Why a Cell Phone?
Cell phones are used by millions the world over. Because you can use a cell phone from just about anywhere to talk to anybody it is one of the greatest inventions for social and business life today.
Many functions are available for convenient and efficient cell phone usage. They are growing so fast that the cell phone was noted by Forbes ( September 20, 2004 ) to become the PERSONAL CONTROLLER FOR ANYTHING humans come in contact with.”
For instance, you can use cell phones to:
- Keep a list of tasks
- Manage e-mail
- Surf the Internet and get the information you need
- Keep your contact list
- Enjoy a large number of games on your cell phone
- Hook up with accessories like MP3 players, GPS receivers, and PDAs
Because cell phones are increasingly important, it's good that you are checking up on them. What follows should clear up some misconceptions about cell phones and make you more of an expert than the average person.
Did you ever ask yourself, “What's inside the box?” Let's take a look at how the cell phone differs from a traditional phone. We will learn what the important acronyms mean; i.e., TDMA, CDMA, PCS, and GSM. The way you will know how to buy and use the best cell phone for you is to know the nitty-gritty. It will save you money and lots of grief!
of the 19 th century. By combining the telephone with the radio, we essentially have a wireless phone!
Like cell phones, when old-fashioned telephone-radios were installed in cars, they greatly helped people on the move to communicate. They utilized a central tower in each city, having around 20-25 channels. Of course, the towering antenna had to transmit signals some 50 miles (approximately 70 km). That meant great power was needed. Its nature also was that only a few people could access these 20-some channels.
The cell phone miracle is that an area can now be divided into many smaller cells. This enables frequency to be reused many times over, and allows millions of people to take advantage of the cell phone's convenience and efficiency.
Cell phone carriers usually get about 800 frequencies to use throughout a city, in the typical analog cell phone system. The city is divided into numerous cells of about 10 square miles (26 square kilometers). Usually, we conceive these as hexagons in a huge hexagonal grid.
Having low-power transmitters in the cell phones and base stations permits identical frequencies to be reused in non-adjacent cells. Within each cell is its own base station that is made of a little building, some radio equipment inside of it, and a tower.
Cell Phone
Transmission
Low-strength transmitters in cell phones are the reason they can send
signals. Cell phones in general have a couple of signal strengths:
six-tenths of a watt and three watts. Along with the base station
transmitting at low power, being lower than the four watts of the average
citizen's band radio provides two advantages for cell phones:
First, it is not necessary for the transmissions to exceed the boundaries of the cell, and indeed they don't go too far out. That enables each cell to reuse the 56 frequencies.
Second, low-power transmissions keep the battery consumption low, permitting the installation of ever smaller cell phone batteries.
Regardless of the city size, numerous base stations are required in the cell phone system. Several hundred towers are necessary in the average large city. The cost is kept low for the users through economies of scale; i.e., lots of people are using their cell phones.
In addition to the above, the cell phone system requires a Mobile Telephone Switching Office (MTSO). All base stations are under its control, and every phone connection to the land-based phone system is also managed by it.
Codes that Cell Phones Use
Unique codes are integrated into all cell phones. By these codes, the cell phones can be positively identified, along with their respective service providers and owners. These codes are described now:
- Electronic Serial Number (ESN) – every cell phone has a special 32-bit number programmed into it when made
- Mobile Identification Number (MIN) – the phone number of the device helps generate this 10-digit number
- System Identification Code (SID) – the FCC assigns this unique 5-digit number to each carrier.
When you buy a service plan and have the cell phone activated the Mobile Identification Number and the System Identification Code get programmed onto it. The Electronic Serial Number, however, is permanently affixed to the phone during manufacture.
