| 摘要 |
PURPOSE:To inform emergency information to receivers of medium wave broadcast bands, by applying frequency-modulation to a master oscillator of a transmitter of amplitude modulation system with a frequency shift over the entier broadcast bands of medium waves, in a system transmitting emergency information such as earthquake to publics or cars under driving. CONSTITUTION:An output of a high frequency oscillator 1 is amplitude-modulated with emergency information from a microphone 4 at a modulator 2 and transmitted from an antenna 9. An output of an oscillator 7 is applied to a reactance circuit 8 connected to a tank circuit of the oscillator 1 to change the signal level of the reactance circuit 8 at a sufficiently higher frequency than the upper limit frequency of a low frequency amplifier 3. Further, the high frequency oscillator 1 can be oscillated between 650-1,500kHz by taking 850kHz as a center. |
