The McGill Physiology Virtual Lab

Biomedical Signals Acquisition

Sine Wave Acquisition
  In this experiment, an electrical sine wave generated by a function generator is sampled and displayed, in order to demonstrate some key issues in data acquisition and A/D conversion. For a full understanding of this section, it is highly recommended that you first review the basics of Analogue to Digital Conversion.


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The signal source

For this part of the laboratory session you will be collecting data generated from a function generator which may look like the model above.


The signal display

Any data acquisition software must permit you to set the following parameters:

  1. channel settings: you may need to acquire data coming from more than 1 channel, in case there are more than one device connected to the recording system.
  2. You then need to specify the number of channels and disregard the rest of the available channels.
  3. for each channel: you need to specify the sampling range and whether you have a differential recording arrangement or not.
  4. you can specify the acquisition rate or sampling frequency: how often you need to collect points from your waveform, in order to reconstruct your waveform without artifact.
  5. you can also specify whether you want to apply digital filtering, amplification (gain) etc...
  6. you can also control the time axis, displaying your waveform.

The recorded sine wave would appear as shown below. Note the maximum and minimum amplitude of the wave. The following pages will explore how changes in the display and acquisition parameters will affect the sampled signal.


To continue with the topic Gain Settings, click here