METHOD FOR DETERMINING THE FREQUENCY-RESPONSE CHARACTERISTICS OF AN ELEMENT OR SYSTEM FROM THE SYSTEM TRANSIENT OUTPUT RESPONSE TO A KNOWN INPUT FUNCTION

摘要

A method is presented for the determination of the frequency-response characteristics of an element or system by utilizing the tran¬sient output response to a known but arbitrary input to the system. Since the application of special inputs, such as step functions or sinusoids, is often imperfect or impractical, a method for utilizing arbitrary inputs is desirable. Simple flight-test data may be reduced by this method to give the frequency response of an aircraft. Examples are given as determinations of aircraft frequency responses;however, the method can be applied to any type of dynamic system, such as automatic-control components, vibration-absorption equipment, and many types of instruments. The method requires that the arbitrary input function tend to, a finite value after a finite time and that the system or element output be measured as a representative quantity having a static sensitivity.