Test method for FOG loop eigenfrequency

Based on the principle of square wave modulation and demodulation in digital closed-loop FOG, the reasons that results in modulation dead area by using the symmetry square wave were presented and its influence on the measurement accuracy was analyzed. The approach was presented to solve the problem of FOG loop eigenfrequency measuring based on asymmetric square wave modulation of arbitrary duty cycle, and the relationship between the arbitrary duty cycle and the ineffective -modulation area was found.The optimal range of duty cycle of the modulation square was given when testing the loop eigenfrequency.Theory and experiment prove the influence of the duty cycle on measurement accuracy of the loop eigenfrequency.Compared with the symmetry square wave, the method of asymmetry square wave improves measurement accuracy, and reduces the cost of the system hardware.