| 摘要 |
PURPOSE:To easily spread a spectrum inversely and to widely reduce a circuit by spreading the spectrum by an NRZ spreading code at a modulating side and removing an interference wave mixing into an influential frequency band and inversely spreading the spectrum at a demodulating side. CONSTITUTION:At a modulating part 10, information data are supplied through an LPF1 to a multiplier 2, and a primary modulated (PSK modulated) signal is generated by multiplying the data by a first carrier at this multiplier 2 and supplied to an adder 6. The adder 6 supplies an added signal obtained by adding the PSK modulated signal and a second carrier to a multiplier 3. At the multiplier 3, a spreading code obtained from a spreading code generating circuit 9 and another spreading code obtained from a multiplier circuit 4 are multiplied with each other, a spectrum spreading signal SM(t) is outputted, and only the main lobe of the signal is outputted through a BPF11. At a demodulating part 20, only the pass band component of the input signal SM(t) is passed through BPFs 12 and 13, the outputs of the BPFs 12 and 13 are added and supplied to spreading filters 18 and 19, and only a primary modulated wave and a carrier are separated into respectively spread signals. At a multiplier 4, both the signals are inversely spread, obtained two two-phase PSK signals are passed through a BPF14, and only one out of the two two-phase PSK signals is separated and outputted. |
