Honda Accord 2008 Manual page 2593

07/11/02 09:54:02 61TA0000_230_0149
Navigation System
System Description (cont'd)
Navigation Unit
The navigation unit calculates the vehicle position and guides you to the destination. The unit performs map matching
correction, GPS correction, and distance tuning. It also controls the menu functions and the DVD-ROM drive, and
interprets voice commands. With control of all these items, the navigation unit makes the navigation picture signal,
then it transmits the signal to the display panel control unit and audio driving instructions to the audio unit.
Calculation of Vehicle Position
The navigation unit calculates the vehicle position (the driving direction and the current position) by receiving the
directional change signals from the yaw rate sensor and the travel distance signals from vehicle speed pulse (VSP)
signal of the ECM/PCM.
Map Matching Tuning
The map matching tuning is accomplished by indicating the vehicle position on the roads on the map. The map data
transmitted from the DVD-ROM is checked against the vehicle position data, and the vehicle position is indicated on
the nearest road. Map matching tuning does not occur when the vehicle travels on a road not shown on the map, or
when the vehicle position is far away from a road on the map.
GPS Tuning
The GPS tuning is accomplished by indicating the vehicle position as the GPS's vehicle position. The navigation unit
compares its calculated vehicle position data with the GPS vehicle position data. If there is large difference between
the two, the indicated vehicle position is adjusted to the GPS vehicle position.
Distance Tuning
The distance tuning reduces the difference between the travel distance signal from the VSP and the distance data on
the map. The navigation unit compares its calculated vehicle position data with the GPS vehicle position data. The
navigation unit then decreases the tuning value when the vehicle position is always ahead of the GPS vehicle position,
and it increases the tuning value when the vehicle position is always behind the GPS vehicle position.
23-148