| 摘要 |
PROBLEM TO BE SOLVED: To provide a spread spectrum transmitter and a spread spectrum receiver which can eliminate the influence of mutual interference caused between the orthogonal and in-phase components regardless of a carrier frequency error and also can accurately decode the data. SOLUTION: In a spread spectrum communication method which uses a quadrature phase (QPSK) modulation system, a demodulation circuit is prepared to receive and demodulate the signals which are transmitted with a prescribed time difference secured between the in-phase quadrature phase (IQ) components together with a correlator 26 which secures the mutual correlation between the IQ component and a spread code, a sampling circuit 27 which samples the output signal of the correlator 26, a phase computer 28 which calculates a phase from the ratio of the IQ component of the output signal, a differential decoding circuit 29 which differentially decodes the output signal, an automatic frequency control circuit 30 which corrects the frequency error of the output signal, a decoding circuit 31 which decodes the data from the output signal, and a clock reproduction circuit 32. At the receiver side, the clock reproduction and a carrier frequency error are corrected based on the vector of the signal received at time (t) and the vector of the signal received at time (t+Td) and the data are demodulated. |
