How Do Mobile Phones Really Work?

Mobile phones are everywhere. You’ve likely got one in your pocket (or beside you) right now. They are so widespread in use that it would probably shock you if you found out someone you know doesn’t have one.

But have you ever stopped to consider how they really work? It is a little daunting to think about all the tech that goes into making a smartphone. It might seem like a little block of magic until you investigate further – sometimes even more so after you do!

Of course, it is difficult to show in the space of an article how they work down to the lowest level. Some people study electronics like this for years at university. What we can do, however, is give you a sense of how they work in general. We have all heard of the basic scientific concepts that go into phones. It’s just a case of putting it all together! In the following paragraphs, we’ll take a look at the way key components work, as well as the concepts behind some of the functionalities of mobile phones.

How Do Mobile Phones Really Work?

Making Calls

To make and receive phone calls, your phone uses a tiny radio transmitter and an equally tiny radio receiver. These are the mediators between your phone and the nearest radio tower (AKA cell tower). Alongside the radio equipment, there is a microphone, which picks up your voice, and there is a conversion device, which converts your voice into electrical signals that can then be transmitted using the transmitter. This happens the other way for incoming transmissions, and the speaker near the top of the phone plays the converted signal (sound). Notice that this is exactly how a walkie-talkie works, but without the go-between of a radio tower, so they only work short range.

To be able to make calls, you need to have a signal. You can check how strong your signal is by looking at how many ‘bars’ you have in your notification ribbon at the top of your screen. What your phone is showing you there is essentially just the quality of the radio waves that it is receiving, as well as how well it can transmit. Usually, this depends on how close you are to the nearest radio tower. Modern mobile phones are often made to save battery life by using only as much ‘transmitting power’ or ‘receiving power’ as they need to just get data across.

It is interesting to note that your phone transmits data on the radio constantly as you travel about your day, no matter where you are. Regardless, you never have to worry about switching between radio towers, as your mobile network handles this for you seamlessly.

Wi-Fi and 4G (and 5G)

It is not surprising that your phone also uses the same mechanism to connect to the internet that it does to make phone calls. Wi-fi and 4G are also just radio waves, so your call making equipment can handle an internet connection as well. When you are connected to 4G or 5G, then your phone is downloading data from the nearest cell tower, which is connected to the wider network. If you are on Wi-fi, then you are connected to a local receiver (wi-fi box) of that wider network.

Signal Processing between millions of devices connected to a network is essentially all that the internet is.

Camera

Phone cameras have come a long way since their first debut. Today’s 20-megapixel snaps are a far cry from the grainy, dark photos of the 2000s. The mechanism for phone cameras is essentially the same as that which is in a real camera. The difference is that it had to be miniaturised to fit into a small phone body.

Light traveling from the object you wish to take a photo of lands on the lens first. This focuses all the incoming light to create a clear image. The focused light then hits the image sensor behind the lens. Image sensors in real cameras come in several forms, both digital and analog, but suffice it to say that in phones, they are digital. The amount of light that your phone camera’s lens allows through is the aperture. The more light that gets into the light sensor, the better quality image you will get in the end.

Once the image has been taken, your phone runs the raw data through a processing program to tune it. You can set your phone to stop doing this part, and you will end up with a lot of blurry, off-balance raw image files in the form of ISO files. Without the magic of digital processing, raw images are less than impressive, but some people prefer to have these so that they can edit every image themselves.

Screen

There are touch screens everywhere these days, including our phones. There are a couple of different ways that mobile phone screens can work, but we’ll focus on the two most common; capacitive and resistive screens.

Capacitive Screens

Capacitance is a characteristic of some electrical circuits. Capacitors hold on to the electricity conveyed by the battery to the circuit and prevent flow. This means the electricity can’t circulate… until something closes the circuit, like a switch. In the case of phone screens, the switch is your finger.

Your screen is threaded by a tiny web of ‘broken’ circuits with capacitance. Since human skin conducts electricity, it is suitable for conveying the electricity in these tiny phone screen circuits. When you touch the screen, electricity can flow through your finger to the other side of the broken circuit. Next, the programming of your phone picks up on the changes in voltage across the screen’s web. Using the voltage data, it works out where the touch occurred and translates it into user input.

You can’t use these types of screens with gloves on, because the fabric doesn’t conduct electricity very well.

Resistive Screens

Resistive screens have been a lot less common recently than capacitive screens. These rely on physical resistance from your finger to get their input. They are set up so that there are two sheets of electrically conductive material running all across the screen. They are one on top of the other, and they do not touch. The fact that they don’t touch means that they are not conducting electricity between each other, so, again, we have a ‘broken’ circuit. The circuit closes when you put your finger on the screen, and the physical pressure pushes the two sheets to touch at that point.

The rest is just the programming figuring out where the circuit was closed using voltage changes, and making sense of it.

This type of screen is used in ATMs and mail signature collection machines for example. You can use these with gloves on because they don’t rely on your finger’s conductivity.

Software

Basically, all modern phones use either an Android or an iOS operating system. There are some companies that stick to their own frameworks, but they are a lot less popular on the market. Android and iOS are written in different programming languages, but there is a lot of commonality between the two. They are both obviously made for mobile phones, as their input is taken overwhelmingly by touch.

Android is Linux based and is much easier to customize than iOS. Linux was originally made for PCs, so this is not surprising. The way that controls and settings work in an Android phone reflects this fact, too.

iOS is a system that was made specifically to facilitate the use of touchscreen phones. It is completely intuitive but doesn’t have much room for user preferences and adjustments.

Battery

It is likely that the battery in your phone is based on lithium-ion technology. These types of batteries have one huge difference from traditional batteries: they can be recharged. This means that the chemical reaction that takes place in the battery when you are using it (the reaction that releases electrical energy) can be reversed.

Put simply, lithium-ion batteries have a negative electrode, a positive electrode, and electrolytes in between. When the battery is charging, lithium ions travel through the electrolyte from the positive to the negative electrode. When the battery is being depleted (you’re using it), then the reverse happens. Electrical energy from charging is stored as chemical energy and released when we need it.

GPS

The GPS system in your phone works just like it does in your car, and quite a bit like the way you make calls. The radio receiver and transmitter in your phone issues and takes position data from the Global Positioning System satellites in orbit. There are currently 27 GPS satellites in orbit, of which 3 are backup. To find your location, your phone signal is detected by the three closest satellites in the system. Then, a perimeter is drawn around each of those three satellites, and the place where those intersect is where your phone is positioned (and you).

Memory

Phones, like computers, have two types of ‘memory’ built-in. One is the type that we would normally call memory or RAM, and the other is like hard disk space. RAM stores information for your phone to run its current session properly. Internal memory (usually a flash drive) is what you use to store photos and apps, amongst many other things.

Random Access Memory (RAM)

Random-Access Memory is a very technical thing at its core. RAM is wiped if it loses power (when your phone is turned off), so it is obvious that it serves a different purpose than internal memory.

It is very fast and is much smaller than a flash drive, so it is very convenient and speedy for your phone to use this memory to store data on things it is doing right at that moment. This can be data on apps it’s running, or any calculations it is doing. The point of this is that it is like a temporary jotter pad for the work that your phone is doing. It is wiped when the processes your phone was working on are done.

Flash Drive

Internal storage space is going out of fashion for mobile phones with the advent of cloud storage solutions. However, most phones still need some amount of local storage to be able to install apps. The internal memory in your phone works differently from that which is in your laptop. Laptops typically use hard disk drives. Phones, on the other hand, use flash drives.

Flash drives are much faster than HDDs the same size, and they consume less power as well. The reason they are used in phones is that they take up less space, and have no moving parts. They are essentially solid-state drives (SSDs). This is very advantageous because phones are moved around a lot. It is much less likely that motion will damage a Flash drive than a hard drive.

Flash drives are essentially small printed circuit boards with many flash memory chips installed. Your phone accesses the data on the chips and can read it, delete it, or overwrite it. USB sticks work on the same principle.

Conclusion

Mobile phones are not just made of the above, of course. They also have all sorts of components inside that link the major organs listed above together. To us, our phones are not just the sum of their parts. We use them every day for everything, and often we grow attached to them. Because they are so close to us, it can be interesting to find out what really goes on underneath the ‘hood’.

The components all work together to bring you the experience that they do. For example, when you take a photo with your phone, the lens captures the image, the programming fine-tunes it, and the flash memory stores it. Then, when you want to view the image again, you access your gallery through the user interface on your screen, which then reads the image data from your flash drive and puts it on your display.

Every single operation that your phone can do is dependent on many different parts of the whole. There is so much technology packed into a modern mobile phone that it is hard not to be amazed by the complexity in such a small device.

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