There are billions of mobile phones all communicating with each other sending wireless signals across the globe. How does each signal know where to go exactly, and how are they not intercepted by other signals?
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Wireless transceivers use antennas, analog filtering, and digital signal processing to talk on the right frequencies. Sometimes the transceivers are point-to-point, and the antennas are aimed at each other. Sometimes like cellphones, it’s a point to multipoint system, when one side provides coverage to a certain area and the subscribers have an antenna that works in all directions.
The signals are part of the electromagnetic spectrum, where the power comes from the transmitting side.
Now a really good question is, what are EM waves and how do they travel through space? Ask your mom..
Ordinary aerials transmit in every direction so the radio wave will bump into a receiving aerial. Throw a pebble into a pond and the waves will reach the side. Bigger pond use a stone. Aerials can be shaped to transmit or receive in one direction. This reduces the power needed.
Think of it like sound. If someone shouts loud enough, it doesn’t matter whether they point their mouth at you or not. If you are close enough, or the sound is loud enough, you will hear it because the sound waves bounce and travel in all directions.
The wireless signal doesn’t need to know where the device is, it just sends the signal out. The device knows where the signal is and is waiting to hear it’s name (number, ip address etc.)
Think of it like sound. If someone shouts loud enough, it doesn’t matter whether they point their mouth at you or not. If you are close enough, or the sound is loud enough, you will hear it because the sound waves bounce and travel in all directions.
The wireless signal doesn’t need to know where the device is, it just sends the signal out. The device knows where the signal is and is waiting to hear it’s name (number, ip address etc.)
So, the signal from a phone or a broadcast tower will not send a signal in a specific direct but in a wave that goes out in ALL directions. Like throwing a rock into water. The thing that happens to make sense of it all is that all of the signals sent are encoded to send as much info as possible. When decoded, it’ll send various bits of info like when the signal was sent and how it was sent and what type of device. The receiving device will decode that, determine the closest part of the network that can send and receive all the data between the two devices and will try to work with the device more specifically until the device is moved. All of this happens very quickly and automatically without any input from the users.
Also, interference can and will happen, especially with older devices that use parts of the electromagnetic wave spectrum that that are no longer used or become too crowded. For example, using my wifi on my phone will interfere with the signal from my mouse to my PC, so I have to keep telling my phone to swap wi-fi signals or I have to download updates for when I’m not using my PC. Also, if you’re in a crowded space like a stadium with thousands of people, issues CAN crop up with everyone’s phones interfering with any data getting out. It’s less and less likely nowadays with more and more of the spectrum getting opened up.
So, the signal from a phone or a broadcast tower will not send a signal in a specific direct but in a wave that goes out in ALL directions. Like throwing a rock into water. The thing that happens to make sense of it all is that all of the signals sent are encoded to send as much info as possible. When decoded, it’ll send various bits of info like when the signal was sent and how it was sent and what type of device. The receiving device will decode that, determine the closest part of the network that can send and receive all the data between the two devices and will try to work with the device more specifically until the device is moved. All of this happens very quickly and automatically without any input from the users.
Also, interference can and will happen, especially with older devices that use parts of the electromagnetic wave spectrum that that are no longer used or become too crowded. For example, using my wifi on my phone will interfere with the signal from my mouse to my PC, so I have to keep telling my phone to swap wi-fi signals or I have to download updates for when I’m not using my PC. Also, if you’re in a crowded space like a stadium with thousands of people, issues CAN crop up with everyone’s phones interfering with any data getting out. It’s less and less likely nowadays with more and more of the spectrum getting opened up.
For being an ELI5 thread there are a lot of not ELI5 answers (as is tradition).
Short answer is that you have a radio in your pocket and that radio picks up lots of different stations depending on where you are. Your pocket pal picks which station it likes the most and sends your bleep bloops to the internet. When you move your little buddy picks another station and viola, you have the bulk of all human knowledge in your hands you whippersnapper
For being an ELI5 thread there are a lot of not ELI5 answers (as is tradition).
Short answer is that you have a radio in your pocket and that radio picks up lots of different stations depending on where you are. Your pocket pal picks which station it likes the most and sends your bleep bloops to the internet. When you move your little buddy picks another station and viola, you have the bulk of all human knowledge in your hands you whippersnapper
The signals go in all directions, and there are thousands of them zipping around all the time.
The genius way they don’t all get mixed up is by using resonant circuits. If you’ve ever tuned a guitar, you’ve probably seen that when a string is tuned exactly to the tone of another, the other will start vibrating as well. Radio tuning works the same way, making sure the receiver only vibrates along with the intended transmitter.
These circuits are incredibly selective, and can easily find the whisper of your particular phone within the roar of every other transmitter. It’s like going to a rock concert and only hearing when the keyboardist hits middle C.
As for interception, phones use frequency hopping, which means the sender and receiver change their tuning automatically several times a second, according to a pattern which an outside receiver won’t know how to follow. So even if you tuned into one of the frequencies and started listening, you wouldn’t get very much information.
This also help with transmission robustness. If you happen to be transmitting on someone else’s frequency, you’ll soon leave it because you both hop to different frequencies. There are built-in protocols for how they should react to interference in order to mostly keep it from affecting the call.
The signals go in all directions, and there are thousands of them zipping around all the time.
The genius way they don’t all get mixed up is by using resonant circuits. If you’ve ever tuned a guitar, you’ve probably seen that when a string is tuned exactly to the tone of another, the other will start vibrating as well. Radio tuning works the same way, making sure the receiver only vibrates along with the intended transmitter.
These circuits are incredibly selective, and can easily find the whisper of your particular phone within the roar of every other transmitter. It’s like going to a rock concert and only hearing when the keyboardist hits middle C.
As for interception, phones use frequency hopping, which means the sender and receiver change their tuning automatically several times a second, according to a pattern which an outside receiver won’t know how to follow. So even if you tuned into one of the frequencies and started listening, you wouldn’t get very much information.
This also help with transmission robustness. If you happen to be transmitting on someone else’s frequency, you’ll soon leave it because you both hop to different frequencies. There are built-in protocols for how they should react to interference in order to mostly keep it from affecting the call.
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