4. Gyroscope and gyrometer performance

The quality of a gyroscope is characterized by its drift; this is a quantity homogeneous to a rotation speed, numerically equal to the quotient of the torque uncertainty applied to the spinner, by its angular momentum.

In the case of a two-degree-of-freedom gyroscope, this drift can actually be observed at the spinner axis.

In the case of a 1-axis gyroscope, this drift can be observed:

• by trying to stabilize a platform with the gyroscope in question; we then show that the drift of the platform, around the gyroscope's input axis, is equal to the drift of the gyroscope, as just defined ;

• by setting up the device as a gyrometer (figure