Antennas, Base and Mobile Stations -16.Quartz Oscillator and Flash Memory
The quartz oscillator is a device that governs the frequency of electric signals through voltage inputs to a plate of quartz that is cut to a required shape. It serves to prevent interference by accurately determining the transmission and reception frequencies for the base station and mobile unit. NTT DOCOMO secures frequency precision by using temperature-compensation quartz oscillators (TCXO) and AFC control to control transmission and reception frequencies on the basis of high-precision frequency signals transmitted from the base station.
The flash memory, or EEPROM, can maintain data even when the power of the portable unit is turned off, and makes it possible to write a large volume of data and erase it instantly. The adoption of the flash memory has facilitated the expansion of user settings such as memory dialing functions. It has also contributed to improved efficiency in the manufacturing and adjusting processes, as the manufacture of portable unit hardware can proceed simultaneously with control program confirmation work and radio parameter adjustments can be made by writing them to the memory.
Functions of Crystal Oscillators