FAQ

FAQ | Calibration

Q1: How are the particle velocity sensors calibrated?
Q2: What is the calibrated frequency range?
Q3: What do the corner frequencies of the calibration report represent?
Q4: What does "corrected mode" and "uncorrected mode" mean?
Q5: Are the probe and signal conditioner interchangeable?
Q6: Are all probes calibrated with the POS system?
Q7: When is recommended to re-calibrate a probe? 
Q8: How is the calibration correction applied?
Q9: Is there any way to test my sensor response before its usage?
Q10: What is the mv/pa+?

Q1: How are the particle velocity sensors calibrated?  

As there is no such thing as particle velocity reference sensor, a reference microphone in combination with the Piston On Sphere (POS) setup is used to obtain the response of the Microflown.



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Q2: What is the calibrated frequency range?  

The calibration is specified to be used from 0.1Hz to10KHz. If higher frequencies need to be measured please contact Microflown Technologies customer services: and specify this need.



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Q3: What do the corner frequencies of the calibration report represent? 

The response of the Microflown is not flat as traditional microphones. The calibration process measures the response of the sensor and adjusts a model on it, to be able to define the response with small data set. These values respond to the model fitted to the response of each specific sensor.



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Q4: What does "corrected mode" and "uncorrected mode" mean?   

The signal conditioner has two operating modes, corrected and uncorrected. The calibration is performed in uncorrected mode to obtain all parameters and the electronics of the signal conditioner are adjusted to partially perform the correction via hardware. For this reason every probe must be used with its own signal conditioner, which is coupled to that specific sensor. If the sensor is to be used with a Microflown Technologies software package, always select uncorrected mode and perform the correction via software.



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Q5: Are the probe and signal conditioner interchangeable?

Every probe is calibrated with its own signal conditioner. They should not be used with any other system element.



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Q6: Are all probes calibrated with the POS system?  

Yes, all probes are calibrated with the same POS method.



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Q7: When is recommended to re-calibrate a probe?

Every 2 years. 



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Q8: How is the calibration correction applied?   

Microflown software allows applying the calibration settings from the settings tab in every software module. Other third party systems also incorporate a Microflown calibration module, such as: LMS TestLab, Mueller-BBM Pak, Head Acoustics Artemis and Oros.



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Q9: Is there any way to test my sensor response before its usage?

Pressure and particle velocity should measure the same in the far field. A good test is to expose the probe to a noise field and compare the dB results of both sensors.



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Q10: What is the mv/pa+?

It is a way to describe the senstivity of a Microflown  in a comparable scale to the one used to describe a microphone response. To change the sensitivity from V/(m/s) to mV/Pa*  one need to divide the V/(m/s) value by ((343*1,2)/1000).



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