Noise filtering
To filter the noise in the UV-signal, a moving average filter is used. The averaging time
is the time interval used for calculating the moving average of the absorbance signal.
A long averaging time will smooth out noise efficiently, but it will also distort the peaks.
Peaks narrower than the minimum peak width value may be distorted. Because of this
the averaging time should be as short as possible, see the table below. On delivery the
averaging time is set to 2.56 s.
Display
Action
Step
Select menu Set Averaging Time, press OK.
1
Use the arrow keys to set the value. Use the fixed
values between 5.12 seconds and 0.08 seconds.
When monitoring more than one wavelength, the
recommended averaging time is a minimum of 1.28
s.
2
Min. peak width at half
height (s)
Time constant (s) (approxi-
mate)
Averaging time (s)
32
2.0
5.12
16
1.0
2.56
8.0
0.5
1.28
3.2
0.2
0.64
1.6
0.1
0.32
0.8
0.05
0.16
0.5
0.03
0.08
In UNICORN the averaging time is set with the instruction AveragingTime in System
Control:Manual:Alarm&Mon.
5.4
Changing flow cell
The flow cell can be changed when required, for example from 2 mm to 10 mm when
the sensitivity of the measurement must change due to a small amount of sample being
applied, or from a 10 mm to 2 mm when a lower sensitivity is desired, due to output
signal limitation.
See
Section 4.4 Assembly, on page 31
.
50
Monitor UV-900 Operating Instructions 28962214 AD
5 Operation
5.3 Menu selection and settings
