| 摘要 |
PURPOSE:To stop the reproduction of a tone with the component of a high frequency and to make a reception sound easy to be heard when the reception sound is small and reception sound volume is enlarged by providing a cut-off frequency changing over switch interlocked with a reception sound volume changing over switch on a low-pass filter. CONSTITUTION:A reception signal transmitted from a host equipment is inputted through an antenna 1 to a reception circuit 2 and the demodulated reception sound is outputted. This output passes through a low-pass filter 3 and the frequency component more than a sound frequency band is removed. Then, the output is amplified by a speaker amplifier 5 and reproduced by a loud-speaker 7. At this time, the amplification factor of the speaker amplifier 5 is switched by a reception sound volume changing over switch 6. A cut-off frequency changing over switch 4 of the low-pass filter is operated while being interlocked with the reception sound volume changing over switch 6. Then, the switch 4 is operated so that when the amplification factor of the speaker amplifier 5 is small, the cut-off frequency of the low-pass filter 3 can be made high and when the amplification factor of the speaker amplifier 5 is large, the cut-off frequency of the low-pass filter 3 can be made low. |
