| 摘要 |
PURPOSE:To improve the secrecy of sent/received signals by optionally attenuating the strength of a signal delayed by plural delay means. CONSTITUTION:A signal received from an input terminal 1 via a telephone line receives time delay differences t1, t2,t3 by delay circuits 11-13 till the signal is sent to antennas 17-19. On the other hand, variable attenuators 14-16 attenuate an input signal power freely under the control of a control circuit 5 to control the signal strength of a spread spectrum communication system SS at a phase difference of the time t1. When the SS signal is sent with the phase difference of the time t1, the attenuation of only the attenuator 14 is minimized and the attenuation of the other attenuators 15, 16 is set to be a somewhat larger attenuation. According to the control, the SS signal with the phase difference t<1> is sent from the antenna 17 at a strong signal strength, and the SS signal with smaller signal strength having phase differences t<2>, t<3> is sent from the antennas 18, 19. |
