Your Paw-some Question | How do cell phones work?

Cosmo and I learn how cell phones send texts, images and calls from phone to phone—thanks to our friend, electrical engineer Ben Belzer. 

Resources you can use:

• Learn more about binary code with Crash Course
• Check out this binary code character table to make your own messages
• Get more info about pixels from NSU Florida library

Sound effects courtesy Zapsplat and Pixabay

As always, submit burning questions at askdruniverse.wsu.edu. Who knows where your questions will take us next.

Transcript

Cosmo: Hey, Dr. Universe!
 Dr. Universe: Hey, Cosmo!
 Cosmo: Why was the cell phone so polite?
 Dr. Universe: Hmm, why?
 Cosmo: Because it always had good cell-f control!

Dr. Universe: Hey friends, I’m Dr. Universe.
Cosmo: And I’m Cosmo.
Dr. Universe: And if you’re anything like us, you’ve got lots of big questions about our world.
Today, we’re talking about a question from Colleen in Michigan. She wants to know: How do cell phones work?

Cosmo: Ooo, I love my phone! But I never thought about how it actually works.

Dr. Universe: Well my friend Ben Belzer is an engineer at Washington State University, and he told me that your cell phone is basically a digital radio.

Cosmo: Wait—like the radio in a car?

Dr. Universe: Exactly! You know how a radio picks up music, voices, or even static between channels? Cell phones also use invisible energy called radio waves to send messages.

Cosmo: So when I text you “hi,” what happens?

Dr. Universe: First, your phone’s computer translates “hi” into computer language. It’s called binary code because it’s only made of two things: 0s and 1s. The letter h is 01101000 and the letter i is 01101001. So “hi” is 01101000 01101001.

Cosmo: That’s so many numbers for just two letters!

Dr. Universe: It is. But that’s how you use two things—just 0s and 1s—to represent all the letters and symbols we use.

Once your message is in binary code, your phone modulates the radio waves. That means it changes their shape—like how tall or fast the wave is—to represent the 0s and 1s. 

Then your phone beams out those waves. They zoom through the air to the nearest cell tower.

Cosmo: Like those really tall towers with antennas on top?

Dr. Universe: Exactly. The tower catches the radio waves and sends them to the cell tower closest to me. It usually sends them through underground cables.

The tower near me beams the message to my phone. Then my phone decodes the waves back into letters. Your “hi” shows up on my screen.

Cosmo: Wow. It goes all the way from one side of Washington to the other side like that?

Dr. Universe: And it happens so fast, you don’t even notice a delay.

Cosmo: What if I want to send you a picture or call you?

Dr. Universe: It’s basically the same. For a picture, your phone breaks the image into tiny dots called pixels. Then it maps each dot’s color and position in binary code.

Dr. Universe: Or your phone’s microphone picks up the vibrations of your voice. That moves a tiny magnet and coil inside the phone—and that makes an electrical signal. Then your phone turns that into binary code.

Dr. Universe: From there, the process is the same—radio waves, towers, cables, and back again.

Cosmo: I guess when it comes to communication, cell phones really tower above the rest.

Dr. Universe: That’s all for this episode, friends. 

Cosmo: Big thanks to engineer Ben Belzer of Washington State University.

Dr. Universe: As always, if you’ve got a question for me, you can submit it at askdruniverse.wsu.edu. That’s A-S-K-D-R-U-N-I-V-E-R-S-E dot W-S-U dot E-D-U.
 Who knows where your questions will take us next!