Cell Phones – How Do They Work?
If you ask someone how a cell phone works you will likely get an answer involving radios and signals, but the odds are it will not be very clear. Considering how integral they are to a communications based society, it is kind of funny how so few people really understand how they work. This report will present a few facts to make sense of it all and explain cell phones’ innovations over the preceding technology.
Before cell phones became so ubiquitous, people on the cutting edge of communications technology had car phones. They worked on the same principles as a radio but it had a few limited features. For one, it was connected to only one central antenna per city, and each car needed a transmitter big enough to transmit up to forty or fifty miles. Each central antenna had twenty-five channels. The car phone was a big step over “half duplex radio,” or walkie talkies, which used only one frequency. As a result, only one person could talk at a time while the other person had to listen. In car radios (and cell phones) each transmitter uses different frequencies, so you can talk and listen at the same time.
But cell phones function way more efficiently than car phones because the city is divided up into different transmitting areas, called “cells” (hence the term “cell phone”) rather than using one central antenna. Each cell takes up about ten square miles, and this division allows the same signals to get reused across the city. Essentially, cell phones no longer require you to be in contact with one base anymore. There are now not only more towers, but the technology has expanded to allow you to utilize their power interchangeably. When you turn on your cell phone, after you have established communication with your base station, your phone sends out a registration request that keeps track of what cell of the city you are in. When you are on the border of one cell it registers that you are losing signal power, but simultaneously you gain signal strength from the cell you are approaching. As a result, you can be in the middle of a conversation and switch from cell to cell and you’d have no idea that anything is different. Indeed, most people don’t know that they’re in a “cell” in the first place.
There is an old joke about the Soviets during the Cold War who were convinced they had superior technology because they had the biggest computers in the world. Sometimes less is more, and this is very true of cell phones. One of the biggest innovations was the realization that actually it was better to have lower power transmitters in order to consume less power. This is why cell phones are able to have such a small battery. The key isn’t raw power, but portability.
Bell has changed the industry here in Canada by joining with Telus in adopting a technology known as HSPA (High Speed Packet Access). This improves cell phone performance by refining the communication process between individual handsets and bases. Essentially, it is a technology that better utilizes existing radio bandwidth. Though several breakthroughs were necessary to usher in the modern era of cellphone technology, it still boils down to radios and signals!
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