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Velocity Sensor Engineering Vibration Signal

Sinocera Piezotronics, INC | Updated: Sep 04, 2017

Velocity Sensor Engineering vibration signal

Technical Principle and Characteristics of Low Frequency Acceleration Sensor

The physical parameters of the engineering vibration magnitude are expressed by the commonly used displacement, velocity and acceleration. Since the magnitude of the vibration displacement amplitude is small in the normal frequency range and the displacement, velocity and acceleration can be switched between each other, the magnitude of the vibration amount in actual use is generally measured by the value of the acceleration. Commonly used units are: m / s 2 (m / s2), or gravitational acceleration (g).

Another important parameter describing the vibration signal is the frequency of the signal. Most engineering vibration signals can be decomposed into a series of sinusoidal signals of specific frequency and amplitude, so the measurement of a vibration signal is actually a measure of the sinusoidal frequency component that makes up the vibration signal. The main performance indicators of the sensor assessment is based on the sensor in its specified frequency range to measure the magnitude of the accuracy of the assessment.

The charge output type accelerometer is not suitable for low frequency measurement

As the low-frequency vibration of the acceleration signal is very small, and high-impedance small charge signal is very susceptible to interference; when the measurement of the larger the volume, the lower the measurement frequency, the signal signal to noise ratio problem is more prominent. Therefore, in the current with the built-in circuit acceleration sensor is becoming increasingly common circumstances should try to use the electrical noise is relatively small, low frequency characteristics of excellent low-impedance voltage output type piezoelectric acceleration sensor.

The low frequency cutoff frequency of the sensor

Similar to the high frequency cutoff frequency of the sensor, the low frequency cutoff frequency is the lowest frequency signal that the sensor can measure at the specified sensor frequency response amplitude error (± 5%, ± 10%, or ± 3dB). The lower the error value, the lower the cutoff frequency is. So the low frequency cutoff frequency indicators of different sensors must be compared under the same error conditions.

The low frequency characteristic of the low impedance voltage output type sensor is determined by the integrated electrical parameters of the sensor sensitive core and the built-in circuit. The frequency response characteristics can be described by the first-order high-pass filter characteristics of the analog circuit, so the low-frequency response and cut-off frequency of the sensor can be determined by the time constant of the first-order system. From a practical point of view, it is difficult to calibrate the very low frequency response of the sensor, and the time constant of the sensor can be measured by the response of the sensor to the step signal in the time domain. Therefore, the low frequency response of the sensor is compared with that of the first order high pass filter Characteristics of almost the same characteristics, through the calculation can easily obtain the low-frequency response of the sensor and its corresponding low-frequency cut-off frequency.