Method for frequency estimation by constant gate time

A method to improve the Zero-crossing Fitting Method (ZFM) is proposed. ZFM is the method for calculating the frequency, the velocity, the position, and the acceleration from the signal measured by the digitizer in the Laser Doppler Interferometer (LDI). ZFM is a very useful method to measure the dynamic force. However, the data obtained using ZFM is not against accurate time. In this method, constant gate time is set and the frequency based on accurate time can be calculated using this method. The time-base analysis can be done after obtaining the data from the LDI. The performance of this method is almost same as the former ZFM; therefore this method can be applied as ZFM. In this study, how the method can contribute to the present science and engineering is shown.