A trip meter, such as a taximeter or a mileage meter for a commercial vehicle, such as a truck, are combined with an integral GPS receiver/computer which provides GPS position and time information. Odometer input pulses to the trip meter are accurately calibrated by using GPS position, velocity, and...http://www.google.de/patents/US6087965?utm_source=gb-gplus-sharePatent US6087965 - Vehicle mileage meter and a GPS position tracking system
