Cell phones are everywhere. We all have them, but most of us haven't the vaguest idea of how they actually work.
In its most basic sense, cell phones are two-way radios, sort of a very high-tech walkie-talkie. A cell phone consists of a radio transmitter and a radio receiver. When you're on a phone call, the phone turns your voice into an electronic signal and transmits it by radio waves to the nearest cell tower. The tower then sends the signals to your friend's cell phone, where it is converted to an electrical signal and back to sound. In other words, a walkie-talkie.
Radio waves are the basis for cell phone communication. They move your digitized voice or data as oscillating electric and magnetic fields, called the electromagnetic field (EMF). The rate at which these waves oscillate is called their frequency. Radio waves move at the speed of light when carrying information. Cell phones transmit radio waves in every direction.
All cell phones have at least one radio antenna built into them so they can transmit or receive radio signals. The antenna's transmitter will convert electronic signals to radio waves, while its receiver does the opposite. Some cell phones have one antenna for both functions, while others have multiples of each.
Antennas are usually made of a metal engineered to be the size and shape needed for the specific frequency used by that cell phone. Older cell phones had external antennas which had to be pulled out to take or make a call. Modern cell phones have smaller internal antennas. Many modern cell phones also have different types of antennas. They will have a cellular antenna but may also have a Wi-Fi, Bluetooth, or BPS antenna.
How robust the signal you receive from a cell tower is called the signal strength, represented by bars on the phone's screen. Your phone needs an in-bound and out-bound signal to work. Connectivity between a cell phone and its tower will depend on both signals. It can be affected by the distance to the nearest tower, the obstacles between the tower and the phone, and the wireless technology used. Fewer bars usually indicate a long-distance and a lot of signal interruptions, giving you poor reception.
Your cell phone works only as hard as it needs to when transmitting a signal. When you're in a poor reception area, your battery burns up faster, and you have greatly reduced battery life. Your cell phone, in essence, is working very hard to find a signal.
The microphone in your cell phone converts the sound signals of your voice into electrical signals. A microchip inside the phone turns the signals into numbers. The numbers are put into a random wave and beamed out from the cell phone's transmitter antenna. They travel until they reach a cell tower or cellphone mast. The mast passes the signal to a base station, which coordinates what happens in the various parts of the cellphone network (called cells). From there, they are sent to their destinations. If the cell phones are on the same network, the calls travel by being routed to the base station nearest the destination phone and then to that phone. If the cell phones are on different networks, they have to go through the main telephone network before reaching the ultimate destination phone.
A cell phone mast, also known as a cell tower in the US, is a tall structure designed for sending and receiving cell phone signals. They are gradually spreading everywhere.
A cell phone company divides a region or city into smaller areas, each serviced by its own masts and base station. This area is called a cell. They will, on a map, look like an invisible patchwork. All the calls made within a cell go via the same network travel and are routed through that cell's masts and base station. Different cells can have the same radio wave frequency, thus vastly increasing the number of calls that can be made simultaneously.
In a simple normal call, the first phone in Cell 1 calls a phone in Cell 2. The signal goes from the first phone to Mast 1 and its base station. Then, it goes to Mast 2 and its base station, and finally, the second phone. Simple.
In a roaming call, where the caller or callee is moving, the signal will be constantly handed off from one cell tower to another as the phone moves from cell to cell. Remember, cell phones and towers are meant to send waves only a short distance.
Mobile phones originally used analog technology that recreates your voice with a mechanical analogy of its vibrations. Some land lines - where a land line still exists - still work this way today. Most cellular phones today are based on digital technology, turning the sound of your voice into numbers and beaming the numbers through the air as radio signals. Among its advantages, digital technologies can now use that same technology to send text messages, web pages, MP3 files for playing music, and even photos. Your phone can also be encrypted through digital technology.
A basic consumer cellphone is just a phone. It makes and receives phone calls. It has largely been replaced by the smartphone, which can install apps, receive an email, access the internet, and send a man to the moon. Seriously, your cell phone has more than a million times the RAM that the Apollo 11 computer had.
A satellite telephone is a type of mobile phone that connects to other phones or the network via radio waves through orbiting satellites rather than cell towers. It's primary advantage is that it can be used virtually anywhere.
Mobile broadband is the catchy name for wireless internet access via mobile networks. Access is through a portable modem, wireless modem, tablet, or smartphone.
The first handheld cellular mobile phone was made at Motorola in 1972. These cellular phones weighed four and a half pounds. The first commercial automated cellular network (1G analog) was started in Japan by Nippon Telegraph and Telephone in 1979. By the 1980s, the Nordic Mobile Telephone was launched in Scandinavia.
Digital cell networks arrived in the 1990s. Soon the 1G system was taken over by 2G and 3G, with 4G and 5G now being the standards. The lithium battery is the indispensable power source for mobile phones and dates to 1991.
The infrastructure for cellphones continues to develop. Much of the United States is covered, but connectivity can still be challenging in rural areas.