Abstract: In order to decrease the cost of velocity meter, which is a part of a vehicle navigation system, a new kind of low-cost velocity meter is designed. This velocity meter includes a high-precision photoelectrical coder, and a corresponding phase demodulation circuit, it also has the characteristic of anti-interference. This meter had been experienced by several field-tests accompanying with the navigation system. The results show that this new velocity meter can meet specific requirements of the navigation system.

Key words: Vehicular nevigation system, Velocimeter, Photoelectric coded disk, Phase discrimination circuit