Synchronous dual channel QPSK modulation and demodulation device in CDMA system and its modulation and demodulation method

摘要

The present invention relates to a synchronous dual channel QPSK modulation and demodulation apparatus in a CDMA system and a synchronous dual channel QPSK modulator in a CDMA system for receiving two input signals through two input terminals and modulating the input signals, A first Walsh cover means for receiving a first input signal through a first input terminal and covering the first input signal through Walsh cover, a second Walsh cover means for receiving and outputting a second input signal through a second input terminal, A first pseudo modulation means for pseudo modulating the output signal of the addition means with a predetermined pseudo noise and outputting the pseudo modulated signal to the second Walsh cover means; Second pseudo modulation means for pseudo modulating the output signal of the cover means with the pseudo noise and outputting an output signal of the first pseudo-A second pulse shaping means for shaping an output signal of said second pseudododulation means into a pulse wave and outputting a pulse signal; and a second pulse shaping means for outputting an output signal of said first pulse shaping means A second amplitude modulation means for amplitude modulating an output signal of the second pulse shaping means to a predetermined modulation signal and outputting the modulated signal, and a second amplitude modulation means for amplitude modulating the output signal of the second pulse shaping means to a predetermined modulation signal, And outputs the sum to the output of the second amplitude modulating means and outputs it to the antenna. The effect of the second addition means is to eliminate the crosstalk interference, which has been one of the factors degrading system performance,