ADInstruments BIO, Руководство пользователя

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Owner’s Guide
26
Setting the Range
The Range pop-up menu lets you select the input range of the channel (combined range
of the PowerLab and Bio Amp). Note that range is inversely related to gain (e.g, 100 mV
range is the lowest gain and sensitivity setting). Changing the range in the Bio Amp
dialog is equivalent to changing it using the arrow in the top right hand corner of the
channel in the Chart View Window. Changing the hardware range setting should not be
confusing with adjusting the y axis scaling using the + and - buttons on the left of each
channel. The default setting (if you have not loaded a settings file) is 100 mV and the
ranges go down to 100 µV in 10 steps.
Filtering
The Bio Amp has low-pass, high-pass, and mains filter circuitry that can be adjusted to
suit the application. The mains filter removes excessive mains-frequency interference.
The high-pass and low-pass filters provide bandwidth limiting of low-frequency and
high-frequency signals respectively. Note that the settings for one filter type may
restrict the possible settings for the other.
High-Pass Filtering. The High Pass pop-up menu gives a choice of high-pass filters.
The high-pass filter removes frequencies below the chosen frequency and allows high
frequencies in the signal. These filters are useful for removing slowly moving baselines,
such as motion or respiration artifacts, particularly in ECG (EKG) recordings.
Low-Pass Filtering. The Low Pass pop-up menu gives a choice of low-pass filters.
The low-pass filter removes frequencies above the chosen frequency and allows low
frequencies in the signal. These filters are useful for removing high-frequency signals,
such as noise, and to prevent aliasing in the recorded signal.
Mains Filter. Select or deselect the Mains filter checkbox to turn the mains filter on and
off . The mains filter allows you to remove interference related to the mains frequency
(both fundamental and harmonic frequencies). This is an adaptive filter. It adjusts
to filter the interference by tracking the input signal for a second. Because of this, in
general, using the mains filter is a good option but it does have some limitations. More
details on the mains filter can be found in the LabChart Help Center.
Inverting the Signal
The Invert checkbox provides a simple way to change the polarity of the recorded signal
without having to swap the connections to the recording electrodes.
DC Restore
The DC Restore or Zero button is available in the Bio Amp dialog. It provides a quick
way to bring the recording trace back to zero. It is for use with very low high-pass filter
settings, since the trace can take a long time to zero automatically at those settings. In
later versions of LabChart the
DC Restore All command from the Setup menu performs
this operation on all Bio Amp channels.