Cell phones

Cell phones are everywhere, from "smartphones" to "flip phones." (And yes, I still use one.) Yet regardless of what type of phone one uses or does not use ...

... cell phones are a reality of modern life. Yet how do they work? And what does GPS have to do with it?

Having what it takes

To have a cell phone, you must have at least two pieces of technology.

Telephones

Alexander Graham Bell invented The telephone and received a patent on March 7, 1876. His quest to invent the telephone began when he was working on the way to send several telegraph signals at the same time and on the same wire. The story has it that he was plucking a reed on the equipment, and a sound came out of the other end. Being a teacher of the deaf, he understood the connection between sound and vibrations. As a teacher, he would teach his deaf students to dance by feeling the vibrations in the floor caused by the music.

The telephone was invented.

The telephone was a great invention. Now, people can converse and connect with others miles away and eventually across the world.

Yet, it had a limitation. It requires a wired connection to a telephone network.

Radio

Guglielmo Marconi was born in Bologna, Italy, on April 25, 1874. At an early age, he was interested in all things electrical and developed an interest in sending telegraph signals without wires.

When he was 20 years old, he showed his mother a fun little gadget of his. He had set up a way to press a button and, without any wires between, ring a bell across his room: Behold, the wireless doorbell, something of a marvel in the 1890s.

His father encouraged him to develop his ideas, and, the following year, he found a way to send a wireless radio signal 2 miles away. His brother, who helped with the test, took a gun with him and shot it off to signal Marconi that it had worked.

At first, the radio was called the "wireless telegraph" or simply "wireless" for short. The wireless provided great mobility in communication since you could now send messages almost anywhere, but it also made conversation difficult. The reason is that the two parties had to take turns speaking since only one could talk at a time. Hence, in radio speak, one had to say "over" when they were done talking.

Trivia aside: The original transmitter design was called a spark gap transmitter which involved, you guessed it, creating a spark. Because of this, early radio operators often were nicknamed "sparks" or "sparky."

A marriage for convenience

A mobile phone requires both technologies combined, allowing for the strength of one to balance the weakness of the other.

The first attempt at a mobile phone came not long after World War II—the car phone.

Advances in technology allowed the electronics to be made much smaller. But on the mobile phone end, things are essentially the same. A person talks on the phone.

An antenna in the phone sends a signal out in all directions, where anyone with the proper settings can pick it up. But the goal is for the signal to reach a cell tower.

The tower has an antenna that picks up the signal and either forwards it to a landline phone, to a computer (for internet access), or another antenna in the case that the other phone is also a cell phone.

What could be simpler, eh?

**Spoiler alert – it isn't***

Where are you?

The trick, unless you like being cut off from phone access, is to have a tower listening to your phone at all times and be ready for your beck and call. This requires a whole network of towers.

But this also requires the network to know where you are and which tower is to listen to you.

Here's the trick. And there are two ways of doing this.

Triangulation

Triangulation (from the word for triangle) has been used by surveyors and artillerymen for centuries. In short, you gather information about where something is from different, known positions. From this, you learn the location of what you are interested in.

Usually, the closer a radio source is to a tower, the stronger the signal comes in. And the weaker, the further away it is. In the case of mobile phones, this means different towers determine how strong the radio signal from a phone is.

Using this information, a position for the mobile can be guesstimated. Mind you, it isn't very accurate, but it's usually good enough for use with cell phones.

GPS

For many people, GPS is that device one uses to get directions when driving.

But the GPS (Global Positioning System) was first developed by the U.S. Military between the 1970s and 1990s as a way for soldiers in the field, ships at sea, and planes in the air to accurately know where they are.

The Global Positioning System is a mega-jazzed-up system of triangulation. It starts with a system of satellites orbiting the Earth.

Each satellite has just two jobs:

• Keep a constant and accurate track of its position and time.

• Frequently send out a radio signal giving its current position and time.

That's it.

Then, the GPS or mobile device, takes the signals that reach it and does its job.

• Based on when the signal left and when it arrived, the time it took for the signal to reach can be determined. From this, the distance to the satellite can be determined.

• The device takes these distances, and the position of the satellites, and works out the device's location.

That's it, in a nutshell.

Cell phones combine radio and telephone technology to allow for a near-instantaneous connection to anyone you wish for as much as you want.

Of course, this leads to the more philosophical question: how much you want to be connected?

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