So, how does a mobile phone work?
Well, let’s first look at what they are not.
They don’t work by “Magic”
They don’t communicate directly with each other
You can’t use them very far away from a city or town
A mobile phone won’t work without electricity
Based on “Arthur C. Clarke’s” first law; “Any sufficiently advanced technology is indistinguishable from magic.” Although these days, very few of us would believe that some form of magic is at play to make a mobile phone work, it’s really a matter of having some basic understanding of “what it is” and “how it works”.
Through “Knowledge” we can develop a more realistic expectation of what mobile phones can do for us. “Ignorance” can not only lead to frustration and annoyance, but can actually become dangerous, even “Life Threatening” in some situations.
A mobile phone, “Smart-Phone” or “Cell Phone” is essentially a two-way radio. Yes. That old thing only CB operators or Amateur Radio “HAMs” used to use. “Roger, Roger, Over and Out!” Thankfully we don’t need to take turns to talk, by pressing a PTT (press to talk) button, or say that silly jargon, or have to select the same channel as the person we want to talk to.
A mobile phone does this all for you. Did you know that one mobile phone can’t talk directly to another one? Why?
Well, this is because the transmitting power of a mobile phone is quite low (they only have a limited amount of battery power but need to last a long time). This means they can only transmit over of a few Kilometers. To talk over much larger distances, to another mobile phone, it’s actually “a bit of a trick” requiring an incredible amount of equipment you never see. Your phone provider (Telco) has constructed a network across the country, of many (hundreds/thousands) of fixed radio sites (phone towers). Each site contains a large antenna (on top of tall towers or on top of high buildings), which are connected to many radio receivers and transmitters.
These sites are all connected back into the national optical fiber communications infrastructure covering Australia. So now all these sites are connected together so they can communicate with each other. This network of radio sites, uses many computers to keep track of which “site” each mobile phone is currently closest to. Your mobile phone is automatically providing updates of this information as you move around.
When (say Tom) make a phone call, his phone connects to its closest “site”, then the phone asks the network’s computers to lookup a specific phone number (say Fred). Fred’s mobile phone number is “looked up” and your phone call is then routed (over the national optic fiber network) to the “site” closest to Fred’s mobile phone. Fred’s phone is then signaled to “Ring”. When “Fred” answers, his mobile phone connects to that closest “site” so “Tom” and “Fred” can both talk to each other. Your voices are passed back-and-forth using these radio “sites” and fiber optic infrastructure. When finished and “say Tom” hang up, his phone send a signal to the network releasing the radio connection to both “Tom’s” and “Fred’s closest “sites”. The infrastructure is then made available to be shared for another phone conversation by someone else.
I know that all you Nerds are “shaking your heads”, saying “this is over simplified”.
What about phones unique IMEI numbers, or the fact they also have their own network IP addresses, and how speech is actually digitized and routed over the network using data streaming via voice protocols. Yes, but that’s not important. My point is that when you hold a $1000 mobile phone in your hand and make a phone call, you are using Millions of Dollars’ worth of equipment and infrastructure. It all has to be shared around or your phone calls would get very expensive.
Don’t forget that the network’s computers are also recording the phone call METRICS (who, where, when, how long) so you can be charged for the call. The phone company (your Telco), has to get paid so that they can maintain the radio “sites”, network equipment and infrastructure. Remember, they need to make a profit too for their shareholders. Someone paid for all this.
If only a mobile phone was still only made phone calls, like back in the early 1990’s. Then as this technology developed, mobile phones added “SMS Text Messaging” (a bit like the old “Pagers” of the 80’s). Why not, all the mobile phones are already connected to this enormous phone network.
Then along came “The Internet”. Remember I said that the mobile phone had its own IP address meaning it was actually connected to a “computer network”. So now mobile phones get access to the Internet too from the palm of your hand. Then manufactures put powerful computer chips into the mobile phones themselves. They gave them an Operating System, like Android or IOS. Now mobile phones can run extra programs (we know as Apps) other than for just making phone calls or sending text messages. The display has now been upgraded to a bright (sun-light viewable), high resolution, colour, touch screen. It’s definitely much better than a physical key pad and a two line LCD display.
Mobile phones have continued to evolve over the years, adding a heap of specialized circuitry, such as;
GPS satellite Receiver only (phone listens to dozens of satellites at the same time) to work out where you are in the world.
Bluetooth technology (BLE), a receiver/transmitter for connecting to stuff just 3-4 meters away, an ear piece and microphone, or maybe a car phone interface (Android-Auto, Apple-Car-Play).
Wi-Fi technology, a receiver/transmitter (sometimes two for both 2.4G and 5G bands) so you don’t need to use Internet data from your (Telco) network. You can connect to a localized Wi-Fi Hot-Spot (or AP for nerds).
Electrical power storage. High capacity Lithium Battery, recharging circuits, even contactless recharging (Inductive).
Large amounts of Flash (permanent) memory 64 to 256 GB now quite common, for storing all that useless data, your Apps (Email, Browser, Facebook, Twitter etc), and I nearly forgot!
Cameras for that simple click-and-shoot, low light, zoom in/out, high resolution Photos and Video recordings. Got to fill up all that Flash memory somehow. Why have just one camera. Put one on the front (for video calls) and another on the back, or better still put two of three on the back, each fitted with a different optical zoom lens.
Then there’s all that other electronics for the built-in detectors and measurement sensors: ACCELEROMETER, GRAVITY, GYROSCOPE, HUMIDTY*, AMBIENT LIGHT, MAGNETIC_FIELD, MOTION, ORIENTATION, PRESSURE*, PROXIMITY, STEP_COUNTER*, STEP_DETECTOR*, TEMPERATURE*. (NB: * not all mobile phones support this sensor)
It now seems pretty good value when they squeeze all of that “tech” into your mobile phone. The Apps you run on your mobile phone accesses these various built-in technologies to provide you with seemingly “Magic” stuff (like mapping, navigation, and Yes Facebook).
So, are you confused yet? Your mobile phone is so much more than for just making phone calls. But you already know this. It’s now an integral part of nearly everyone’s life on the planet. It’s our primary form of communications and socialization. We become so “blasé” about what the mobile phone is actually doing, or how it does it, that we just expect it to work for us all of the time.
This leads us to forget about a few basic facts;
You need to pay your “Telco” to use their phone network, even if it’s automatically debited from your credit card each month.
Mobile phones still require recharging every day or two. They don’t have a nuclear power cell yet!
But more importantly, you must always be in range (only a few kilometers) of your “Telco’s” network (one of those radio sites we talked about).
It’s not usually a problem if you live in the big city, but once you leave populated areas the probability that the mobile phone will work for you, becomes ZERO pretty quickly. This is why it’s important to know how your mobile phone works.
You don’t want to be that hiker lost in the forest down in the South West, or in the Kimberley 4-wheel driving on the Gibb River Road, and discover that you can’t use your mobile phone to make an Emergency “000” call or even send an SMS to your friends in that car ahead of you. “It just won’t work.”
If you break down and start walking “a really dumb thing to do”, and don’t run out of water, and if you’re really LUCKY, you might find yourself in range of an industrial mine site or a remote aboriginal community (only true for Telstra customers though), but what’s always true is “No Signally, means Phone No Worky!”
Although you can’t use a mobile phone when you travel into the Out-Back remote areas of Australia, there are better communication systems that you can rely on.
But that’s another Blog.