Communication: Inside A Digital Cell Phone

Ever wonder what's inside your digital cell phone? Here's a guide to the important components and inner workings of a typical cell phone.

The digital cell phone is an amazing product of technology, incredibly advanced but comprised of just a few basic parts. They operate by way of radio FM channels, automatically changing signals to compensate for the user's movement in and out of range of towers.

If you open up a digital phone, inside you will find the following components: a microphone, speaker, display (usually LCD, depending on the age and style of your phone), miniature keyboard, antenna, circuit board, and on the outside, the battery. Many of these perform very basic functions you find in other electronics, but the circuit board is state-of-the-art, handling and delegating all the inner functions of the phone.

The Analog-to-Digital/Digital-to-Analog conversion chips interpret the signal the phone is picking up and so that it can be analyzed by the Digital Signal Processor (DSP). Almost all phones sold today are digital, due to the much higher performance of the system--digital signals are easily compressed and transmitted, and allow for several times more frequencies to be in use at once than analog signals do. The binary compression system used in digital technology creates smaller packets of information that transmit quickly and are still clearer than analog transmissions.

The Digital Signal Processor is an advanced chip that, once it has something to work with, handles the millions of calculations needed to compress and decompress the extremely high number of signals received by the phone before sending them back through conversion. The radio frequency (RF) amplifiers manipulate the signals being picked up and emitted by the antenna.

"Dual Mode" refers to the ability of a phone to switch readily between analog and digital methods (if the phone supports AMPS), depending on the service area. "Dual Band" on the other hand is able to operate on different frequency levels, which can be essential to a traveler, since these frequencies change from country to country, and sometimes even by provider. These functions are also performed by the processing chips on the circuit board.

A power management section operates the phone's recharging and power levels as well as radio frequencies. The board also contains a microprocessor that handles the other functions of the phone, such as keyboard operation, ringers and tones, the display, special features, and more.

Add the memory and you basically have the most important components of the circuit board. These, combined with the microphone, keyboard, antenna and other larger pieces form all that is contained within most cell phones today. The display varies greatly from cell to cell; they are becoming larger and clearer due to the demand for functions such as games, Internet and color backgrounds on phones, and the need for backlighting. Color screens do require more memory to operate as well as a larger size for the Internet browser (also know as the wireless application protocol or WAP), making them a little more expensive, but they are quickly becoming more popular than the older monochrome screens and may be standard fairly quickly.

GSM phones, which aim to be the "global" type of cell phones, also contain a small SIM (subscriber identification module) card that allow users to change the phone number and even the provider by simply swapping one card for another. The other popular type of phone sold in North America, known as a TDMA, does not contain such a card.

Enclose all these components with a casing, and you have yourself a modern digital cell phone!

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