INTRODUCTION

Historical Background. The original motivation for this Handbook came from personnel of The Aerospace Corporation (TAC), who are technical advisors to the Air Force Space and Missile Systems Center. Over the preceding two decades, TAC had observed a seemingly endless series of errors and anomalies in the acquisition and analysis of structural dynamic and aeroacoustic data. To evaluate the scope of data analysis errors alone, TAC arranged a "round robin", where identical magnetic tapes dubs of short time-limited stationary random signals were sent to several data processing centers for a 1/3 octave band analysis with their normally-used equipment. Ten centers responded with analyzed data that revealed discrepancies of nearly 20 dB at some frequencies [1.1, 1.2]. Rather than continue to accept this situation, Don Wong of TAC arranged to have the Air Force fund the development of a Handbook that would help reduce the variability and eliminate the errors commonly found in measured dynamic data. The Jet Propulsion Laboratory (JPL) was selected to prepare the Handbook, as well as perform any research required to achieve the Handbook objectives. Harry Himelblau of JPL was appointed the Task Manager for the preparation of the Handbook. He was assisted by Allan Piersol of the Piersol Engineering Co., James Wise of JPL, and Max Grundvig, who was brought out of retirement from TAC for this assignment. Additional assistance was provided by the numerous reviewers acknowledged in the Foreword.

Purpose. The purpose of this Handbook is to provide guidelines for acquiring and analyzing structural (or mechanical) shock and vibration, and acoustic and aerodynamic noise data from flight and ground tests for all categories of aerospace vehicles. The guidelines may also be used for dynamic measurements on a variety of ground and sea transportation vehicles, industrial machinery, and civil engineering structures (e.g., the response of buildings to earthquake loads). The objectives of the guidelines are to ensure the accuracy and reduce the errors and variability often associated with the acquisition and analysis of dynamic data. Specific procedures are provided unless they are highly dependent on the particular applications or instruments utilized. The ultimate goal is to make accurate measurements of the dynamic phenomenon of interest, without that or any other phenomenon influencing the measurement process.