| 摘要 |
PURPOSE:To improve the confidentiality of a transmission signal and to improve immunity to disturbance at reception of the signal by multiplying spread code series signals different from each other and generated in different timings, synthesizing the spread code series signals and applying modulation-demodulation to the synthesized signal. CONSTITUTION:A double balanced modulator 11 multiplies spread code series signals 3,10, the synthesized spread code series signal 12 becomes a signal 12. Since the phase of a carrier 5 is inverted respectively to 0 deg. and 180 deg. corresponding to the positive and negative voltages of the synthesized spread code series signal 12. a modulation signal 6 being an output signal of the double balanced modulator d becomes a signal (e), and the signal is sent at transmission. In case of the reception, the signal waveform traces the opposite process to that at the transmission. Thus, the confidentiality at modulation and the immunity to disturbance of the demodulator are improved. |
