| 摘要 |
PURPOSE:To prevent the defects of malfunction due to external noise and S/N degradation, etc., by loading an FM modulation to a source oscillation circuit and making a wide band FM mudulating wave. CONSTITUTION:When there is a security signal, a pulse data generating circuit 3 to generate pulse data and to change the oscillating frequency of a source oscillation circuit 2, a switching circuit 11 to control the on-off action of the oscillation circuit 12 by the output signal of the source oscillation circuit 2 and to oscillate the signal an n-times transmitting frequency of the oscillating frequency of the source oscillation circuit 2 and a sound modulation circuit 4 are provided to a transmitter. On the other hand, in correspondence to this, a receiver is constituted as an FM receiver Thus, a radio type communicating device to be strong against external noise and to have a satisfactory S/N can be obtained. |
