| 摘要 |
<p>A navigation device comprises judgment means that judges whether to make a change to the tunnel mode based on the car position detected by detector means for car position, the car velocity detected by speedometer means, and the tunnel feature data read from a database; and control means that, in response to an instruction signal sent from the judgment means to indicate a change to the tunnel mode, presents the features of the tunnel to pass through in display means and starts on-board devices in the tunnel mode.</p> |
