| 摘要 |
PURPOSE:To communicate smoothly with an opposite low in signal level by varying automatically the time from a drop in reception level to power supply cut- off according to the reception level through a communication device whose power supply is cut off when the reception level drops. CONSTITUTION:A circuit which cuts off the power supply of the communication device a specific time after the reception electric field level drops to a specific communication incapable level is provided in the communication device so as to prevent a waste of electric power. This automatic power supply cut-off circuit incorporates gate circuits 2 and 3 which detect the reception electric field level in three stages, a variable frequency divider 4 which divided the frequency of a clock CK at a frequency division ratio corresponding to signals from the circuits 2 and 3, and a gate 1 for resetting. Those circuits operate to vary automatically the time up to power supply cut-off operation according to the reception electric field level when a reception electric field is ceased during communication. Therefore, power supply is cut off in a short time when the communication is carried on while the signal level of an opponent of communication is low and the communication is broken frequently. |
