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We are also able to analyze the specifications what happens signal conditioning by using charge amplifier. A signal-conditioning circuit must have low imput input impedance but piezoelectric transcuder transducer have high input impedance which is bad thing. A typical input impedance for piezoelectric transducer is 3500 kΩ but it varies in different piezoelectric models.
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The signal is converted to digital signal with an A/D converter. It is placed usually in somekind some kind of an embedded system outside of the sensor. The sensor only reacts to pressure changes.
The system has some output noise which is approximately some hundreds of nV/sqrt(Hz). Noises are coming from voltage and current.The sensor is statically calibrated. [5;6]
Piezoelectric sensors are usually very stable so they don't need calibration after purchasing but in extreme conditions characteristics may change over time. In this case the sensors are usually sen to the manufacturer. [9; 10]
Sources
- Pressure definition:http://www.school-for-champions.com/science/pressure.htm#.U1ilsRDFJ8E
- Archimedes' Law: http://www.auburn.edu/~nzk0001/pub/phys1600/10_archimedes.pdf
- Preeti Jain, Pressure Sensors, http://www.engineersgarage.com/articles/pressure-sensors-types-working
- Robert E. Bicking, Fundamentals of Pressure Sensor Technology 1998, http://www.sensorsmag.com/sensors/pressure/fundamentals-pressure-sensor-technology-846
- PiezoStar® Pressure Sensor Datasheet by Kistler
- Piezoelectric Transducers and Applications, editor: Antonio Arnau Vives
- Eduardo Bartolome, Signal conditioning for piezoelectric sensors, http://www.ti.com/lit/an/slyt369/slyt369.pdf
- CONVENTIONAL CHARGE OUTPUT SENSORS, http://www.pcb.com/TechSupport/tech_signal
- Calibration services http://www.pcb.com/SensorCalibrationServices/CalibrationServices
- Accuracy and Calibration http://www.mmf.de/accuracy_and_calibration.htm
Group members: Kiia Tammi, Mikko Heiskanen and Aleksi Väisänen
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