| 摘要 |
PROBLEM TO BE SOLVED: To raise a reception probability of a signal from a portable device at a vehicle side receiving unit in a vehicle communication system, without being affected by a change of a noise environment.SOLUTION: A receiving unit 11 includes a receiving unit 13 that operates intermittently and a CPU 14. When the reception level of a reception signal is equal to or more than a reception level threshold value, the receiving unit operates for a longer time, performs wakeup determination, and starts a CPU that is sleeping. The CPU raises the reception level threshold value and improves the accuracy of the reception level threshold value regarding it as erroneous reception if the number of times when the ON time of the receiving unit within a prescribed time is at a reference value or more is a prescribed value or more. The CPU raises responsiveness and reception probability by preferentially using a channel with a lower reception level threshold value for a wide band and AFC-off, and switching to another channel with a narrow band and AFC-on when reception is failed. This allows wasteful extended operation of the receiving unit and starting of the CPU to be avoided and substantially reduces power consumption. |
