Mobile communications, sometimes called mobile telephony, define the modern world. They make it possible to communicate with people who are thousands of miles away from almost anywhere in the world, even during emergencies and disasters. Even so, most people know very little about how they work. It can be dangerous for a society to rely on something without understanding much about it, so everyone can benefit from learning the basic principles that allow their cell phones to function.
Transmission and Reception
Most mobile communication relies on waves to carry information from one place to another. For the purposes of communication technology, a wave is a pattern of oscillating energy that is traveling through any substance. Radio waves and microwaves are the kinds that see the most use, but there are plenty of other kinds that are occasionally relevant. Waves have variable traits, including their wavelength and their magnitude, and these are the qualities that can carry information.
At the most basic level, a mobile communication system has two parts. It has a transmitter, which converts a message into a wave and sends that wave to its destination. It also has a receiver, which receives the wave and converts it back into the original message.
The transmitters and receivers usually take the form of a mobile phone or a tower with an antenna. They may not look too powerful, but they still have enough strength to send a wave out for several miles. The signal will go to a tower, which has a microwave antenna that will receive the signal. The tower then acts as a secondary transmitter, which sends the wave back out to a receiving phone.
The biggest challenge with this system comes from the fact that waves are physical things. They can only travel for a limited distance before they become useless, and some waves can also run into interference from physical objects that are in their path.
Communication companies solve this problem by building large networks of towers. Each tower is capable of both receiving and transmitting waves, so a wave rarely has to travel for a long distance before it can be captured and sent out again. That minimizes the chance of the signal degrading, and it ensures that everybody can get in contact with people who live far away.
Satellites can also be used for this purpose. They offer many advantages, especially because there are relatively few obstacles between the ground and space. Their high angle also allows them to cover a wide area, so one satellite can stand in for many towers. Putting a satellite into orbit is an expensive proposition, but it is one that is worth the effort for most companies.