SPREAD SPECTRUM COMMUNICATION EQUIPMENT. DEMODULATOR FOR SPREAD SPECTRUM COMMUNICATION, SURFACE ACOUSTIC WAVE ELEMENT AND SURFACE ACOUSTIC WAVE COMPONENT

摘要

PROBLEM TO BE SOLVED: To attain a high transmission speed by integrating an output signal of a surface acoustic wave matched filter and an output signal of plural surface acoustic wave delay lines whose delay differs from each other so as to attain the demodulation of the QPSK system. ;SOLUTION: An output signal a2 of a surface acoustic wave delay line 2 is delayed by (T+1/bc/8) in comparison with an output signal a1 of a surface acoustic wave matched filter 1 to an integration circuit 2, where T is one period of a received demodulation signal, bc is a carrier frequency of an SS input signal, in which a signal of in-phase component is extracted from four states with difference of phases by 90°. On the other hand, an output signal B2 of a surface acoustic wave delay line 4 is delayed by (T-1/bc/8) in comparison with an output signal b1 of the surface acoustic wave matched filter 1 to an integration circuit 5, in which a signal of in-phase component is extracted from four states with difference of phases by 90°. Thus, demodulation by the QPSK system is attained and the SS communication system with a fast transmission speed is built up.;COPYRIGHT: (C)1997,JPO