Waters 2998, Overview And Maintenance Manual

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December 5, 2017, 715004753 Rev. B
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Figure 1–6: Example of how baseline noise increases with higher sampling rates
1.4.3 Filtering data
On the General tab of the PDA Instrument Method Editor you can apply an optional noise filter to
the data acquired.
See also:
the Empower or MassLynx
®
online Help.
The detector uses a Hamming filter to minimize noise. The filter is a digital finite-impulse-response
filter that creates peak-height degradation and enhances the filtering of high frequency noise.
The performance of the filter depends on the filter-time constant that you select. Increasing the
filter-time constant reduces baseline noise, improving the signal-to-noise ratio. Nevertheless,
increasing the constant too much artificially broadens a peak and reduces chromatographic
resolution.
You can choose among these options when programming a filtering time: Fast, Slow, Normal, or
Other. If you select a fast, slow, or normal filtering time, you need not specify a value, because the
filtering constant is determined by the sampling rate. If you select the Other option, you can specify
a value. Nevertheless, the value that you specify is rounded up or down to a value based on the
sampling rate. Selecting Other and entering a value of 0.0 disables all filtering.
5 Hz
10 Hz
20 Hz
40 Hz