Ciclosport RDS II

Sports Independent distance and speed sensor - ideal for jogging, nordic walking, inline skating or skiing

Non-contact measurement of speed and distance by radar waves using the Doppler effect. Developed was that only 65 gr. (Including battery) light unit from the Fraunhofer Institute, manufactured by Siemens and tested as in sled dog race in Alaska.
The high accuracy of 99% generally ensures accurate information. It comes to no interruptions and limitations as GPS devices, or transmission problems caused by power lines.