Cleveland Medical Devices Inc. 0051 ユーザーズマニュアル
Cleveland Medical Devices Inc. RatPaak™ User’s Guide
Adding Filters to a Channel
Capture allows you to filter the data during review and data collection. A digital filter permits suppression
of undesired signals while maximizing the visibility of the signals of interest. This process is actually
implemented as separate high-pass, low-pass filters, and notch filters all of whose respective cutoff and
center frequencies are programmable by the software. The high-pass filter rejects DC offsets and slowly
changing interference signals due to movement and other types of artifacts. The low-pass filter rejects the
very high frequency portion of the acquired signal that is usually associated with unwanted and non-
physiological noise. Notch filters allow a specific frequency to be filtered out that may be causing noise on
the sampled signal. Typically, this filter is used to filter out electrical noise that occurs at 50Hz or 60Hz. It
might also be desirable to "zoom in" a portion of the frequency spectrum while the data is acquired. For
example, transition of wakefulness to sleep is usually associated with changes in the alpha band of EEG (8
to 12 Hz). Therefore, it might be desirable to band-pass filter the EEG in the alpha band to monitor the
onset of sleep.
Low-pass filters let lower frequency content through and attenuate higher frequencies. This can be useful
for removing fast, transient responses from the data. (The filter is a 1st order IIR filter).
High-pass filters let higher frequency content through and attenuate lower frequencies. This can be useful
for eliminating drifting artifacts and DC offsets from the data. (The filter is a 1st order IIR filter.)
Notch filters allow a specific frequency to be filtered out that may be causing noise on the sampled signal.
Typically, this filter is used to filter out electrical noise that occurs at 50Hz or 60Hz.
Group Filter Settings:
The drop-down boxes for the High-pass and Low-pass filters are located in the View Toolbar as shown
above. Each field allows you to enable and/or adjust the value of the filters. Click on the down arrow of
either filter to view the available settings. When you find the desired value, click on that value and the
field will automatically be updated. Your choice of cutoff frequencies will vary depending on the sampling
frequency that is determined by the number of input channels selected and the resolution.
of undesired signals while maximizing the visibility of the signals of interest. This process is actually
implemented as separate high-pass, low-pass filters, and notch filters all of whose respective cutoff and
center frequencies are programmable by the software. The high-pass filter rejects DC offsets and slowly
changing interference signals due to movement and other types of artifacts. The low-pass filter rejects the
very high frequency portion of the acquired signal that is usually associated with unwanted and non-
physiological noise. Notch filters allow a specific frequency to be filtered out that may be causing noise on
the sampled signal. Typically, this filter is used to filter out electrical noise that occurs at 50Hz or 60Hz. It
might also be desirable to "zoom in" a portion of the frequency spectrum while the data is acquired. For
example, transition of wakefulness to sleep is usually associated with changes in the alpha band of EEG (8
to 12 Hz). Therefore, it might be desirable to band-pass filter the EEG in the alpha band to monitor the
onset of sleep.
Low-pass filters let lower frequency content through and attenuate higher frequencies. This can be useful
for removing fast, transient responses from the data. (The filter is a 1st order IIR filter).
High-pass filters let higher frequency content through and attenuate lower frequencies. This can be useful
for eliminating drifting artifacts and DC offsets from the data. (The filter is a 1st order IIR filter.)
Notch filters allow a specific frequency to be filtered out that may be causing noise on the sampled signal.
Typically, this filter is used to filter out electrical noise that occurs at 50Hz or 60Hz.
Group Filter Settings:
The drop-down boxes for the High-pass and Low-pass filters are located in the View Toolbar as shown
above. Each field allows you to enable and/or adjust the value of the filters. Click on the down arrow of
either filter to view the available settings. When you find the desired value, click on that value and the
field will automatically be updated. Your choice of cutoff frequencies will vary depending on the sampling
frequency that is determined by the number of input channels selected and the resolution.
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