Fourier MultiLab, User Manual

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Chapter 1 MultiLogPRO 23
1.3. Sensor Calibration
In this chapter you will learn how to increase the MultiLogPRO system accuracy
using calibration. Most of the sensors are linear, i.e. the output level of each sensor
changes according to the equation:
b aX Y
+ =
Where:
Y - Output of the sensor (voltage level changing from 0 to 5V)
X - Sensor input
a - Sensor gain
b - Sensor offset
The calibration process allows us to control the offset, and in some cases even the
gain, of a sensor. The MultiLogPRO system offers four types of calibration:
•
Hardware offset calibration
• MultiLogPRO automatic zero calibration
• MultiLab Sensor calibration
•
Factory calibration (no manual calibration required)
1.3.1. Hardware Offset Calibration
On some of the sensors there is a screw controlling the sensor offset. To calibrate
the sensor, rotate this screw until the sensor shows the correct measured value
(obtain the actual
correct value from another source that is known to be accurate).
1.3.2. MultiLogPRO Automatic Zero Calibration
MultiLogPRO is able to automatically calibrate the sensor offset for all analog
sensors accurately, quickly, and for every new experiment conducted.
The calibration method is very simple. Whenever you plug in a sensor, the data
logger checks to see if the selected sensor measures a value within
± 2% of its zero
value . If so, MultiLogPRO sets that value as zero.
1. To enable this feature, make sure that the sensors are at their zero
values when you plug them in. To ensure the most accurate zero
value: Shorten the Voltage sensor plugs.
2. Leave the Current sensor plugs open.
3. Cover the Light, Photo-Gate, and Microphone sensors.
4. Insert the pH sensor in a pH-7.0 solution.
5. Unload the Force Transducer.
6. Place the Accelerometer on a stationary surface.
7. Place the Temperature probes in ice water.
8. Place the Pressure sensor in a 1 ATM (1013 mb) chamber.