How does a mobile phone send a response back to a network tower despite its tiny power source? #MobileNetworkTower #RadioWaves #PhoneResponse #PowerSource
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The mobile network tower uses tons of power to reach 10,000 phones all at the same time.
Your individual phone has sufficient power to talk back – the transmission really just *does* work with just a phone battery.
4G radios have a range of about 10 miles – 5G significantly less. Your phone has more than enough power to deal with this.
Mobile phone masts need a lot of power because of the volume of signals they’re dealing with – not for range. They suffer the same limitations in that certain bandwidths fundamentally can only travel so far.
Think of radio frequencies like light. Your phone sends a VERY specific color of “light”. When you send that through just the right filter so you ONLY see that specific color, most of the electromagnetic noise i.e. other lights shining everywhere, can be ignored, and the tower can pick up extremely weak signals.
In fact your phone is also very sensitive in this way, and you might be surprised how little power a cell tower uses to transmit. It’s more than your phone, but on a scale of a wifi router up to radio station you can pick up from hundreds of miles away – a cell tower is much closer to your wifi router.
The GSM base station has multiple more sensitive antennas that each look in one direction and are deaf to signals and noise coming from the sides and behind, with an effective gain of 20 to 30 dB. It’s similar how a TV antenna is usually installed pointing towards a specific transmitter. The phone handset receives from all directions to allow you to turn it freely. It transmits between 0.01 and 2 watts of power, adapting to the minimum required for the distance and obstanles to the base station, which is effectively boosted by the receiver’s gain.
Those huge mobile network towers have large, powerful, amplified antennae in them to pick up the tiny, tiny, tiny signal that your mobile phone sends out.
They’re even directional (i.e. they know where your phone is and can “aim” towards it when you’re on a call – this is all done with fancy tech now so there are no moving parts, it does it by “interfering” a signal from one antenna with another antenna – your wifi now does the same – MIMO).
Basically, the towers are doing all the work, your phone just squeaks out a little and they hear it. That’s why it pretty much doesn’t matter what you do with your phone – wherever you are, that’s the signal you’re going to get in that location and there’s not much you can do about it. You can’t “ramp up” (your phone is likely already broadcasting as powerfully as it can), you can only get somewhere where the tower can see you better.
Think less that your phone is sending something all the way to the tower and more like your phone is shining a light that the tower can see with its very fancy eyes. Radio waves are just light we can’t see(and sometimes goes through stuff). So the tower is like if you stand on a hill with some binoculars and a spot light and you send Morse code to someone who answers back with a flashlight.
Imagine your friend and you are out camping. He’s on a different mountain than you and it is late at night, so dark because there is no moon at all, and it is overcast, so not even the stars are out. His flashlight is still noticeable if he points it at you, because it is super dark and your eyes are really sensitive. Now imagine if your eyes were the size of a house and his flashlight was the one on his phone, not a handheld one. You then use a Lazer pointer to signal to him because you know where he is, but he just relies on you being able to pick him out so he doesn’t need to be as accurate. That is what a tower and your phone are like.
The darkness is what radio wave receivers are capable of doing when they filter out the light they are not interested in. Eyes the size of a house resembles the antenna being just the right length to resonate like when the swinger and pusher are just in sync to get you real high and it doesn’t take much effort to make big swings. The line of sight between the mountains is similar to how certain radio frequencies can see through stuff, like how you can see through the holes in the microwave but the microwaves can’t get/see out. The Lazer pointer resembles how well we are able to make antennas point in a specific direction.
Basically the tower has the radio equivalent of a huge megaphone, it can talk into the megaphone to get the signal really far, or it can listen from the megaphone to ‘hear’ small signals far away like from your phone.
With this setup the mobile device can use much less power and maintain a good signal strength
Sidenote the transmit power for radio is pretty low when you put it in almost any other terms. Towers can have transmit powers up to about 200 watts per channel on the very high end, usually much less 10-50watts, and your phone usually operates somewhere around a few milliwatts for Wi-Fi and max 2 watts for LTE, which is enough to feel your phone heating up if you’re trying to use data in a low signal area.
For comparison, 200watts is moderate exertion on a bicycle, 2 watts would be like moving the effort of moving the pedals backwards. A toaster uses 1200+ watts
From what I understand, the phone doesn’t need to have a lot of transmission power because the receiving antennae are very good at discerning weak signals. It’s the same with deep space probes, they can’t transmit powerful signals, so we need to have really big ‘ears’ to pick up the weak signals.
The Voyager spacecraft uses a 23 watt transmitter and it’s 7 billion miles away, so without interference a radio signal can travel really far.
Your phone is probably 3 watts max, and they operate in good conditions at 0.5 watts when they’re connected.
Imagine a really big circle from the mast and a teeny circle from your phone. Where the circles overlap they can communicate with each other
You have normal ears, the tower is loud so you can hear it.
The tower have ultra sensitive ears, your tiny voice can be heard from their ultra sensitive ears.
You didn’t ask this part, but as for how does 1000 people talk to the tower at once? They don’t. The ELI5 is they just take turns talking to the tower.
“Turns” is different frequencies, hopping patterns, and timing.
I can see a fire fly in a dark field. It’s teeny tiny and barely making any light but it’s making more light than the no light around it so it’s super visible.