WIDE BAND NOISE SPECTRA SIMULATION FOR ACOUSTIC TESTING OF SPACECRAFT AND LAUNCH VEHICLE SUB SYSTEMS

Wide band noise spectra simulation for acoustic testing of spacecraft and launch vehicle sub systems

Noise spectra of various spacecraft and launch vehicle sub systems are required to be simulated in a reverberation chamber to qualify them for acoustic environment.  Powerful noise sources are used to realize these spectra. These noise generators work on the principle of converting pneumatic energy into acoustic energy by modulation of airstream with the help of electro-pneumatic system.  The frequency and amplitude of noise is governed by the shaped electrical signal to the electro-pneumatic system.   Noise spectra are controlled by a closed loop acoustic control system (ACS) where the output signal drives the noise sources with the acoustic spectrum feedback measured through microphones. 

Specifications:

Noise source:

Acoustic power: 4 x 30,000 Watts

Overall sound pressure level realized in the reverberation chamber: 157 dB

Controllable frequency: 25 – 600 Hz

Acoustic Control System:

Number of Input channels      : 16 channels, acoustics. Vib Runner m+P acoustic control system

Number of output channels    : 4 Channels, Analogue

Spectrum control & tolerance: 31.5 & 63 Hz: +/- 1 dB

 125 to 8000 Hz: +/- 0.5 dB