Signal Processing in Laser Radar Vibrometry: A Comparison of Two FrequencyDemodulation Methods

摘要

In this report, comparison of two different frequency demodulation methods isdescribed. The first is the traditional method (bandpass/limiter) and the second is a method proposed by FOA. The FOA method uses a time-frequency distribution, the ambiguity function. The methods are compared with respect to the ability to deal with constant Doppler shift, linear Doppler shift, changes in modulation index and signal-to noise ratio. The FOA method withstands a lower signal-to noise ratio, especially at small modulation indexes, and it is better in finding the vibration frequencies in signals that contain more than one vibration frequency. It is also less sensitive to changes in modulation index. This may be a disadvantage because the modulation index gives information about the amplitude of the vibration.