| 摘要 |
PURPOSE:To improve the articulation of a received sound signal with a mobile radio system by changing the field intensity of the transmission side and converting the fading noise of low pitch into the fading noise of high pitch at the reception side. CONSTITUTION:For a portable mobile radio telephone, the sound signal is amplified by a sound amplifying circuit 1 at the transmission side and supplied to a frequency modulating (phase modulating) circuit 2. Then the modulated output signal is supplied an amplitude modulating circuit 3. The circuit 3 selects the amplitude modulating frequency so that the fading noise having a pitch of about >=40Hz is produced equivalently at the reception side regardless of the sound signal. While the fading noise having an apparently high pitch is secured at the reception side even in case the fading noise of about 2Hz is produced from a portable mobile radio telephone. Thus the sound is demodulated in a cycle corresponding to the amplitude modulating frequency for a part where only the noise is delivered. |
