Applying a Practical Method and an Out of Phase Technique to Estimate the Noise Level of Vibration Sensor

The experimental and practical evaluation methods and results for vibration sensor are described in this paper. Because the vibration sensor accelerometer has the feature of low-noise electronics, the testing is performed in the basement of National Measurement Laboratory (NML), in which environmental vibration amplitude is less than 3μm/sec. First we put the sensor on a spring isolator plate with 3 Hz natural frequency and a big concrete mass with 29 Hz peak value to get the high and low frequency noise level separately. Next we mount two same-type sensors back-to-back horizontally. The output signals of the two sensors are out of phase, so we can calculate their noise level easily. Finally we use an air-bearing shaker to generate a low frequency and low amplitude vibration to verify the sensor measurement ability. The noise level of the sensor can be determined by using the practical method and an out of phase technique.