Measurement of the precision of a timepiece comprising a continuous rotation electromechanical transducer in the analogue time display device thereof

A method for measuring the medium frequency of a digital signal derived from a reference periodic signal generated by an electronic oscillator (quartz oscillator) forming a timepiece (2) which includes an analogue time display device and a continuous rotation electromechanical transducer (generator or continuous rotation motor) which is kinematically linked to this display device and wherein the medium rotational speed is regulated by a regulation device. The medium frequency of the digital signal is determined by a measurement device (70) without galvanic contact with the movement of the timepiece. The measurement method makes it possible to determine the rate of the timepiece and the precision of the electronic oscillator based on regulation impulses detected by a magnetic sensor (72) and over a measurement period limited to the duration of an inhibition cycle of periods of the reference periodic signal.