NAVIGATIONAL AID

摘要

A navigational aid is provided which gives the user information about their current position. In one embodiment, the navigational aid includes a GPS receiver which provides this position information. A secondary position estimating circuit is provided which estimates the user's current position using dead reckoning techniques. The estimated position from the secondary positioning circuit is used when signals are not received from the GPS receiver. In a preferred embodiment the secondary positioning circuit estimates the speed of the user by detecting a speed related vibration.