ABC Listen.
Hello, Nidge here.
And today on Imagine This... Hello?
Hello.
Hello.
Hello.
Can you hear me?
How about now?
We can't hear you.
There's an emu.
Where?
Is he on the phone?
When you go out of signal, you lose reception.
Maybe he's got bad reception.
Did you say reception?
I'm losing mine.
We had a question about reception and how to make a phone call.
Hi, my name's James.
I'm five years old.
Hi, my name's Catherine.
I'm six years old.
My name is Ayla.
I'm six years old.
We would like to know, what is reception?
And why do our mum and dad always lose it?
And I want to know, how does one voice go from one voice to another?
Ah, that's better.
So what is phone reception?
Maybe it's something to do with the wires.
Up in the sky somewhere.
I think it's about electricity.
I think it connects to electricity.
To the power line.
When I lose things, they're usually behind the couch.
Do you think maybe reception is there?
No.
It's in the phone.
I think it's electric.
I think it's an antenna they put in the phone.
Maybe we could put up some signs for it or go to lost property.
No.
No.
Because it's a type of energy.
Ooh, energy.
This little invisible thing.
And it travels through the air to the other phone.
That sounds hard to find.
And even if you do have reception, how does a phone call even work?
I actually don't know.
We better talk to an expert.
Dr. Shahgig Atakaramians.
She's a telecommunications engineer.
She knows all about mobile phones and how they work.
Hi, Dr. Shahgig.
Hello.
Hi there.
This is a cool lab.
Thank you.
Lots and lots of buttons.
So many phones.
Yes.
I spend a lot of time here, working out different ways we can use technology to talk to each other.
You must always get reception in here.
Look at all this high tech equipment.
Do you make reception in here?
Unfortunately, phone reception is a little trickier than that.
Yeah, we're always losing it.
It's so sneaky.
Yeah.
Can you tell us what reception is and how our voices go from one phone to another?
Well, when we talk about reception, we're really talking about a mobile phone signal.
What's a signal?
Signals are the way devices talk to each other.
It is how they send and receive information.
So you can make a phone call?
Yes. sending messages, making phone calls or video calls, even listening to music or podcasts.
This is all the sending and receiving of signals.
If you don't have a signal, these things won't work properly.
Can you show us?
Absolutely.
There are a few steps along the way though, so it may be best if we use our imaginations.
Yeah, cool!
Where to first?
Well, if you want to make a phone call, what's the first step?
The phone number.
Press the buttons.
Oh, I know just who to call.
Cool.
We're inside a phone.
It's kind of squishy in here.
You're on my foot.
Ouch.
Excuse me.
What's this thing?
It's a microphone.
When you're speaking to a phone, your voice goes into the microphone, which turns the sound of your voice into an electric signal.
Really?
Give it a try!
That sound is our voices?
What are all those beeps?
Those beeps are just tiny bits of information that a computer can understand.
I know that digital is like numbers and electricity or something.
Yes, all our sentences get turned into numbers, either one or zero.
It's like another language.
Exactly.
The phone turns our human language of speech, the way we talk, into the language of computers.
Like robot voices.
What happens next?
It gets sent to the air.
We're shooting out of the phone!
We're flying!
I can see houses, buildings, lights.
But how?
The signal, those digital beeps, are being carried on radio waves.
What's a radio wave?
Radiowaves are a special kind of energy.
They are invisible.
They can move through the air and even pass through walls to carry messages from one phone to another.
How do they move through the air?
Have you ever thrown a pebble into a pond and seen those ripples that spread out on the surface of the water?
Yeah, they're like little waves that go in circles.
Radio waves move just like that, like invisible ripples moving in all directions through the air.
Does this signal with our voices in it go straight to the phone we're calling?
No.
Its first stop is a cell tower.
Like a castle?
No, it's a special type of metallic tower that holds the antenna.
I saw one near my house.
Yeah, I see it every day I go on the bus.
And that is carrying the phone calls from one to another.
Yes, the antennas need to be up high to catch all the phone signals in the area and tell them where to go.
I can see one!
We're going inside!
Whoa!
Whoa, who's this?
Are these all the phone calls for one city?
Oh no, there are hundreds, even thousands of cell towers in a city.
You need more towers where more people are living because more phones are being used.
Plus, you need to spread them out.
How come?
Towers can only send signals a few kilometers away, at most from one side of a city to another.
That's why we try to put cell towers all over, so the signal will pass from tower to tower, even if the person you're calling is really far away.
It's like a relay race, where one person passes the baton to another person, who passes it to another person?
And then that person passes it back to another person.
All the way across the city.
Yes.
But sometimes calls do cut out, especially when you're not in a city.
Unfortunately there aren't cell towers everywhere in Australia.
So if you are in the countryside or somewhere a long way from a town, you can lose reception because the nearest tower is too far away.
It's like that ripple in the pond.
The waves in the water get smaller and smaller the further they go, until they run out of energy and the surface goes flat again.
Ah, so the signal wears out if it has to go too far to get to the next tower.
Yeah, for a phone call to work best.
The signal will move in short bursts from one farm to the cell towers and then on to the other farm.
But lots of things can get in the way.
Whoa, we're going down.
We are back on the radio wave.
Whoa, we're going through buildings.
Radiowaves can move through walls.
So we can use phones inside.
But concrete and brick walls weaken the signal.
But there's heaps of concrete where people live.
Yes, and different kinds of metals and glass can reflect the signal too.
That means the signal won't always travel in a straight line.
Don't move, Pop!
Did we just go through a dog?
Gross!
Can radio waves pass through living things?
Yes!
Lots of different waves can pass right through plants and animals, our bodies too.
But don't worry, these radio waves don't have enough energy to hurt us.
We're getting bounced around the trees!
It's raining.
Weather can affect the signal too.
We've slowed down.
Radio waves aren't so good in water.
Does all this happen for every phone call?
It can.
Sometimes all this bouncing around is a good thing.
It can make the signal stronger by bouncing around big obstacles.
But sometimes it can get blocked completely.
Then you might lose perception.
Yes.
The signal will move from tower to tower, through and around cars, buildings, trees and people, until it reaches the other phones.
Woohoo!
We're here!
We made it!
Now the radio waves will go into the phone and move through a speaker.
The speaker will translate the electrical signal, those ones and zeros, back into the sound of a voice.
Pepperoni Beets Pizza Bar, what can I get you?
Nitch, that's what you called?
What?
I was hungry.
This all happens so fast.
Radio waves travel at the speed of light.
You don't have to wait for them to send from one phone and arrive to the other.
You can talk back and forth.
Hello, can you hear me?
Sorry, we'll call you right back.
I'm back in the lab.
Once you end the call, the connection ends and the signal stops.
It's amazing how much stuff is happening just to make a phone call.
It's not just phone calls.
You can look up facts, put on songs.
I like watching movies.
I like sending photos to my family and friends.
All those things are moving through invisible radio waves.
The air must be crowded with signals.
We use our phones and computers all the time.
Yeah, that's another reason you may lose reception.
All those phone calls and messages, emails and videos, it's all like water moving through a pipe.
If there is lots of water trying to get through a small pipe, the whole system moves very slowly.
Like a clogged toilet!
Exactly!
But, you know, I kind of like not having reception sometimes.
You won't really have anything to do on your phone, really.
Yeah, it's a good opportunity to rest and not to be on a phone or a computer.
Yeah, we can go for a walk or paint a picture or...
Okay.
Everyone like margarita?
Yeah.
Cheese.
But a dairy-free one.
A dairy-free one, okay?
So James, Catherine and Ayla, a phone call works by turning the sound of a voice into an electrical signal.
Your voice turns into beeps.
This signal is sent to another phone using radio waves, like invisible ripples passed along by cell towers, But it doesn't always move in a straight line.
It goes through buildings and cars and dogs.
And sometimes the signal can be blocked.
We lose reception.
It might mean the cell tower is too far away, Something blocked the signal, or there are too many people using phones in the same area.
Your call could not be connected.
By sending signals on radio waves, we can make calls, send messages, share pictures, watch videos and play games on our phones, connecting us all over the world in an instant.
It can be frustrating when we lose reception, but it can be a chance to put our phones down.
Playing with my toys.
Chat to people.
Read books.
I like cuddling.
And my favourite, imagine.
Here at Imagine This, we love questions.
Why is the sky blue?
Why is the sea salty?
How did the universe start?
There are so many things to wonder and questions to ask.
But sometimes science doesn't have an answer.
Questions like, do you have to forgive someone who says sorry?
Or is it okay to not invite all your friends to your birthday party?
If you're curious about curly questions that don't always have a straight answer, Check out Short and Curly on ABC Listens.
