CLASSIFICATION AND IDENTIFICATION OF SOLID PROPELLANT ROCKET MOTORS

摘要

Pressure variations within a solid propellant rocket motor produce like variations in the optical radiance of the motor exhaust plume. The periodicity of the variation is related to the length L of the rocket motor or speed of sound in the rocket motor combustion chamber to length ratio a/L. The optical radiance is collected and converted to electrical signals that are sampled at or above the Nyquist rate. An array of single-pixel photo detectors is well suited to provide amplitude data at high sample rates. The sampled data from the one or more detectors is assembled to form a high fidelity time sequence. A window of sampled data is processed to form a signal frequency spectrum. The mode structure in the frequency spectrum is related to the rocket motor length or speed of sound in the rocket motor chamber to length ratio. The rocket motor length or speed of sound to length ratio is used alone or in combination with other information to either classify or identify the rocket motor.

主权项

1. A method of classification or identification of solid propellant rocket motors, comprising:
collecting optical radiance in a spectral band over a field-of-view (FOV) that encompasses the launch and initial flight of a rocket and its exhaust plume; detecting the optical radiance from the rocket's exhaust plume with one or more detectors sensitive to the spectral band and configured to convert optical radiance to analog electrical signals; sampling the one or more analog electrical signals at or above the Nyquist rate of twice the highest measurable frequency component of amplitude modulation of the optical radiance to generate sampled data; assembling the sampled data from the one or more detectors to form a time sequence of sampled data for the exhaust plume; processing a window of the time sequence of sampled data to generate a signal frequency spectrum; identifying the frequency of a mode in the signal frequency spectrum; estimating a length L or speed of sound to length ratio a/L of the rocket motor from the frequency of the mode; and using the estimated length L or speed of sound to length ratio a/L of the rocket motor to classify or identify the rocket.