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Biomedical Signals Acquisition |
Gain settings |
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To be able to better resolve the signal, one
can adjust the gain after acquiring the signal |
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| A 10 V peak-to peak sine
wave is acquired. The A/D board is configured to acquire signals of +/-
10V. |
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| If one wants to
better display the signal by enlarging the signal, the following can be
done: |
| A given
channel can be multiplied by the gain one wants to achieve. In this
case, a gain of 4 is applied, with the results below. The amplitude (+/-
5V) of the signal becomes (+/- 20V). |
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If the A/D board is configured to acquire a
signal from +/-2 V, then the situation below occurs: |
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To the left of the display, the sine shows a
gain of 4 while being acquired with a sampling range of +/-10V (gain of
4: +/-20V). When the acquisition range is
changed to 2 V (right of the display), the Powerlab recording system is
only able to digitize signals with original amplitude of 4V (+/-2V); the sine wave shows clipping of
the signal at the hardware limits of the recording instrument (at +/- 8V
of the amplified signal). This is saturation. |
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