| 摘要 |
There is disclosed a vehicle-mounted device (30) with a sleep function for use in a road-to-vehicle communication system. After having indicated a switching period T1 and reception frequencies F1, F2 to a frequency switching controller (2), a controller (1) stops operation of an internal counter, and enters a sleep mode until it cancels the sleep mode in response to a detected signal from a receiver (3). While a vehicle with the vehicle-mounted device (30) is running outside of a communication range of a road radio unit installed at a toll gate or the like, the frequency switching controller (2) independently performs a frequency search process on an RF module (4), and the controller (1) is in the sleep mode. Therefore, the vehicle-mounted device (30) has a relatively low power requirement. <IMAGE> |
