices work or your cellphone “connecting” to the nearest tower. The devices are communicating with each other and agreeing “OK, I’m sending *this* wave, so you use *this* bobber”. So you don’t really need to to “tune” your cellphone manually to the tower before each call, it’s still happening just by computer chips behind the scene.

Anonymous 0 Comments

Your question is about radio transmission in general. In the beginning, like your car radio receives analog signals through either Amplitude Modulation (AM Radio) or Frequency Modulation (FM Radio). In your terms, the “medium” is a particular Radio channel and the way the signal is transmitted is through either making your “ripples” higher and lower (Amplitude) or making them closer together or further apart (Frequency) and the receiver simply makes a speaker vibrate in sync with the vibrations that were transmitted in one of those ways, not entirely unlike a record making a needle vibrate as it travels around the groove and picks up the analog info that was originally carved into it.

Now we are in a digital age and the way data gets transmitted is much much more complex that not only involves *both* amplitude and frequency modulation but also simultaneously operates on multiple channels to create quadrature phase shifting and advances are constantly being made that can allow more and more dense data to be encoded into radio waves.