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Noise suppression: ADF™
AZURA® Detector ECD 2.1 Instructions, V6685
Note that the sum of coefficients is exactly 1. Y[n] is the output data point,
X[n] are input data points. Generally spoken, the performance of a digi-
tal filter improves with more input data points, but also more processor
capacity is required for the large number of calculations.
7.5 Applying ADF in chromatography
If noise frequencies in LC-EC differ from the frequency of the signal, noise
can be suppressed. Using the right filter setting (cut-off frequency) will
specifically attenuate noise and improve the signal-to-noise (S/N) ratio.
No matter how ‘advanced’ a filter is, it is only possible to apply low pass
filtering if noise frequencies are higher than the frequency of the signal.
Fig. 35
From top to bottom filter setting of 0.5, 0.02 and 0.002 Hz. Narrow
peaks in front of the chromatogram are deformed at 0.002 Hz, where-
as wider peaks show hardly any deformation (see peak at t~ 13 min).
Attenuation of noise is shown in the close up on the right.
Prerequisite for a ‘good’ noise filter for data acquisition in liquid chroma-
tography is that it improves the S/N ratio without significant distortion of
the signal of interest. This is particularly difficult if the frequency of the
signal is close to the frequency of the noise.
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Summary of Contents for Azura ECD 2.1
Page 1: ...HPLC Detector ECD 2 1 Instructions Document No V6685 ...
Page 32: ...28 ECD 2 1 controller AZURA Detector ECD 2 1 Instructions V6685 Pulse mode ...
Page 33: ...29 ECD 2 1 controller AZURA Detector ECD 2 1 Instructions V6685 Scan mode CONFIC menu ...
Page 34: ...30 ECD 2 1 controller AZURA Detector ECD 2 1 Instructions V6685 DIAG menu ...
