TEST PROGRAM 



Instrumentation 



The equipment used for the investigation is described 

 below and illustrated in figure 2. 



An Ampex Model 350 was used as the record and play- 

 back recorder. This model has a good low-frequency 

 response to below 20 c/s. 



The filters following the recorder were an Allison 

 Laboratories Model 2-A (used mainly as a low-pass filter) 

 and a B & K Band Pass Filter Set, Type 1611. 



A Mcintosh amplifier, Model MC30, was used to 

 raise the signal level to 1 volt rms or greater. 



The B & K Probability Density Analyzer, Model 160 

 (to be referred to as the PDA) was the main piece of equip- 

 ment and has been primarily designed to obtain the prob- 

 ability density curves of disturbances that are essentially 

 random in character. A brief description of the PDA and 

 its use in this investigation is given in Appendix A. A com- 

 plete and detailed description of the PDA can be obtained 

 from the instruction manual. 1 



AMPEX 350 

 PLAYBACK UNIT 



ALLISON LABS FILTER 



MODEL 2-A 



OR 



B & K, TYPE 1611 



Mcintosh 

 amplifier 



MODEL MC30 



B&K 



PROBABILITY DENSITY 



ANALYZER 



MODEL 160 



CRO 



VAR I PLOTTER 

 XY RECORDER 



COUNTER 



Figure 2. Block diagram of Probability Density Analysis system. 



