| 摘要 |
A car navigation system is provided to create traveling direction information of a vehicle base on the acceleration data transmitted from the acceleration data source without electric connection with the back-up lamp. A car navigation system comprises a speed data source(21) outputting pulse type speed data, a dead reckoning positioning apparatus including an acceleration data source(22) installed in the vehicle body, and a traveling direction information generator(30). The traveling direction information generator includes an edge detector(31) producing edge signals at the rising edge and falling edge of the speed pulse, an acceleration integration controller(32) producing acceleration integral control signal when the next edge signal is not inputted from the edge detector and the minimum time considered as pause has elapsed, an acceleration integrator(33) integrating acceleration data from the acceleration data source when the acceleration integral control signal is input from the acceleration integration control part, and a traveling direction decision unit(34) determining that the vehicle is traveling forward or rearward when the integrated value of the acceleration integrator is positive or negative.
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