ADInstruments BIO, Руководство пользователя

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Owner’s Guide
50
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Replace the cable and try again. Immediately label all cables that proved faulty
so that you don’t use them again by accident.
The Neuro Amp EX is faulty.
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This is the least likely event. If the front-end will not work properly aft er the
previous measures, try using it on another PowerLab. If the same problems
recur with a second PowerLab, the front-end may be faulty. Contact your
ADInstruments representative to arrange for repairs.
The trace will not zero properly when adjusting high-pass filtering
The Neuro Amp EX is receiving signals at a level that has saturated the input amplifier,
resulting in a large off set. This is normally due to poor contact between the electrodes
and the subject.
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Check the connections for proper contact and try again.
The signal appears to display a constant amplitude oscillation
Frequency interference from power lines can become superimposed on the biological
signal being measured.
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You can use the mains filter in the Neuro Amp EX to remove excessive line voltage
frequency interference (use the checkbox in the Neuro Amp EX dialog).
The leads you are using may be unshielded or of low quality.
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Check to make sure that you are using high-quality leads. Only the supplied
Neuro Amp EX headstage cable should be used.
The signal is noisy at lower ranges
This is probably the amplified noise from the electrodes, not a fault as such. There is, in
addition, noise that cannot be avoided by any amplifier (called ‘thermal’ or ‘Johnson’
noise).
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Set the low-pass filter to remove the noise. (But be careful, since important
components of the signal could also be attenuated.)
This could be due an electrically noisy environment, particularly if there is some
equipment that produces a radio frequency that interacts with the Neuro Amp EX
modulator, giving a heterodyne eff ect.
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Turn off pieces of unnecessary equipment to try and isolate the cause, then
either leave the equipment off or, if possible, move the subject or equipment
outside the area of any interfering field.
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At the lowest ranges you may have to shield, shorten, or even replace the leads,
since they will tend to act as radio receptors.
The signal appears to be unusual, very weak, clipped or distorted in some way
This may be a problem of technique: the sampling rate, range or filter settings may be
inappropriate for the signal you are recording.
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Make sure the settings are appropriate for the expected signal.