The simple radio became a communication device which can also serve as a small trasmitter. Thus, giving it the capability to become a mobile phone (cellular phone) Mobile phons are small radios imbedded with mimi trasmitters.Today ,Cellular phons are simply the most common telecom device around the world . In evry city there is mobile teliphone switching office (MTSO)& handels every activity of the base station. The city of any size requires large number cells .The mobile srvice is also provided along the roads joining different cities.
WORKING CELL PHONES: The cell phones have low power trasmitter about 0.3 to 3 watt and the base station also has low transits power. Because of this low power trasmission. Because of this low power trasmission, there is no interference between the adjacent cells, saves power consumption. In every city there is mobile teliphone switching office (MTSO)&and handles every activity of the base station. The cell phones have spetial code associated with them and are used to identify the phones, phon's owner, and service provider. When the phone is switched ON, it listens for special identification code (SID).A unique 5-digit SID is assigned to each carrier and are trasmitted on a control channel. When the cell phone receive SID,it compares it with internal progmmed SID and if it matches ,the MTSO tracks the cell phone continuosly through the base station. When the user gets call ,thenvit communicates with it through the control chnnel. It informs regarding which frequency paire is to be used over control channel. Then the base station and user phone strart communication over this frequency paire and the call is established. The control also informs about calling party phone number. Part of cellular phone:microphon, amplifier and filter, A/D Converter ,Microprocessor, FSK Modulator(Frequency-Shift Keying),Antenna,FSK Detector,D/A Converter,Filter &Amlifires,Speaker,RAM&ROM,Flash Meory Card, and Keyboard, LCD Display .
FUNCTIONS PERFORMED BY CELL PHONES : 1.Cell phones can make a phone call to any other phone. 2.It stores information such as phone numbers ,names etc. 3.Cell phones can keep track of youre appointments and remind youre about them. 4.Some models of cell phones can send and receive e-mails. 5.cell phones can also browse on internet.