A method of calibrating an axisymmetrical Force-Rebalance Coriolis Vibrating Gyroscope (CVG), the CVG comprising: a first gyroscope having a ring-like resonator; and, eight electrodes (1-8) located on or near the resonator at equal positions separated by 45°; wherein the method comprises: (a) feeding an excitation signal to a first electrode of the eight electrodes to drive a principal vibration mode along a first axis (X); (b) obtaining an output of a second electrode of the eight electrodes along a second axis (Y) at a 45° angle relative to the first axis (X); (c) after a period, switching the excitation signal from the first electrode to the second electrode to drive a secondary vibration mode along the second axis (Y); and, (d) obtaining an output of the first electrode along the first axis (X), (e) calculating a bias according to the following equation: B = U y + U x 2 × SF where U y is the output when the vibration is driven along the first axis (X), U x is the output when the vibration is driven along the second axis (Y), and SF is a scale factor of the first gyroscope; the method being characterised by : (f) performing steps (a)-(e) across all of the positions of the eight electrodes to identify an entire bias function of the first gyroscope. a first gyroscope having a ring-like resonator; and, eight electrodes (1-8) located on or near the resonator at equal positions separated by 45°; wherein the method comprises: (a) feeding an excitation signal to a first electrode of the eight electrodes to drive a principal vibration mode along a first axis (X); (b) obtaining an output of a second electrode of the eight electrodes along a second axis (Y) at a 45° angle relative to the first axis (X); (c) after a period, switching the excitation signal from the first electrode to the second electrode to drive a secondary vibration mode along the second axis (Y); and, (d) obtaining an output of the first electrode along the first axis (X), (e) calculating a bias according to the following equation: B = U y + U x 2 × SF where U y is the output when the vibration is driven along the first axis (X), U x is the output when the vibration is driven along the second axis (Y), and SF is a scale factor of the first gyroscope; (a) feeding an excitation signal to a first electrode of the eight electrodes to drive a principal vibration mode along a first axis (X); (b) obtaining an output of a second electrode of the eight electrodes along a second axis (Y) at a 45° angle relative to the first axis (X); (c) after a period, switching the excitation signal from the first electrode to the second electrode to drive a secondary vibration mode along the second axis (Y); and, (d) obtaining an output of the first electrode along the first axis (X), (e) calculating a bias according to the following equation: B = U y + U x 2 × SF where U y is the output when the vibration is driven along the first axis (X), U x is the output when the vibration is driven along the second axis (Y), and SF is a scale factor of the first gyroscope; the method being characterised by : (f) performing steps (a)-(e) across all of the positions of the eight electrodes to identify an entire bias function of the first gyroscope. <EOS>