The tachometer is an measuring instrument making it possible to estimate the speed of a mobile.

The Speedometer of a vehicle Automobile is a tachometer . It uses the rotation of the transmission to determine the speed of the vehicle. The GPS can also be regarded as a cinenometer when consequently configured.

The radar used by the police force during speed controls on the roads is of very an other type. The Radar is based on the Effect Doppler (modification of the frequency reflected by the mobile) to calculate the speed of the mobile.

See too

• Radar of road control
• Automatic radar
• Speedometer Automatic radar in France
• Maximum speed authorized on road