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Pressure Sensors Forum Discussions

Azureus
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First reply posted First question asked Welcome!
Level 1

Is the calibrated / compenstated pressure output supposed to correct for ambient temperature changing?

the scaled raw temp value is featured in the equation for the comp pressure but if i heat the sensor without changing the pressure, the comp pressure reading drops (not expected) and the calibrated (degrees C ) temperature climbs (as expected)

i have 2 different sensors that behave the same, i can see the calibration coeffs are different but in the same ranges for each parameter so I am pretty sure I am doing all the right stuff with the numbers as the calibrated outputs are 'correct' in as much as they output believable numbers but with heat alone as a modulation to the sensor, the pressure is moving

am i missing something here?

i am hoping to use the 2 in a differential mode which seems ok so far as long as the temperatue doesn't change

thanks

Andy

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GeorgeT
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Moderator 25 solutions authored 10 likes received 50 replies posted
Moderator

Hi @Azureus,

You are right regarding the calibration coefficients. They are different for different sensors as they are individually calibrated. The purpose of calibration coefficients is to correct the pressure reading with respect to the variations in the ambient temperature.

In an open measurement setup as you increase the ambient temperature, the pressure will drop. This is exactly the trend your measurement results are showing. Please modify your measurement setup such that instead of heating the sensor, increase the ambient temperature. Then observe the change in temperature and pressure readings, which will be more accurate.

Please note that both the temperature and pressure readings will increase if you perform the same experiment in a closed chamber.

Let me know if this clarifies your question.

Thanks and regards,

George

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Azureus
Level 1
First reply posted First question asked Welcome!
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I was only heating the air around the sensor, not the sensor directly

 

 what is the point in the calibrated compensated outputs then?

 

 As far as I am concerned if you only modulate the temperature in an open lab by applying some heat around the sensor the pressure should not move beyond measurement  noise if compensation works properly

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GeorgeT
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Moderator 25 solutions authored 10 likes received 50 replies posted
Moderator

Hi @Azureus,

The purpose of compensation is to improve the absolute accuracy of the sensor across temperature and to minimize unit to unit output variation. This algorithm makes use of both the temperature sensor readings and the individual calibration coefficients. So the compensation helps to get better accuracy even when temperature variations occur. 

It is also mentioned in the datasheet that  the temperature measurements can be disabled if there is a requirement to measure pressure rapidly, but it will make accurate temperature drift compensation impossible. (DPS368 datasheet section:4.7, page -14).

Measurement settings for some of the possible applications are also given in the Applications section of datasheet. (section:5, page-18)

Thanks and regards,

George

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