Digital communication technology has the various advantages in view of high quality data service, a compacted mobile and base station, and frequency efficiency. The practical advantage of spread spectrum communication is the fact that they can implement various diversity combing using a simple structure.
The ISM band is 902 to 928 MHz. The availability of frequency spectrum in ISM band has spurred the development of a new generation. Wireless products have been appilicated to point of scale terminals, to point-to-point radios in addition to digital cordless telephones.
In this thesis, the spread spectrum digital cordless telephone is implemented. The receiver frequency is 902.3∼905.0M HZ and transmitter frequency is 925.05∼927.75 MHz. In 900 MHz ISM-band, the spread spectrum cordless telephone with QPSK modulation scheme is designed by HP's ADS simulation tool.
The transmitter filter used chebyshev filter with three step and it was constructed of 0.1 dB ripple characteristic. The receiver filter used chebyshev filter with five step and unloaded Q of resonator sets to 1500 in this simulation. From the results of simulation, the processing gain of direct sequence method is shown sufficiently.
The spread spectrum CT is implemented. Characteristics of implemented cordless telephone board is satisfied with designed parameter.