Navigation system
A navigation system includes a map database 11 that stores map information, broadcast wave receivable area information indicating an area capable of receiving a broadcast wave, and broadcast wave reception blocked area information indicating an area incapable of receiving a broadcast wave; a vehicle position detecting unit 15 for detecting a current position of a vehicle; a control unit for estimating a direction of travel from the current position of the vehicle detected by the vehicle position detecting unit, and for deciding, from the broadcast wave receivable area information and broadcast wave reception blocked area information acquired from the map database, as to whether an area capable of receiving the broadcast wave continuously exists in the direction of travel estimated; and an output unit for producing a message indicating existence of an area capable of receiving the broadcast wave continuously in response to a decision result of the control unit.
1. A navigation system comprising:
a map database that stores map information, broadcast wave receivable area information indicating an area capable of receiving a broadcast wave, and broadcast wave reception blocked area information indicating an area incapable of receiving the broadcast wave;
a current position detecting unit for detecting a current position;
a control unit for estimating a direction of travel from the current position detected by the current position detecting unit, and for deciding, from the broadcast wave receivable area information and the broadcast wave reception blocked area information acquired from the map database, as to whether the area capable of receiving the broadcast wave continuously exists in the direction of travel estimated; and
an output unit for producing a message indicating existence of the area capable of receiving the broadcast wave continuously in response to a decision result of the control unit, wherein,
the control unit comprises a guidance route arithmetic unit for searching for a route which connects the current position to a destination and is capable of receiving the broadcast wave continuously according to the broadcast wave receivable area information and the broadcast wave reception blocked area information acquired from the map database; and
the output unit shows the route searched for by the guidance route arithmetic unit, and produces a message indicating whether the route searched for includes the area incapable of receiving the broadcast wave continuously or not.
2. The navigation system according to claim 1 , further comprising:
a map database update management unit for updating the broadcast wave receivable area information and the broadcast wave reception blocked area information stored in the map database.
3. The navigation system according to claim 1 , wherein
the control unit causes, when the area incapable of receiving the broadcast wave continuously exists in the direction of travel estimated, the output unit to display an estimated time period up to a point of time at which the broadcast wave becomes unreceivable continuously.
4. The navigation system according to claim 1 , wherein
the control unit causes, when the area incapable of receiving the broadcast wave continuously exists on the route searched for by the guidance route arithmetic unit, the output unit to display an estimated time period up to a point of time at which the broadcast wave becomes unreceivable continuously.
5. The navigation system according to claim 1 , further comprising a monitoring range input unit for inputting a monitoring range of observing a received state of the broadcast wave, wherein
the control unit makes a decision as to whether the broadcast wave can be received continuously in the monitoring range input from the monitoring range input unit.
6. The navigation system according to claim 5 , further comprising a vehicle speed sensor for detecting a traveling speed, wherein
the control unit varies the monitoring range input from the monitoring range input unit in accordance with the traveling speed obtained from the vehicle speed sensor.
7. The navigation system according to claim 1 , further comprising a broadcast wave receiving tuner for receiving the broadcast wave, wherein
the control unit, when the area incapable of receiving the broadcast wave continuously exists in the direction of travel estimated, switches an output of the broadcast wave received by the broadcast wave receiving tuner to an output of an AV source, or turns down volume of the output of the broadcast wave before receiving the broadcast wave continuously becomes difficult.
8. The navigation system according to claim 1 , further comprising a broadcast wave receiving tuner for receiving the broadcast wave, wherein
the control unit, when the area incapable of receiving the broadcast wave continuously exists on the route searched for by the guidance route arithmetic unit, switches an output of the broadcast wave received by the broadcast wave receiving tuner to an output of an AV source, or turns down volume of the output of the broadcast wave before receiving the broadcast wave continuously becomes difficult.