A system is proposed for characterizing the performance of a sportsman. The system is capable of using motion data it receives describing a movement during the sport, to distinguish the type of sport, and type of stroke, which is being played. The system can furthermore detect the quality of a stroke involving an impact (e.g. an impact between an item of sports equipment and a ball), based on the observation that a good stroke will be in a “sweet spot” in which the amount of vibration caused by the impact is limited.
