| 摘要 |
PURPOSE:To store automatically an antenna without malfunction by detecting noise at engine operation so as to discriminate or not the antenna is to be descended. CONSTITUTION:When the engine is started, a noise (a) is given to an input of a noise amplifier 1, and after the noise is amplified, the result is fed to comparators 3, 5 via a smoothing circuit 2. Then the converter 3 is inverted earlier than the comparator 5 according to the difference of a reference voltage. An output of the comparator 3 activates a timer 4, a signal of H level is generated for a prescribed time and fed as a reference voltage to the comparator 5. An H level signal is outputted from the comparator 5 after a prescribed time is elapsed. The prescribed time is provided to prevent malfunction if the engine is not started by one starting operation. Then a timer 6 is operated by the H level signal from the comparator 5, an antenna drive circuit 7 is driven for the time to store the antenna. |
