A mobile phone is a wireless telecommunications device. Basically, radio frequencies are responsible for linking mobile radio transmitters (or just transmitters) to transmitting and destination base stations. Standard telephone networks are connected to users by receiving stations. The geographic region offered by a cellular system is subdivided into areas called cells. Each cell has a central base station and two sets of designated transmit frequencies. One set is used by the base station and the other by mobile phones.
To avoid radio interference, each cell uses different frequencies than the surrounding cells use. However, cells that are far enough apart can use the same frequencies. When a mobile phone leaves one cell and enters another, the phone call is transferred from one base station to another and the set of transmission frequencies to the next, using a computerized switching system.
The process of transmitting radio frequencies from one cell phone to another can be made possible through the different parts and functions of the cell phone.
These are the main parts of a mobile phone:
o LCD screen – or liquid crystal screen is the front screen with little power. It is generally slim, so it fits well with battery-powered cell phones.
o Menu button: this is the control key that activates the menu. The menu page has access to various phone functions such as settings, reminders, games, messages, and media player.
o Keyboard: is a group of alphanumeric keys on a keyboard. Keys are pressed to enter data, such as when composing a message or entering the number to be called.
o Antenna: emits and captures radio signals. Some earlier variations of mobile phones have antennas attached outside of the handset. The antennas on later models are built in-house.
o Battery: a device that stores energy and is practical in electrical form. The first cell phone batteries were made of nickel cadmium (NiCad). This element is believed to be harmful to the environment and should be disposed of as toxic waste. It also causes interruptions in sending information when the battery is not charged properly. It has a tendency to lose its power quickly if not used properly and regularly. Nickel cadmium tends to break down when overcharged.
Nickel Metal Hydride (NiMH) was used in subsequent battery productions to solve NiCad’s problems. They do not contain toxins and are relatively safe for the environment. They do not need to be completely drained before recharging. However, overcharging can also affect battery life.
Today, most rechargeable batteries are made of lithium-ion. They last longer than NiMH and can be overcharged without damaging the phone unit.
o Microphone: device that captures and receives sound energy. It can amplify sounds.
o Headset – This is also known as a headset, car kit, or hands-free kit. A headset allows users to talk to someone without having to hold the unit to their ears. This is very practical for people who drive.
o Power switch: it is the button to turn the mobile phone on and off. A faulty power switch will not be able to turn on a unit. Always check your lead terminal if it is connected with the power IC.
o Battery terminal – Connects the battery to the mobile phone. These are usually the little shiny gold metals that we see before putting in the batteries.
o Power IC: acts as a voltage regulator and turns on. The whole unit will not work if it is faulty.
o Oscillator – also called clock frequency. It creates low frequencies, which are used to run digital components and helps to postpone power in the event of failure.
o Frequency divider: used in mobile phones to divide the clock frequency and achieve a precise frequency to run digital components. This part is integrated radio ICs, the equivalent of Hagar IC or Mojoelner in Nokia mobile phones.
o CPU: the central processing unit is the brain of the mobile phone and controls the main parts of the unit. It is vital in the boot test process. The CPU is fundamentally associated with memory chips and flash chips.
o Flash chips: Flash chips contain boot information. It has stored instructions for the CPU to control other components.