초록 ▼

In a direct sequence spread spectrum communications system wherein user binary information symbols are spread spectrum modulated and transmitted to the other party, a non-coherent Walsh QPSK and a coherent Walsh QPSK modulation methods, wherein the PN spreading sequences for inphase and quadrature d

In a direct sequence spread spectrum communications system wherein user binary information symbols are spread spectrum modulated and transmitted to the other party, a non-coherent Walsh QPSK and a coherent Walsh QPSK modulation methods, wherein the PN spreading sequences for inphase and quadrature data in a conventional QPSK PN modulation scheme are coded by Walsh sequences indexed by a special rule to reduce the envelope variation of the transmitted signal, can reduce the envelope variation of transmit signal. And, in a direct sequence spread spectrum communications system wherein several user binary information symbols are spread spectrum modulated, the information symbols of each user are covered by user-specified different Walsh codes and transmitted to the other party, a QPSK modulation methods, wherein the polarity of quadrature PN spreading sequence of a user is controlled by a system controller to make the number of users using the quadrature PN sequence equal to that of users using NOT of the sequence, can reduce the envelope variation of transmit signal.

대표청구항 ▼

[ What we claim:] [1.] In a direct sequence spread spectrum communications system wherein user binary information symbol sequence from one party are spread spectrum modulated and transmitted to another party for reducing the envelope variation of a transmitted signal, a spread spectrum modulating ap

[ What we claim:] [1.] In a direct sequence spread spectrum communications system wherein user binary information symbol sequence from one party are spread spectrum modulated and transmitted to another party for reducing the envelope variation of a transmitted signal, a spread spectrum modulating apparatus comprising:means for generating a first and a second Walsh sequences of indexes (2i) and (2i+1), wherein i is an integer value greater than or equal to 0;means for generating a pseudo-noise binary code;means for generating spread symbol sequence operating exclusive-OR of said user binary information symbol sequence and said pseudo-noise binary code;means for generating inphase sequence operating exclusive-OR of said spread symbol sequence and said first Walsh sequence, and for generating quadrature sequence operating exclusive-OR of said spread symbol sequence and said second Walsh sequence; andmeans for generating inphase signal shaping waveform of said inphase sequence, adjusting the gain and converting said shaped waveform of said inphase sequence into an analog signal, and for generating quadrature signal shaping waveform of said quadrature sequence, adjusting the gain and converting the shaped waveform of said quadrature sequence into an analog signal in which the sum of an inphase carrier modulated by said inphase signal and a quadrature carrier modulated by said quadrature signal is transmitted to an antenna via a frequency up-converter and an amplifier.