Inside a Digital Cell Phone(Part01)

If you take a basic digital cell phone apart, you find that it contains just a few individual parts:

· An amazing circuit board containing the brains of the phone

· An antenna

· A liquid crystal display(LCD)

· A keyboard (not unlike the one you find in a TV remote control)

· A microphone

· A speaker

· A battery

The circuit board is the heart of the system. Here is one from a typical Nokia digital phone:

In the photos above, you see several computer chips. Let's talk about what some of the individual chips do. The analog-to-digital and digital-to-analog conversion chips translate the outgoing audio signal from analog to digital and the incoming signal from digital back to analog. You can learn more about A-to-D and D-to-A conversion and its importance to digital audio in How Compact Discs Work. The digital signal processor (DSP) is a highly customized processor designed to perform signal-manipulation calculations at high speed.

The microprocessor handles all of the housekeeping chores for the keyboard and display, deals with command and control signaling with the base station and also coordinates the rest of the functions on the board.

The ROM and Flash memory chips provide storage for the phone's operating system and customizable features, such as the phone directory. The radio frequency (RF) and power section handles power management and recharging, and also deals with the hundreds of FM channels. Finally, the RF amplifiers handle signals traveling to and from the antenna.