Joint Time-frequency Analysis Method And Its Application Launcher Experiments

Joint Time-Frequency Analysis is a new-style theory in Signal-Analysis, which combines the signals' characters in time domain with those in frequency domain. For reflecting the integral character, JTFT possesses good effect in analyzing unstationary or time-changing signals.The vibration characteristic of launch tube in launching state can reflect the dynamic performance and the structural rationality of launch system, and it will influence the shooting precision. Angular velocity is selected to represent the vibration characteristic. The angular velocity signal is measured by using piezoelectric-jet-flow gyroscope during launching state in experiment, and then is processed by using Joint Time-Frequency Analysis algorithm.The characteristic of rocket noise is also one of the important factors in integration of rocket system. Rocket exhausted flow noise was measured and analyzed by Joint Time-Frequency Analysis, so as to obtain the changing range of its peak frequency and determine the relation between the peak frequency and chamber pressure according to the result of Joint Time-Frequency Analysis. Experiment results show noise frequency has little relation to chamber pressure, but noise magnitude does much. These conclusions can serve as important reference to prediction of rocket noise.