Environnement AS32M, Техническое руководство, Страница: 34 / 186

Environnement
S.A
AS32M
Duplication prohibited
DECEMBER 2013
2–10
2.5 AUTOMATIC RESPONSE TIME
In order to optimize its metrology, the AS32M is equipped with a software function called Automatic
Response Time, which enables filtration of measurements.
The Response Time Index, or RT , is an index from which to choose the operating mode; consequently
it has no unit. When the index is set to 11 (default), it corresponds to the analyzer’s optimum response
time, giving both a quick response and a low minimum detection limit.
2.5.1 PRINCIPLE
The RT allows the user to change the analyzer response time. The value of RT can be programmed
from 01 to 20, which falls into two groups:

Manual RT from 01 to 10

Automatic RT from 11 to 20
01 to 10: For each acquisition, a number of elements equal to RT replaces the same number of oldest
RT values in a group of 60 elements. Therefore, the response time varies from 60 to 6 seconds. To
calculate the theoretical value of the response time (in seconds), it is necessary to divide:
RT
60
.
With Manual RT , the user is advised that the greater the RT, the noisier the measurement.
The greater the RT , the quicker the response.
11 to 20: The response time is automatically adjusted depending on the measurements. It is
calculated as an average of the instantaneous readings:
 
AVERAGE
MEAS
=
 

n
OUS INSTANTANE
MEAS
n
1
1
Where n is the number of instantaneous measurements; it depends on programmed Response Time
Index
 
MIN
RT
.
Then a weighted average between the filtered values (
 
FILTERED
MEAS
) and the average
measurements (
 
AVERAGE
MEAS
) is recursively calculated according to the following formula:
     
AVERAGE previous FILTERED new FILTERED DISPLAYED
MEAS Y MEAS X MEAS MEAS ] [ =
) ( ) (
 
When the difference (
   
AVERAGE previous FILTERED
MEAS MEAS

) (
) exceeds a determined threshold, the
value of Y is increased up to a 99 % maximum value that corresponds to a fixed Response Time
Index ,
 
MIN
RT
: X + Y = 100 %.
When (
   
AVERAGE FILTERED
MEAS MEAS

(previous)
) is below the threshold, the value is progressively
decreased.
The more stable the measurement, the more X tends toward 99 %.