| CPC G01C 19/5776 (2013.01) [G01C 19/5621 (2013.01); G01C 25/005 (2013.01)] | 18 Claims |

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1. A force-feedback gyroscope apparatus, comprising:
a first resonator as a drive resonator having an x-mode excited at its resonant frequency;
a second resonator as a sense resonator having a y-mode which is driven by receiving a Coriolis force signal from the output of said first resonator;
wherein said second resonator has a feedback signal which combines the y-mode output signal with a calibration signal that is synchronous with the excitation in the x-mode, and modulated at one or more calibration frequencies within the bandwidth of the angular rate input;
wherein the calibration signal, Ycal(t), is the sum of two periodic signals with calibration frequencies ωcal1 and ωcal2 and carriers which are modulated in-phase and quadrature with the x-mode displacement;
wherein said calibration signal Ycal(t) is generated in response to the relation:
Ŷcal1·cos (ωxt+Θerr) sin (ωcal1t)+Ŷcal2·sin (ωxt+Θerr) sin (ωcal2t); and
wherein Ŷcal1 is a first calibration input, ωx is the tone frequency of the x-mode of said first resonator, t is time, ωcal1 is a first calibration tone frequency and ωcal2 is the second calibration tone, and Θerr represents an arbitrary but constant phase shift and accounts for processing delay.
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