The LDW 9000 Noise Measurement System is based on the Campbell Scientific CR9000 datalogger.
The CR-9000 can sample up to 4500 Hz in normal mode and up to 100000 Hz in Burst mode.
The LDW 9000 Noise Measurement System utilizes uni-axial piezo accelerometers at each corner and a high-sensitivity in-cabin microphone to measure and report brake noise occurrences.
The system is configured to measure the maximum acceleration level and frequency at each corner and then find the corresponding frequency and dB level at that moment in time on the microphone.
For each noise occurrence we record a 1024 bin FFT spectra from the accelerometer and microphone.
The heart of the system is the Campbell Scientific CR9052 Anti-Aliasing Filter Module.
This module for the CR9000 datalogger contains 6 discrete input channels each with programmable-gain low noise instrumentation amplifier and A-to-D converter.
The spectrum analyzer can provide real-time spectra from seamless 50 kHz, 2048-point time-series sample sets from each of its six channels. A variety of spectrum options are available, including binning, and various windowing functions.
Spectral binning can be linear or logarithmic (1/n octave, where 1<=n<=12).
The flexibility of the CR9000 datalogger allows us to capture a multitude of other test parameters. They vary from brake pad temperatures, hydraulic pressure, vehicle deceleration, vehicle speed, % relative humidity, ambient temperature, pedal travel, pedal force, and booster vacuum, among others.
