Alpha MED Scientific MED64-Entry, Руководство пользователя

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5. Abnormal noise
5.1. Noise check point
- The amplitude of normal baseline noise has about ±8 µV peak-peak value in bandwidth between Low cut freq 1 Hz and High cut
freq 10,000 Hz for signal acquisition. Visually check whether the baseline noise is flat on the display with 20 ms/div on the
horizontal axis and a display 500 ms/div on the horizontal axis.
Normal baseline noise.
- For electrodes with noise, check whether noise occurs in a particular subset of electrodes or in all 16 electrodes and whether
there is any bias in the noise.
- For the shape of noise, set the horizontal axis at 20 ms/div and check whether the noise is a sinusoidal-like noise repeated 5 or 6
times or a high-frequency noise disproportionately observed in particular electrodes.
- There are two types of extrinsic noise; noise that can be shielded by an electric shield regardless of distance, and noise for which
an electric shield is not effective but can be reduced by moving the noise source to a distant position. The latter noise may be
caused by a magnetic field generated by a device connected to the power cable (power adaptor, perfusion pump, and water
bath, etc.). Move the responsible device to a position where the noise disappears or unplug the power cable of that device when
MED64-Entry is being used.
Note: To contact our help desk, select Copy Image by right clicking on SIGNAL WAVEFORM, paste the image of 16 electrode on an
image editor such as paint, store in jpg or tif format, and send it to the help desk as an e-mail attachment. Do not use bmp
format because it has a large file size. Prepare images with 20 ms/div and 500 ms/div horizontal axis and 25 µV/div vertical
axis, or a vertical axis automatically adjusted by Autoscale.
5.2. Noise relating to installation
- A fixation screw of the MED connector is loose.
An example of noise when a fixation screw is loose. Noise is likely to occur in all 16 electrodes.
20 ms
25 µV
25 µV
0.5 s