Hamilton Electronics EPHUM011 - Manual (Page 27)

pH ARC Sensors Modbus RTU Programmer ’ s Manual (EPHUM011)
624300/01 page 27 / 67
2.6.2 PA9: Moving Average
The pH ARC Sensor provides new pH readings every 3 seconds. One has the possibility to smoothen
the pH reading (PMC1) by means of a moving average applied to the 3-seconds-readings.
PA9 can be applied on 1 to 16 3-seconds-readings. The default value is 2.
Effect of Moving Average (n=1 vs n=16)
2
2.5
3
3.5
4
4.5
5
5.5
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time
p
H
mov av = 1
mov av = 16
Effect of Moving Average (n=1 vs n=16)
5.1
5.12
5.14
5.16
5.18
5.2
1
5
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tim e
p
H
mov av = 1
mov av = 16
Figure 2.6.2.1: Comparison of the response of a pH ARC Sensor to a change from pH 5.1 to pH 2.5,
using no moving average (n=1) or a moving average over 16 3-seconds-readings.
Using moving average, the short term signal stability can be improved; on the other hand, the response
time of the sensor increases with increasing moving average. A moving average over 16 samples
results in a response time of at least 48 s.
Note:
 PA9 is applied to both PMC1 and PMC6.