Frequency Aliasing Used in Interior Ballistic Velocity Measurements for Gas Guns

The occurrence of frequency aliasing and its representation in time and frequency domain are analyzed with sampling theory. Relationship between the sampled signal and the original signal is calculated and shows that the frequency of the original signal can be recovered by using the rule of frequency aliasing. Ideal sampled signals with frequency aliasing are simulated, and the frequency recovering method is confirmed by numerical simulations. The interior ballistic velocity in a two-stage light gas gun is measured by a laser displacement interferometer and the optical beam break method. The frequency of the laser interference signal recovered by aliasing rules is the same as the frequency obtained from the optical beam break method, which solves the contradiction between the recording length and the sampling frequency in high velocity measurements of long time duration, such as interior ballistic velocity measurement.