| 摘要 |
<p>PURPOSE:To demodulate a data accurately by obtaining a correlation between a spread spectrum signal and plural PN series and comparing the quantities of a quaternary moment around square mean values of the correlation. CONSTITUTION:A modulator M outputs a spread spectrum signal modulated to output a PN 0 series when the state value of the information whose transmission speed is 1/To is 0 and output a PN1 series of the same period length as that of a PN0 series when the state value of the information whose transmission speed is 1/To is 1. Correlation devices 14,15 of a demodulator D obtain simultaneously the correlation of the spread signal and the PN0 and PN1 series. Outputs of the correlation devices 14, 15 are added by an adder 20 through PN series generators 16,17 and square circuits 18,19 generating the same PN0, PN1 series as those on the modulator side. From the output, quaternary moment arithmetic operation circuits 22,23 calculate a quaternary moment and a comparator 25 compares the quantities. Then in which PN series a peak of the correlation value exists is estimated to demodulate the data.</p> |
